Skip to content

fix: engine/bpe: map byte 0xAD like GPT-2 byte-level BPE (not identity) #805

New issue

Have a question about this project? Sign up for a free GitHub account to open an issue and contact its maintainers and the community.

Sign up for GitHub

By clicking “Sign up for GitHub”, you agree to our terms of service and privacy statement. We’ll occasionally send you account related emails.

Already on GitHub? Sign in to your account

Open
Rasaboun wants to merge 1 commit into
base: main
Choose a base branch
from
Open

fix: engine/bpe: map byte 0xAD like GPT-2 byte-level BPE (not identity) #805

Changes from all commits
Commits
Show all changes
1 commit
Select commit
File filter

Filter by extension

Filter by extension
Conversations
Failed to load comments.
Loading
Jump to
Jump to file
Failed to load files.
Loading
Diff view
Diff view
4 changes: 3 additions & 1 deletion cactus-engine/src/bpe.cpp
View file
Open in desktop
Original file line number Diff line number Diff line change
Expand Up @@ -267,13 +267,15 @@ void BPETokenizer::init_byte_mappings() const {


for (int i = 161; i <= 255; ++i) {
if (i == 173) continue; // U+00AD is not an identity byte in GPT-2 byte-level BPE
bytes.push_back(i);
}

std::vector<int> remaining_bytes;
for (int i = 0; i <= 32; ++i) remaining_bytes.push_back(i);
remaining_bytes.push_back(127);
for (int i = 128; i <= 160; ++i) remaining_bytes.push_back(i);
remaining_bytes.push_back(173); // -> U+0143, matching GPT-2 bytes_to_unicode()

int unicode_start = 256;
for (int byte : remaining_bytes) {
Expand All @@ -287,7 +289,7 @@ void BPETokenizer::init_byte_mappings() const {
std::string unicode_char(1, static_cast<char>(byte));
byte_to_unicode_[byte] = unicode_char;
unicode_to_byte_[unicode_char] = byte;
} else if (byte >= 161 && byte <= 255) {
} else if (byte >= 161 && byte <= 255 && byte != 173) { // 173 -> remaining branch
std::string unicode_char;
unicode_char += static_cast<char>(0xC0 | (byte >> 6));
unicode_char += static_cast<char>(0x80 | (byte & 0x3F));
Expand Down