games/nes: mmc3 and bugfixes

[plan9front.git] / sys / src / games / nes / ppu.c

diff --git a/sys/src/games/nes/ppu.c b/sys/src/games/nes/ppu.c
index 2301d556501cd0aa7c1aeb4a87142b7a99bafc73..77a759034b61446d999d1030d01188b6a06a43b2 100644 (file)
--- a/sys/src/games/nes/ppu.c
+++ b/sys/src/games/nes/ppu.c
@@ -167,7 +167,7 @@ static void
 drawsprites(void)
 {
        uchar *p;
-       int big, dx, dy, i, x;
+       int big, dx, dy, i, x, cc, pri;
        u8int r1, r2, c;
        static int n, m, nz, s0, t0;
        static struct { u8int x, a; u16int t; } s[8], *sp;
@@ -212,18 +212,22 @@ drawsprites(void)
                                mem[PPUSTATUS] |= SPRITE0HIT;
                        nz >>= 1;
                }
+               cc = -1;
+               pri = 0;
                for(i = m - 1; i >= 0; i--){
                        dx = x - t[i].x;
                        if(dx < 0 || dx > 7)
                                continue;
                        c = (t[i].r1 & 1) | (t[i].r2 & 1) << 1;
                        if(c != 0){
-                               if((t[i].a & (1<<5)) == 0 || !iscolor(x, ppuy))
-                                       pixel(x, ppuy, pal(c, t[i].a & 3, 1), 0);
+                               cc = pal(c, t[i].a & 3, 1);
+                               pri = (t[i].a & (1<<5)) == 0;
                        }
                        t[i].r1 >>= 1;
                        t[i].r2 >>= 1;
                }
+               if(cc != -1 && (pri || !iscolor(x, ppuy)))
+                       pixel(x, ppuy, cc, 0);
        }
        if(ppux == 257){
                for(i = 0; i < n; i++){
@@ -276,18 +280,22 @@ void
 ppustep(void)
 {
        extern int nmi;
-       int bg;
+       int mask;
 
        if(ppuy < 240 || ppuy == 261){
-               bg = (mem[PPUMASK] & BGDISP) != 0;
-               if(bg)
+               mask = mem[PPUMASK];
+               if((mask & BGDISP) != 0)
                        drawbg();
-               if((mem[PPUMASK] & SPRITEDISP) != 0 && ppuy != 261)
+               if(((mask & BGDISP) == 0 && ppux <= 257 || ppux <= 10 && (mask & BG8DISP) == 0) && ppux >= 2)
+                       pixel(ppux - 2, ppuy, ppuread(0x3F00), 1);
+               if((mask & SPRITEDISP) != 0 && ppuy != 261 && (ppux > 10 || (mask & SPRITE8DISP) != 0))
                        drawsprites();
+               if(ppux == 240 && (mask & SPRITEDISP) != 0)
+                       mapper[map](SCAN, 0);
                if(ppuy == 261){
                        if(ppux == 1)
                                mem[PPUSTATUS] &= ~(PPUVBLANK|SPRITE0HIT);
-                       else if(ppux >= 280 && ppux <= 304 && bg)
+                       else if(ppux >= 280 && ppux <= 304 && (mask & BGDISP) != 0)
                                ppuv = (pput & 0x7BE0) | (ppuv & 0x041F);
                }
        }else if(ppuy == 241){
@@ -304,7 +312,7 @@ ppustep(void)
                ppuy++;
                if(ppuy > 261){
                        ppuy = 0;
-                       if(odd && (mem[PPUCTRL] & (BGDISP | SPRITEDISP)) != 0)
+                       if(odd && (mem[PPUMASK] & (BGDISP | SPRITEDISP)) != 0)
                                ppux++;
                        odd ^= 1;
                }