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Since the lexer buffer wraps, the refilling gets handled in two steps: First, iff the buffer would wrap, the buffer is refilled until its end. Then, if more characters are requested, that amount is refilled too. An important detail is that `read()` may not return as many characters as requested; for this reason, the first step checks if its `read()` was "full", and skips the second step otherwise. This is also where a bug lied. After a *lot* of trying, I eventually managed to reproduce the bug on an OpenBSD VM, and after adding a couple of `assert`s in `peekInternal`, this is what happened, starting at line 724: 0. `lexerState->nbChars` is 0, `lexerState->index` is 19; 1. We end up with `target` = 42, and `writeIndex` = 19; 2. 42 + 19 is greater than `LEXER_BUF_SIZE` (= 42), so the `if` is entered; 3. Within the first `readChars`, **`read` only returns 16 bytes**, advancing `writeIndex` to 35 and `target` to 26; 4. Within the second `readChars`, a `read(26)` is issued, overflowing the buffer. The bug should be clear now: **the check at line 750 failed to work!** Why? Because `readChars` modifies `writeIndex`. The fix is simply to cache the number of characters expected, and use that.
RGBDS ===== RGBDS (Rednex Game Boy Development System) is a free assembler/linker package for the Game Boy and Game Boy Color. It consists of: - rgbasm (assembler) - rgblink (linker) - rgbfix (checksum/header fixer) - rgbgfx (PNG‐to‐Game Boy graphics converter) This is a fork of the original RGBDS which aims to make the programs more like other UNIX tools. This toolchain is maintained on `GitHub <https://github.com/rednex/rgbds>`__. The documentation of this toolchain can be viewed online `here <https://rgbds.gbdev.io/docs/>`__, it is generated from the man pages found in this repository. 1. Installing RGBDS ------------------- The `installation procedure <https://rgbds.gbdev.io/install>`__ is available online for various platforms. `Building from source <https://rgbds.gbdev.io/install/source>`__ is possible using ``make`` or ``cmake``; follow the link for more detailed instructions. .. code:: sh make sudo make install .. code:: sh cmake -S . -B build cmake --build build cmake --install build 2. History --------- - Around 1997, Carsten Sørensen (AKA SurfSmurf) writes ASMotor as a general-purpose assembler/linker system for DOS/Win32 - Around 1999, Justin Lloyd (AKA Otaku no Zoku) adapts ASMotor to read and produce GBZ80 assembly/machine code, and releases this version as RGBDS. - 2009, Vegard Nossum adapts the code to be more UNIX-like and releases this version as rgbds-linux on `GitHub <https://github.com/vegard/rgbds-linux>`__. - 2010, Anthony J. Bentley forks that repository. The fork becomes the reference implementation of rgbds. - 2017, Bentley's repository is moved to a neutral name. - 2018, codebase relicensed under the MIT license. - 2020, repository is moved to the `gbdev <https://github.com/gbdev>`__ organisation. The `rgbds.gbdev.io <https://rgbds.gbdev.io>`__ website serving documentation and downloads is created.