bsnes/higan/sfc/ppu-fast/mode7.cpp

auto PPU::Line::renderMode7(PPU::IO::Background& self, uint source) -> void {
  int Y = this->y - (self.mosaicEnable ? this->y % (1 + io.mosaicSize) : 0);
  int y = !io.mode7.vflip ? Y : 255 - Y;

  int a = (int16)io.mode7.a;
  int b = (int16)io.mode7.b;
  int c = (int16)io.mode7.c;
  int d = (int16)io.mode7.d;
  int hcenter = (int13)io.mode7.x;
  int vcenter = (int13)io.mode7.y;
  int hoffset = (int13)io.mode7.hoffset;
  int voffset = (int13)io.mode7.voffset;

  uint mosaicCounter = 1;
  uint mosaicPalette = 0;
  uint mosaicPriority = 0;
  uint mosaicColor = 0;

  auto clip = [](int n) -> int { return n & 0x2000 ? (n | ~1023) : (n & 1023); };
  int originX = (a * clip(hoffset - hcenter) & ~63) + (b * clip(voffset - vcenter) & ~63) + (b * y & ~63) + (hcenter << 8);
  int originY = (c * clip(hoffset - hcenter) & ~63) + (d * clip(voffset - vcenter) & ~63) + (d * y & ~63) + (vcenter << 8);

  array<bool[256]> windowAbove;
  array<bool[256]> windowBelow;
  renderWindow(self.window, self.window.aboveEnable, windowAbove);
  renderWindow(self.window, self.window.belowEnable, windowBelow);

  for(int X : range(256)) {
    int x = !io.mode7.hflip ? X : 255 - X;
    int pixelX = originX + a * x >> 8;
    int pixelY = originY + c * x >> 8;
    int tileX = pixelX >> 3 & 127;
    int tileY = pixelY >> 3 & 127;
    bool outOfBounds = (pixelX | pixelY) & ~1023;
    uint15 tileAddress = tileY * 128 + tileX;
    uint15 paletteAddress = ((pixelY & 7) << 3) + (pixelX & 7);
    uint8 tile = ppu.vram[tileAddress].byte(0);
    if(io.mode7.repeat == 3 && outOfBounds) tile = 0;
    uint8 palette = ppu.vram[paletteAddress + (tile << 6)].byte(1);
    if(io.mode7.repeat == 2 && outOfBounds) palette = 0;

    uint priority;
    if(source == Source::BG1) {
      priority = self.priority[0];
    } else if(source == Source::BG2) {
      priority = self.priority[palette >> 7];
      palette &= 0x7f;
    }

    if(!self.mosaicEnable || --mosaicCounter == 0) {
      mosaicCounter = 1 + io.mosaicSize;
      mosaicPalette = palette;
      mosaicPriority = priority;
      if(io.col.directColor && source == Source::BG1) {
        mosaicColor = directColor(0, palette);
      } else {
        mosaicColor = cgram[palette];
      }
    }
    if(!mosaicPalette) continue;

    if(self.aboveEnable && !windowAbove[x]) plotAbove(x, source, mosaicPriority, mosaicColor);
    if(self.belowEnable && !windowBelow[x]) plotBelow(x, source, mosaicPriority, mosaicColor);
  }
}