Minor code restructuring.

bsnes/sfc/ppu/background.cpp

@@ -150,6 +150,42 @@ auto PPU::Background::getTile() -> void {
   }
 }
 
+auto PPU::Background::getTile(uint x, uint y) -> uint16 {
+  uint tileHeight = 3 + io.tileSize;
+  uint tileWidth = !hires() ? tileHeight : 4;
+  uint screenX = io.screenSize.bit(0) ? 32 << 5 : 0;
+  uint screenY = io.screenSize.bit(1) ? 32 << 5 + io.screenSize.bit(0) : 0;
+  uint tileX = x >> tileWidth;
+  uint tileY = y >> tileHeight;
+  uint16 offset = (tileY & 0x1f) << 5 | (tileX & 0x1f);
+  if(tileX & 0x20) offset += screenX;
+  if(tileY & 0x20) offset += screenY;
+  uint16 address = latch.screenAddress + offset;
+  return ppu.vram[address];
+}
+
+auto PPU::Background::getTileColor() -> uint {
+  uint color = 0;
+
+  switch(io.mode) {
+  case Mode::BPP8:
+    color += data[1] >> 24 & 0x80;
+    color += data[1] >> 17 & 0x40;
+    color += data[1] >> 10 & 0x20;
+    color += data[1] >>  3 & 0x10;
+    data[1] <<= 1;
+  case Mode::BPP4:
+    color += data[0] >> 28 & 0x08;
+    color += data[0] >> 21 & 0x04;
+  case Mode::BPP2:
+    color += data[0] >> 14 & 0x02;
+    color += data[0] >>  7 & 0x01;
+    data[0] <<= 1;
+  }
+
+  return color;
+}
+
 auto PPU::Background::run(bool screen) -> void {
   if(ppu.vcounter() == 0) return;
 
@@ -188,42 +224,6 @@ auto PPU::Background::run(bool screen) -> void {
   if(!hires() || screen == Screen::Below) if(io.belowEnable) output.below = pixel;
 }
 
-auto PPU::Background::getTile(uint x, uint y) -> uint16 {
-  uint tileHeight = 3 + io.tileSize;
-  uint tileWidth = !hires() ? tileHeight : 4;
-  uint screenX = io.screenSize.bit(0) ? 32 << 5 : 0;
-  uint screenY = io.screenSize.bit(1) ? 32 << 5 + io.screenSize.bit(0) : 0;
-  uint tileX = x >> tileWidth;
-  uint tileY = y >> tileHeight;
-  uint16 offset = (tileY & 0x1f) << 5 | (tileX & 0x1f);
-  if(tileX & 0x20) offset += screenX;
-  if(tileY & 0x20) offset += screenY;
-  uint16 address = latch.screenAddress + offset;
-  return ppu.vram[address];
-}
-
-auto PPU::Background::getTileColor() -> uint {
-  uint color = 0;
-
-  switch(io.mode) {
-  case Mode::BPP8:
-    color += data[1] >> 24 & 0x80;
-    color += data[1] >> 17 & 0x40;
-    color += data[1] >> 10 & 0x20;
-    color += data[1] >>  3 & 0x10;
-    data[1] <<= 1;
-  case Mode::BPP4:
-    color += data[0] >> 28 & 0x08;
-    color += data[0] >> 21 & 0x04;
-  case Mode::BPP2:
-    color += data[0] >> 14 & 0x02;
-    color += data[0] >>  7 & 0x01;
-    data[0] <<= 1;
-  }
-
-  return color;
-}
-
 auto PPU::Background::power() -> void {
   io = {};
   io.tiledataAddress = (random() & 0x0f) << 12;

bsnes/sfc/ppu/background.hpp

@@ -14,6 +14,7 @@ struct Background {
   auto getTile() -> void;
   auto getTile(uint x, uint y) -> uint16;
   auto getTileColor() -> uint;
+
   alwaysinline auto clip(int n) -> int;
   auto beginMode7() -> void;
   auto runMode7() -> void;

bsnes/sfc/ppu/ppu.cpp

@@ -61,23 +61,23 @@ auto PPU::Enter() -> void {
 auto PPU::main() -> void {
   scanline();
   step(28);
-  bg1.begin();
-  bg2.begin();
-  bg3.begin();
   bg4.begin();
+  bg3.begin();
+  bg2.begin();
+  bg1.begin();
 
   if(vcounter() < vdisp()) {
     for(int pixel = -7; pixel <= 255; pixel++) {
-      bg1.run(1);
-      bg2.run(1);
-      bg3.run(1);
       bg4.run(1);
+      bg3.run(1);
+      bg2.run(1);
+      bg1.run(1);
       step(2);
 
-      bg1.run(0);
-      bg2.run(0);
-      bg3.run(0);
       bg4.run(0);
+      bg3.run(0);
+      bg2.run(0);
+      bg1.run(0);
       if(pixel >= 0) {
         obj.run();
         window.run();