README

Installation Setup

1. Install FPC GBA cross-compiler from here: https://www.freepascal.org/download.html

   • The version that I use is FPC 3.0.0

2. Download & install DevkitPro from here: https://github.com/devkitPro/installer/releases

3. Set up a compile script with the proper flags (save it as compile.bat)

   powershellCopy

   E:\fpc-arm-gba\bin\i386-win32\fpc.exe -Parm -Tgba -XParm-none-eabi- -Fl"E:\devkitPro\devkitARM\arm-none-eabi\lib" .\game.pas

   The path that I use for FPC is E:\fpc-arm-gba\ and the path for DevkitPro is E:\devkitPro\

   The -Fl option is required because FPC cross-compiler can't find libsysbase.a

4. Get a GBA emulator: mGBA, VisualBoyAdvance-M or No$GBA

   If you want a debugger, No$GBA is a good option

BMP Extractor

This tool helps with extracting a PNG image to raw binary files: palette.bin and sprite.bin, which can be used with arm-none-eabi-objcopy later

About make_obj.bat

One line looks like this:

E:\fpc-arm-gba\bin\i386-win32\arm-none-eabi-objcopy.exe -I binary -O elf32-littlearm -B arm --rename-section .data=.rodata sprite.bin sprite.o

-I binary - The input format is raw binary

• This treats the .bin file (sprite.bin) as pure data

-O elf32-littlearm - The output format is ELF for 32-bit ARM (little-endian)

• This creates an object file that the linker can use
• "little-endian" means least significant byte first (the standard format for GBA / ARM)

-B arm - The target architecture is ARM

--rename-section .data=.rodata - This puts the data in the read-only section

• By default, objcopy puts it in .data, which is writable & not what we expect
• But with --rename-section, the data gets placed in ROM instead of RAM

Why this matters? The GBA has only 256KB of RAM but 32MB of ROM space, so it's better to keep both the palette & sprite data in ROM

And then, the last 2 arguments: sprite.bin sprite.o - these are the input and the output filenames

Prototype Order

Mode 3

First is the prototype

Second is the fontdata_embed

Third is the t_counter

All the 3 demos above use Mode 3, which is excellent for displaying a still screen / image

Mode 4

First is mode_4_starter

Second is mode_4_pset, which demonstrates a moving square across the screen

Third is mode_4_buttons

Fourth is mode_4_sprite, which demonstrates how to load a palette file and a sprite file