1 files changed, 45 insertions, 22 deletions

diff --git a/src/common.h b/src/common.h
index 6047e5f..669fb6e 100644
--- a/src/common.h
+++ b/src/common.h
@@ -47,16 +47,10 @@
 #define DISP_ENABLE_SPRITES DISP_OBJ | DISP_OBJ_1D
 
 // Registers to control of BG layers.
-#define BG_CTRL_0 *((vu16*)(0x04000008 + 0x0002 * 0))
-#define BG_CTRL_1 *((vu16*)(0x04000008 + 0x0002 * 1))
-#define BG_CTRL_2 *((vu16*)(0x04000008 + 0x0002 * 2))
-#define BG_CTRL_3 *((vu16*)(0x04000008 + 0x0002 * 3))
+#define BG_CTRL(N) *((vu16*)(0x04000008 + 0x0002 * (N)))
 
 // Bits to control the background.
-#define BG_PRIORITY_0     0x0
-#define BG_PRIORITY_1     0x1
-#define BG_PRIORITY_2     0x2
-#define BG_PRIORITY_3     0x3
+#define BG_PRIORITY(N)    ((N) & 0x3)
 #define BG_CHARBLOCK(N)   ((N) << 2)
 #define BG_MOSAIC         (1 << 6)
 #define BG_HIGH_COLOR     (1 << 7)
@@ -76,20 +70,6 @@
 #define BG_V_SCROLL_2 *((vu16*)(0x04000012 + 0x0004 * 2))
 #define BG_V_SCROLL_3 *((vu16*)(0x04000012 + 0x0004 * 3))
 
-// Screenblocks for BGs.
-typedef u16 ScreenBlock[1024];
-#define SCREENBLOCK_MEM ((ScreenBlock*)MEM_VRAM)
-
-// Screenblock entry bits.
-#define SCREENBLOCK_ENTRY_H_FLIP (1 << 0xA)
-#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 sbb = ((tile_x >> 5) + (tile_y >> 5) * (map_width >> 5));
-    return sbb * 1024 + ((tile_x & 31) + (tile_y & 31) * 32);
-}
-
 // Screen settings.
 #define SCREEN_WIDTH 240
 #define SCREEN_HEIGHT 160
@@ -113,6 +93,23 @@ typedef struct Tile {
 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.
+#define SCREENBLOCK_ENTRY_H_FLIP (1 << 0xA)
+#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 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:
 //
@@ -293,4 +290,30 @@ key_hold(u32 key) {
 // Check if the given key/button is currently pressed.
 #define KEY_PRESSED(key) (~(KEY_INPUTS) & key)
 
+// Back/unpack bits.
+static inline u32
+unpack_1bb(u8 hex) {
+    const u32 conversion_u32[16] = {
+        0x00000000, 0x00000001, 0x00000010, 0x00000011,
+        0x00000100, 0x00000101, 0x00000110, 0x00000111,
+        0x00001000, 0x00001001, 0x00001010, 0x00001011,
+        0x00001100, 0x00001101, 0x00001110, 0x00001111,
+    };
+    u8 low = hex & 0xF;
+    u8 high = (hex >> 4) & 0xF;
+    return (conversion_u32[high] << 16) | conversion_u32[low];
+}
+
+// Unpack N tiles packed at 1bpp.
+unpack_tiles(u32 *src, u32 *dst, size_t n_tiles) {
+    u32 *target_src = src + n_tiles * 2;
+    while (src != target_src) {
+        *dst++ = unpack_1bb((*src >> 24) & 0xFF);
+        *dst++ = unpack_1bb((*src >> 16) & 0xFF);
+        *dst++ = unpack_1bb((*src >> 8) & 0xFF);
+        *dst++ = unpack_1bb(*src & 0xFF);
+        src++;
+    }
+}
+
 #endif // GBAEXP_COMMON_H