<style> .reveal section img { background:none; border:none; box-shadow:none; } </style> # GBA Workshop ---- ## Hardware - 32-bit ARMv4T CPU - 240x160 pixel LCD - 2D Video with bitmap and sprite modes - 6 Audio Channels - controlled via memory mapped I/O registers - Buttons, Link port, ... ---- ## Memory mapped I/O ? Some special memory adress, that does not just store data, but controls peripherals when you read or write to it. ---- ### GBA's memory MAP ``` General Internal Memory 00000000-00003FFF BIOS ROM (16 KBytes) 02000000-0203FFFF RAM (256 KBytes) 03000000-03007FFF Some faster RAM (32 KBytes) >>> 04000000-040003FE I/O Registers <<< Internal Display Memory 05000000-050003FF Color Palette (1 Kbyte) 06000000-06017FFF Video Memory (96 KBytes) 07000000-070003FF Sprite Attributes (1 Kbyte) ``` ---- ### GBA's I/O Registers ``` LCD I/O Registers 4000000h 2 R/W DISPCNT LCD Control 4000002h 2 R/W - Undocumented 4000004h 2 R/W DISPSTAT General LCD Status (STAT,LYC) 4000006h 2 R VCOUNT Vertical Counter (LY) 4000008h 2 R/W BG0CNT BG0 Control 400000Ah 2 R/W BG1CNT BG1 Control 400000Ch 2 R/W BG2CNT BG2 Control 400000Eh 2 R/W BG3CNT BG3 Control ... ``` ---- ### LCD Control ``` 4000000h - DISPCNT - LCD Control (Read/Write) Bit Expl. 0-2 BG Mode (0-5=Video Mode 0-5, 6-7=Prohibited) 3 Reserved / CGB Mode (0=GBA, 1=CGB; can be set only by BIOS opcodes) 4 Display Frame Select (0-1=Frame 0-1) (for BG Modes 4,5 only) 5 H-Blank Interval Free (1=Allow access to OAM during H-Blank) 6 OBJ Character VRAM Mapping (0=Two dimensional, 1=One dimensional) 7 Forced Blank (1=Allow FAST access to VRAM,Palette,OAM) 8 Screen Display BG0 (0=Off, 1=On) 9 Screen Display BG1 (0=Off, 1=On) 10 Screen Display BG2 (0=Off, 1=On) 11 Screen Display BG3 (0=Off, 1=On) 12 Screen Display OBJ (0=Off, 1=On) ``` --- ## Example ### Getting pixels on the LCD ---- #### GBA Video  source > https://www.youtube.com/watch?v=mpNWEbZdXNw ---- #### The hard way ``` int main() { *(unsigned int*)0x04000000 = 0x0403; ((unsigned short*)0x06000000)[120+80*240] = 0x001F; ((unsigned short*)0x06000000)[136+80*240] = 0x03E0; ((unsigned short*)0x06000000)[120+96*240] = 0x7C00; while(1); return 0; } ``` ---- #### Compile and run >>  ---- #### But why? ``` 0x04000000 = 0x0403 ???? ``` Reminder: ``` 4000000h 2 R/W DISPCNT LCD Control ``` ---- Configures LCD to use Mode 3 ``` Bit Expl. 0-2 BG Mode (0-5=Video Mode 0-5, 6-7=Prohibited) ... ``` and to enable Background 2 ``` Bit Expl. 8 Screen Display BG0 (0=Off, 1=On) 9 Screen Display BG1 (0=Off, 1=On) 10 Screen Display BG2 (0=Off, 1=On) 11 Screen Display BG3 (0=Off, 1=On) ``` 0000 0100 0000 0011 == 0x0403 ---- #### The C way / tonclib ``` #include "toolbox.h" int main() { REG_DISPCNT= DCNT_MODE3 | DCNT_BG2; m3_plot( 120, 80, RGB15(31, 0, 0) ); // or CLR_RED m3_plot( 136, 80, RGB15( 0,31, 0) ); // or CLR_LIME m3_plot( 120, 96, RGB15( 0, 0,31) ); // or CLR_BLUE while(1); return 0; } ``` ---- #### The C++ way / bugba ``` #include "gba_mem_sym.hpp" int main() { using namespace gba::dtypes; using namespace gba::hw; reg_disp.lcd_conf = { .mode = lcd_mode_t::mode3, .bg2 = true, }; mem_vram.mode3.pix[72][112] = {.red = 31}; mem_vram.mode3.pix[72][128] = {.green = 31}; mem_vram.mode3.pix[88][112] = {.blue = 31}; loop(); } ``` --- ## Howto ---- ### Install - SDK https://devkitpro.org/wiki/Getting_Started - (dkp-)pacman -Syu gba-dev - Intro https://www.coranac.com/tonc/ - Docs https://problemkaputt.de/gbatek.htm - flash https://github.com/lesserkuma/FlashGBX - bugba https://github.com/deheisenbug/bugba - edit Makefile.conf. uncomment #USE_DKP=1 - butano https://github.com/GValiente/butano - rust https://github.com/rust-console/gba - slides https://s.42l.fr/gbaworkshop ---- ## Todo - put all examples in one repo