Finish sprite rendering

src/ppu.c

@@ -56,6 +56,40 @@ void nes_ppu_find_hit_line(nes_PPU* ppu, nes_PPU_Memory* mem) {
     }
 }
 
+static const uint8_t sprite_rev[256] = {
+    0x00, 0x40, 0x80, 0xC0, 0x10, 0x50, 0x90, 0xD0,
+    0x20, 0x60, 0xA0, 0xE0, 0x30, 0x70, 0xB0, 0xF0,
+    0x04, 0x44, 0x84, 0xC4, 0x14, 0x54, 0x94, 0xD4,
+    0x24, 0x64, 0xA4, 0xE4, 0x34, 0x74, 0xB4, 0xF4,
+    0x08, 0x48, 0x88, 0xC8, 0x18, 0x58, 0x98, 0xD8,
+    0x28, 0x68, 0xA8, 0xE8, 0x38, 0x78, 0xB8, 0xF8,
+    0x0C, 0x4C, 0x8C, 0xCC, 0x1C, 0x5C, 0x9C, 0xDC,
+    0x2C, 0x6C, 0xAC, 0xEC, 0x3C, 0x7C, 0xBC, 0xFC,
+    0x01, 0x41, 0x81, 0xC1, 0x11, 0x51, 0x91, 0xD1,
+    0x21, 0x61, 0xA1, 0xE1, 0x31, 0x71, 0xB1, 0xF1,
+    0x05, 0x45, 0x85, 0xC5, 0x15, 0x55, 0x95, 0xD5,
+    0x25, 0x65, 0xA5, 0xE5, 0x35, 0x75, 0xB5, 0xF5,
+    0x09, 0x49, 0x89, 0xC9, 0x19, 0x59, 0x99, 0xD9,
+    0x29, 0x69, 0xA9, 0xE9, 0x39, 0x79, 0xB9, 0xF9,
+    0x0D, 0x4D, 0x8D, 0xCD, 0x1D, 0x5D, 0x9D, 0xDD,
+    0x2D, 0x6D, 0xAD, 0xED, 0x3D, 0x7D, 0xBD, 0xFD,
+    0x02, 0x42, 0x82, 0xC2, 0x12, 0x52, 0x92, 0xD2,
+    0x22, 0x62, 0xA2, 0xE2, 0x32, 0x72, 0xB2, 0xF2,
+    0x06, 0x46, 0x86, 0xC6, 0x16, 0x56, 0x96, 0xD6,
+    0x26, 0x66, 0xA6, 0xE6, 0x36, 0x76, 0xB6, 0xF6,
+    0x0A, 0x4A, 0x8A, 0xCA, 0x1A, 0x5A, 0x9A, 0xDA,
+    0x2A, 0x6A, 0xAA, 0xEA, 0x3A, 0x7A, 0xBA, 0xFA,
+    0x0E, 0x4E, 0x8E, 0xCE, 0x1E, 0x5E, 0x9E, 0xDE,
+    0x2E, 0x6E, 0xAE, 0xEE, 0x3E, 0x7E, 0xBE, 0xFE,
+    0x03, 0x43, 0x83, 0xC3, 0x13, 0x53, 0x93, 0xD3,
+    0x23, 0x63, 0xA3, 0xE3, 0x33, 0x73, 0xB3, 0xF3,
+    0x07, 0x47, 0x87, 0xC7, 0x17, 0x57, 0x97, 0xD7,
+    0x27, 0x67, 0xA7, 0xE7, 0x37, 0x77, 0xB7, 0xF7,
+    0x0B, 0x4B, 0x8B, 0xCB, 0x1B, 0x5B, 0x9B, 0xDB,
+    0x2B, 0x6B, 0xAB, 0xEB, 0x3B, 0x7B, 0xBB, 0xFB,
+    0x0F, 0x4F, 0x8F, 0xCF, 0x1F, 0x5F, 0x9F, 0xDF,
+    0x2F, 0x6F, 0xAF, 0xEF, 0x3F, 0x7F, 0xBF, 0xFF,
+};
 
