wwwbasic.mjs

// Copyright 2018 Google LLC
//
// Licensed under the Apache License, Version 2.0 (the "License");
// you may not use this file except in compliance with the License.
// You may obtain a copy of the License at
//
//     https://www.apache.org/licenses/LICENSE-2.0
//
// Unless required by applicable law or agreed to in writing, software
// distributed under the License is distributed on an "AS IS" BASIS,
// WITHOUT WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied.
// See the License for the specific language governing permissions and
// limitations under the License.

'use strict';

var DYNAMIC_HEAP_SIZE = 1024 * 1024 * 16;
var STACK_SIZE = 64 * 1024;
var MAX_DIMENSIONS = 7;

var SIMPLE_TYPE_INFO = {
  'byte': {array: 'Uint8Array', size: 1, shift: 0, view: 'b'},
  'short': {array: 'Int16Array', size: 2, shift: 1, view: 'i16'},
  'long': {array: 'Int32Array', size: 4, shift: 2, view: 'i'},
  'single': {array: 'Float32Array', size: 4, shift: 2, view: 's'},
  'double': {array: 'Float64Array', size: 8, shift: 3, view: 'd'},
  'string': {array: 'Array', size: 1, shift: 0, view: 'str'},
};

var IMPLICIT_TYPE_MAP = {
  '$': 'string', '%': 'short', '&': 'long', '!': 'single', '#': 'double',
};

function NextChar(ch) {
  return String.fromCharCode(ch.charCodeAt(0) + 1);
}

function DecodeTag(code) {
  code = code.replace(/&lt;/g, '<');
  code = code.replace(/&gt;/g, '>');
  code = code.replace(/&amp;/g, '&');
  return code;
}

function Basic(code, options) {
  options = options === undefined ? {} : options;
  var bindings = options.bindings;
  bindings = bindings === undefined ? ConsoleBindings() : bindings;
  var debugging_mode = options.debug || (typeof debug == 'boolean' && debug);

  // Parsing and Run State.
  var labels = {};
  var data_labels = {};
  var flow = [];
  var types = {};
  var functions = {};
  var global_vars = {};
  var vars = global_vars;
  var allocated = 0;
  var const_count = 0;
  var temp_count = 0;
  var inside_type = false;
  var inside_function = false;
  var var_decls = '';
  var data = [];
  var data_pos = 0;
  var ops = [];
  var curop = '';
  var ip = 0;
  var function_define_pos = 0;
  var function_old_allocated = 0;
  var function_name = null;

  // Error handler state.
  var error_handler = Throw;
  var error_resume_point = null;

  // Yield State
  var yielding = 0;
  var quitting = 0;
  var delay = 0;

  // Call stack
  var stack = 0;
  var sp = 0;
  var bp = 0;

  // Language Options
  var option_base = 0;
  var option_explicit = false;

  // Variable declaration defaults.
  var letter_default = {};
  // Default is single.
  var i = 'a';
  do {
    letter_default[i] = 'single';
    i = NextChar(i);
  } while (i != 'z');

  const toklist = [
    ':', ';', ',', '(', ')', '{', '}', '[', ']',
    '+=', '-=', '*=', '/=', '\\=', '^=', '&=',
    '+', '-', '*', '/', '\\', '^', '&', '.',
    '<=', '>=', '<>', '=>', '=', '<', '>', '@', '\n',
  ];
  code = code.replace(/\r/g, ' ');
  code = code.replace(/\t/g, ' ');

  var tok = null;
  var tok_count = 0;
  var line = bindings.Render ? 0 : 1;

  function Next() {
    tok = '';
    tok_count++;
    for (;;) {
      while (code.substr(0, 1) == ' ' ||
             code.substr(0, 1) == '\t') {
        if (tok != '') {
          return;
        }
        code = code.substr(1);
      }
      if (code.search(/^_[ \t]*('[^\n]*)?\n/) != -1) {
        if (tok != '') {
          return;
        }
        code = code.substr(code.search('\n') + 1);
        ++line;
        continue;
      }
      if (code.substr(0, 1) == '\'') {
        if (tok != '') {
          return;
        }
        while (code.length > 0 && code.substr(0, 1) != '\n') {
          code = code.substr(1);
        }
        continue;
      }
      if (code.substr(0, 1) == '"') {
        if (tok != '') {
          return;
        }
        tok = '"';
        code = code.substr(1);
        while (code.length > 0 && code.substr(0, 1) != '"') {
          if (code.substr(0, 1) == '\n') {
            // Allow strings to cut off at end of line.
            // GW-Basic seems to allow it.
            tok += '"';
            return;
          }
          tok += code.substr(0, 1);
          code = code.substr(1);
        }
        tok += '"';
        code = code.substr(1);
        return;
      }
      if (tok == '' && /[.0-9][#]?/.test(code.substr(0, 1))) {
        var n = code.match(/^([0-9]*([.][0-9]*)?([eE][+-]?[0-9]+)?[#]?)/);
        if (n === null) {
          Error('Bad number');
        }
        tok = n[1];
        code = code.substr(tok.length);
        if (tok[tok.length - 1] == '#') {
          tok = tok.substr(0, tok.length - 1);
        }
        return;
      }
      for (var i = 0; i < toklist.length; ++i) {
        if (code.substr(0, toklist[i].length) == toklist[i]) {
          if (tok != '') {
            if (code.substr(0, 1) == '&' &&
              code.substr(code.length - 1) != '$') {
              tok += '&';
              code = code.substr(1);
            }
            return;
          }
          tok = toklist[i];
          code = code.substr(toklist[i].length);
          if (tok == '\n') {
            ++line;
            tok = '<EOL>';
          } else if (tok == '&' && code.substr(0, 1).toLowerCase() == 'h') {
            code = code.substr(1);
            var n = code.match(/^([0-9a-fA-F]+)/);
            if (n === null) {
              Error('Bad hex number');
            }
            tok = '0x' + n[1];
            code = code.substr(n[1].length);
          }
          return;
        }
      }
      tok += code.substr(0, 1).toLowerCase();
      code = code.substr(1);
      if (code == '') {
        return;
      }
    }
  }
  Next();

  function ConsumeData() {
    var quote = false;
    var had_quote = false;
    var item = '';
    for (;;) {
      var ch = code.substr(0, 1);
      if (ch == '\n' || ch == '') {
        if (!had_quote) {
          if (!quote) {
            item = item.trim();
          }
          data.push(item);
        }
        break;
      } else if (ch == '"') {
        if (quote) {
          data.push(item);
          item = '';
          quote = false;
          had_quote = true;
        } else {
          quote = true;
          if (item.search(/[^ \t]/) != -1) {
            Error('Data statement extra text: "' + item + '"');
          }
          item = '';
        }
      } else if (ch == ',') {
        if (!quote) {
          if (!had_quote) {
            data.push(item.trim());
          } else {
            had_quote = false;
            if (item.search(/[^ \t]/) != -1) {
              Error('Data statement extra text: "' + item + '"');
            }
          }
          item = '';
        } else {
          item += ',';
        }
      } else {
        item += ch;
      }
      code = code.substr(1);
    }
    Next();
  }

  function Error(msg, lineno) {
    if (lineno === undefined) {
      lineno = line;
    }
    error_resume_point = ip - 1;
    error_handler(msg + ' at line ' + lineno);
  }

  function ErrorGoto(target) {
    return function() {
      ip = target;
    };
  }

  function Resume0() {
    ip = error_resume_point;
    error_resume_point = null;
  }

  function ResumeNext() {
    ip = error_resume_point + 1;
    error_resume_point = null;
  }

  function Resume(target) {
    if (error_resume_point === null) {
      // Bypass error handler.
      Throw('RESUME without error');
    }
    error_resume_point = null;
    ip = target;
  }

  function Throw(msg) {
    throw msg;
  }

  function Skip(t) {
    if (tok != t) {
      Error('Expected "' + t + '" found "' + tok + '"');
    }
    Next();
  }

  function EndOfStatement() {
    return tok == ':' || tok == '<EOL>';
  }

  function SkipEndOfStatement() {
    if (!EndOfStatement()) {
      Error('Expected : or EOL');
    }
    Next();
  }

  function NewOp() {
    ops.push(curop);
    curop = '';
  }

  function If(e, n) {
    if (n === undefined) {
      n = [];
    }
    NewOp();
    ops[ops.length - 1] += 'if (!(' + e + ')) { ip = ';
    flow.push(['if', ops.length - 1, []]);
  }

  function Else() {
    var f = flow.pop();
    if (f[0] != 'if') {
      Error('ELSE unmatched to IF');
    }
    NewOp();
    var pos = ops.length - 1;
    ops[pos] += 'ip = ';
    NewOp();
    ops[f[1]] += ops.length + '; }\n';
    flow.push(['else', null, f[2].concat(pos)]);
  }

  function ElseIf(e) {
    var f = flow.pop();
    if (f[0] != 'if') {
      Error('ELSEIF unmatched to IF');
    }
    NewOp();
    var pos = ops.length - 1;
    ops[pos] += 'ip = ';
    NewOp();
    ops[f[1]] += ops.length + '; }\n';
    NewOp();
    ops[ops.length - 1] += 'if (!(' + e + ')) { ip = ';
    flow.push(['if', ops.length - 1, f[2].concat([pos])]);
  }

  function EndIf() {
    NewOp();
    var f = flow.pop();
    if (f[0] == 'else') {
      // nothing needed
    } else if (f[0] == 'if') {
      ops[f[1]] += ops.length + '; }\n';
    } else {
      Error('Unmatch end if');
    }
    for (var i = 0; i < f[2].length; ++i) {
      ops[f[2][i]] += ops.length + ';\n';
    }
  }

  function VarPtr(vname) {
    var vinfo;
    if (vars[vname] !== undefined) {
      vinfo = vars[vname];
    } else if (global_vars[vname] !== undefined) {
      vinfo = global_vars[vname];
    }
    if (vinfo === undefined) {
      Error('Undefined variable name');
    }
    if (vinfo.global) {
      return vinfo.offset;
    } else {
      return '(bp + ' + vinfo.offset + ')';
    }
  }

  function AddLabel(name) {
    if (labels[name] !== undefined) {
      Error('Label ' + name + ' defined twice');
    }
    NewOp();
    curop += '// LABEL ' + name + ':\n';
    labels[name] = ops.length;
    data_labels[name] = data.length;
  }

  function Factor3() {
    if (tok == '(') {
      Skip('(');
      var ret = Expression();
      Skip(')');
      return ret;
    } else {
      var name = tok;
      Next();
      if (name.substr(0, 1) == '"' ||
          /^[0-9]*([.][0-9]*)?([eE][+-]?[0-9]+)?$/.test(name) ||
          /^0x[0-9a-fA-F]+$/.test(name)) {
        return name;
      }
      if (name == 'rnd') {
        if (tok == '(') {
          Skip('(');
          if (tok != ')') {
            var e = Expression();
          }
          Skip(')');
        }
        return 'Math.random()';
      }
      if (name == 'varptr') {
        Skip('(');
        var vname = tok;
        Next();
        Skip(')');
        return VarPtr(vname);
      }
      if (name == 'stackdepth') {
        Skip('(');
        Skip(')');
        return 'sp';
      }
      if (name == 'basedepth') {
        Skip('(');
        Skip(')');
        return 'bp';
      }
      if (name == 'log' || name == 'ucase$' || name == 'lcase$' ||
          name == 'chr$' || name == 'sqr' ||
          name == 'int' || name == 'cint' || name == 'fix' ||
          name == 'asc' ||
          name == 'abs' || name == 'len' || name == 'val' ||
          name == 'cos' || name == 'sin' || name == 'tan' || name == 'atn' ||
          name == 'exp' || name == 'str$' || name == 'peek' ||
          name == 'ltrim$' || name == 'rtrim$' ||
          name == 'space$' || name == 'tab') {
        Skip('(');
        var e = Expression();
        Skip(')');
        switch (name) {
        case 'log': return 'Math.log(' + e + ')';
        case 'ucase$': return '(' + e + ').toUpperCase()';
        case 'lcase$': return '(' + e + ').toLowerCase()';
        case 'chr$': return 'String.fromCharCode(' + e + ')';
        case 'asc': return '(' + e + ').charCodeAt(0)';
        case 'sqr': return 'Math.sqrt(' + e + ')';
        case 'int': return 'Math.floor(' + e + ')';
        case 'cint': return 'Math.round(' + e + ')';
        case 'fix': return 'Math.trunc(' + e + ')';
        case 'abs': return 'Math.abs(' + e + ')';
        case 'cos': return 'Math.cos(' + e + ')';
        case 'sin': return 'Math.sin(' + e + ')';
        case 'tan': return 'Math.tan(' + e + ')';
        case 'atn': return 'Math.atan(' + e + ')';
        case 'exp': return 'Math.exp(' + e + ')';
        case 'str$': return 'ToString(' + e + ')';
        case 'val': return 'parseInt(' + e + ')';
        case 'peek': return 'Peek(' + e + ').toString()';
        case 'len': return '((' + e + ').length)';
        case 'ltrim$': return '((' + e + ').trimStart())';
        case 'rtrim$': return '((' + e + ').trimEnd())';
        case 'space$': return 'StringRep((' + e + '), " ")';
        case 'tab': return 'StringRep((' + e + '), "\t")';
        case 'stackdepth': return 'sp';
        }
        Error('This cannot happen');
      }
      if (name == 'atan2' || name == 'string$' ||
          name == 'left$' || name == 'right$' ||
          name == 'instr' || name == 'point') {
        Skip('(');
        var a = Expression();
        Skip(',');
        var b = Expression();
        Skip(')');
        if (name == 'atan2') {
          return 'Math.atan2(' + a + ', ' + b + ')';
        } else if (name == 'string$') {
          return 'StringRep(' + a + ', ' + b + ')';
        } else if (name == 'left$') {
          return '((' + a + ').substr(0, (' + b + ')))';
        } else if (name == 'right$') {
          return 'Right((' + a + '), (' + b + '))';
        } else if (name == 'instr') {
          return '((' + a + ').indexOf(' + b + ') + 1)';
        } else if (name == 'point') {
          return 'Point((' + a + '), (' + b + '))';
        } else {
          throw 'impossible';
        }
      }
      if (name == 'mid$' || name == 'seg$') {
        Skip('(');
        var a = Expression();
        Skip(',');
        var b = Expression();
        if (tok == ')') {
          Skip(')');
          return '((' + a + ').substr((' + b + ') - 1))';
        } else {
          Skip(',');
          var c = Expression();
          Skip(')');
          return '((' + a + ').substr((' + b + ') - 1, (' + c + ')))';
        }
      }
      if (name == 'inkey$') {
        return 'Inkey()';
      }
      if (name == 'timer') {
        return 'GetTimer()';
      }
      if (functions[name] !== undefined && !functions[name].is_subroutine) {
        return FunctionCall(name, {is_subroutine: false});
      }
      return IndexVariable(name);
    }
  }

  function Factor2() {
    var a = Factor3();
    while (tok == '^') {
      Next();
      var b = Factor3();
      a = 'Math.pow(' + a + ', ' + b + ')';
    }
    return a;
  }

  function Factor1() {
    var ret = '';
    while (tok == '+' || tok == '-') {
      ret += tok;
      Next();
    }
    return ret + '(' + Factor2() + ')';
  }

  function Factor() {
    var a = Factor1();
    while (tok == '*' || tok == '/') {
      var op = tok;
      Next();
      var b = Factor1();
      a = '(' + a + ')' + op + '(' + b + ')';
    }
    return a;
  }

  function Term2() {
    var a = Factor();
    while (tok == '\\') {
      Next();
      var b = Factor();
      a = 'Math.floor((' + a + ')/(' + b + '))';
    }
    return a;
  }

  function Term1() {
    var a = Term2();
    while (tok == 'mod') {
      Next();
      var b = Term2();
      a = '((' + a + ')%(' + b + '))';
    }
    return a;
  }

  function Term() {
    var a = Term1();
    while (tok == '+' || tok == '-') {
      var op = tok;
      Next();
      var b = Term1();
      a = '(' + a + ')' + op + '(' + b + ')';
    }
    return a;
  }

  function Relational() {
    var a = Term();
    while (tok == '=' || tok == '<' || tok == '>' ||
           tok == '<>' || tok == '<=' || tok == '>=' || tok == '=>') {
      var op = tok;
      Next();
      if (op == '=>') {
        op = '>=';
      }
      var b = Term();
      if (op == '=') {
        a = '(' + a + ') == (' + b + ') ? -1 : 0';
      } else if (op == '<>') {
        a = '(' + a + ') != (' + b + ') ? -1 : 0';
      } else {
        a = '(' + a + ') ' + op + ' (' + b + ') ? -1 : 0';
      }
    }
    return a;
  }

