Use constants for Oam .shape and .size fields

Also some general formatting fixes for constants.

include/gba/types.h

@@ -87,6 +87,29 @@ struct OamData
 #define ST_OAM_H_RECTANGLE 1
 #define ST_OAM_V_RECTANGLE 2
 
+#define ST_OAM_SIZE_0   0
+#define ST_OAM_SIZE_1   1
+#define ST_OAM_SIZE_2   2
+#define ST_OAM_SIZE_3   3
+
+#define SPRITE_SIZE_8x8     ((ST_OAM_SIZE_0 << 2) | (ST_OAM_SQUARE))
+#define SPRITE_SIZE_16x16   ((ST_OAM_SIZE_1 << 2) | (ST_OAM_SQUARE))
+#define SPRITE_SIZE_32x32   ((ST_OAM_SIZE_2 << 2) | (ST_OAM_SQUARE))
+#define SPRITE_SIZE_64x64   ((ST_OAM_SIZE_3 << 2) | (ST_OAM_SQUARE))
+
+#define SPRITE_SIZE_16x8    ((ST_OAM_SIZE_0 << 2) | (ST_OAM_H_RECTANGLE))
+#define SPRITE_SIZE_32x8    ((ST_OAM_SIZE_1 << 2) | (ST_OAM_H_RECTANGLE))
+#define SPRITE_SIZE_32x16   ((ST_OAM_SIZE_2 << 2) | (ST_OAM_H_RECTANGLE))
+#define SPRITE_SIZE_64x32   ((ST_OAM_SIZE_3 << 2) | (ST_OAM_H_RECTANGLE))
+
+#define SPRITE_SIZE_8x16    ((ST_OAM_SIZE_0 << 2) | (ST_OAM_V_RECTANGLE))
+#define SPRITE_SIZE_8x32    ((ST_OAM_SIZE_1 << 2) | (ST_OAM_V_RECTANGLE))
+#define SPRITE_SIZE_16x32   ((ST_OAM_SIZE_2 << 2) | (ST_OAM_V_RECTANGLE))
+#define SPRITE_SIZE_32x64   ((ST_OAM_SIZE_3 << 2) | (ST_OAM_V_RECTANGLE))
+
+#define SPRITE_SIZE(dim) (SPRITE_SIZE_##dim >> 2)
+#define SPRITE_SHAPE(dim) (SPRITE_SIZE_##dim & 0xFF)
+
 struct BgAffineSrcData
 {
     s32 texX;