Universal Include for FASM (by Tomasz Grysztar).

Comprehensive Usage Example

Since the file contains macros for both the kernel (e.g., vprint, isr_wrapper) and Linux user-space (SYS_WRITE, unisys), it is impossible to meaningfully use all of them in a single executable context. Below is a user-space program example demonstrating the power of the HLL macros, structure manipulation, memory management, and system calls.

include 'universal.inc'

; Defining a custom structure using type macros
struct UserData
    id      uint32_t ?
    active  uint8_t  ?
    buffer  size_t   ?
ends

section '.data' writeable
    dstr msg_start, "Processing started...", 10
    dstr msg_done,  "Processing finished.", 10
    dstr msg_err,   "Memory error!", 10
    
    heap_bottom dq ? ; Required for the mallc macro

section '.text' executable
    global _start

_start:
    ; 1. Using the universal system call macro
    unisys SYS_WRITE, 1, msg_start, 22
    
    ; 2. Preserving the register context
    preserve

    ; 3. Allocating memory via the wrapper (assumes a malloc function exists)
    kmalloc 1024
    
    ; 4. Using HLL branching (.if / .else)
    .if rax = 0
        unisys SYS_WRITE, 1, msg_err, 14
        jmp .exit
    .else
        mov rbx, rax ; Save the memory pointer
    .endif

    ; 5. Working with the structure
    mov [rbx + UserData.id], 100
    mov [rbx + UserData.active], 1

    ; 6. Using the advanced .for loop
    ; Counter initialization, condition, operation (+), step (1)
    mov rsi, 0
    .for rsi, <, 10, +, 1
        ; You can nest other HLL structures inside the loop
        .if [rbx + UserData.active] = 1
            ; Execute payload
            inc [rbx + UserData.id]
        .endif
    .endf

    ; 7. Freeing memory
    kfree rbx
    
    ; 8. Restoring registers
    restore

.exit:
    unisys SYS_WRITE, 1, msg_done, 21
    
    ; Exit system call (SYS_EXIT)
    unisys SYS_EXIT, 0, 0, 0, 0, 0, 0

---

Deep Analysis of uniinc.inc

The provided file is a powerful header (include) file for FASM/UASM assemblers that transforms basic assembly into a high-level programming language. The file can be divided into five key subsystems.

1. Linux System Calls

• The file contains a comprehensive list of x86_64 Linux syscall constants, ranging from SYS_READ (0) to SYS_STATX (332)[cite: 2].
• The unisys macro provides an elegant wrapper for kernel calls: it takes the syscall number and up to six parameters, automatically distributing them across the rax, rdi, rsi, rdx, r10, r8, and r9 registers before executing the syscall instruction.

2. High-Level Logic (HLL)

This is the most complex part of the preprocessor in the file, abstracting away routine cmp and jcc instructions.

• Branching: Implements .if, .elseif, .else, and .endif constructs. They support a complex condition parsing tree (the PARSECOND macro), allowing the use of operators like <, >, == and compound expressions with & (AND) and | (OR).
• Loops: Supports pre-condition loops (.while / .endw), post-condition loops (.repeat / .until), as well as a specialized .for loop.
• The .endf macro (which closes a .for loop) contains an automatic optimization: if the loop step is 1, it generates efficient inc or dec instructions; otherwise, it falls back to add or sub.

3. Advanced Data Structures

The file redefines standard data allocation directives, adding robust support for complex nested structures and unions.

• Standard C-like type aliases are introduced: uint8_t (db), uint16_t (dw), uint32_t (dd), uint64_t, and size_t (dq).
• The struct and ends macro system tracks virtual offsets (virtual at), allowing it to dynamically calculate field sizes (sizeof.#name) and create nested data layouts.
• For string creation, a convenient dstr macro is included, which automatically appends a null-terminator to the end of the defined string.

4. Memory Management

The code contains built-in logic for heap management operations.

• It defines a MemoryBlock structure containing the block's size, an is_free flag, and a pointer to the next block in the chain.
• The mallc macro implements a basic algorithm to find a free memory block by traversing a linked list starting from the [heap_bottom] address.
• It includes high-level wrapper macros kmalloc, kfree, kcalloc, and krealloc. These prepare the registers (for example, aligning the allocation size to a 16-byte boundary using add rcx, 15 and and rcx, -16) and call the respective underlying procedures.

5. Low-Level and Hardware Utilities

The file contains multiple helpers that are specifically useful when writing an OS kernel or bare-metal applications.

• Register Management: Includes preserve and restore for quickly saving and restoring general-purpose registers to the stack (rax through r11), as well as pushm / popm for bulk pushing/popping arbitrary arguments.
• CPU Control: Features macros like halt (disables interrupts and halts execution), wait_irq (enables interrupts and halts), pcpu (a repeating nop loop for exact delays), and ULcpu (controls the interrupt flag based on a passed parameter).
• TSC Reading: The read_tsc macro is used for reading the processor's time-stamp counter, smoothly combining the rdx and rax registers using a bitwise shift.
• Procedures and Interrupts: Macros proc_start and proc_end help manage the stack frame via the rbp register, while isr_wrapper is designed to safely wrap interrupt service routines.
• I/O Operations: The writectrl macro sends a byte to port 0x20 (the PIC / interrupt controller), and vprint allows for direct writing of characters with color attributes to the VGA text mode video memory at address 0xB8000.*

6. LICENSE

GPLv3 License.