  function Logical1() {
    var ret = '';
    while (tok == 'not') {
      Next();
      ret += '~';
    }
    return ret + '(' + Relational() + ')';
  }

  function Logical() {
    var a = Logical1();
    while (tok == 'and') {
      Next();
      var b = Logical1();
      a = '(' + a + ') & (' + b + ')';
    }
    return a;
  }

  function Expression() {
    var a = Logical();
    while (tok == 'or') {
      Next();
      var b = Logical();
      a = '(' + a + ') | (' + b + ')';
    }
    return a;
  }

  function TypeName() {
    if (SIMPLE_TYPE_INFO[tok]) {
      var type = tok;
      Next();
      return type;
    } else if (tok == 'integer') {
      Skip('integer');
      return 'long';
    } else if (tok == 'any') {
      Skip('any');
      // TODO: Handle this properly.
      return 'string';
    } else if (types[tok] !== undefined) {
      var type_name = tok;
      if (types[type_name] === undefined) {
        Error('Undefined type');
      }
      Next();
      return type_name;
    }
    Error('Undefined type "' + tok + '"');
  }

  function ImplicitType(name) {
    return IMPLICIT_TYPE_MAP[name[name.length - 1]] ||
      letter_default[name[0]] || 'single';
  }

  function Align(alignment) {
    allocated = Math.floor((allocated + alignment - 1) /
        alignment) * alignment;
  }

  function Allocate(size) {
    Align(size > 8 ? 8 : size);
    var ret = allocated;
    allocated += size;
    return ret;
  }

  function DimScalarVariable(name, type_name, defaults) {
    var info = types[type_name] || SIMPLE_TYPE_INFO[type_name];
    if (info === undefined) {
      Error('Unknown type');
    }
    var size = info.size;
    var offset = Allocate(size);
    vars[name] = {
      offset: offset,
      dimensions: 0,
      type_name: type_name,
      global: vars === global_vars,
    };
    if (inside_type) {
      var_decls += '//   field ' + name + ' is at ' + offset + '\n';
    } else if (vars[name].global) {
      var_decls += '// ' + name + ' is at ' + offset + '\n';
    } else {
      if (inside_function) {
        curop += '//   ' + name + ' is at (bp + ' + offset + ')\n';
      } else {
        var_decls += '//   ' + name + ' is at (bp + ' + offset + ')\n';
      }
    }
    if (defaults.length > 0) {
      curop += IndexVariable(name, true) + ' = ' + defaults[0] + ';\n';
    }
  }

  function MaybeImplicitDimVariable(name, argument_to_function) {
    // TODO: Handle array variables.
    if (argument_to_function &&
        argument_to_function.vars[name] !== undefined) {
      return argument_to_function.vars[name];
    }
    if (vars[name] !== undefined) {
      return vars[name];
    }
    if (global_vars[name] !== undefined) {
      return global_vars[name];
    }
    if (option_explicit) {
      Error('Undeclared variable ' + name);
    }
    var type_name = ImplicitType(name);
    DimScalarVariable(name, type_name, []);
    return vars[name];
  }

  function ArrayPart(offset, i) {
    return SIMPLE_TYPE_INFO['long'].view +
      '[((' + offset + '>>2)+' + i + ')]';
  }

  function ReserveArrayCell(name) {
    if (vars[name] === undefined &&
        global_vars[name] == undefined) {
      var offset = Allocate(4 + MAX_DIMENSIONS * 4 * 2);
      vars[name] = {
        offset: offset,
        dimensions: null,
        type_name: null,
        global: vars === global_vars,
      };
      var boffset = offset;
      if (!vars[name].global) {
        boffset = '(bp+' + boffset + ')';
      }
      var_decls += '// ' + name + ' is at ' + ArrayPart(boffset, 0) +
        ' (cell-addr: ' + offset + ')\n';
    }
    if (vars[name] !== undefined) {
      return vars[name];
    }
    return global_vars[name];
  }

  function ImplicitDimArray(name) {
    var dimensions = [[option_base, 10]];
    DimArrayVariable(name, ImplicitType(name), false, dimensions, []);
  }

  function DimArrayVariable(
    name, type_name, is_declare, dimensions, defaults) {
    if (dimensions.length > MAX_DIMENSIONS) {
      Error('Too many dimensions');
    }
    var offset = ReserveArrayCell(name).offset;
    var info = types[type_name] || SIMPLE_TYPE_INFO[type_name];
    var parts = [];
    for (var i = 0; i < dimensions.length; i++) {
      parts.push('((' + dimensions[i][1] + ')-(' + dimensions[i][0] + ')+1)');
    }
    if (!is_declare) {
      if (!vars[name].global) {
        offset = '(bp+' + offset + ')';
      }
      curop += '// Allocate ' + name + '\n';
      curop += 'if (' + ArrayPart(offset, 0) + ' === 0) {\n';
      curop += '  ' + ArrayPart(offset, 0) + ' = Allocate(' +
        [info.size].concat(parts).join('*') + ');\n';
      for (var i = 0; i < dimensions.length; i++) {
        curop += '  ' + ArrayPart(offset, i * 2 + 1) + ' = ' +
          dimensions[i][0] + ';\n';
        curop += '  ' + ArrayPart(offset, i * 2 + 2) + ' = ' +
          [info.size].concat(parts).slice(0, i + 1).join('*') + ';\n';
      }
      if (defaults.length > 0) {
        if (dimensions.length > 1) {
          Error('Only 1-d array defaults supported');
        }
        if (!SIMPLE_TYPE_INFO[type_name]) {
          Error('Only simple type array defaults supported');
        }
        for (var i = 0; i < defaults.length; i++) {
          curop += '  ' + info.view + '[' +
            ' + (' + ArrayPart(offset, 0) + ' >> ' + info.shift + ') + '
            + i + '] = (' + defaults[i] + ');\n';
        }
      }
      curop += '}\n';
      NewOp();
    }
    vars[name] = {
      offset: offset,
      dimensions: dimensions.length > 0 ? dimensions.length : -1,
      type_name: type_name,
      global: vars === global_vars,
    };
  }

  function DimVariable(default_tname, redim, is_declare) {
    var name = tok;
    Next();
    // Pick default.
    if (default_tname === null) {
      default_tname = ImplicitType(name);
    }
    var type_name = default_tname;
    var dimensions = [];
    var defaults = [];
    var is_scalar = true;
    if (tok == '(') {
      Skip('(');
      is_scalar = false;
      while (tok != ')') {
        var e = Expression();
        var d = 'dim' + const_count++;
        var_decls += 'const ' + d + ' = (' + e + ');\n';
        if (tok == 'to') {
          Skip('to');
          var e1 = Expression();
          var d1 = 'dim' + const_count++;
          var_decls += 'const ' + d1 + ' = (' + e1 + ');\n';
          dimensions.push([d, d1]);
        } else {
          dimensions.push([option_base, d]);
        }
        if (tok != ',') {
          break;
        }
        Skip(',');
      }
      Skip(')');
      if (tok == '=') {
        Skip('=');
        Skip('{');
        var e = Expression();
        defaults.push(e);
        while (tok == ',') {
          Skip(',');
          var e = Expression();
          defaults.push(e);
        }
        Skip('}');
      }
    } else if (tok == '=') {
      Skip('=');
      var e = Expression();
      defaults.push(e);
    }
    if (tok == 'as') {
      Skip('as');
      type_name = TypeName();
    }
    if (vars[name] !== undefined && vars[name].dimensions != null) {
      if (redim) {
        return;
      }
      Error('Variable ' + name + ' defined twice');
    }
    if (is_scalar) {
      DimScalarVariable(name, type_name, defaults);
    } else {
      DimArrayVariable(name, type_name, is_declare, dimensions, defaults);
    }
  }

  function Invoke(name, kind_vals) {
    var kind = kind_vals[0];
    var vals = kind_vals[1];
    curop += 'var t = ' + name + '(';
    var pos = 0;
    for (var i = 0; i < kind.length; i++) {
      var k = kind.charAt(i);
      var kl = k.toLowerCase();
      if (kl == 'i' || kl == 's' || kl == 'p' || kl == 'v') {
        if (pos != 0) {
          curop += ', ';
        }
        if (kl == 'p') {
          curop += vals[i][0];
          curop += ', ';
          curop += vals[i][1];
        } else if (kl == 'v') {
          curop += 'buffer, ';
          curop += vals[i];
        } else {
          curop += vals[i];
        }
        pos++;
      }
    }
    curop += ');';
    pos = 0;
    for (var i = 0; i < kind.length; i++) {
      var k = kind.charAt(i);
      if (k == 'o' || k == 'O') {
        if (vals[i] !== undefined) {
          curop += '  ' + vals[i] + ' = t[' + pos + '];';
        }
        pos++;
      }
    }
    curop += '\n';
  }

  function ParenArguments(kind) {
    if (kind.length == 0) {
      return [[], []];
    }
    Skip('(');
    var ret = Arguments(kind);
    Skip(')');
    return ret;
  }

  function Arguments(kind) {
    // i - input / I - optional input
    // o - output / O - optional output
    // p - point (x, y) / P - optional point (passes 2 values)
    // s - string flag / S - optional string flag (e.g. BF for LINE)
    // d - dash (e.g. in words like LINE)
    // v - varptr (e.g. in words list GET / PUT, passes buffer, offset)
    var ret = [];
    for (var i = 0; i < kind.length; i++) {
      var k = kind.charAt(i);
      if (k == 'I' || k == 'O' || k == 'P' || k == 'S') {
        if (tok == ')' || tok == ',' || EndOfStatement()) {
          if (k == 'P') {
            ret.push([undefined, undefined]);
          } else {
            ret.push(undefined);
          }
          if (tok == ',') {
            Skip(',');
          }
          continue;
        }
      }
      if (k == 'o' || k == 'O') {
        ret.push(GetVar());
      } else if (k == 'i' || k == 'I') {
        ret.push(Expression());
      } else if (k == 's' || k == 'S') {
        ret.push('"' + tok + '"');
        Next();
      } else if (k == 'p' || k == 'P') {
        Skip('(');
        var x = Expression();
        Skip(',');
        var y = Expression();
        Skip(')');
        ret.push([x, y]);
      } else if (k == 'd') {
        Skip('-');
        ret.push(undefined);
      } else if (k == 'v') {
        var name = tok;
        Next();
        ret.push(ArrayPart(ReserveArrayCell(name).offset, 0));
      } else {
        Error('Bad binding');
      }
      if (tok == ',' && i != kind.length - 1) {
        Skip(',');
      }
    }
    return [kind, ret];
  }

  function IndexVariable(name, assignable, argument_to_function) {
    var v = MaybeImplicitDimVariable(name, argument_to_function);
    var offset = v.offset;
    if (!v.global) {
      if (argument_to_function) {
        offset = '(sp+' + offset + ')';
      } else {
        offset = '(bp+' + offset + ')';
      }
    }
    var type_name = v.type_name;
    while (!argument_to_function && (tok == '(' || tok == '.')) {
      if (tok == '(') {
        Skip('(');
        var dims = [];
        while (tok != ')') {
          var e = Expression();
          dims.push(e);
          if (tok != ',') {
            break;
          }
          Skip(',');
        }
        Skip(')');
        var info = types[type_name] || SIMPLE_TYPE_INFO[type_name];
        // Extra indirection for array parameter access.
        if (v.dimensions === -1) {
          offset = 'i[' + offset + ']';
        }
        var noffset = '(';
        noffset += ArrayPart(offset, 0) + ' + (';
        if (v.dimensions !== -1 && dims.length != v.dimensions) {
          ImplicitDimArray(name);
          // TODO: This is sus.
          //Error('Array dimension expected ' + v.dimensions +
          //      ' but found ' + dims.length + ', array named: ' + name);
        }
        for (var i = 0; i < dims.length; ++i) {
          noffset += '(((' + dims[i] + ')|0)-' +
              ArrayPart(offset, i * 2 + 1) + ')';
          noffset += '*' + ArrayPart(offset, i * 2 + 2);
          if (i != dims.length - 1) {
            noffset += '+';
          }
        }
        noffset += '))';
        offset = noffset;
      } else if (tok == '.') {
        Skip('.');
        v = types[type_name];
        if (v === undefined) {
          Error('Not a struct type');
        }
        var field = v.vars[tok];
        if (field === undefined) {
          Error('Invalid field name');
        }
        Next();
        offset = '(' + offset + ' + ' + field.offset + ')';
        type_name = field.type_name;
      }
    }
    var info = SIMPLE_TYPE_INFO[type_name];
    if (!info) {
      Error('Expected simple type');
    }
    var vname = info.view + '[' + offset + '>>' + info.shift + ']';
    if (info.view == 'str' && assignable === undefined) {
      vname = '((' + vname + ')||"")';
    }
    return vname;
  }

  function FunctionDefine(options) {
    var name = tok;
    Next();
    if (vars !== global_vars) {
      Error('Nested SUB/FUNCTION not allowed');
    }
    if (functions[name] !== undefined && !functions[name].is_declaration) {
      Error('SUB/FUNCTION already defined: ' + name);
    }
    NewOp();
    var pos = ops.length - 1;
    var parameters = [];
    var old_allocated = allocated;
    allocated = 0;
    vars = {};
    var nfunc = {
      vars: vars,
      parameters: parameters,
      ip: ops.length,
      allocation: -1,
      is_subroutine: options.is_subroutine || false,
      is_declaration: options.is_declaration || false,
    };
    if (nfunc.is_declaration) {
      if (nfunc.is_subroutine) {
        var_decls += '// SUB ' + name + '\n';
      } else {
        var_decls += '// FUNCTION ' + name + '\n';
      }
    } else {
      if (nfunc.is_subroutine) {
        curop += '// SUB ' + name + '\n';
      } else {
        curop += '// FUNCTION ' + name + '\n';
      }
    }
    if (!nfunc.is_declaration) {
      inside_function = true;
    }
    DimScalarVariable(name, ImplicitType(name), []);
    // In case return value gets redefined.
    Align(8);
    if (tok == '(') {
      Skip('(');
      if (tok != ')') {
        parameters.push(tok);
        DimVariable(null, undefined, true);
        while (tok == ',') {
          Skip(',');
          parameters.push(tok);
          DimVariable(null, undefined, true);
        }
      }
      Skip(')');
      Align(8);
    }
    nfunc.allocation = allocated;
    if (options.is_declaration) {
      vars = global_vars;
      allocated = old_allocated;
      if (functions[name] == undefined) {
        functions[name] = nfunc;
      } else {
        // TODO: Check for declaration mismatch in type.
        if (functions[name].parameters.length != nfunc.parameter.length) {
          Error('DECLARE and definition parameters do not match');
        }
      }
    } else {
      function_old_allocated = old_allocated;
      function_define_pos = pos;
      function_name = name;
      functions[name] = nfunc;
    }
    if (tok == 'as') {
      Skip('as');
      var type_name = TypeName();
      if (!SIMPLE_TYPE_INFO[type_name]) {
        Error('Expected basic type');
      }
      functions[name].type_name = type_name;
    }
    if (tok == 'static') {
      Skip('static');
      // TODO: Implement.
    }
  }

  function FunctionExit() {
    if (vars === global_vars) {
      Error('SUB/FUNCTION EXIT only allowed inside SUB/FUNCTION.');
    }
    curop += 'sp -= 8; ip = i[sp>>2];\n';
    NewOp();
  }

  function FunctionEnd() {
    if (vars === global_vars) {
      Error('SUB/FUNCTION END only allowed at end of SUB/FUNCTION.');
    }
    inside_function = false;
    FunctionExit();
    ops[function_define_pos] += 'ip = ' + ops.length + ';\n';
    vars = global_vars;
    Align(8);
    functions[function_name].allocation = allocated;
    function_name = null;
    allocated = function_old_allocated;
  }

