Proof of concept of UXN on the GBA

1 files changed, 79 insertions, 0 deletions

diff --git a/src/sprites.h b/src/sprites.h
new file mode 100644
index 0000000..a64b784
--- /dev/null
+++ b/src/sprites.h
@@ -0,0 +1,79 @@
+#ifndef GBAEXP_SPRITES_H
+#define GBAEXP_SPRITES_H
+
+#include "common.h"
+
+typedef struct Sprite {
+    // A unique sprite identifier.
+    size_t id;
+    // The number of tiles for a single sprite frame.
+    size_t n_tiles;
+    // The starting tile of this sprite.
+    size_t tile_start;
+    // The associated palette bank for this sprite.
+    size_t pal_bank;
+} Sprite;
+
+
+#define NUM_SPRITES 128
+Sprite sprites[NUM_SPRITES];
+
+// Keeping track of unique sprites and current sprite memory pointer using
+// global singletons.
+size_t sprite_counter = 0;
+size_t sprite_tile_counter = 0;
+u32 *sprite_memory = NULL;
+
+// Loads the sprite data into video memory and initialize the Sprite structure.
+size_t
+load_sprite_data(u32 *sprite_data, size_t n_tiles, size_t n_frames) {
+    memcpy(sprite_memory, sprite_data, 8 * n_tiles * n_frames * sizeof(u32));
+    sprite_memory += 8 * n_tiles * n_frames;
+    Sprite sprite = {
+        .id = sprite_counter,
+        .n_tiles = n_tiles,
+        .tile_start = sprite_tile_counter,
+    };
+    sprite_tile_counter += n_tiles * n_frames;
+    sprites[sprite_counter] = sprite;
+    return sprite_counter++;
+}
+
+size_t
+load_packed_sprite_data(u32 *sprite_data, size_t n_tiles, size_t n_frames) {
+    unpack_tiles(sprite_data, sprite_memory, n_tiles * n_frames);
+    sprite_memory += 8 * n_tiles * n_frames;
+    Sprite sprite = {
+        .id = sprite_counter,
+        .n_tiles = n_tiles,
+        .tile_start = sprite_tile_counter,
+    };
+    sprite_tile_counter += n_tiles * n_frames;
+    sprites[sprite_counter] = sprite;
+    return sprite_counter++;
+}
+
+void
+init_sprites(size_t starting_tile) {
+    // Initialize all attributes by disabling rendering. If we don't do this,
+    // glitches may appear.
+    for (size_t i = 0; i < 128; ++i) {
+        OBJ_ATTR_0(i) = (1 << 9);
+    }
+
+    sprite_counter = 0;
+    // Prepare global sprite_memory address.
+    sprite_memory = &TILE_MEM[4][starting_tile];
+    sprite_tile_counter = starting_tile;
+}
+
+void
+init_sprite_pal(size_t starting_index, Color col) {
+    // Add colors to the sprite color palette. Tiles with color number 0 are
+    // treated as transparent.
+    for (size_t i = 0; i < 16; ++i) {
+        PAL_BUFFER_SPRITES[i + starting_index] = col;
+    }
+}
+
+#endif // GBAEXP_SPRITES_H