games/snes: added open bus emulation

diff --git a/sys/src/games/snes/dat.h b/sys/src/games/snes/dat.h
index 8489b9f9bcf0ca6d4846fb2db6db24b277332d24..aad4ab5f59f1a3fdc2b49a06bc952bceb2a75b96 100644 (file)
--- a/sys/src/games/snes/dat.h
+++ b/sys/src/games/snes/dat.h
@@ -12,6 +12,7 @@ extern int nprg, nsram, hirom;
 extern u32int keys, keylatch, lastkeys;
 extern u8int reg[32768], mem[131072], spcmem[65536], vram[65536], oam[544];
 extern u16int cgram[256], vramlatch;
+extern u8int mdr, mdr1, mdr2;
 
 extern int ppux, ppuy, rx;
 extern u16int vtime, htime, subcolor, oamaddr;

diff --git a/sys/src/games/snes/mem.c b/sys/src/games/snes/mem.c
index 9716b7387882ae8878b125eb4886337f16cb37f3..1c8728e99570543e17a003ca96ee0fc3f976000c 100644 (file)
--- a/sys/src/games/snes/mem.c
+++ b/sys/src/games/snes/mem.c
@@ -22,6 +22,8 @@ enum {
        OPVCTH,
 };
 
+u8int mdr, mdr1, mdr2;
+
 extern void calc7(void);
 
 static u16int
@@ -120,51 +122,54 @@ regread(u16int p)
        switch(p){
        case 0x2134: case 0x2135: case 0x2136:
                r = ((signed short)m7[0] * (signed char)reg[0x211c]) & 0xffffff;
-               return r >> 8 * (p - 0x2134);
+               return mdr1 = r >> 8 * (p - 0x2134);
        case 0x2137:
                if((reg[0x4201] & 0x80) != 0)
                        hvlatch();
-               return 0;
+               return mdr;
        case 0x2138:
                if(oamaddr < 0x200)
                        v = oam[oamaddr];
                else
                        v = oam[oamaddr & 0x21f];
                oamaddr = (oamaddr + 1) & 0x3ff;
-               return v;
+               return mdr1 = v;
        case 0x2139:
                v = vramlatch;
                incvram(0, 1);
-               return v;
+               return mdr1 = v;
        case 0x213a:
                v = vramlatch >> 8;
                incvram(1, 1);
-               return v;
+               return mdr1 = v;
        case 0x213b:
                a = swaprb(cgram[reg[0x2121]]);
                if(reg[CGLH] != 0){
                        a >>= 8;
+                       a |= mdr2 & 0x80;
                        reg[0x2121]++;
                }
                reg[CGLH] ^= 1;
-               return a;
+               return mdr2 = a;
        case 0x213c:
                reg[OPCTLATCH] ^= 1;
                if((reg[OPCTLATCH] & 1) == 0)
-                       return reg[OPHCTH];
-               break;
+                       return mdr2 = reg[OPHCTH] | mdr2 & 0xfe;
+               return mdr2 = reg[p];
        case 0x213d:
                reg[OPCTLATCH] ^= 2;
                if((reg[OPCTLATCH] & 2) == 0)
-                       return reg[OPVCTH];
-               break;
+                       return reg[OPVCTH] | mdr2 & 0xfe;
+               return mdr2 = reg[p];
+       case 0x213e:
+               return (mdr1 = reg[p]) | mdr & 0x10;
        case 0x213f:
                v = 2 | reg[OPCTLATCH] & 0x40;
                if((reg[0x4201] & 0x80) != 0)
                        reg[OPCTLATCH] &= ~0x43;
                else
                        reg[OPCTLATCH] &= ~3;
-               return v;
+               return mdr2 = v | mdr2 & 0x20;
        case 0x2180:
                v = memread(0x7e0000 | reg[0x2181] | reg[0x2182] << 8 | (reg[0x2183] & 1) << 16);
                incwram();
@@ -180,13 +185,15 @@ regread(u16int p)
                }
                v = keylatch >> 31;
                keylatch = (keylatch << 1) | 1;
-               return v;
+               return v | mdr & 0xfc;
        case 0x4017:
-               return 0;
+               return 0x1f | mdr & 0xe0;
+       case 0x4210:
+               return reg[p] | mdr & 0x70;
        case 0x4211:
                v = irq;
                irq &= ~IRQPPU;
-               return v;
+               return v | mdr & 0x7f;
        case 0x4212:
                v = 0;
                if(ppux >= 274 || ppux == 0)
@@ -197,11 +204,17 @@ regread(u16int p)
                        if(ppuy <= a + 2 && (reg[NMITIMEN] & AUTOJOY) != 0)
                                v |= 1;
                }
-               return v;
+               return v | mdr & 0x3e;
+       case 0x4214: case 0x4215: case 0x4216: case 0x4217: case 0x4218:
+       case 0x4219: case 0x421a: case 0x421b: case 0x421c: case 0x421d:
+       case 0x421e: case 0x421f:
+               return reg[p];
        }
-       if((p & 0xff40) == 0x2140)
+       if((p & 0xff80) == 0x4300)
+               return reg[p];
+       if((p & 0xffc0) == 0x2140)
                return spcmem[0xf4 | p & 3];
-       return reg[p];
+       return mdr;
 }
 