  function FunctionCall(name, options) {
    var func = functions[name];
    if (func === undefined || options.is_subroutine !== func.is_subroutine) {
      if (options.is_subroutine) {
        Error('Expected valid subroutine name, found: ' + name);
      } else {
        Error('Expected valid function name, found: ' + name);
      }
    }
    curop += 'i[sp>>2] = bp; sp += 8;\n';
    var has_parens = tok == '(' || func.parameters.length != 0;
    if (options.is_call || (!options.is_subroutine && has_parens)) {
      Skip('(');
    }
    var args = [];
    for (var i = 0; i < func.parameters.length; ++i) {
      if (func.vars[func.parameters[i]].dimensions == -1) {
        var vname = tok;
        Next();
        Skip('(');
        Skip(')');
        args.push(null);
        curop += 'i[sp + ' + func.vars[func.parameters[i]].offset + '] = ' +
          VarPtr(vname) + ';\n';
      } else {
        var old_tok_count = tok_count;
        var old_tok = tok;
        var e = Expression();
        curop += IndexVariable(func.parameters[i], true, func) +
          ' = ' + e + ';\n';
        if (vars[old_tok] && tok_count - old_tok_count == 1) {
          args.push(old_tok);
        } else {
          args.push(null);
        }
      }
      if (i != func.parameters.length - 1) {
        Skip(',');
      }
    }
    if (options.is_call || (!options.is_subroutine && has_parens)) {
      Skip(')');
    }
    // Blank return value.
    if (!options.is_subroutine) {
      curop += IndexVariable(name, true, func) + ' = 123;\n';
    }
    curop += 'bp = sp;\n';
    curop += 'sp += functions["' + name + '"].allocation;\n';
    curop += 'i[sp>>2] = ip; sp += 8;\n';
    curop += 'ip = functions["' + name + '"].ip;\n';
    NewOp();
    // TODO: Types?
    curop += 'sp -= functions["' + name + '"].allocation;\n';
    curop += 'bp = i[(sp-8)>>2];\n';
    var temp = '#temp' + temp_count;
    if (!options.is_subroutine) {
      ++temp_count;
      DimScalarVariable(temp, func.vars[name].type_name, []);
      curop += IndexVariable(temp, true) +
        ' = ' + IndexVariable(name, false, func) + ';\n';
    }
    for (var i = 0; i < args.length; ++i) {
      if (args[i]) {
        curop += IndexVariable(args[i], true) + ' = ' +
          IndexVariable(func.parameters[i], false, func) + ';\n';
      }
    }
    curop += 'sp -= 8;\n';
    if (!options.is_subroutine) {
      return IndexVariable(temp, false);
    }
  }

  function StringRep(n, ch) {
    var ret = '';
    var cch;
    if (typeof ch == 'string') {
      cch = ch;
    } else {
      cch = String.fromCharCode(ch);
    }
    for (var i = 0; i < n; ++i) {
      ret += cch;
    }
    return ret;
  }

  function ToString(s) {
    if (s < 0) {
      return s.toString();
    } else {
      return ' ' + s.toString();
    }
  }

  function GetVar() {
    var name = tok;
    Next();
    return IndexVariable(name, true);
  }

  var DEFAULT_TYPES = {
    'defdbl': 'double',
    'defsng': 'single',
    'defint': 'short',
    'deflng': 'long',
    'defstr': 'string',
  };

  function Statement() {
    if (EndOfStatement()) {
      // Ignore empty lines.
    } else if (tok == 'rem') {
      do {
        Next();
      } while (tok != '<EOL>');
    } else if (tok == 'if') {
      Skip('if');
      var e = Expression();
      Skip('then');
      if (EndOfStatement()) {
        If(e);
        while (tok == ':') {
          Skip(':');
          Statement();
        }
        if (tok == 'else') {
          Skip('else');
          Else();
          while (tok == ':') {
            Skip(':');
            Statement();
          }
        }
        if (tok == 'end') {
          Skip('end');
          Skip('if');
          EndIf();
        }
      } else {
        // Classic if <e> then
        If(e);
        if (tok.match(/^[0-9]+$/)) {
          var name = tok;
          Next();
          curop += 'ip = labels["' + name + '"];\n';
          NewOp();
        } else {
          Statement();
          while (tok == ':') {
            Skip(':');
            Statement();
          }
        }
        var f = flow.pop();
        if (f[0] != 'if') {
          Error('If in mixed style');
        }
        flow.push(f);
        NewOp();
        if (tok == 'else') {
          Skip('else');
          Else();
          // TI style else.
          if (tok.match(/^[0-9]+$/)) {
            var name = tok;
            Next();
            curop += 'ip = labels["' + name + '"];\n';
            NewOp();
            EndIf();
            return;
          }
          Statement();
          while (tok == ':') {
            Skip(':');
            Statement();
          }
        }
        EndIf();
      }
    } else if (tok == 'elseif') {
      Skip('elseif');
      var e = Expression();
      Skip('then');
      ElseIf(e);
    } else if (tok == 'else') {
      Skip('else');
      Else();
      if (!EndOfStatement()) {
        Statement();
      }
    } else if (tok == 'do') {
      Skip('do');
      if (tok == 'while') {
        // Support DO WHILE
        Statement();
        return;
      }
      NewOp();
      flow.push(['do', ops.length]);
    } else if (tok == 'loop') {
      Skip('loop');
      var is_while;
      if (tok == 'while') {
        Skip('while');
        is_while = true;
      } else if (tok == 'until') {
        Skip('until');
        is_while = false;
      } else if (EndOfStatement()) {
        var f = flow.pop();
        if (f[0] != 'while' && f[0] != 'do') {
          Error('LOOP does not match DO / WHILE');
        }
        curop += 'ip = ' + f[1] + ';\n';
        NewOp();
        if (f[0] == 'while') {
          ops[f[1]] += ops.length + '; }\n';
        }
        return;
      } else {
        Error('Expected while/until');
      }
      var e = Expression();
      var f = flow.pop();
      if (f[0] != 'do') {
        Error('LOOP does not match DO');
      }
      if (is_while) {
        curop += 'if (' + e + ') { ip = ' + f[1] + '; }\n';
      } else {
        curop += 'if (!(' + e + ')) { ip = ' + f[1] + '; }\n';
      }
      NewOp();
    } else if (tok == 'while') {
      Skip('while');
      var e = Expression();
      NewOp();
      curop += 'if (!(' + e + ')) { ip = ';
      NewOp();
      flow.push(['while', ops.length - 1]);
    } else if (tok == 'wend') {
      Skip('wend');
      var f = flow.pop();
      if (f[0] != 'while') {
        Error('Wend does not match while');
      }
      curop += 'ip = ' + f[1] + ';\n';
      NewOp();
      ops[f[1]] += ops.length + '; }\n';
    } else if (tok == 'exit') {
      Skip('exit');
      if (tok == 'sub') {
        Skip('sub');
        FunctionExit();
      } else if (tok == 'function') {
        Skip('function');
        FunctionExit();
      } else {
        Error('Expected sub/function');
      }
    } else if (tok == 'end') {
      Skip('end');
      if (tok == 'if') {
        Skip('if');
        EndIf();
      } else if (tok == 'select') {
        Skip('select');
        NewOp();
        var f = flow.pop();
        if (f[0] != 'select') {
          Error('end select outside select');
        }
        var disp = 'var t = (' + f[1] + ');\n';
        disp += 'if (false) {}\n';
        for (var i = 0; i < f[3].length; i++) {
          var ii = f[3][i];
          if (ii[0] == ii[1]) {
            disp += 'else if (t == (' + ii[0] +
                    ')) { ip = ' + ii[2] + '; }\n';
          } else {
            disp += 'else if (t >= (' + ii[0] + ') && t <= (' + ii[1] +
                    ')) { ip = ' + ii[2] + '; }\n';
          }
        }
        if (f[5] !== null) {
          disp += 'else { ip = ' + f[5] + '; }\n';
        } else {
          disp += 'else { ip = ' + ops.length + '; }\n';
        }
        ops[f[2]] += disp;
        for (var i = 0; i < f[4].length; i++) {
          ops[f[4][i]] += 'ip = ' + ops.length + ';\n';
        }
      } else if (tok == 'sub') {
        Skip('sub');
        FunctionEnd();
      } else if (tok == 'function') {
        Skip('function');
        FunctionEnd();
      } else {
        curop += 'End();\n';
      }
    } else if (tok == 'goto') {
      Skip('goto');
      var name = tok;
      Next();
      curop += 'ip = labels["' + name + '"];\n';
      NewOp();
    } else if (tok == 'gosub') {
      Skip('gosub');
      var name = tok;
      Next();
      curop += 'i[sp>>2] = ip; sp += 8;\n';
      curop += 'ip = labels["' + name + '"];\n';
      NewOp();
    } else if (tok == 'return') {
      Skip('return');
      curop += 'sp -= 8; ip = i[sp>>2];\n';
      NewOp();
    } else if (tok == 'declare') {
      Skip('declare');
      if (tok == 'sub') {
        Skip('sub');
        FunctionDefine({is_subroutine: true, is_declaration: true});
      } else if (tok == 'function') {
        Skip('function');
        FunctionDefine({is_subroutine: false, is_declaration: true});
      } else {
        Error('Unexpected declaration');
      }
    } else if (tok == 'type') {
      var old_allocated = allocated;
      vars = {};
      Skip('type');
      var type_name = tok;
      Next();
      if (types[type_name] !== undefined) {
        Error('Duplicate type definition');
      }
      types[type_name] = {
        vars: vars,
        size: 0,
      };
      inside_type = true;
      var_decls += '// TYPE ' + type_name + '\n';
      SkipEndOfStatement();
      while (tok != 'end') {
        while (!EndOfStatement()) {
          DimVariable(null);
          while (tok == ',') {
            Skip(',');
            DimVariable(null);
          }
        }
        SkipEndOfStatement();
      }
      Skip('end');
      Skip('type');
      inside_type = false;
      types[type_name].size = allocated;
      vars = global_vars;
      allocated = old_allocated;
    } else if (tok == 'const') {
      Skip('const');
      // TODO: Enforce consts are const.
      for (;;) {
        var name = tok;
        Next();
        var v = vars[name];
        if (v !== undefined) {
          Error('Constant ' + name + ' defined twice');
        }
        var offset = Allocate(8);
        vars[name] = {
          offset: offset,
          type_name: 'double',
          global: vars === global_vars,
        };
        v = vars[name];
        Skip('=');
        var value = Expression();
        var_decls += SIMPLE_TYPE_INFO['double'].view +
          '[' + (offset >> 3) + ']' +
          ' = (' + value + ');  // ' + name + '\n';
        if (tok == ',') {
          Skip(',');
          continue;
        }
        break;
      }
    } else if (tok == 'dim' || tok == 'redim') {
      var op = tok;
      Next();
      if (tok == 'shared') {
        Skip('shared');
      }
      var tname = null;
      if (tok == 'as') {
        Skip('as');
        tname = TypeName();
      }
      DimVariable(tname, op == 'redim');
      while (tok == ',') {
        Skip(',');
        DimVariable(tname, op == 'redim');
      }
    } else if (tok == 'error') {
      Skip('error');
      var e = Expression();
      curop += 'Error("Error " + ' + e + ', ' + line + ');\n';
      NewOp();
    } else if (tok == 'on') {
      Skip('on');
      if (tok == 'error') {
        Skip('error');
        if (tok == 'goto') {
          Skip('goto');
          if (tok == '0') {
            curop += 'error_handler = Throw;\n';
            Next();
            NewOp();
          } else {
            curop += 'error_handler = ErrorGoto(labels["' + tok + '"]);\n';
            Next();
            NewOp();
          }
        } else if (tok == 'resume') {
          Skip('resume');
          Skip('next');
          curop += 'error_handler = (function() {});\n';
          NewOp();
        } else {
          Error('Expected goto / resume next.');
        }
      } else {
        var name = Expression();
        if (tok == 'goto' || tok == 'gosub') {
          var isGosub = (tok == 'gosub');
          Next();
          if (EndOfStatement()) {
            Error('Expected labels.');
          }
          if (isGosub) {
            curop += 'i[sp>>2] = ip; sp += 8;\n';
          }
          curop += 'ip = labels[[';
          while (!(EndOfStatement())) {
            curop += '"' + tok + '"';
            Next();
            if (EndOfStatement()) {
              if (isGosub) {
                curop += '][((' + name + ')|0) - 1]];\n';
                curop += 'if(ip == undefined){ sp -= 8; ip = i[sp>>2]; }\n';
              } else {
                curop += '][((' + name + ')|0) - 1]] || ip;\n';
              }
            } else {
              curop += tok;
              Skip(',');
            }
          }
        } else {
          Error('Expected GOTO or GOSUB. Found ' + tok);
        }
        NewOp();
      }
    } else if (tok == 'resume') {
      Skip('resume');
      if (tok == 'next') {
        Skip('next');
        curop += 'ResumeNext();\n';
        NewOp();
      } else if (tok == '0') {
        Skip('0');
        curop += 'Resume0();\n';
        NewOp();
      } else {
        curop += 'Resume(labels["' + String(tok) + '"]);\n';
        Next();
        NewOp();
      }
    } else if (tok == 'sub') {
      Skip('sub');
      FunctionDefine({is_subroutine: true});
    } else if (tok == 'function') {
      Skip('function');
      FunctionDefine({is_subroutine: false});
    } else if (tok == 'def') {
      Skip('def');
      if (tok == 'seg') {
        Skip('seg');
        if (tok == '=') {
          Skip('=');
          var e = Expression();
          // TODO: Do something useful with it?
        }
      } else if (tok.substr(0, 2) == 'fn') {
        var fname = tok;
        var pos = FunctionDefine({is_subroutine: false});
        Skip('=');
        var e = Expression();
        curop += IndexVariable(fname, true) + ' = ' + e + ';\n';
        FunctionEnd(pos);
      } else {
        Error('Expected SEG/FNxxx');
      }
    } else if (tok == 'open') {
      Skip('open');
      var filename = Expression();
      Skip('for');
      if (tok == 'input') {
        Skip('input');
      } else if (tok == 'output') {
        Skip('output');
      } else {
        Error('Expected input/output');
      }
      Skip('as');
      Next();
      // TODO: Implement.
    } else if (tok == 'close') {
      Skip('close');
      if (!EndOfStatement()) {
        // #n
        Next();
      }
      // TODO: Implement.
    } else if (tok == 'system') {
      Skip('system');
      // TODO: Implement.
    } else if (tok == 'beep') {
      Skip('beep');
      // TODO: Implement.
    } else if (tok == 'view') {
      Skip('view');
      if (tok == 'print') {
        Skip('print');
        if (!EndOfStatement()) {
          var top = Expression();
          Skip('to');
          var bottom = Expression();
        }
        // TODO: Implement.
      } else if (tok == 'screen') {
        Skip('screen');
        // TODO: Implement.
      } else {
        Error('Expected PRINT/SCREEN');
      }
    } else if (tok == 'randomize') {
      Skip('randomize');
      if (!EndOfStatement()) {
        var seed = Expression();
        // TODO: Implement seed handling.
      }
    } else if (tok == 'poke') {
      Skip('poke');
      var addr = Expression();
      Skip(',');
      var value = Expression();
      // TODO: Do something useful with it?
    } else if (tok == 'key') {
      Skip('key');
      if (tok == 'on') {
        Skip('on');
      } else if (tok == 'off') {
        Skip('off');
      } else {
        Error('Expected on/off');
      }
      // Implement this?
    } else if (tok == 'chain') {
      Skip('chain');
      var filename = Expression();
      if (tok == ',') {
        Skip(',');
        var name = tok;
        Next();
      }
      // TODO: Implement this.
    } else if (tok == 'option') {
      Skip('option');
      if (tok == 'explicit') {
        Skip('explicit');
        option_explicit = true;
      } else if (tok == 'base') {
        Skip('base');
        if (tok == '0') {
          option_base = 0;
        } else if (tok == '1') {
          option_base = 1;
        } else {
          Error('Unexpected option base "' + tok + '"');
        }
        Next();
      } else {
        Error('Unexpected option "' + tok + '"');
      }
    } else if (tok == 'defdbl' || tok == 'defsng' || tok == 'deflng' ||
               tok == 'defint' || tok == 'defstr') {
      var def_type = tok;
      Next();
      for (;;) {
        var start = tok;
        Next();
        Skip('-');
        var end = tok;
        Next();
        if (!start.match(/^[a-z]$/) ||
            !end.match(/^[a-z]$/) ||
            start.charCodeAt(0) > end.charCodeAt(0)) {
          Error('Invalid variable range');
        }
        var i = start;
        do {
          letter_default[i] = DEFAULT_TYPES[def_type];
          i = NextChar(i);
        } while (i != end);
        if (tok == ',') {
          Skip(',');
          continue;
        }
        break;
      }
    } else if (tok == 'for') {
      Skip('for');
      var name = tok;
      var v = IndexVariable(name, true);
      Next();
      Skip('=');
      var start = Expression();
      Skip('to');
      var end = Expression();
      var step = 1;
      if (tok == 'step') {
        Skip('step');
        step = Expression();
      }
      curop += v + ' = (' + start + ');';
      NewOp();
      curop += 'if (((' + step + ' > 0) && ' +
                    v + ' > (' + end + ')) || ' +
                   '((' + step + ' < 0) && ' +
                    v + ' < (' + end + '))) { ip = ';
      NewOp();
      flow.push(['for', v, ops.length - 1, step]);
    } else if (tok == 'next') {
      Skip('next');
      var f = flow.pop();
      if (f[0] != 'for') {
        Error('Expected NEXT');
      }
      if (!EndOfStatement()) {
        var name = tok;
        // TODO: Shouldn't this fail?
        /*
        if (name != f[1]) {
          Error('Expected ' + f[1]);
        }
        */
        Next();
      }
      curop += f[1] + ' += (' + f[3] + ');\n';
      curop += 'ip = ' + f[2] + ';\n';
      NewOp();
      ops[f[2]] += ops.length + '; }\n';
    } else if (tok == 'mid$') {
      Skip('mid$');
      Skip('(');
      var a = GetVar();
      Skip(',');
      var x = Expression();
      var y = '(' + a + '.length)';
      if (tok == ')') {
        Skip(')');
      } else {
        Skip(',');
        y = Expression();
        Skip(')');
      }
      Skip('=');
      var z = Expression();
      curop += a + ' = MidReplace(' + a + ', ' + x + ', ' +
               y + ', ' + z + ');\n'
    } else if (tok == 'line') {
      Skip('line');
      if (tok == 'input') {
        Skip('input');
        if (tok == ';') {
          Skip(';');
        }
        var prompt = '""';
        if (tok.substr(0, 1) == '"') {
          var prompt = tok;
          Next();
          if (tok == ';' || tok == ',') {
            Next();
          }
        }
        curop += 'Print([' + prompt + ', ";"]);\n';
        curop += 'PutCh(String.fromCharCode(219));\n';
        curop += 'LineClear();\n';
        NewOp();
        curop += 'ip += LineInput();\n';
        NewOp();
        var a = GetVar();
        curop += a + ' = LineValue();\n';
        return;
      }
      Invoke('Line', Arguments('PdpIS'));
    } else if (tok == 'sleep') {
      Next();
      Invoke('Sleep', Arguments('i'));
      NewOp();
    } else if (tok == 'swap') {
      Skip('swap');
      var a = GetVar();
      Skip(',');
      var b = GetVar();
      curop += 'var t = ' + a + ';\n';
      curop += a + ' = ' + b + ';\n';
      curop += b + ' = t;\n';
    } else if (tok == 'data') {
      ConsumeData();
    } else if (tok == 'read') {
      Skip('read');
      curop += GetVar() + ' = Read();\n';
      while (tok == ',') {
        Skip(',');
        curop += GetVar() + ' = Read();\n';
      }
    } else if (tok == 'restore') {
      Skip('restore');
      if (!EndOfStatement()) {
        curop += 'data_pos = data_labels["' + tok + '"];\n';
        Next();
      } else {
        curop += 'data_pos = 0;\n';
      }
    } else if (tok == 'input') {
      Skip('input');
      if (tok[0] == '#') {
        // TODO: Implement.
        Next();
        if (tok == ';' || tok == ',') {
          Next();
        }
      }
      if (tok == ';') {
        Skip(';');
      }
      var prompt = '"? "';
      if (tok.substr(0, 1) == '"') {
        var prompt = tok;
        Next();
        if (tok == ';' || tok == ',') {
          Next();
        }
      }
      curop += 'Print([' + prompt + ', ";"]);\n';
      curop += 'PutCh(String.fromCharCode(219));\n';
      curop += 'LineClear();\n';
      NewOp();
      curop += 'ip += LineInput();\n';
      NewOp();
      var n = 0;
      while (!EndOfStatement()) {
        curop += GetVar() + ' = LineValue().split(",")[' + n++ + '];\n';
        if (tok != ',') {
          break;
        }
        Skip(',');
      }
    } else if (tok == 'print') {
      Skip('print');
      if (EndOfStatement()) {
        curop += 'Print([]);\n';
        return;
      }
      var fmt = null;
      if (tok == 'using') {
        Skip('using');
        fmt = Expression();
        Skip(';');
      }
      var items = [];
      var e = Expression();
      items.push(e);
      while (tok == ';' || tok == ',') {
        items.push('"' + tok + '"');
        Next();
        if (EndOfStatement()) {
          break;
        }
        var e = Expression();
        items.push(e);
      }
      if (fmt !== null) {
        curop += 'PrintUsing(' + fmt + ', [' + items.join(', ') + ']);\n';
      } else {
        curop += 'Print([' + items.join(', ') + ']);\n';
      }
    } else if (tok == 'select') {
      Skip('select');
      Skip('case');
      if (tok == 'as') {
        Skip('as');
        Skip('const');
      }
      var e = Expression();
      NewOp();
      flow.push(['select', e, ops.length - 1, [], [], null]);
    } else if (tok == 'case') {
      Skip('case');
      var f = flow.pop();
      if (f[0] != 'select') {
        Error('Case outside select');
      }
      NewOp();
      f[4].push(ops.length - 1);
      if (tok == 'else') {
        Skip('else');
        f[5] = ops.length;
        flow.push(f);
        return;
      }
      var e = Expression();
      if (tok == 'to') {
        Skip('to');
        var e1 = Expression();
        f[3].push([e, e1, ops.length]);
      } else {
        f[3].push([e, e, ops.length]);
        while (tok == ',') {
          Skip(',');
          var e = Expression();
          f[3].push([e, e, ops.length]);
        }
      }
      flow.push(f);
    } else if (tok == '') {
      return;
    } else if (tok == 'call' || (functions[tok] !== undefined &&
                                 functions[tok].is_subroutine)) {
      var name = tok;
      Next();
      if (name == 'call') {
        name = tok;
        Next();
        for (var method in bindings) {
          var parts = method.split('_');
          if (parts.length == 3 && parts[0] == 'call') {
            if (name == parts[1]) {
              Invoke(method, ParenArguments(parts[2]));
              return;
            }
          }
        }
        FunctionCall(name, {is_subroutine: true, is_call: true});
      } else {
        FunctionCall(name, {is_subroutine: true});
      }
    } else {
      var name = tok;
      Next();
      for (var method in bindings) {
        var parts = method.split('_');
        if (parts.length == 3 && parts[0] == 'statement') {
          if (name == parts[1]) {
            Invoke(method, Arguments(parts[2]));
            return;
          }
        }
      }
      if (tok == ':') {
        Skip(':');
        AddLabel(name);
        Statement();
        return;
      }
      if (name == 'let') {
        name = tok;
        Next();
      }
      var vname = IndexVariable(name, true);
      if (tok == '=' || tok == '+=' || tok == '-=' ||
          tok == '*=' || tok == '/=' || tok == '\\=' ||
          tok == '^=' || tok == '&=') {
        var op = tok;
        Next();
        var e = Expression();
        if (op == '&=') {
          op = '+=';
        } else if (op == '\\=') {
          op = '//=';
        } else if (op == '^=') {
          curop += vname + ' = Math.pow(' + vname + ', ' + e + ');\n';
          return;
        }
        curop += vname + ' ' + op + ' (' + e + ');\n';
      } else {
        Error('Expected "=" or "x=" found "' + tok + '"');
      }
    }
  }

