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#include "shorthand.h"
#include "bd-font.c"
//
// Memory sections.
//
// Defines for the different memory sections in the GBA.
#define MEM_SROM 0x00000000
#define MEM_EW 0x02000000
#define MEM_IW 0x03000000
#define MEM_IO 0x04000000
#define MEM_PAL 0x05000000
#define MEM_VRAM 0x06000000
#define MEM_OAM 0x07000000
#define MEM_PAK 0x08000000
#define MEM_CART 0x0E000000
//
// Display modes.
//
// Display registers.
#define DISP_CONTROL *((vu32*)(MEM_IO + 0x0000))
#define DISP_STATUS *((vu32*)(MEM_IO + 0x0004))
#define DISP_VCOUNT *((vu32*)(MEM_IO + 0x0006))
// Display modes.
#define DISP_MODE_0 0x0000
#define DISP_MODE_1 0x0001
#define DISP_MODE_2 0x0002
#define DISP_MODE_3 0x0003
#define DISP_MODE_4 0x0004
#define DISP_MODE_5 0x0005
// Layers.
#define DISP_BG0 0x0100
#define DISP_BG1 0x0200
#define DISP_BG2 0x0400
#define DISP_BG3 0x0800
#define DISP_OBJ 0x1000
static inline void
set_display_mode(u16 value) {
*((vu32*)(MEM_IO + 0x0000)) = value;
}
// Screen settings.
#define SCREEN_WIDTH 240
#define SCREEN_HEIGHT 160
// The GBA in mode 3 expects rbg15 colors in the VRAM, where each component
// (RGB) have a 0--31 range. For example, pure red would be rgb15(31, 0, 0).
typedef u16 Color;
// We can treat the screen as a HxW matrix. With the following macro we can
// write a pixel to the screen at the (x, y) position using:
//
// FRAMEBUFFER[y][x] = color;
//
typedef Color Scanline[SCREEN_WIDTH];
#define FRAMEBUFFER ((Scanline*)MEM_VRAM)
#define SCREEN_BUFFER ((vu16*) MEM_VRAM)
//
// Colors.
//
static inline Color
rgb15(u32 red, u32 green, u32 blue ) {
return (blue << 10) | (green << 5) | red;
}
// Using bd-font, an 8x8 bitmap font.
static inline void
put_char(int x, int y, Color clr, u8 chr) {
for (size_t i = 0; i < 8; ++i) {
for (size_t j = 0; j < 8; ++j) {
if ((font[chr][i] >> (7 - j)) & 0x1) {
FRAMEBUFFER[y + i][x + j] = clr;
}
}
}
}
static inline void
put_line(int x, int y, Color clr, char *msg) {
int count = 0;
while (*msg) {
put_char(x + count, y, clr, *msg++);
count += 8;
}
}
static inline void
wait_vsync() {
while(DISP_VCOUNT >= 160);
while(DISP_VCOUNT < 160);
}
//
// Main functions.
//
int main(void) {
set_display_mode(DISP_MODE_3 | DISP_BG2);
while(true) {
wait_vsync();
put_line(16, 20 + 16, rgb15(28, 0, 0), "Hello world from the GBA!");
put_line(16, 20 + 32, rgb15(0, 28, 28), "Using my little 8x8 bd-font");
put_line(16, 20 + 64, rgb15(16, 0, 28), "Isn't that neat? :D");
};
return 0;
}
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