1 files changed, 16 insertions, 12 deletions

diff --git a/src/ppu.c b/src/ppu.c
index 19e530b..a8d7dc6 100644
--- a/src/ppu.c
+++ b/src/ppu.c
@@ -21,7 +21,8 @@ static size_t screen_height = 0;
 static u32 *framebuffer = 0;
 
 static u32 palette[16];
-static u8 *pixels_buf;
+static u8 *pixels_fg;
+static u8 *pixels_bg;
 static u8 *dirty_lines;
 static u8 reqdraw = 0;
 // TODO: Probably should consider this
@@ -35,17 +36,18 @@ static u8 blending[5][16] = {
     {1, 1, 1, 1, 1, 0, 1, 1, 1, 1, 0, 1, 1, 1, 1, 0}};
 
 void
-ppu_pixel(u8 layer, u16 x, u16 y, u8 color) {
-    size_t idx = y * screen_width + x;
-    u8 *pixel = &pixels_buf[idx], shift = layer * 2;
-    if(x < screen_width && y < screen_height) {
-        *pixel = (*pixel & ~(0x3 << shift)) | (color << shift);
-    }
+ppu_pixel(u8 *layer, u16 x, u16 y, u8 color) {
+        if(x < screen_width && y < screen_height) {
+                Uint32 i = x + y *screen_width;
+                if(color != layer[i]) {
+                        layer[i] = color;
+                }
+        }
     dirty_lines[y] |= 1;
 }
 
 void
-ppu_1bpp(u8 layer, u16 x, u16 y, u8 *sprite, u8 color, u8 flipx, u8 flipy) {
+ppu_1bpp(u8 *layer, u16 x, u16 y, u8 *sprite, u8 color, u8 flipx, u8 flipy) {
     u16 v, h;
     for(v = 0; v < 8; v++)
         for(h = 0; h < 8; h++) {
@@ -59,7 +61,7 @@ ppu_1bpp(u8 layer, u16 x, u16 y, u8 *sprite, u8 color, u8 flipx, u8 flipy) {
 }
 
 void
-ppu_2bpp(u8 layer, u16 x, u16 y, u8 *sprite, u8 color, u8 flipx, u8 flipy) {
+ppu_2bpp(u8 *layer, u16 x, u16 y, u8 *sprite, u8 color, u8 flipx, u8 flipy) {
     u16 v, h;
     for(v = 0; v < 8; v++)
         for(h = 0; h < 8; h++) {
@@ -106,7 +108,8 @@ ppu_init(void) {
         }
 
         // Allocate intermediate buffers.
-        pixels_buf = malloc(screen_width * screen_height);
+        pixels_fg = malloc(screen_width * screen_height);
+        pixels_bg = malloc(screen_width * screen_height);
         dirty_lines = malloc(screen_height);
 
     // Initialize default palette.
@@ -116,7 +119,8 @@ ppu_init(void) {
     palette[3] = 0xff7777;
 
     // Clear pixel buffer memory.
-    memset(pixels_buf, 0, screen_width * screen_height);
+    memset(pixels_fg, 0, screen_width * screen_height);
+    memset(pixels_bg, 0, screen_width * screen_height);
     memset(dirty_lines, 1, screen_height);
 
     // Make sure we perform an initial screen drawing.
@@ -135,7 +139,7 @@ blit_framebuffer(void) {
         if (dirty_lines[j] != 0) {
             for (size_t i = 0; i < screen_width; i++) {
                 size_t idx = i + j * screen_width;
-                framebuffer[idx] = palette[pixels_buf[idx] % 16];
+                framebuffer[idx] = palette[pixels_fg[idx] << 2 | pixels_bg[idx]];
             }
         }
         dirty_lines[j] = 0;