  function Compile() {
    NewOp();
    while (tok != '') {
      for (;;) {
        // Implement line numbers.
        if (tok.match(/^[0-9]+$/)) {
          AddLabel(tok);
          Next();
        }
        Statement();
        while (tok == ':') {
          Next();
          Statement();
        }
        if (tok == '') {
          break;
        }
        SkipEndOfStatement();
      }
    }

    // Check for matching flow control.
    if (flow.length != 0) {
      var f = flow.pop();
      Error('Unmatched ' + f[0]);
    }

    // Implicit End.
    NewOp();
    curop += 'End();';
    NewOp();

    // Align to 8.
    Align(8);

    // Allocate stack.
    stack = Allocate(STACK_SIZE);
    sp = stack;
    bp = sp;

    var total = '';
    total += '(function(bindings) {\n';
    for (var i in bindings) {
      total += 'var ' + i + ' = bindings["' + i + '"];\n';
    }
    total += 'var buffer = new ArrayBuffer(' +
        allocated + ' + ' + DYNAMIC_HEAP_SIZE + ');\n';
    for (var i in SIMPLE_TYPE_INFO) {
      var info = SIMPLE_TYPE_INFO[i];
      if (i == 'string') {
        total += 'var str = [];\n';
      } else {
        total += 'var ' + info.view +
          ' = new ' + info.array + '(buffer);\n';
      }
    }
    total += var_decls;
    total += 'for (var j = 0; j < ops.length; ++j) {\n';
    if (debugging_mode) {
      total += '  console.info("L" + j + ":\\n" + ops[j]);\n';
    }
    total += '  ops[j] = eval("(function() {\\n" + ops[j] + "})\\n");\n';
    total += '}\n';
    total += '})';
    if (debugging_mode) {
      console.info(total);
    }
    eval(total)(bindings);
  }

  function MidReplace(a, n, m, v) {
    var k = Math.min(m, v.length);
    return a.substr(0, n - 1) + v.substr(0, k) + a.substr(n - 1 + k);
  }

  function Right(s, n) {
    return s.substr(s.length - n);
  }

  function Read() {
    if (data_pos >= data.length) {
      Error('Out of data');
    }
    return data[data_pos++];
  }

  function Print(items) {
    if (items.length == 0) {
      bindings.PutCh();
      return;
    }
    for (var i = 0; i < items.length; i += 2) {
      var text;
      if (items[i] === undefined) {
        text = '';
      } else {
        text = items[i].toString();
      }
      for (var j = 0; j < text.length; j++) {
        bindings.PutCh(text[j]);
      }
      if (items[i + 1] == ',') {
        bindings.PutCh(' ');
        bindings.PutCh(' ');
        bindings.PutCh(' ');
      }
      if (items[i + 1] != ';' && items[i + 1] != ',') {
        bindings.PutCh();
      }
    }
  }

  function Using(format, value) {
    var sgn = value < 0 ? -1 : (value > 0 ? 1 : 0);
    value = Math.abs(value);
    var before = 0;
    var after = 0;
    var found_point = false;
    for (var i = 0; i < format.length; ++i) {
      if (format[i] == '.') {
        found_point = true;
      } else if (format[i] == '#') {
        if (found_point) {
          ++after;
        } else {
          ++before;
        }
      }
    }
    var t = value;
    var fail = Math.floor(t * Math.pow(10, -before)) > 0;
    value = value * Math.pow(10, after);
    var ret = '';
    var done = false;
    for (var i = format.length - 1; i >= 0; --i) {
      if (format[i] == '#') {
        if (fail) {
          ret = '*' + ret;
        } else if (done) {
          ret = ' ' + ret;
        } else {
          ret = Math.floor(value % 10) + ret;
          value = Math.floor(value / 10);
          if (value == 0) {
            done = true;
          }
        }
      } else if (format[i] == '+' || format[i] == '-') {
        if (fail) {
          ret = '*' + ret;
        } else if (sgn < 0) {
          ret = '-' + ret;
        } else if (sgn > 0) {
          if (format[i] == '+') {
            ret = '+' + ret;
          }
        } else {
          ret = ' ' + ret;
        }
      } else if (format[i] == ',') {
        if (fail) {
          ret = '*' + ret;
        } else if (done) {
          ret = ' ' + ret;
        } else {
          ret = ',' + ret;
        }
      } else {
        ret = format[i] + ret;
      }
    }
    return ret;
  }

  function PrintUsing(format, items) {
    var parts = [];
    var p = '';
    var has_num = false;
    for (var i = 0; i < format.length; ++i) {
      if (format[i] == '#' || format[i] == ',' || format[i] == '.') {
        has_num = true;
      } else {
        if (has_num) {
          parts.push(p)
          p = '';
          has_num = false;
        }
      }
      p += format[i];
    }
    if (p != '') {
      if (has_num) {
        parts.push(p);
      } else {
        parts[parts.length - 1] += p;
      }
    }
    var values = [];
    for (var i = 0; i < items.length; i += 2) {
      if (parts.length * 2 > i) {
        items[i] = Using(parts[(i / 2) | 0], items[i]);
      }
    }
    Print(items);
  }

  function Sleep(t) {
    yielding = 1;
    delay = t;
  }

  function Yield() {
    yielding = 1;
  }

  function End() {
    yielding = 1;
    quitting = 1;
    bindings.Halt();
  }

  function Run(pace) {
    for (;;) {
      var last_time = new Date().getTime();
      var speed = pace !== undefined ? pace() : 100000;
      for (var i = 0; i < speed; ++i) {
        ops[ip++]();
        if (yielding) {
          yielding = 0;
          if (quitting) {
            return;
          }
          break;
        }
      }
      setTimeout(function() { Run(pace); }, delay + 16);
      delay = 0;
      break;
    }
  }

  bindings.Yield = Yield;
  var compiled_ok = false;
  try {
    Compile();
    compiled_ok = true;
  } catch (e) {
    if (bindings.Render) {
      bindings.statement_locate_iiI(1, 1);
      bindings.statement_color_iII(15);
      Print([e.toString(), ';']);
    } else {
      console.error(e.toString());
    }
    if (e.stack !== undefined) {
      console.info(e.stack);
    }
  }
  if (compiled_ok) {
    Run(bindings.Pace);
  }
}

function SetupCanvas(tag, full_window) {
  if (full_window) {
    document.body.style.width = '100%';
    document.body.style.height = '100%';
    document.body.style.margin = '0';
    document.body.style.border = '0';
    document.body.style.overflow = 'hidden';
    document.body.style.display = 'block';
  }
  var canvas = document.createElement('canvas');
  canvas.width = 800;
  canvas.height = 600;
  canvas.fromWWWBasic = true;
  if (full_window) {
    document.body.appendChild(canvas);
  } else {
    tag.insertAdjacentElement('beforebegin', canvas);
  }
  var context = canvas.getContext('2d');
  context.fillStyle = 'black';
  context.fillRect(0, 0, canvas.width, canvas.height);
  context.fillStyle = 'white';
  context.strokeStyle = 'white';
  return canvas;
}

var timer_halted = 0;
var timer_offset = 0;

function GetTimer() {
  var t = new Date().getTime() / 1000;
  return t + timer_offset;
}

function Init() {
  var tags = document.getElementsByTagName('script');
  var count = 0;
  for (var t = 0; t < tags.length; ++t) {
    if (tags[t].type != 'text/basic') {
      continue;
    }
    ++count;
  }
  var full_window = count == 1 && document.body.innerText == '';
  for (var t = 0; t < tags.length; ++t) {
    if (tags[t].type != 'text/basic') {
      continue;
    }
    var tag = tags[t];
    var canvas = SetupCanvas(tag, full_window);
    var bindings = GraphicsBindings(canvas);
    if (tags[t].src) {
      var request = new XMLHttpRequest();
      request.addEventListener('load', function(e) {
        Basic(request.responseText, { bindings: bindings });
      }, false);
      request.open('GET', tag.src);
      request.send();
    } else {
      Basic(DecodeTag(tag.text), { bindings: bindings });
    }
  }
}

function Main() {
  if (typeof window !== 'undefined') {
    window.addEventListener('load', Init);
    window.addEventListener('focusout', function() {
      timer_halted = GetTimer();
    });
    window.addEventListener('focusin', function() {
      timer_offset = timer_halted - (new Date().getTime() / 1000);
    });
    window.Basic = function(code, canvas) {
      Basic(code, { bindings: GraphicsBindings(canvas) });
    };
  } else {
    for (var key in basic) {
      exports[key] = basic[key];
    }
  }
}

function ConsoleBindings() {
  var bindings = {};

  var output_buffer = '';

  // TODO: Cleanup, this should be hidden.
  bindings.PutCh = function(ch) {
    if (ch === undefined) {
      console.log(output_buffer);
      output_buffer = '';
    } else {
      output_buffer += ch;
    }
  }

  bindings.Halt = function() {
    if (output_buffer != '') {
      bindings.PutCh();
    }
  };

  return bindings;
}

function GraphicsBindings(canvas) {
  var bindings = {};

  const BLACK = 0xff000000;
  const WHITE = 0xffffffff;

