gpl2asm

A command-line utility that converts GIMP palette files (.gpl) to assembly include files (.inc) for retro programming and palette-based systems.

Overview

gpl2asm reads color palettes in GIMP's palette format and converts them to assembly language DB (Define Byte) directives. The tool automatically converts 8-bit RGB values (0-255) to 6-bit RGB values (0-63), which is the standard for VGA mode 13h.

Features

• Converts GIMP palette files to assembly include files
• Automatic 8-bit to 6-bit RGB color conversion
• Cross-platform support (Linux, Windows, macOS)
• Available as standalone binary or Docker container

Installation

Download Pre-built Binary

Download the latest release for your platform from the releases page.

Using Docker

docker pull ghcr.io/laghoule/gpl2asm:latest

Or from Docker Hub:

docker pull laghoule/gpl2asm:latest

Build from Source

Requires Go 1.25.6 or later:

git clone https://github.com/laghoule/gpl2asm.git
cd gpl2asm
go build

Usage

Basic Usage

gpl2asm --src input.gpl --dst output.inc

Using Default Files

If no arguments are provided, it uses pal.gpl as input and pal.inc as output:

gpl2asm

Command-line Options

• --src <file>: Path to the GIMP palette file to convert (default: pal.gpl)
• --dst <file>: Path to the output assembly include file (default: pal.inc)

Docker Usage

docker run -v $(pwd):/data ghcr.io/yourusername/gpl2asm:latest \
  --src /data/input.gpl --dst /data/output.inc

Input Format

The tool expects GIMP palette format (.gpl files):

GIMP Palette
Name: My Palette
Columns: 16
#
  0   0   0 Black
255 255 255 White
255   0   0 Red
  0 255   0 Green
  0   0 255 Blue

Each color line consists of:

• Three integers (0-255) representing RGB values
• A name or comment for the color (can include spaces)

Output Format

The tool generates assembly include files with DB directives:

palette LABEL BYTE
  DB 00,00,00 ; Black
  DB 63,63,63 ; White
  DB 63,00,00 ; Red
  DB 00,63,00 ; Green
  DB 00,00,63 ; Blue

Note that RGB values are automatically converted from 8-bit (0-255) to 6-bit (0-63) by dividing by 4.