games/nes: minor ppu improvements

[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 77a759034b61446d999d1030d01188b6a06a43b2..09b875851071e5587c556dfef41b2531badb1a5e 100644 (file)
--- a/sys/src/games/nes/ppu.c
+++ b/sys/src/games/nes/ppu.c
@@ -109,13 +109,14 @@ drawbg(void)
        static int t;
        u8int c, a;
        static u8int nr1, nr2, na;
-       static u32int r1, r2, a1, a2;
+       static u16int r1, r2, a1, a2;
        
        if(ppux >= 2 && ppux <= 257 || ppux >= 322 && ppux <= 337){
                c = (r1 >> (15-ppusx)) & 1 | (r2 >> (14-ppusx)) & 2;
-               a = (a1 >> (15-ppusx)) & 1 | (a2 >> (14-ppusx)) & 2;
-               if(ppuy < 240 && ppux <= 257)
+               if(ppuy < 240 && ppux <= 257){
+                       a = (a1 >> (15-ppusx)) & 1 | (a2 >> (14-ppusx)) & 2;
                        pixel(ppux-2, ppuy, pal(c, a, 0), c == 0);
+               }
                r1 <<= 1;
                r2 <<= 1;
                a1 <<= 1;