  // Display Info (in browser only).
  var screen_mode = -1;
  var screen_bpp = 4;
  var text_mode = false;
  var text_width = 80;
  var text_height = 60;
  var font_height = 16;
  var screen_aspect = 1;
  var font_data;
  var ctx;
  var display;
  var display_data;
  var display_rgba;
  var display_text;
  var display_fg;
  var display_bg;
  var prepalette = new Uint32Array(256);
  var palette = new Uint32Array(256);
  var border_color = 0;
  var scale_canvas;

  function SetupDisplay(width, height, aspect, fheight) {
    if (!canvas) {
      return;
    }
    ctx = canvas.getContext('2d', { alpha: false });
    display = ctx.createImageData(width, height);
    display_rgba = new Uint32Array(display.data.buffer);
    display_data = new Uint32Array(display_rgba.length);
    if (!scale_canvas) {
      scale_canvas = document.createElement('canvas');
    }
    scale_canvas.width = width;
    scale_canvas.height = height;
    text_width = Math.floor(width / 8);
    text_height = Math.floor(height / fheight);
    display_text = new Uint8Array(text_width * text_height);
    display_fg = new Uint8Array(text_width * text_height);
    display_bg = new Uint8Array(text_width * text_height);
    border_color = 0;
    screen_aspect = aspect;
    font_height = fheight;
    var sctx = scale_canvas.getContext('2d', { alpha: false });
    font_data = CreateFont(sctx, font_height);
  }

  // Drawing and Console State
  var color_map;
  var fg_color = 7;
  var bg_color = 0;
  var default_fg_color = 7;
  var max_color = 15;
  var text_x = 0;
  var text_y = 0;
  var pen_x = 0;
  var pen_y = 0;

  // Input State
  var key_buffer = [];
  var ti_key_mode = 3;
  var input_string = '';
  var mouse_x = 0;
  var mouse_y = 0;
  var mouse_buttons = 0;
  var mouse_wheel = 0;
  var mouse_clip = 0;

  bindings.statement_getmouse_ooOOO = function() {
    bindings.Yield();
    return [mouse_x, mouse_y, mouse_wheel, mouse_buttons, mouse_clip];
  };

  bindings.Inkey = function() {
    bindings.Yield();
    if (key_buffer.length == 0) {
      return '';
    }
    var e = key_buffer.shift();
    return DecodeKey(e);
  };

  bindings.Point = function(x, y) {
    // TODO: Implement.
    return 0;
  };

  bindings.Peek = function(addr) {
    return 0;
  };

  function RGB(r, g, b) {
    return BLACK | r | (g << 8) | (b << 16);
  }

  const L = 0x55, M = 0xAA, H = 0xFF;
  const EGA16 = [
    RGB(0, 0, 0), RGB(0, 0, M), RGB(0, M, 0), RGB(0, M, M),
    RGB(M, 0, 0), RGB(M, 0, M), RGB(M, L, 0), RGB(M, M, M),
    RGB(L, L, L), RGB(L, L, H), RGB(L, H, L), RGB(L, H, H),
    RGB(H, L, L), RGB(H, L, H), RGB(H, H, L), RGB(H, H, H),
  ];
  const CGA1 = [
    [EGA16[0], EGA16[2], EGA16[4], EGA16[6]],
    [EGA16[0], EGA16[3], EGA16[5], EGA16[7]],
    [EGA16[0], EGA16[10], EGA16[12], EGA16[14]],
    [EGA16[0], EGA16[11], EGA16[13], EGA16[15]],
  ];
  const TI99 = [
    0, RGB(0x00, 0x00, 0x00),
    RGB(0x21, 0xC8, 0x42), RGB(0x5E, 0xDC, 0x78),
    RGB(0x54, 0x55, 0xED), RGB(0x7D, 0x76, 0xFC),
    RGB(0xD4, 0x52, 0x4D), RGB(0x42, 0xEB, 0xF5),
    RGB(0xFC, 0x55, 0x54), RGB(0xFF, 0x79, 0x78),
    RGB(0xD4, 0xC1, 0x54), RGB(0xE6, 0xCE, 0x80),
    RGB(0x21, 0xB0, 0x3B), RGB(0xC9, 0x5B, 0xBA),
    RGB(0xCC, 0xCC, 0xCC), RGB(0xFF, 0xFF, 0xFF),
  ];

  bindings.statement_screen_iIII = function(mode, cswitch, active, visual) {
    // TODO: Factor mode setup better.
    // TODO: Support pages.
    if (!canvas) {
      return;
    }
    if (mode == screen_mode) {
      return;
    }
    var monochrome = [BLACK, WHITE];
    var modes = {
      0: [640, 200, 2.4, 8, EGA16, 4],
      1: [320, 200, 1.2, 8, CGA1[1], 2],
      2: [640, 200, 2.4, 8, monochrome, 1],
      7: [320, 200, 1.2, 8, EGA16, 4],
      8: [640, 200, 2.4, 8, EGA16, 4],
      9: [640, 350, 480 / 350, 14, EGA16, 4],
      11: [640, 480, 1, 16, monochrome, 2],
      12: [640, 480, 1, 16, EGA16, 4],
      13: [320, 200, 1.2, 8, undefined, 24],
      14: [320, 240, 1, 16, undefined, 24],
      15: [400, 300, 1, 16, undefined, 24],
      16: [512, 384, 1, 16, undefined, 24],
      17: [640, 400, 1.2, 16, undefined, 24],
      18: [640, 480, 1, 16, undefined, 24],
      19: [800, 600, 1, 16, undefined, 24],
      20: [1024, 768, 1, 16, undefined, 24],
      21: [1280, 1024, 1, 16, undefined, 24],
      100: [256, 192, 1, 8, TI99, 6]
    };
    var m = modes[mode];
    if (m === undefined) {
      Error('Invalid mode ' + mode);
    }
    text_mode = mode == 0 || mode == 100;
    SetupDisplay(m[0], m[1], m[2], m[3]);
    color_map = m[4];
    screen_bpp = m[5];
    if (color_map === undefined || color_map.length == 16) {
      default_fg_color = 7;
    } else {
      default_fg_color = color_map.length - 1;
    }
    max_color = (1 << screen_bpp) - 1;
    fg_color = default_fg_color;
    bg_color = 0;
    if (color_map !== undefined) {
      for (var i = 0; i < 256; ++i) {
        prepalette[i] = i;
        palette[i] = color_map[i] | 0;
      }
    }
    screen_mode = mode;
    text_x = 0;
    text_y = mode == 100 ? text_height - 1 : 0;
    pen_x = display.width / 2;
    pen_y = display.height / 2;
    // TI default palette setup.
    if (mode == 100) {
      // TODO: Factor out by platform.
      bindings.call_screen_i(4);
      for (var i = 0; i < 32; i++) {
        bindings.call_color_iii(i, 2, 1);
      }
      bindings.call_clear_();
    } else {
      bindings.statement_cls_I(0);
    }
  }

  bindings.statement_width_iI = function(w, h) {
    // TODO: support height?
    if (screen_mode == 0 && (w == 80 || w == 40)) {
      SetupDisplay(w * 8, display.height, w == 80 ? 2.4 : 1.2, font_height);
    }
  };

  bindings.Halt = function() {
    console.log('=== BASIC END ===');
  };

  // TODO: Cleanup, this should be hidden.
  bindings.DrawChar = function(col, row, ch, fg, bg) {
    var ch = (ch & 0xff) >>> 0;
    var chpos = ch * font_height * 8;
    for (var y = 0; y < font_height; ++y) {
      var pos = col * 8 + (y + row * font_height) * display.width;
      for (var x = 0; x < 8; ++x) {
        display_data[pos++] = font_data[chpos++] ? fg : bg;
      }
    }
  };

  function SetChar(x, y, ch, fg, bg) {
    var pos = x + y * text_width;
    display_text[pos] = ch;
    display_fg[pos] = fg;
    display_bg[pos] = bg;
  }

  function SetTiChar(x, y, ch) {
    var bank = (ch >> 3) << 1;
    SetChar(x, y, ch, bank, bank + 1);
  }

  // TODO: Separate.
  bindings.call_screen_i = function(col) {
    palette[0] = TI99[col - 1];
    border_color = palette[0];
  };

  // TODO: Separate.
  bindings.call_clear_ = function() {
    if (screen_mode != 100) {
      bindings.statement_screen_iIII(100);
    }
    for (var j = 0; j < text_height; ++j) {
      for (var i = 0; i < text_width; ++i) {
        SetTiChar(i, j, 32);
      }
    }
  };

  // TODO: Separate.
  bindings.call_char_ii = function(ch, pattern) {
    pattern = (pattern + '0000000000000000').substr(0, 16);
    var chpos = ch * font_height * 8;
    for (var i = 0; i < 16; i++) {
      var code = parseInt(pattern.substr(i, 1), 16);
      for (var j = 0; j < 4; j++) {
        font_data[chpos++] = code & (0x8 >> j) ? 255 : 0;
      }
    }
  };

  function DecodeTiKeyPos(e) {
    const base_map = [
      '1234567890=',
      'qwertyuiop/',
      'asdfghjkl;\n',
      'zxcvbnm,.',
    ];
    for (var j = 0; j < base_map.length; j++) {
      for (var i = 0; i < base_map[j].length; ++i) {
        if (e.key == base_map[j][i]) {
          return [i, j, i < 5 ? 1 : 2];
        }
      }
    }
    return [-1, -1, -1];
  }

  function DecodeTiCtrl(ch) {
    if (ch.length != 1) {
      return -1;
    } else if (ch == '.') {
      return 27;
    } else if (ch == ';') {
      return 28;
    } else if (ch == '=') {
      return 29;
    } else if (ch == '8') {
      return 30;
    } else if (ch == '9') {
      return 31;
    }
    var k = ch.toUpperCase().charCodeAt(0);
    if (k >= 65 && k <= 90) {
      return k - 64;
    }
    return -1;
  }

  function DecodeTiFunction(e) {
    const map3 = [
      [3, 4, 7, 2, 14, 12, 1, 6, 15, -1, 5],
      [-1, -1, 11, -1, -1, -1, -1, -1, -1, -1, -1],
      [-1, 8, 9, -1, -1, -1, -1, -1, -1, -1, 13],
      [-1, 10, -1, -1, -1, -1, -1, -1, -1],
    ];
    // [col, row, side]
    var pos = DecodeTiKeyPos(e);
    if (pos[0] == -1) {
      return -1;
    }
    return map3[pos[1]][pos[0]];
  }

  function DecodeTiSide(e, side) {
    const map12 = [
      [19, 7, 8, 9, 10, 19, 7, 8, 9, 10, -1],
      [18, 4, 5, 6, 11, 18, 4, 5, 6, 11, 16],
      [1, 2, 3, 12, 17, 1, 2, 3, 12, 17, -1],
      [15, 0, 14, 13, 16, 15, 0, 14, 13],
    ];
    // [col, row, side]
    var pos = DecodeTiKeyPos(e);
    if (pos[0] == -1 || pos[2] != side) {
      return -1;
    }
    return map12[pos[1]][pos[0]];
  }

  // TODO: Separate.
  bindings.call_key_ioo = function(key_unit) {
    // TODO: Hold state better + allow sides to be independent.
    ti_key_mode = key_unit != 0 ? key_unit : ti_key_mode;
    bindings.Yield();
    if (key_buffer.length == 0) {
      return [-1, 0];
    }
    var e = key_buffer.shift();
    var state = e.repeat ? -1 : 1;

    if (ti_key_mode == 1 || ti_key_mode == 2) {
      var k = DecodeTiSide(e, ti_key_mode);
      if (k >= 0) {
        return [k, state];
      }
    } else if (ti_key_mode >= 3 && ti_key_mode <= 5) {
      if (e.key == 'Enter') {
        return [13, state];
      }
      if (e.altKey) {
        var k = DecodeTiFunction(e);
        if (k >= 0) {
          return [k + (ti_key_mode == 4 ? 128 : 0), state];
        }
      } else if (e.ctrlKey && ti_key_mode >= 4) {
        if (e.key == '/' && ti_key_mode == 5) {
          return [187, state];
        }
        var k = DecodeTiCtrl(e.key);
        if (k >= 0) {
          return [k + (ti_key_mode == 5 ? 128 : 0), state];
        }
      } else if (!e.altKey && !e.ctrlKey && e.key.length == 1) {
        var ch = ti_key_mode == 3 ? e.key.toUpperCase() : e.key;
        return [ch.charCodeAt(0), state];
      }
    }
    return [-1, 0];
  };

  // TODO: Separate.
  bindings.call_sound_iiiIIIIII = function(
    duration, f1, v1, f2, v2, f3, v3, f4, v4) {
    // TODO: Implement.
  };

  // TODO: Separate.
  bindings.call_color_iii = function(bank, fg, bg) {
    // Bank 1 is 32.
    bank += 3;
    prepalette[bank * 2 + 0] = fg - 1;
    prepalette[bank * 2 + 1] = bg - 1;
  };

  // TODO: Separate.
  bindings.call_hchar_iiiI = function(row, col, ch, n) {
    n = n === undefined ? 1 : n;
    row -= 1;
    col -= 1;
    if (n < 0) { Error('Bad value'); }
    for (var i = 0; i < n; i++) {
      SetTiChar(col, row, ch);
      ++col;
      if (col >= 32) {
        col = 0;
        ++row;
        if (row >= 24) {
          row = 0;
        }
      }
    }
  };

  // TODO: Separate.
  bindings.call_vchar_iiiI = function(row, col, ch, n) {
    n = n === undefined ? 1 : n;
    row -= 1;
    col -= 1;
    if (n < 0) { Error('Bad value'); }
    for (var i = 0; i < n; i++) {
      SetTiChar(col, row, ch);
      ++row;
      if (row >= 24) {
        row = 0;
        ++col;
        if (col >= 24) {
          col = 0;
        }
      }
    }
  };

  // TODO: Separate.
  bindings.call_gchar_iio = function(row, col) {
    row -= 1;
    col -= 1;
    return [display_text[col + row * text_width]];
  };

  function ScrollUp() {
    for (var j = 0; j < text_height - 1; ++j) {
      if (text_mode) {
        var pos = j * text_width;
        for (var i = 0; i < text_width; ++i) {
          display_text[i + pos] = display_text[i + pos + text_width];
          display_fg[i + pos] = display_fg[i + pos + text_width];
          display_bg[i + pos] = display_bg[i + pos + text_width];
        }
      } else {
        var pos = j * text_width * text_height;
        var offset = text_width * font_height * 8;
        for (var k = 0; k < font_height; ++k) {
          for (var i = 0; i < text_width; ++i) {
            display_data[i + pos] = display_data[i + pos + offset];
          }
        }
      }
    }
    if (text_mode) {
      var pos = (text_height - 1) * text_width;
      for (var i = 0; i < text_width; ++i) {
        display_text[i + pos] = 32;
        display_fg[i + pos] = fg_color;
        display_bg[i + pos] = bg_color;
      }
    } else {
      for (var i = 0; i < text_width; ++i) {
        bindings.DrawChar(i, text_height - 1, 32, fg_color, bg_color);
      }
    }
  }

