1 files changed, 153 insertions, 36 deletions

diff --git a/src/common.h b/src/common.h
index ff5ea12..7a0c50c 100644
--- a/src/common.h
+++ b/src/common.h
@@ -83,29 +83,45 @@
 #define SCREEN_WIDTH 240
 #define SCREEN_HEIGHT 160
 
+//
+// Colors.
+//
+
 // 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;
 
-// A palette is composed of 16 colors, with color at index 0 being transparent.
+// A palette is composed of 16 colors, with color at index 0 being transparent
+// for sprites.
 typedef Color Palette[16];
 
+// Inline function to calculate the 15 bit color value.
+static inline Color
+rgb15(u32 red, u32 green, u32 blue ) {
+    return (blue << 10) | (green << 5) | red;
+}
+
+// Some nice default colors.
+#define COLOR_RED   rgb15(31, 0, 12)
+#define COLOR_BLUE  rgb15(2, 15, 30)
+#define COLOR_CYAN  rgb15(0, 30, 30)
+#define COLOR_GREY  rgb15(4, 4, 4)
+#define COLOR_BLACK rgb15(0, 0, 0)
+#define COLOR_WHITE rgb15(28, 28, 28)
+
 //
 // Tile memory access.
 //
 
 // NOTE: Only defining 4bpp tiles for now.
 typedef struct Tile {
-    u32 data[8];
+    u32 row[8];
 } Tile;
 
+// Screenblocks and charblocks (tile blocks).
 typedef Tile TileBlock[512];
 #define TILE_MEM ((TileBlock*) MEM_VRAM)
-
-// Screenblocks and charblocks for backgrounds.
 typedef u16 ScreenBlock[1024];
-typedef Tile CharBlock[512];
-#define CHARBLOCK_MEM   ((CharBlock*)MEM_VRAM)
 #define SCREENBLOCK_MEM ((ScreenBlock*)MEM_VRAM)
 
 // Screenblock entry bits.
@@ -113,40 +129,24 @@ typedef Tile CharBlock[512];
 #define SCREENBLOCK_ENTRY_V_FLIP (1 << 0xB)
 #define SCREENBLOCK_ENTRY_PAL(N) ((N) << 0xC)
 
-size_t se_index(size_t tile_x, size_t tile_y, size_t map_width) {
+size_t
+se_index(size_t tile_x, size_t tile_y, size_t map_width) {
     size_t sbb = ((tile_x >> 5) + (tile_y >> 5) * (map_width >> 5));
     return sbb * 1024 + ((tile_x & 31) + (tile_y & 31) * 32);
 }
 
-
 // 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 FRAMEBUFFER        ((Scanline*) MEM_VRAM)
 #define SCREEN_BUFFER      ((u16*) MEM_VRAM)
 #define PAL_BUFFER_BG      ((u16*) MEM_PAL)
-#define PAL_BUFFER_SPRITES ((u16*) 0x05000200)
+#define PAL_BUFFER_SPRITES ((u16*)(MEM_PAL + 0x200))
 #define PAL_BANK_BG        ((Palette*) MEM_PAL)
-#define PAL_BANK_SPRITES   ((Palette*) 0x05000200)
-
-//
-// Colors.
-//
-
-static inline Color
-rgb15(u32 red, u32 green, u32 blue ) {
-    return (blue << 10) | (green << 5) | red;
-}
-
-#define COLOR_RED   rgb15(31, 0, 12)
-#define COLOR_BLUE  rgb15(2, 15, 30)
-#define COLOR_CYAN  rgb15(0, 30, 30)
-#define COLOR_GREY  rgb15(4, 4, 4)
-#define COLOR_BLACK rgb15(0, 0, 0)
-#define COLOR_WHITE rgb15(28, 28, 28)
+#define PAL_BANK_SPRITES   ((Palette*)(MEM_PAL + 0x200))
 
 //
 // Sprites.
@@ -191,12 +191,6 @@ rgb15(u32 red, u32 green, u32 blue ) {
 #define OBJ_PRIORITY(N)   ((N) << 0xA)
 #define OBJ_PAL_BANK(N)   ((N) << 0xC)
 
-static inline void
-wait_vsync(void) {
-    while(DISP_VCOUNT >= 160);
-    while(DISP_VCOUNT < 160);
-}
-
 //
 // Mode 4 page flipping
 //
@@ -505,11 +499,12 @@ irs_set(IrqIndex idx, IrsFunc func) {
     IRQ_CTRL = irq_ctrl;
 }
 
-#define IRS_MAIN *(IrsFunc*)(0x03007FFC)
-
 // External irs_main function, has to be written in ARM assembly.
 void irs_main(void);
 