 void nes_ppu_render_line(nes_PPU* ppu, nes_PPU_Memory* mem) {
     uint8_t* scanline_ptr = ppu->screen_data +
@@ -65,14 +99,7 @@ void nes_ppu_render_line(nes_PPU* ppu, nes_PPU_Memory* mem) {
 
     if (!(mem->mask & ppu_Mask_Back)) {
         memset(ptr, 0xFFU, nes_ppu_render_w);
-/*
-        // Emulate the happy part of the backdrop override quirk
-        int pal_idx = ((mem->addr & 0x3F00U) == 0x3F00U) ?
-                      (mem->addr & 0x1FU) : 0;
-        // Don't use the rendering palette (masked transparency)
-        memset(ptr, mem->pal_bank[0x300 + pal_idx],
-               nes_ppu_render_w);
-*/
+
     } else {
         int back_bank = nes_PPU_Nametable_Bank_Index +
                    ((mem->addr >> 10) & 3);
@@ -197,16 +224,13 @@ void nes_ppu_render_line(nes_PPU* ppu, nes_PPU_Memory* mem) {
     }
 
     // TODO: Mapper VROM switch
-/*
-    if (mem->mask & ppu_Mask_Sprite) {
-        // This time, we do need overflow protection
-//        uint8_t sprite_data[nes_ppu_render_w + 8] = {0};
 
+    if (mem->mask & ppu_Mask_Sprite) {
         const int sprite_height = (mem->ctrl & ppu_Control_Sprite_Size) ?
                                   16 : 8;
         const int scanline = ppu->scanline - nes_ppu_visible_line;
 
-        int bank = !!(mem->ctrl & ppu_Control_Sprite_Bank) << 2;
+        int sprite_bank = !!(mem->ctrl & ppu_Control_Sprite_Bank) << 2;
 
         int n_sprites = 0;
         const oam_sprite* sprites = (oam_sprite*)mem->oam;
@@ -219,8 +243,11 @@ void nes_ppu_render_line(nes_PPU* ppu, nes_PPU_Memory* mem) {
             }
 
             int y_off = scanline - y;
-            if (sprite->attr & oam_Attr_Flip_Y) y_off = sprite_height - y_off - 1;
+            if (sprite->attr & oam_Attr_Flip_Y) {
+                y_off = sprite_height - y_off - 1;
+            }
 
+            int bank = sprite_bank;
             int ch = sprite->index;
             if (mem->ctrl & ppu_Control_Sprite_Size) {
                 bank = (ch & 1) << 2;
@@ -228,22 +255,29 @@ void nes_ppu_render_line(nes_PPU* ppu, nes_PPU_Memory* mem) {
             }
 
             bank += (ch >> 6);
-            const int addr_off = ((ch & 0x3fU) << 4) + ((y_off & 8) << 1) + (y_off & 7);
+            const int addr_off = ((ch & 0x3fU) << 4) +
+                                 ((y_off & 8) << 1) +
+                                 (y_off & 7);
             const uint8_t* data = mem->bank[bank] + addr_off;
             const uint8_t pl0 = data[0];
             const uint8_t pl1 = data[8];
-            const int pat0 = (pl0 & 0x55) | ((pl1 << 1) & 0xAA);
-            const int pat1 = ((pl0 >> 1) & 0x55) | (pl1 & 0xAA);
+            int pat0 = (pl0 & 0x55) | ((pl1 << 1) & 0xAA);
+            int pat1 = ((pl0 >> 1) & 0x55) | (pl1 & 0xAA);
 
             const uint8_t* pal = &mem->palette[0x10 + ((sprite->attr & oam_Attr_Pal_Mask) << 2)];
             uint8_t* dst = scanline_ptr + sprite->x;
 
             const int over_x = ((int)sprite->x + 8) - nes_ppu_render_w;
 