  // TODO: Cleanup, this should be hidden.
  bindings.PutCh = function(ch) {
    if (ch === undefined) {
      if (text_mode) {
        var n = text_width - text_x;
        for (var i = 0; i < n; ++i) {
          bindings.PutCh(' ');
        }
        return;
      }
      text_x = 0;
      text_y++;
      return;
    }
    var code = ch.charCodeAt(0);
    if (screen_mode == 0) {
      // PC - text
      SetChar(text_x, text_y, code, fg_color, bg_color);
    } else if (screen_mode == 100) {
      // TI
      SetTiChar(text_x, text_y, code);
    } else {
      // PC - graphics
      bindings.DrawChar(text_x, text_y, code, fg_color, bg_color);
    }
    text_x++;
    if (text_x >= text_width) {
      text_y++;
      text_x = 0;
    }
    if (text_y >= text_height) {
      ScrollUp();
      --text_y;
    }
  };

  bindings.LineClear = function() {
    input_string = '';
  };

  bindings.LineValue = function() {
    return input_string;
  };

  bindings.LineInput = function() {
    while (key_buffer.length > 0) {
      const key = DecodeKey(key_buffer.shift());
      if (key == String.fromCharCode(13)) {
        --text_x;
        bindings.PutCh(' ');
        bindings.PutCh();
        return 0;
      }
      if (key == String.fromCharCode(8) && input_string.length > 0) {
        input_string = input_string.substr(0, input_string.length - 1);
        --text_x;
        bindings.PutCh(' ');
        text_x -= 2;
        bindings.PutCh(String.fromCharCode(219));
      }
      if (key.charCodeAt(0) >= 32 && key.charCodeAt(0) <= 126) {
        --text_x;
        bindings.PutCh(key);
        bindings.PutCh(String.fromCharCode(219));
        input_string += key;
      }
    }
    bindings.Yield();
    return -1;
  };

  function ColorFlip(c) {
    return BLACK |
      ((c & 0xff0000) >> 16) | ((c & 0xff) << 16) | (c & 0x00ff00);
  }

  bindings.statement_palette_ii = function(c, p) {
    var r = 85 * (((p >> 1) & 2) | (p >> 5) & 1);
    var g = 85 * ((p & 2) | (p >> 4) & 1);
    var b = 85 * (((p << 1) & 2) | (p >> 3) & 1);
    palette[c] = RGB(r, g, b);
  };

  bindings.statement_color_iII = function(fg, bg, border) {
    if (screen_mode == 0) {
      border_color = EGA16[border];
    }
    if (screen_mode == 2) {
      Error('Illegal function call');
      return;
    }
    if (screen_mode == 1) {
      if (fg !== undefined) {
        palette[0] = EGA16[fg & 15];
        border_color = palette[0];
      }
      if (bg !== undefined) {
        for (var i = 1; i < 4; ++i) {
          palette[i] = CGA1[bg & 3][i];
        }
      }
      return;
    }
    fg_color = fg === undefined ? default_fg_color : fg;
    if (screen_mode > 0) {
      bg_color = 0;
    } else {
      bg_color = bg === undefined ? 0 : bg;
    }
  };

  bindings.statement_locate_iiI = function(y, x, cursor) {
    // TODO: Support cursor?
    text_x = x - 1;
    text_y = y - 1;
    // Hack to yield more often (for NIBBLES.BAS)
    if (x == 1 && y == 1) {
      bindings.Yield();
    }
  };

  function Box(x1, y1, x2, y2, c) {
    x1 = x1 | 0;
    y1 = y1 | 0;
    x2 = x2 | 0;
    y2 = y2 | 0;
    c = c | 0;
    if (x1 > x2) {
      var t = x2;
      x2 = x1;
      x1 = t;
    }
    if (y1 > y2) {
      var t = y2;
      y2 = y1;
      y1 = t;
    }
    if (x1 >= display.width ||
        y1 >= display.height ||
        x2 < 0 || y2 < 0) {
      return;
    }
    if (x1 < 0) x1 = 0;
    if (x2 > display.width - 1) x2 = display.width - 1;
    if (y1 < 0) y1 = 0;
    if (y2 > display.height - 1) y2 = display.height - 1;
    for (var y = y1; y <= y2; ++y) {
      var pos = x1 + y * display.width;
      for (var x = x1; x <= x2; ++x) {
        display_data[pos++] = c;
      }
    }
  }

  function RawLine(x1, y1, x2, y2, c) {
    x1 = x1 | 0;
    y1 = y1 | 0;
    x2 = x2 | 0;
    y2 = y2 | 0;
    if (x1 == x2 || y1 == y2) {
      Box(x1, y1, x2, y2, c);
      return;
    }
    if (Math.abs(x1 - x2) > Math.abs(y1 - y2)) {
      if (x1 > x2) {
        var tmp;
        tmp = x1; x1 = x2; x2 = tmp;
        tmp = y1; y1 = y2; y2 = tmp;
      }
      for (var x = x1; x <= x2; ++x) {
        var t = (x - x1) / (x2 - x1);
        var y = y1 + Math.floor(t * (y2 - y1));
        Box(x, y, x, y, c);
      }
    } else {
      if (y1 > y2) {
        var tmp;
        tmp = x1; x1 = x2; x2 = tmp;
        tmp = y1; y1 = y2; y2 = tmp;
      }
      for (var y = y1; y <= y2; ++y) {
        var t = (y - y1) / (y2 - y1);
        var x = x1 + Math.floor(t * (x2 - x1));
        Box(x, y, x, y, c);
      }
    }
  }

  // Not bound direct otherwise would be statement_line_PdpIS.
  bindings.Line = function(x1, y1, x2, y2, c, fill) {
    c = c === undefined ? default_fg_color : (c & max_color);
    if (x1 === undefined) {
      x1 = pen_x;
      y1 = pen_y;
    }
    if (fill == 'bf') {
      Box(x1, y1, x2, y2, c);
    } else if (fill == 'b') {
      Box(x1, y1, x2, y1, c);
      Box(x1, y2, x2, y2, c);
      Box(x1, y1, x1, y2, c);
      Box(x2, y1, x2, y2, c);
    } else {
      RawLine(x1, y1, x2, y2, c);
    }
  };

  bindings.statement_cls_I = function(mode) {
    if (screen_mode == 100) {
      for (var j = 0; j < text_height; ++j) {
        for (var i = 0; i < text_width; ++i) {
          SetTiChar(i, j, 32);
        }
      }
    } else if (text_mode) {
      for (var j = 0; j < text_height; ++j) {
        for (var i = 0; i < text_width; ++i) {
          SetChar(i, j, 32, fg_color, bg_color);
        }
      }
    } else {
      Box(0, 0, display.width, display.height, bg_color);
    }
    text_x = 0;
    text_y = 0;
  };

  bindings.statement_pset_pI = function(x, y, c) {
    c = c === undefined ? default_fg_color : (c & max_color);
    display_data[x + y * display.width] = c;
    pen_x = x;
    pen_y = y;
  }

  bindings.statement_preset_pI = function(x, y, c) {
    c = c === undefined ? 0 : (c & max_color);
    display_data[x + y * display.width] = c;
    pen_x = x;
    pen_y = y;
  }

  bindings.statement_sound_ii = function(freq, duration) {
    // TODO: implement.
  };

  bindings.statement_play_i = function(cmds) {
    // TODO: implement.
  };

  function Paint(x, y, r, c, start, end, aspect, fill) {
    c = c === undefined ? default_fg_color : (c & max_color);
    start = start === undefined ? 0 : start;
    end = end == undefined ? Math.PI * 2 : end;
    x += 0.5;
    y += 0.5;
    var complete = false;
    if (start < 0) { start = -start; complete = true; }
    if (end < 0) { end = -end; complete = true; }
    if (end < start) {
      end += Math.PI * 2;
    }
    var rx, ry;
    if (aspect == null) {
      rx = r;
      ry = r / screen_aspect;
    } else if (aspect > 1) {
      rx = r / aspect;
      ry = r;
    } else {
      rx = r;
      ry = r * aspect;
    }
    var oxx = x + Math.cos(start) * rx;
    var oyy = y - Math.sin(start) * ry;
    if (complete) {
      RawLine(x, y, oxx, oyy, c);
    }
    for (var ang = start; ang <= end; ang += 0.03) {
      var xx = x + Math.cos(ang) * rx;
      var yy = y - Math.sin(ang) * ry;
      if (ang == start) { oxx = xx; oyy = yy; }
      RawLine(oxx, oyy, xx, yy, c);
      oxx = xx;
      oyy = yy;
    }
    if (complete) {
      RawLine(x, y, xx, yy, c);
    }
    if (fill && start == 0 && end == Math.PI * 2) {
      bindings.statement_paint_pII(x, y, c, c);
    }
  }
  bindings.statement_circle_piIIIIS = Paint;

  bindings.statement_get_pdpv = function(x1, y1, x2, y2, buffer, offset) {
    x1 = x1 | 0;
    y1 = y1 | 0;
    x2 = x2 | 0;
    y2 = y2 | 0;
    var d16 = new Uint16Array(buffer);
    if (screen_bpp <= 2) {
      d16[(offset >> 1) + 0] = (x2 - x1 + 1) * screen_bpp;
    } else {
      d16[(offset >> 1) + 0] = (x2 - x1 + 1);
    }
    d16[(offset >> 1) + 1] = y2 - y1 + 1;
    var d = new Uint8Array(buffer);
    var src = display_data;
    if (screen_bpp > 8) {
      var dstpos = offset + 4;
      for (var y = y1; y <= y2; ++y) {
        var srcpos = x1 + y * display.width;
        for (var x = x1; x <= x2; ++x) {
          var v = src[srcpos++];
          d[dstpos++] = v;
          d[dstpos++] = (v >> 8);
          d[dstpos++] = (v >> 16);
        }
      }
    } else {
      var dstpos = offset + 4;
      var shift = 8;
      var v = 0;
      for (var y = y1; y <= y2; ++y) {
        var srcpos = x1 + y * display.width;
        for (var x = x1; x <= x2; ++x) {
          shift -= screen_bpp;
          var cc = src[srcpos++];
          v |= (cc << shift);
          if (shift == 0) {
            d[dstpos++] = v;
            v = 0;
            shift = 8;
          }
        }
        if (shift != 8) {
          d[dstpos++] = v;
          v = 0;
          shift = 8;
        }
      }
    }
  };

  bindings.statement_put_pvS = function(x1, y1, buffer, offset, mode) {
    x1 = x1 | 0;
    y1 = y1 | 0;
    mode = mode === undefined ? 'xor' : mode;
    var s16 = new Uint16Array(buffer);
    var x2;
    if (screen_bpp <= 2) {
      x2 = x1 + (s16[(offset >> 1) + 0] / screen_bpp) - 1;
    } else {
      x2 = x1 + s16[(offset >> 1)] - 1;
    }
    var y2 = y1 + s16[(offset >> 1) + 1] - 1;
    var s = new Uint8Array(buffer);
    var dst = display_data;
    if (screen_bpp > 8) {
      var srcpos = offset + 4;
      for (var y = y1; y <= y2; ++y) {
        var dstpos = x1 + y * display.width;
        for (var x = x1; x <= x2; ++x) {
          var v = s[srcpos] | (s[srcpos + 1] << 8) | (s[srcpos + 2] << 16);
          srcpos += 3;
          // TODO: Optimize
          if (x < 0 || x >= display.width || y < 0 || y >= display.height) {
            dstpos++;
            continue;
          }
          if (mode == 'xor') {
            dst[dstpos++] = (dst[dstpos] ^ v) | BLACK;
          } else if (mode == 'preset') {
            dst[dstpos++] = (~v) | BLACK;
          } else if (mode == 'and') {
            dst[dstpos++] = (dst[dstpos] & v) | BLACK;
          } else if (mode == 'or') {
            dst[dstpos++] = (dst[dstpos] | v) | BLACK;
          } else {
            dst[dstpos++] = v | BLACK;
          }
        }
      }
    } else {
      var srcpos = offset + 4;
      var mask = (1 << screen_bpp) - 1;
      for (var y = y1; y <= y2; ++y) {
        var dstpos = x1 + y * display.width;
        var v = 0;
        var shift = 8;
        for (var x = x1; x <= x2; ++x) {
          if (shift == 8) {
            v = s[srcpos++];
          }
          shift -= screen_bpp;
          var cc = (v >> shift) & mask;
          var old = dst[dstpos] | 0;
          if (mode == 'xor') {
            cc ^= old;
          } else if (mode == 'preset') {
            cc = cc ^ mask;
          } else if (mode == 'and') {
            cc &= old;
          } else if (mode == 'or') {
            cc |= old;
          }
          // TODO: Optimize
          if (y >= 0 && y < display.height && x >= 0 && x < display.width) {
            dst[dstpos++] = cc;
          } else {
            dstpos++;
          }
          if (shift == 0) {
            shift = 8;
          }
        }
      }
    }
  };

  var draw_state = {
    noplot: false,
    nomove: false,
    angle: 0,
    turn_angle: 0,
    color: undefined,
    scale: 1,
  };

  function StepUnscaled(dx, dy) {
    if (!draw_state.noplot) {
      bindings.Line(
        pen_x, pen_y, pen_x + dx, pen_y + dy, draw_state.color, 0);
    }
    if (!draw_state.nomove) {
      pen_x += dx;
      pen_y += dy;
    }
    draw_state.noplot = false;
    draw_state.nomove = false;
  }

  function Step(dx, dy) {
    StepUnscaled(dx * draw_state.scale, dy * draw_state.scale);
  }

  bindings.statement_draw_i = function(cmds) {
    cmds = cmds.toLowerCase();
    var m;
    while (cmds.length) {
      if (m = cmds.match(/^(u|d|l|r|e|f|g|h|a|ta|c|s)([0-9]+)?/)) {
        var op = m[1];
        var n = m[2] == '' ? 1 : parseInt(m[2]);
        if (op == 'c') {
          draw_state.color = n & max_color;
        } else if (op == 'a') {
          draw_state.angle = n;
          // TODO: Implement.
        } else if (op == 'ta') {
          draw_state.turn_angle = n;
          // TODO: Implement.
        } else if (op == 's') {
          draw_state.scale = n / 4;
        } else if (op == 'u') {
          Step(0, -n);
        } else if (op == 'd') {
          Step(0, n);
        } else if (op == 'l') {
          Step(-n, 0);
        } else if (op == 'r') {
          Step(n, 0);
        } else if (op == 'e') {
          Step(n, -n);
        } else if (op == 'f') {
          Step(n, n);
        } else if (op == 'g') {
          Step(-n, n);
        } else if (op == 'h') {
          Step(-n, -n);
        }
      } else if (m = cmds.match(/^(m)([+-]?)([0-9]+)[,]([+-]?[0-9]+)/)) {
        var op = m[1];
        var sx = m[2];
        var x = parseInt(m[3]);
        var y = parseInt(m[4]);
        if (sx) {
          x = parseInt(sx + '1') * x;
          Step(x, y);
        } else {
          StepUnscaled(x - pen_x, y - pen_y);
        }
      } else if (m = cmds.match(/^(p)([0-9]+),([0-9]+1)/)) {
        var op = m[1];
        var x = parseInt(m[2]);
        var y = parseInt(m[3]);
        // TODO: Implement.
      } else if (m = cmds.match(/^(b|n)/)) {
        var op = m[1];
        if (op == 'b') {
          draw_state.noplot = true;
        } else if (op == 'n') {
          draw_state.nomove = true;
        }
      } else {
        Error('Bad drop op: ' + cmds);
      }
      cmds = cmds.substr(m[0].length);
    }
  };

  bindings.statement_paint_pII = function(x, y, paint, border) {
    if (paint === undefined) {
      paint = default_fg_color;
    }
    if (border === undefined) {
      border = paint;
    }
    paint = paint & max_color;
    border = border & max_color;
    var data = display_data;
    var pending = [];
    pending.push([Math.floor(x), Math.floor(y)]);
    while (pending.length) {
      var p = pending.pop();
      if (p[0] < 0 || p[0] >= display.width ||
          p[1] < 0 || p[1] >= display.height) {
        continue;
      }
      var pos = p[0] + p[1] * display.width;
      if ((data[pos] | 0) == border ||
          (data[pos] | 0) == paint) {
        continue;
      }
      data[pos] = paint;
      pending.push([p[0] - 1, p[1]]);
      pending.push([p[0] + 1, p[1]]);
      pending.push([p[0], p[1] - 1]);
      pending.push([p[0], p[1] + 1]);
    }
  };

  var viewport_x, viewport_y;
  var viewport_w, viewport_h;
  var border_x, border_y;
  var border_w, border_h;

  function Resize() {
    if (canvas.fromWWWBasic) {
      canvas.width = window.innerWidth;
      canvas.height = window.innerHeight;
    }
    var raspect = canvas.width / canvas.height;
    var aspect = display.width / (display.height * screen_aspect);
    const non_border = 0.9;
    if (raspect > aspect) {
      border_w = Math.floor(
        display.width * canvas.height / (display.height * screen_aspect));
      border_h = canvas.height;
    } else {
      border_w = canvas.width;
      border_h = Math.floor(
        (display.height * screen_aspect) * canvas.width / display.width);
    }
    border_x = Math.floor((canvas.width - border_w) / 2);
    border_y = Math.floor((canvas.height - border_h) / 2);
    viewport_w = Math.floor(border_w * non_border);
    viewport_h = Math.floor(border_h * non_border);
    viewport_x = Math.floor((canvas.width - viewport_w) / 2);
    viewport_y = Math.floor((canvas.height - viewport_h) / 2);
  }

  function RenderTextMode() {
    if (!text_mode) {
      return;
    }
    var pos = 0;
    for (var j = 0; j < text_height; ++j) {
      for (var i = 0; i < text_width; ++i) {
        var ch = display_text[pos];
        var fg = display_fg[pos];
        var bg = display_bg[pos];
        bindings.DrawChar(i, j, ch, fg, bg);
        ++pos;
      }
    }
  }

  function TranslatePalette() {
    var sz = display_rgba.length;
    if (screen_bpp < 24) {
      for (var i = 0; i < sz; ++i) {
        display_rgba[i] = palette[prepalette[display_data[i]]];
      }
    } else {
      for (var i = 0; i < sz; ++i) {
        display_rgba[i] = ColorFlip(display_data[i]);
      }
    }
  }

  function ToHex(c) {
    c = ColorFlip(c) & 0xffffff;
    var ret = c.toString(16);
    while (ret.length < 6) {
      ret = '0' + ret;
    }
    return '#' + ret;
  }

  function Render() {
    if (!canvas) {
      return;
    }
    var scale_ctx = scale_canvas.getContext('2d');
    RenderTextMode();
    TranslatePalette();
    scale_ctx.putImageData(display, 0, 0);
    var ctx = canvas.getContext('2d');
    ctx.fillStyle = '#111';
    ctx.fillRect(0, 0, canvas.width, canvas.height);
    ctx.fillStyle = ToHex(border_color);
    ctx.fillRect(border_x, border_y, border_w, border_h);
    //      ctx.imageSmoothingQuality = 'low';
    //      ctx.imageSmoothingEnabled = false;
    ctx.drawImage(scale_canvas, viewport_x, viewport_y,
      viewport_w, viewport_h);
    requestAnimationFrame(Render);
  }