+// Initialize the function pointer for the main IRS routine written in ARM
+// assembly and enable interrupts.
+#define IRS_MAIN *(IrsFunc*)(0x03007FFC)
 void
 irq_init() {
     IRS_MAIN = irs_main;
@@ -519,6 +514,128 @@ irq_init() {
 // Stub function pointer needed for when we want to enable interrupts that don't
 // require a custom function, such as for the BIOS VSync.
 void
-irq_stub() {}
+irs_stub() {}
+
+//
+// BIOS function declarations.
+//
+
+// These functions declarations can be used to call the BIOS functions from the
+// asm code.
+int bios_vblank_wait();
+int bios_div(int num, int denom);
+
+//
+// Sound.
+//
+
+// Sound registers.
+#define SOUND_SQUARE1_SWEEP *((vu16*)(MEM_IO + 0x60))
+#define SOUND_SQUARE1_CTRL  *((vu16*)(MEM_IO + 0x62))
+#define SOUND_SQUARE1_FREQ  *((vu16*)(MEM_IO + 0x64))
+#define SOUND_SQUARE2_CTRL  *((vu16*)(MEM_IO + 0x68))
+#define SOUND_SQUARE2_FREQ  *((vu16*)(MEM_IO + 0x6C))
+#define SOUND_WAVE_MODE     *((vu16*)(MEM_IO + 0x70))
+#define SOUND_WAVE_CTRL     *((vu16*)(MEM_IO + 0x72))
+#define SOUND_WAVE_FREQ     *((vu16*)(MEM_IO + 0x74))
+#define SOUND_NOISE_CTRL    *((vu16*)(MEM_IO + 0x78))
+#define SOUND_NOISE_FREQ    *((vu16*)(MEM_IO + 0x7C))
+#define SOUND_DMG_MASTER    *((vu16*)(MEM_IO + 0x80))
+#define SOUND_DSOUND_MASTER *((vu16*)(MEM_IO + 0x82))
+#define SOUND_STATUS        *((vu16*)(MEM_IO + 0x84))
+#define SOUND_BIAS          *((vu16*)(MEM_IO + 0x88))
+
+// Sound DMG master bits.
+#define SOUND_VOLUME_LEFT(N)       (N)
+#define SOUND_VOLUME_RIGHT(N)      ((N) << 4)
+#define SOUND_ENABLE_SQUARE1_LEFT  (1 << 0x8)
+#define SOUND_ENABLE_SQUARE2_LEFT  (1 << 0x9)
+#define SOUND_ENABLE_WAVE_LEFT     (1 << 0xA)
+#define SOUND_ENABLE_NOISE_LEFT    (1 << 0xB)
+#define SOUND_ENABLE_SQUARE1_RIGHT (1 << 0xC)
+#define SOUND_ENABLE_SQUARE2_RIGHT (1 << 0xD)
+#define SOUND_ENABLE_WAVE_RIGHT    (1 << 0xE)
+#define SOUND_ENABLE_NOISE_RIGHT   (1 << 0xF)
+
+typedef enum {
+    SOUND_SQUARE1 = (0x1 << 0),
+    SOUND_SQUARE2 = (0x1 << 1),
+    SOUND_WAVE =    (0x4 << 2),
+    SOUND_NOISE =   (0x8 << 3),
+} SoundChannel;
+
+u16
+sound_volume(SoundChannel channels, u8 volume) {
+    volume = volume & 0x7;
+    channels = channels & 0xF;
+    return volume | (volume << 0x4) | (channels << 0x8) | (channels << 0xC);
+}
+
+// Sound Direct Sound master bits.
+#define SOUND_DMG25           0x0
+#define SOUND_DMG50           0x1
+#define SOUND_DMG100          0x2
+#define SOUND_DSOUND_RATIO_A  (1 << 0x2)
+#define SOUND_DSOUND_RATIO_B  (1 << 0x3)
+#define SOUND_DSOUND_LEFT_A   (1 << 0x8)
+#define SOUND_DSOUND_RIGHT_A  (1 << 0x9)
+#define SOUND_DSOUND_TIMER_A  (1 << 0xA)
+#define SOUND_DSOUND_RESET_A  (1 << 0xB)
+#define SOUND_DSOUND_LEFT_B   (1 << 0xC)
+#define SOUND_DSOUND_RIGHT_B  (1 << 0xD)
+#define SOUND_DSOUND_TIMER_B  (1 << 0xE)
+#define SOUND_DSOUND_RESET_B  (1 << 0xF)
+
+// Sound status bits.
+#define SOUND_ENABLE (1 << 0x7)
+
+// DMG square control bits.
+#define SOUND_SQUARE_LEN(N)      (N)
+#define SOUND_SQUARE_DUTY(N)     ((N) << 0x6)
+#define SOUND_SQUARE_ENV_TIME(N) ((N) << 0x8)
+#define SOUND_SQUARE_ENV_INC     (1 << 0xB)
+#define SOUND_SQUARE_ENV_VOL(N)  ((N) << 0xC)
+
+// DMG square frequency bits.
+#define SOUND_SQUARE_TIMED (1 << 0xE)
+#define SOUND_SQUARE_RESET (1 << 0xF)
+
+typedef enum {
+    NOTE_C,
+    NOTE_C_SHARP,
+    NOTE_D,
+    NOTE_D_SHARP,
+    NOTE_E,
+    NOTE_F,
+    NOTE_F_SHARP,
+    NOTE_G,
+    NOTE_G_SHARP,
+    NOTE_A,
+    NOTE_A_SHARP,
+    NOTE_B,
+} Note;
+
+u32
+sound_rate(Note note, u32 octave) {
+    const u32 base_rate[12] = {
+        8013, 7566, 7144, 6742, // C , C#, D , D#
+        6362, 6005, 5666, 5346, // E , F , F#, G
+        5048, 4766, 4499, 4246  // G#, A , A#, B
+    };
+    return 2048 - (base_rate[note] >> (4 + octave));
+}
+
+//
+// Misc.
+//
+
+// Custom VSync option. This will waste a lot of battery power, since the
+// machine is not clocked down. Prefer using `bios_vblank_wait()` if interrupts
+// are enabled.
+static inline void
+wait_vsync(void) {
+    while(DISP_VCOUNT >= 160);
+    while(DISP_VCOUNT < 160);
+}
 
 #endif // GBAEXP_COMMON_H