 void
@@ -381,25 +394,28 @@ memread(u32int a)
        b = (a>>16) & 0x7f;
        if(al < 0x8000){
                if(b < 0x40){
-                       if(hirom && al >= 0x6000 && nsram != 0)
-                               return sram[(b << 13 | al & 0x1ffff) & (nsram - 1)];
-                       return regread(al);
+                       if(hirom && al >= 0x6000 && nsram != 0){
+                               if(a < 0x800000 || (reg[MEMSEL] & 1) == 0)
+                                       memcyc += 2;
+                               return mdr = sram[(b << 13 | al & 0x1ffff) & (nsram - 1)];
+                       }
+                       return mdr = regread(al);
                }
                if(!hirom && (b & 0xf8) == 0x70 && nsram != 0){
                        if(a < 0x800000 || (reg[MEMSEL] & 1) == 0)
                                memcyc += 2;
-                       return sram[a & 0x07ffff & (nsram - 1)];
+                       return mdr = sram[a & 0x07ffff & (nsram - 1)];
                }
        }
        if(b >= 0x7e && (a & (1<<23)) == 0){
                memcyc += 2;
-               return mem[a - 0x7e0000];
+               return mdr = mem[a - 0x7e0000];
        }
        if(a < 0x800000 || (reg[MEMSEL] & 1) == 0)
                memcyc += 2;
        if(hirom)
-               return prg[((b & 0x3f) % nprg) << 16 | al];
-       return prg[(b%nprg) << 15 | al & 0x7fff];
+               return mdr = prg[((b & 0x3f) % nprg) << 16 | al];
+       return mdr = prg[(b%nprg) << 15 | al & 0x7fff];
 }
 
 void

diff --git a/sys/src/games/snes/state.c b/sys/src/games/snes/state.c
index a206cf3405b207e7f04800ba786b10dd97111106..c516a073ebbc4238dda4d7b6ccf89fe1aaffb005 100644 (file)
--- a/sys/src/games/snes/state.c
+++ b/sys/src/games/snes/state.c
@@ -106,6 +106,9 @@ loadstate(char *file)
        dma = get8();
        hdma = get32();
        wai = get8();
+       mdr = get8();
+       mdr1 = get8();
+       mdr2 = get8();
        oamaddr = get16();
        vramlatch = get16();
        keylatch = get32();
@@ -163,6 +166,9 @@ savestate(char *file)
        put8(dma);
        put32(hdma);
        put8(wai);
+       put8(mdr);
+       put8(mdr1);
+       put8(mdr2);
        put16(oamaddr);
        put16(vramlatch);
        put32(keylatch);