  // Decode PC Keycode.
  function DecodeKey(e) {
    function RegularKey(n) {
      return String.fromCharCode(n);
    }

    function ExtendedKey(n) {
      return String.fromCharCode(0) + String.fromCharCode(n);
    }

    const SIMPLE_KEYMAP = {
      // BACKSPACE, ENTER, ESCAPE
      8: { regular: 8 }, 13: { regular: 13 }, 27: { regular: 27 },
      // INS, DEL
      45: { regular: 82 }, 46: { regular: 83 },
      // LEFT, RIGHT
      37: { extended: 75 }, 39: { extended: 77 },
      // UP, DOWN
      38: { extended: 72 }, 40: { extended: 80 },
      // PGUP, PGDN
      33: { extended: 73 }, 34: { extended: 81 },
      // HOME, END
      36: { extended: 71 }, 35: { extended: 79 },
    };
    if (e.keyCode >= 112 && e.keyCode <= 123) {
      // F1 - F10
      if (e.altKey) {
        return ExtendedKey(e.keyCode - 112 + 104);
      } else if (e.ctrlKey) {
        return ExtendedKey(e.keyCode - 112 + 94);
      } else if (e.shiftKey) {
        return ExtendedKey(e.keyCode - 112 + 84);
      } else {
        return ExtendedKey(e.keyCode - 112 + 59);
      }
    } else if (e.keyCode == 9) {
      // TAB, Shift-TAB
      if (e.shiftKey) {
        return RegularKey(15);
      } else {
        return RegularKey(9);
      }
    } else if (SIMPLE_KEYMAP[e.keyCode]) {
      if (SIMPLE_KEYMAP[e.keyCode].regular) {
        return RegularKey(SIMPLE_KEYMAP[e.keyCode].regular);
      } else {
        return ExtendedKey(SIMPLE_KEYMAP[e.keyCode].extended);
      }
    } else if (e.ctrlKey && e.keyCode >= 65 && e.keyCode <= 90) {
      // Ctrl-A to Ctrl-Z
      return RegularKey(e.keyCode - 65 + 1);
    } else if (e.altKey) {
      const ch = String.fromCharCode(e.keyCode);
      const row1 = '1234567890-='.indexOf(ch);
      const row2 = 'QWERTYUIOP'.indexOf(ch);
      const row3 = 'ASDFGHJKL'.indexOf(ch);
      const row4 = 'ZXCVBNM'.indexOf(ch);
      if (row1 >= 0) {
        return ExtendedKey(row1 + 120);
      } else if (row2 >= 0) {
        return ExtendedKey(row2 + 16);
      } else if (row3 >= 0) {
        return ExtendedKey(row3 + 30);
      } else if (row4 >= 0) {
        return ExtendedKey(row4 + 44);
      }
    } else {
      const code = e.key.charCodeAt(0);
      if (e.key.length == 1 && code >= 32 && code <= 126) {
        return RegularKey(code);
      }
    }
    return '';
  }

  function InitEvents() {
    if (!canvas) {
      return;
    }
    Resize();
    if (canvas.fromWWWBasic) {
      window.addEventListener('resize', Resize, false);
    }
    window.addEventListener('keydown', function(e) {
      key_buffer.push(e);
      if (canvas.fromWWWBasic && (!e.ctrlKey || !e.shiftKey)) {
        e.preventDefault();
      }
    }, false);
    canvas.addEventListener('mousemove', function(e) {
      // TODO: Generalize for non-fullscreen.
      //var rect = canvas.getBoundingClientRect();
      var rect = {left: 0, top: 0};
      mouse_x = Math.floor(
        (e.clientX - rect.left - viewport_x) * display.width / viewport_w);
      mouse_y = Math.floor(
        (e.clientY - rect.top - viewport_y) * display.height / viewport_h);
    }, false);
    canvas.addEventListener('touchmove', function(e) {
      var touch = e.touches.item(0);
      const evt = new Event('mousemove');
      evt.clientX = touch.clientX;
      evt.clientY = touch.clientY;
      canvas.dispatchEvent(evt);
    }, false);
    canvas.addEventListener('mousedown', function(e) {
      mouse_buttons = 1;
    }, false);
    canvas.addEventListener('touchstart', function(e) {
      canvas.dispatchEvent(new Event('mousedown'));
    }, false);
    canvas.addEventListener('mouseup', function(e) {
      mouse_buttons = 0;
    }, false);
    canvas.addEventListener('touchend', function(e) {
      canvas.dispatchEvent(new Event('mouseup'));
    }, false)
    // TODO: Implement Mouse Wheel!
    // TODO: Implement Mouse Clip!
  }

  bindings.Pace = function() {
    if ((screen_mode > 0 && screen_mode <= 2) || screen_mode == 100) {
      return 2;
    } else {
      return 100000;
    }
  };

  function CreateFont(ctx, height) {
    function RenderFont(ctx, height) {
      const CHARSET =
        '\u0020\u263a\u263b\u2665\u2666\u2663\u2660\u2022' +
        '\u25d8\u25cb\u25d9\u2642\u2640\u266a\u266b\u263c' +
        '\u25ba\u25c4\u2195\u203c\u00b6\u00a7\u25ac\u21a8' +
        '\u2191\u2193\u2192\u2190\u221f\u2194\u25b2\u25bc' +
        '\u0020\u0021\u0022\u0023\u0024\u0025\u0026\u0027' +
        '\u0028\u0029\u002a\u002b\u002c\u002d\u002e\u002f' +
        '\u0030\u0031\u0032\u0033\u0034\u0035\u0036\u0037' +
        '\u0038\u0039\u003a\u003b\u003c\u003d\u003e\u003f' +
        '\u0040\u0041\u0042\u0043\u0044\u0045\u0046\u0047' +
        '\u0048\u0049\u004a\u004b\u004c\u004d\u004e\u004f' +
        '\u0050\u0051\u0052\u0053\u0054\u0055\u0056\u0057' +
        '\u0058\u0059\u005a\u005b\u005c\u005d\u005e\u005f' +
        '\u0060\u0061\u0062\u0063\u0064\u0065\u0066\u0067' +
        '\u0068\u0069\u006a\u006b\u006c\u006d\u006e\u006f' +
        '\u0070\u0071\u0072\u0073\u0074\u0075\u0076\u0077' +
        '\u0078\u0079\u007a\u007b\u007c\u007d\u007e\u2302' +
        '\u00c7\u00fc\u00e9\u00e2\u00e4\u00e0\u00e5\u00e7' +
        '\u00ea\u00eb\u00e8\u00ef\u00ee\u00ec\u00c4\u00c5' +
        '\u00c9\u00e6\u00c6\u00f4\u00f6\u00f2\u00fb\u00f9' +
        '\u00ff\u00d6\u00dc\u00a2\u00a3\u00a5\u20a7\u0192' +
        '\u00e1\u00ed\u00f3\u00fa\u00f1\u00d1\u00aa\u00ba' +
        '\u00bf\u2310\u00ac\u00bd\u00bc\u00a1\u00ab\u00bb' +
        '\u2591\u2592\u2593\u2502\u2524\u2561\u2562\u2556' +
        '\u2555\u2563\u2551\u2557\u255d\u255c\u255b\u2510' +
        '\u2514\u2534\u252c\u251c\u2500\u253c\u255e\u255f' +
        '\u255a\u2554\u2569\u2566\u2560\u2550\u256c\u2567' +
        '\u2568\u2564\u2565\u2559\u2558\u2552\u2553\u256b' +
        '\u256a\u2518\u250c\u2588\u0020\u258c\u2590\u2580' +
        '\u03b1\u00df\u0393\u03c0\u03a3\u03c3\u00b5\u03c4' +
        '\u03a6\u0398\u03a9\u03b4\u221e\u03c6\u03b5\u2229' +
        '\u2261\u00b1\u2265\u2264\u2320\u2321\u00f7\u2248' +
        '\u00b0\u2219\u00b7\u221a\u207f\u00b2\u25a0\u0020';
      var data = new Uint8Array(256 * 8 * height);
      var pos = 0;
      for (var i = 0; i < 256; ++i) {
        ctx.fillStyle = '#000';
        ctx.fillRect(0, 0, 16, 32);
        ctx.textBaseline = 'top';
        ctx.font = 'bold 16px monospace';
        ctx.save();
        ctx.scale(1, height / 16);
        ctx.fillStyle = '#fff';
        ctx.fillText(CHARSET.charAt(i), 0, 0);
        ctx.restore();
        var pix = ctx.getImageData(0, 0, 8, height);
        var pdata = pix.data;
        for (var j = 0; j < pdata.length; j += 4) {
          var level = pdata[j] * 0.1140 +
            pdata[j + 1] * 0.5870 +
            pdata[j + 2] * 0.2989;
          data[pos++] = level > 128 ? 255 : 0;
        }
      }
      return data;
    }

    function LoadFont(s, dup) {
      var data = new Uint8Array(s.length * dup);
      var pos = 0;
      for (var i = 0; i < 256; ++i) {
        var row = Math.floor(i / 8);
        var col = i % 8;
        for (var y = 0; y < 8; ++y) {
          for (var d = 0; d < dup; ++d) {
            for (var x = 0; x < 8; ++x) {
              data[pos++] = s[x + y * 8 * 8 + col * 8 + row * 64 * 8]
                != ' ' ? 255 : 0;
            }
          }
        }
      }
      return data;
    }

    var FONT8 =
      'x     x   XXX     XXX   xx   xx x     x                         ' +
      '         X   X   XXXXX                                          ' +
      '        X X X X XX X XX            x                            ' +
      '        X     X XXXXXXX                                         ' +
      '        X XXX X XX   XX                                         ' +
      '         X   X   XXXXX                                          ' +
      'x     x   XXX     XXX   xx   xx x     x                         ' +
      '                                                                ' +

      'XXXXXXX XXXXXXX XXXXXXX XXXXXXX XXXXXXX XXXXXXX XXXXXXX XXXXXXX ' +
      'XXXXXXX XXXXXXX XXXXXXX XXXXXXX XXXXXXX XXXXXXX XXXXXXX XXXXXXX ' +
      'XXXXXXX XXXXXXX XXXXXXX XXXXXXX XXXXXXX XXXXXXX XXXXXXX XXXXXXX ' +
      'XXXXXXX XXXXXXX XXXXXXX XXXXXXX XXXXXXX XXXXXXX XXXXXXX XXXXXXX ' +
      'XXXXXXX XXXXXXX XXXXXXX XXXXXXX XXXXXXX XXXXXXX XXXXXXX XXXXXXX ' +
      'XXXXXXX XXXXXXX XXXXXXX XXXXXXX XXXXXXX XXXXXXX XXXXXXX XXXXXXX ' +
      'XXXXXXX XXXXXXX XXXXXXX XXXXXXX XXXXXXX XXXXXXX XXXXXXX XXXXXXX ' +
      '                                                                ' +

      'XXXXXXX XXXXXXX XXXXXXX XXXXXXX XXXXXXX XXXXXXX XXXXXXX XXXXXXX ' +
      'XXXXXXX XXXXXXX XXXXXXX XXXXXXX XXXXXXX XXXXXXX XXXXXXX XXXXXXX ' +
      'XXXXXXX XXXXXXX XXXXXXX XXXXXXX XXXXXXX XXXXXXX XXXXXXX XXXXXXX ' +
      'XXXXXXX XXXXXXX XXXXXXX XXXXXXX XXXXXXX XXXXXXX XXXXXXX XXXXXXX ' +
      'XXXXXXX XXXXXXX XXXXXXX XXXXXXX XXXXXXX XXXXXXX XXXXXXX XXXXXXX ' +
      'XXXXXXX XXXXXXX XXXXXXX XXXXXXX XXXXXXX XXXXXXX XXXXXXX XXXXXXX ' +
      'XXXXXXX XXXXXXX XXXXXXX XXXXXXX XXXXXXX XXXXXXX XXXXXXX XXXXXXX ' +
      '                                                                ' +

      '   X       X                    XXXXXXX XXXXXXX XXXXXXX XXXXXXX ' +
      '  XXX      X        X     X     XXXXXXX XXXXXXX XXXXXXX XXXXXXX ' +
      ' XXXXX     X        XX   XX     XXXXXXX XXXXXXX XXXXXXX XXXXXXX ' +
      '   X       X    XXXXXXX XXXXXXX XXXXXXX XXXXXXX XXXXXXX XXXXXXX ' +
      '   X     XXXXX      XX   XX     XXXXXXX XXXXXXX XXXXXXX XXXXXXX ' +
      '   X      XXX       X     X     XXXXXXX XXXXXXX XXXXXXX XXXXXXX ' +
      '   X       X                    XXXXXXX XXXXXXX XXXXXXX XXXXXXX ' +
      '                                                                ' +

      '           XX    XX XX   XX XX   XX XX  XX       XXX       XX   ' +
      '           XX    XX XX   XX XX  XXXXXXX XX  XX  XX XX      XX   ' +
      '           XX           XXXXXXX XX         XX    XXX            ' +
      '           XX            XX XX   XXXXX    XX    XXXX XX         ' +
      '           XX           XXXXXXX      XX  XX     XX XXX          ' +
      '                         XX XX  XXXXXXX XX  XX  XX XXX          ' +
      '           XX            XX XX   XX XX      XX   XXX XX         ' +
      '                                                                ' +

      '   XX     XX                                                    ' +
      '  XX       XX   XX X XX   XX                                 XX ' +
      ' XX         XX    XXX     XX                                XX  ' +
      ' XX         XX  XXXXXXX XXXXXX           XXXXX             XX   ' +
      ' XX         XX    XXX     XX                              XX    ' +
      '  XX       XX   XX X XX   XX       XX                    XX     ' +
      '   XX     XX                       XX              XX   XX      ' +
      '                                  XX               XX           ' +

      ' XXXXX     XX    XXXXX   XXXXX  XX  XX  XXXXXXX  XXXXX  XXXXXXX ' +
      'XX  XXX   XXX   XX   XX XX   XX XX  XX  XX      XX   XX      XX ' +
      'XX XXXX  XXXX        XX      XX XX  XX  XX      XX          XX  ' +
      'XXXX XX    XX      XXX    XXXX  XXXXXXX  XXXXX  XXXXXX     XX   ' +
      'XX   XX    XX    XXX         XX     XX       XX XX   XX   XX    ' +
      'XX   XX    XX   XX      XX   XX     XX  XX   XX XX   XX   XX    ' +
      ' XXXXX  XXXXXXX XXXXXXX  XXXXX      XX   XXXXX   XXXXX    XX    ' +
      '                                                                ' +

      ' XXXXX   XXXXX                                           XXXXX  ' +
      'XX   XX XX   XX    XX      XX       XXX         XXX     XX   XX ' +
      'XX   XX XX   XX    XX      XX     XXX   XXXXXXX   XXX   XX   XX ' +
      ' XXXXX   XXXXXX                 XXX                 XXX     XX  ' +
      'XX   XX      XX    XX      XX     XXX   XXXXXXX   XXX      XX   ' +
      'XX   XX XX   XX    XX      XX       XXX         XXX             ' +
      ' XXXXX   XXXXX            XX                               XX   ' +
      '                                                                ' +

      ' XXXXX    XXX   XXXXXX   XXXXXX XXXXXX  XXXXXXX XXXXXXX  XXXXX  ' +
      'XX  XXX  XX XX  XX   XX XX      XX   XX XX      XX      XX   XX ' +
      'XX XXXX XX   XX XX   XX XX      XX   XX XX      XX      XX      ' +
      'XX XXXX XXXXXXX XXXXXX  XX      XX   XX XXXXX   XXXXX   XX XXXX ' +
      'XX  XXX XX   XX XX   XX XX      XX   XX XX      XX      XX   XX ' +
      'XX      XX   XX XX   XX XX      XX   XX XX      XX      XX   XX ' +
      ' XXXXX  XX   XX XXXXXX   XXXXXX XXXXXX  XXXXXXX XX       XXXXX  ' +
      '                                                                ' +

