From bb63a8f2226669939c23a7cedf7a3ef60f89d6de Mon Sep 17 00:00:00 2001
From: Bad Diode <bd@badd10de.dev>
Date: Thu, 22 Apr 2021 11:16:43 +0200
Subject: Test loading packed 1bpp sprites to VRAM

---
 src/main.c | 53 +++++++++++++++++++++++++++++++++++++++++++----------
 1 file changed, 43 insertions(+), 10 deletions(-)

diff --git a/src/main.c b/src/main.c
index 563340e..54a153b 100644
--- a/src/main.c
+++ b/src/main.c
@@ -444,6 +444,20 @@ copy_font_to_tile_memory(Tile *tile) {
     }
 }
 
+
+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];
+}
+
 typedef struct Sprite {
     // A unique sprite identifier.
     size_t id;
@@ -488,6 +502,27 @@ load_sprite_data(u32 *sprite_data, size_t n_tiles, size_t n_frames) {
     return sprite_counter++;
 }
 
+size_t
+load_packed_sprite_data(u32 *sprite_data, size_t n_tiles, size_t n_frames) {
+    size_t counter = 0;
+    for (size_t i = 0; i < 8 * n_tiles * n_frames / 4; ++i) {
+        u32 hex = sprite_data[i];
+        sprite_memory[counter++] = unpack_1bb((hex >> 24) & 0xFF);
+        sprite_memory[counter++] = unpack_1bb((hex >> 16) & 0xFF);
+        sprite_memory[counter++] = unpack_1bb((hex >> 8) & 0xFF);
+        sprite_memory[counter++] = unpack_1bb((hex) & 0xFF);
+    }
+    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++;
+}
+
 int main(void) {
     // Configure the display in mode 0 to show OBJs, where tile memory is
     // sequential.
@@ -512,7 +547,7 @@ int main(void) {
     int buttons_x = SCREEN_WIDTH / 2;
     int buttons_y = SCREEN_HEIGHT / 2;
     ButtonSprite btn_b = {
-        .id = load_sprite_data(&gba_btn_b_data, 16, 7),
+        .id = load_packed_sprite_data(&gba_btn_b_data, 16, 7),
         .x = buttons_x + 32,
         .y = buttons_y + 32,
         .frame = 0,
@@ -523,7 +558,7 @@ int main(void) {
     OBJ_ATTR_2(btn_b.id) = sprites[btn_b.id].tile_start;
 
     ButtonSprite btn_a = {
-        .id = load_sprite_data(&gba_btn_a_data, 16, 7),
+        .id = load_packed_sprite_data(&gba_btn_a_data, 16, 7),
         .x = buttons_x + 32 + 20,
         .y = buttons_y + 32 - 16,
         .frame = 0,
@@ -534,7 +569,7 @@ int main(void) {
     OBJ_ATTR_2(btn_a.id) = sprites[btn_a.id].tile_start;
 
     ButtonSprite btn_down = {
-        .id = load_sprite_data(&gba_btn_down_data, 16, 7),
+        .id = load_packed_sprite_data(&gba_btn_down_data, 16, 7),
         .x = buttons_x - 64 - 16,
         .y = buttons_y + 32,
         .frame = 0,
@@ -545,7 +580,7 @@ int main(void) {
     OBJ_ATTR_2(btn_down.id) = sprites[btn_down.id].tile_start;
 
     ButtonSprite btn_up = {
-        .id = load_sprite_data(&gba_btn_up_data, 16, 7),
+        .id = load_packed_sprite_data(&gba_btn_up_data, 16, 7),
         .x = buttons_x - 64 - 16,
         .y = buttons_y + 32 - 18,
         .frame = 0,
@@ -556,7 +591,7 @@ int main(void) {
     OBJ_ATTR_2(btn_up.id) = sprites[btn_up.id].tile_start;
 
     ButtonSprite btn_left = {
-        .id = load_sprite_data(&gba_btn_left_data, 16, 7),
+        .id = load_packed_sprite_data(&gba_btn_left_data, 16, 7),
         .x = buttons_x - 64 - 16 - 12,
         .y = buttons_y + 32 - 10,
         .frame = 0,
@@ -567,7 +602,7 @@ int main(void) {
     OBJ_ATTR_2(btn_left.id) = sprites[btn_left.id].tile_start;
 
     ButtonSprite btn_right = {
-        .id = load_sprite_data(&gba_btn_right_data, 16, 7),
+        .id = load_packed_sprite_data(&gba_btn_right_data, 16, 7),
         .x = buttons_x - 64 - 16 + 11,
         .y = buttons_y + 32 - 10,
         .frame = 0,
@@ -578,7 +613,7 @@ int main(void) {
     OBJ_ATTR_2(btn_right.id) = sprites[btn_right.id].tile_start;
 
     ButtonSprite btn_l = {
-        .id = load_sprite_data(&gba_btn_l_data, 16, 7),
+        .id = load_packed_sprite_data(&gba_btn_l_data, 16, 7),
         .x = buttons_x - 64 - 28,
         .y = buttons_y - 32 - 20,
         .frame = 0,
@@ -589,7 +624,7 @@ int main(void) {
     OBJ_ATTR_2(btn_l.id) = sprites[btn_l.id].tile_start;
 
     ButtonSprite btn_r = {
-        .id = load_sprite_data(&gba_btn_r_data, 16, 7),
+        .id = load_packed_sprite_data(&gba_btn_r_data, 16, 7),
         .x = buttons_x + 32 + 20,
         .y = buttons_y - 32 - 20,
         .frame = 0,
@@ -599,8 +634,6 @@ int main(void) {
     OBJ_ATTR_1(btn_r.id) = btn_r.x | (1 << 0xF);
     OBJ_ATTR_2(btn_r.id) = sprites[btn_r.id].tile_start;
 
-    // draw_logo();
-
     int frame_counter = 0;
     while(true) {
         wait_vsync();
-- 
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