-            // TODO: X Flip
+            if (sprite->attr & oam_Attr_Flip_X) {
+                uint8_t tmp = pat0;
+                pat0 = sprite_rev[pat1];
+                pat1 = sprite_rev[tmp];
+            }
+
             switch (over_x) {
             default:
-            {   int pal_idx = (pat1 << 0) & 3;
+            {   int pal_idx = (pat0 >> 0) & 3;
                 if (    (   !(sprite->attr & oam_Attr_Background) ||
                             dst[7] == 0xFFU)
                         && pal_idx) {
@@ -251,7 +285,7 @@ void nes_ppu_render_line(nes_PPU* ppu, nes_PPU_Memory* mem) {
                 }
             }
             case 1:
-            {   int pal_idx = (pat0 << 0) & 3;
+            {   int pal_idx = (pat1 >> 0) & 3;
                 if (    (   !(sprite->attr & oam_Attr_Background) ||
                             dst[6] == 0xFFU)
                         && pal_idx) {
@@ -259,7 +293,7 @@ void nes_ppu_render_line(nes_PPU* ppu, nes_PPU_Memory* mem) {
                 }
             }
             case 2:
-            {   int pal_idx = (pat1 << 2) & 3;
+            {   int pal_idx = (pat0 >> 2) & 3;
                 if (    (   !(sprite->attr & oam_Attr_Background) ||
                             dst[5] == 0xFFU)
                         && pal_idx) {
@@ -267,7 +301,7 @@ void nes_ppu_render_line(nes_PPU* ppu, nes_PPU_Memory* mem) {
                 }
             }
             case 3:
-            {   int pal_idx = (pat0 << 2) & 3;
+            {   int pal_idx = (pat1 >> 2) & 3;
                 if (    (   !(sprite->attr & oam_Attr_Background) ||
                             dst[4] == 0xFFU)
                         && pal_idx) {
@@ -275,7 +309,7 @@ void nes_ppu_render_line(nes_PPU* ppu, nes_PPU_Memory* mem) {
                 }
             }
             case 4:
-            {   int pal_idx = (pat1 << 4) & 3;
+            {   int pal_idx = (pat0 >> 4) & 3;
                 if (    (   !(sprite->attr & oam_Attr_Background) ||
                             dst[3] == 0xFFU)
                         && pal_idx) {
@@ -283,7 +317,7 @@ void nes_ppu_render_line(nes_PPU* ppu, nes_PPU_Memory* mem) {
                 }
             }
             case 5:
-            {   int pal_idx = (pat0 << 4) & 3;
+            {   int pal_idx = (pat1 >> 4) & 3;
                 if (    (   !(sprite->attr & oam_Attr_Background) ||
                             dst[2] == 0xFFU)
                         && pal_idx) {
@@ -291,7 +325,7 @@ void nes_ppu_render_line(nes_PPU* ppu, nes_PPU_Memory* mem) {
                 }
             }
             case 6:
-            {   int pal_idx = (pat1 << 6) & 3;
+            {   int pal_idx = (pat0 >> 6) & 3;
                 if (    (   !(sprite->attr & oam_Attr_Background) ||
                             dst[1] == 0xFFU)
                         && pal_idx) {
@@ -299,7 +333,7 @@ void nes_ppu_render_line(nes_PPU* ppu, nes_PPU_Memory* mem) {
                 }
             }
             case 7:
-            {   int pal_idx = (pat0 << 6) & 3;
+            {   int pal_idx = (pat1 >> 6) & 3;
                 if (    (   !(sprite->attr & oam_Attr_Background) ||
                             dst[0] == 0xFFU)
                         && pal_idx) {
@@ -317,7 +351,6 @@ void nes_ppu_render_line(nes_PPU* ppu, nes_PPU_Memory* mem) {
             mem->status &= ~ppu_Status_Overflow;
         }
     }
-*/
 
     // Increment internal registers
     if (mem->mask & (ppu_Mask_Sprite | ppu_Mask_Back)) {