      'XX   XX XXXXXXX      XX XX   XX XX      XX   XX XX   XX  XXXXX  ' +
      'XX   XX   XXX        XX XX  XX  XX      XXX XXX XXX  XX XX   XX ' +
      'XX   XX   XXX        XX XX XX   XX      XXXXXXX XXXX XX XX   XX ' +
      'XXXXXXX   XXX        XX XXXX    XX      XX X XX XXXXXXX XX   XX ' +
      'XX   XX   XXX   XX   XX XX XX   XX      XX   XX XX XXXX XX   XX ' +
      'XX   XX   XXX   XX   XX XX  XX  XX      XX   XX XX  XXX XX   XX ' +
      'XX   XX XXXXXXX  XXXXX  XX   XX XXXXXXX XX   XX XX   XX  XXXXX  ' +
      '                                                                ' +

      'XXXXXX   XXXXX  XXXXXX   XXXXX  XXXXXXX XX   XX XX   XX XX   XX ' +
      'XX   XX XX   XX XX   XX XX   XX   XXX   XX   XX XX   XX XX   XX ' +
      'XX   XX XX   XX XX   XX XX        XXX   XX   XX XX   XX XX   XX ' +
      'XXXXXX  XX   XX XXXXXX   XXXXX    XXX   XX   XX XX   XX XX   XX ' +
      'XX      XXXX XX XX   XX      XX   XXX   XX   XX XX   XX XX X XX ' +
      'XX      XX XXX  XX   XX XX   XX   XXX   XX   XX  XX XX  XX X XX ' +
      'XX       XXX XX XX   XX  XXXXX    XXX    XXXXX    XXX    XX XX  ' +
      '                                                                ' +

      'XX   XX XX   XX XXXXXXX  XXXXX           XXXXX     XX           ' +
      'XX   XX XX   XX      XX  XX     XX          XX    XXXX          ' +
      ' XX XX   XX XX      XX   XX      XX         XX   XX  XX         ' +
      '  XXX     XXX     XXX    XX       XX        XX                  ' +
      ' XX XX    XXX    XX      XX        XX       XX                  ' +
      'XX   XX   XXX   XX       XX         XX      XX                  ' +
      'XX   XX   XXX   XXXXXXX  XXXXX       XX  XXXXX                  ' +
      '                                                        XXXXXXX ' +

      '  XX            XX                   XX            XXXX         ' +
      '   XX           XX                   XX           XX            ' +
      '         XXXXXX XX       XXXXX       XX  XXXX     XX     XXXXX  ' +
      '        XX   XX XXXXXX  XX       XXXXXX XX  XX  XXXXXXX XX   XX ' +
      '        XX   XX XX   XX XX      XX   XX XXXXXX    XX    XX   XX ' +
      '        XX   XX XX   XX XX      XX   XX XX        XX     XXXXXX ' +
      '         XXXXXX XXXXXX   XXXXX   XXXXXX  XXXXX    XX         XX ' +
      '                                                         XXXXX  ' +

      'XX        XX       XX   XX        XXX                           ' +
      'XX                      XX   XX    XX                           ' +
      'XXXXXX   XXX      XXXX  XX  XX     XX   XXXXXX  XXXXXX   XXXXX  ' +
      'XX   XX   XX        XX  XXXXX      XX   XX X XX XX   XX XX   XX ' +
      'XX   XX   XX        XX  XX  XX     XX   XX X XX XX   XX XX   XX ' +
      'XX   XX   XX        XX  XX   XX    XX   XX X XX XX   XX XX   XX ' +
      'XX   XX  XXXX       XX  XX   XX   XXXX  XX X XX XX   XX  XXXXX  ' +
      '                  XXX                                           ' +

      '                                                                ' +
      '                                  XX                            ' +
      'XXXXXX   XXXXX  XX XXX   XXXXXX   XX    XX   XX XX   XX XX   XX ' +
      'XX   XX XX  XX  XXXX XX XX      XXXXXXX XX   XX XX   XX XX   XX ' +
      'XX   XX XX  XX  XX       XXXXX    XX    XX   XX XX   XX XX X XX ' +
      'XXXXXX   XXXXX  XX           XX   XX XX XX   XX  XX XX  XX X XX ' +
      'XX          XX  XX      XXXXXX     XXX   XXXXXX   XXX    XXXXX  ' +
      'XX          XX                                                  ' +

      '                             XX   XX    XX                 X    ' +
      '                           XX     XX      XX     XXX XX   XXX   ' +
      'XX   XX XX   XX XXXXXXX    XX     XX      XX    XX XXX   XX XX  ' +
      ' XX XX  XX   XX    XXX    XX      XX       XX           XX   XX ' +
      '  XXX   XX   XX   XXX      XX     XX      XX            XX   XX ' +
      ' XX XX   XXXXXX  XXX       XX     XX      XX            XX   XX ' +
      'XX   XX      XX XXXXXXX      XX   XX    XX              XXXXXXX ' +
      '         XXXXX                                                  ' +

      ' XXXXXX                                                  XXXXXX ' +
      'XX      XX   XX                                         XX      ' +
      'XX               XXXX    XXXXXX  XXXXXX  XXXXX   XXXXXX XX      ' +
      'XX      XX   XX XX  XX  XX   XX XX   XX XX   XX XX   XX XX      ' +
      'XX      XX   XX XXXXXX  XX   XX XX   XX XX   XX XX   XX XX      ' +
      'XX      XX   XX XX      XX   XX XX   XX XX   XX XX   XX XX      ' +
      ' XXXXXX  XXXXXX  XXXXX   XXXXXX  XXXXXX  XXXXXX  XXXXXX  XXXXXX ' +
      '                                                                ' +

      '                          XX      XX      XX      XXX     XXX   ' +
      '                          XX      XX      XX     XX XX   XX XX  ' +
      ' XXXX    XXXX    XXXX                           XX   XX XX   XX ' +
      'XX  XX  XX  XX  XX  XX   XXX     XXX     XXX    XXXXXXX XXXXXXX ' +
      'XXXXXX  XXXXXX  XXXXXX    XX      XX      XX    XX   XX XX   XX ' +
      'XX      XX      XX        XX      XX      XX    XX   XX XX   XX ' +
      ' XXXXX   XXXXX   XXXXX   XXXX    XXXX    XXXX   XX   XX XX   XX ' +
      '                                                                ' +

      'XXXXXXX XXXXXXX XXXXXXX                                         ' +
      'XX      XX      XX                                              ' +
      'XX      XX      XX                                              ' +
      'XXXXX   XXXXX   XXXXX    XXXXX   XXXXX   XXXXX  XX   XX XX   XX ' +
      'XX      XX      XX      XX   XX XX   XX XX   XX XX   XX XX   XX ' +
      'XX      XX      XX      XX   XX XX   XX XX   XX XX   XX XX   XX ' +
      'XXXXXXX XXXXXXX XXXXXXX  XXXXX   XXXXX   XXXXX   XXXXXX  XXXXXX ' +
      '                                                                ' +

      '         XXXXX  XX   XX  XXXXXX  XXXXXX  XXXXXX  XXXXXX  XXXXXX ' +
      '        XX   XX XX   XX XX      XX      XX      XX      XX      ' +
      'XX   XX XX   XX XX   XX XX      XX      XX      XX      XX      ' +
      'XX   XX XX   XX XX   XX XX      XX      XX      XX      XX      ' +
      'XX   XX XX   XX XX   XX XX      XX      XX      XX      XX      ' +
      ' XXXXXX XX   XX XX   XX XX      XX      XX      XX      XX      ' +
      '     XX  XXXXX   XXXXX   XXXXXX  XXXXXX  XXXXXX  XXXXXX  XXXXXX ' +
      ' XXXXX                                                          ' +

      '          XX                                                    ' +
      '          XX                                                    ' +
      ' XXXXXX          XXXXX  XX   XX XXXXXX  XXXXXX   XXXXXX  XXXXX  ' +
      'XX   XX  XXX    XX   XX XX   XX XX   XX XX   XX XX   XX XX   XX ' +
      'XX   XX   XX    XX   XX XX   XX XX   XX XX   XX XX   XX XX   XX ' +
      'XX   XX   XX    XX   XX XX   XX XX   XX XX   XX XX   XX XX   XX ' +
      ' XXXXXX  XXXX    XXXXX   XXXXXX XX   XX XX   XX  XXXXXX  XXXXX  ' +
      '                                                                ' +

      '   XX                   X       X          XX                   ' +
      '                        X  X    X  X              XX XX XX XX   ' +
      '   XX                     X       X        XX    XX XX   XX XX  ' +
      ' XXX    XXXXXXX XXXXXXX  X XX    X XX      XX   XX XX     XX XX ' +
      'XX      XX           XX      X       X     XX    XX XX   XX XX  ' +
      'XX   XX XX           XX     X       X      XX     XX XX XX XX   ' +
      ' XXXXX                     XXXX    XXXX    XX                   ' +
      '                                                                ' +

      'X   X    X X X X XXX XXX   X       X       X      X X           ' +
      '  X   X X X X X XX XXX X   X       X       X      X X           ' +
      'X   X    X X X X XXX XXX   X       X    XXXX      X X           ' +
      '  X   X X X X X XX XXX X   X    XXXX       X    XXX X   XXXXX   ' +
      'X   X    X X X X XXX XXX   X       X    XXXX      X X     X X   ' +
      '  X   X X X X X XX XXX X   X       X       X      X X     X X   ' +
      'X   X    X X X X XXX XXX   X       X       X      X X     X X   ' +
      '  X   X X X X X XX XXX X   X       X       X      X X     X X   ' +

      '          X X     X X             X X     X X      X            ' +
      '          X X     X X             X X     X X      X            ' +
      'XXXX    XXX X     X X   XXXXX   XXX X     X X   XXXX            ' +
      '   X        X     X X       X       X   XXXXX      X    XXXX    ' +
      'XXXX    XXX X     X X   XXX X   XXXXX           XXXX       X    ' +
      '   X      X X     X X     X X                              X    ' +
      '   X      X X     X X     X X                              X    ' +
      '   X      X X     X X     X X                              X    ' +

      '   X       X               X               X       X      X X   ' +
      '   X       X               X               X       X      X X   ' +
      '   X       X               X               X       XXXXX  X X   ' +
      '   XXXXXXXXXXXXXXXXXXXXX   XXXXXXXXXXXXXXXXXXXXX   X      X XXXX' +
      '                   X       X               X       XXXXX  X X   ' +
      '                   X       X               X       X      X X   ' +
      '                   X       X               X       X      X X   ' +
      '                   X       X               X       X      X X   ' +

      '  X X             X X             X X             X X      X    ' +
      '  X X             X X             X X             X X      X    ' +
      '  X XXXX  XXXXXXXXX XXXXXXXXXXXX  X XXXXXXXXXXXXXXX XXXXXXXXXXXX' +
      '  X       X                       X                             ' +
      '  XXXXXX  X XXXXXXXXXXXXXXX XXXX  X XXXXXXXXXXXXXXX XXXXXXXXXXXX' +
      '          X X             X X     X X             X X           ' +
      '          X X             X X     X X             X X           ' +
      '          X X             X X     X X             X X           ' +

      '  X X                     X X      X                      X X   ' +
      '  X X                     X X      X                      X X   ' +
      '  X X   XXXXXXXX          X X      XXXXX   XXXXX          X X   ' +
      'XXXXXXXX        XXXXXXXX  XXXXXX   X       X      XXXXXXXXXXXXXX' +
      '        XXXXXXXX  X X              XXXXX   XXXXX  X X     X X   ' +
      '           X      X X                      X      X X     X X   ' +
      '           X      X X                      X      X X     X X   ' +
      '           X      X X                      X      X X     X X   ' +

      '   X       X            XXXXXXXX        XXXX        XXXXXXXXXXXX' +
      '   X       X            XXXXXXXX        XXXX        XXXXXXXXXXXX' +
      'XXXXXXXX   X            XXXXXXXX        XXXX        XXXXXXXXXXXX' +
      '        XXXX       XXXXXXXXXXXXX        XXXX        XXXXXXXXXXXX' +
      'XXXXXXXX           X    XXXXXXXXXXXXXXXXXXXX        XXXX        ' +
      '   X               X    XXXXXXXXXXXXXXXXXXXX        XXXX        ' +
      '   X               X    XXXXXXXXXXXXXXXXXXXX        XXXX        ' +
      '   X               X    XXXXXXXXXXXXXXXXXXXX        XXXX        ' +

      '          XXX    XXXXXX          XXXXXX                         ' +
      ' XX   X  X   X   X               X                              ' +
      'X  X X   X  X    X                X                             ' +
      'X   X    XXXXX   X       XXXXXX    X     XXXXXX                 ' +
      'X  X X   X    X  X        X  X    X     X    X                  ' +
      ' XX   X  X    X  X        X  X   X      X    X                  ' +
      '        X XXXX   X        X  X   XXXXXX  XXXX                   ' +
      '                                                                ' +

      'XXXXXXX XXXXXXX XXXXXXX XXXXXXX XXXXXXX XXXXXXX XXXXXXX XXXXXXX ' +
      'XXXXXXX XXXXXXX XXXXXXX XXXXXXX XXXXXXX XXXXXXX XXXXXXX XXXXXXX ' +
      'XXXXXXX XXXXXXX XXXXXXX XXXXXXX XXXXXXX XXXXXXX XXXXXXX XXXXXXX ' +
      'XXXXXXX XXXXXXX XXXXXXX XXXXXXX XXXXXXX XXXXXXX XXXXXXX XXXXXXX ' +
      'XXXXXXX XXXXXXX XXXXXXX XXXXXXX XXXXXXX XXXXXXX XXXXXXX XXXXXXX ' +
      'XXXXXXX XXXXXXX XXXXXXX XXXXXXX XXXXXXX XXXXXXX XXXXXXX XXXXXXX ' +
      'XXXXXXX XXXXXXX XXXXXXX XXXXXXX XXXXXXX XXXXXXX XXXXXXX XXXXXXX ' +
      '                                                                ' +

      'XXXXXXX XXXXXXX XXXXXXX XXXXXXX XXXXXXX XXXXXXX XXXXXXX XXXXXXX ' +
      'XXXXXXX XXXXXXX XXXXXXX XXXXXXX XXXXXXX XXXXXXX XXXXXXX XXXXXXX ' +
      'XXXXXXX XXXXXXX XXXXXXX XXXXXXX XXXXXXX XXXXXXX XXXXXXX XXXXXXX ' +
      'XXXXXXX XXXXXXX XXXXXXX XXXXXXX XXXXXXX XXXXXXX XXXXXXX XXXXXXX ' +
      'XXXXXXX XXXXXXX XXXXXXX XXXXXXX XXXXXXX XXXXXXX XXXXXXX XXXXXXX ' +
      'XXXXXXX XXXXXXX XXXXXXX XXXXXXX XXXXXXX XXXXXXX XXXXXXX XXXXXXX ' +
      'XXXXXXX XXXXXXX XXXXXXX XXXXXXX XXXXXXX XXXXXXX XXXXXXX XXXXXXX ' +
      '                                                                ' +

      'XXXXXXX XXXXXXX XXXXXXX XXXXXXX XXXXXXX XXXXXXX XXXXXXX XXXXXXX ' +
      'XXXXXXX XXXXXXX XXXXXXX XXXXXXX XXXXXXX XXX XXX XXXXXXX XXXXXXX ' +
      'XXXXXXX XXXXXXX XXXXXXX XXXXXXX XXXXXXX XX   XX XXXXXXX XXXXXXX ' +
      'XXXXXXX XXXXXXX XXXXXXX XXXXXXX XXXXXXX XXX XXX XXXXXXX XXXXXXX ' +
      'XXXXXXX XXXXXXX XXXXXXX XXXXXXX XXXXXXX XX   XX XXXXXXX XXXXXXX ' +
      'XXXXXXX XXXXXXX XXXXXXX XXXXXXX XXXXXXX XXX XXX XXXXXXX XXXXXXX ' +
      'XXXXXXX XXXXXXX XXXXXXX XXXXXXX XXXXXXX XXXXXXX XXXXXXX XXXXXXX ' +
      '                                                                ' +
      '';

    if (height == 8) {
      return LoadFont(FONT8, 1);
    } else if (height == 16) {
      return LoadFont(FONT8, 2);
    } else {
      return RenderFont(ctx, height);
    }
  }

  bindings.statement_screen_iIII(0);
  InitEvents();
  Render();
  return bindings;
}

var basic = {
  Basic: Basic,
  GraphicsBindings: GraphicsBindings,
  ConsoleBindings: ConsoleBindings,
};

export default basic;