sa1.cpp

著名SFC模拟器Snes9x的源代码。

	break;
    case 0x2203:
//	printf ("SA1 reset vector: %04x\n", byte | (Memory.FillRAM [0x2204] << 8));
	break;
    case 0x2204:
//	printf ("SA1 reset vector: %04x\n", (byte << 8) | Memory.FillRAM [0x2203]);
	break;

    case 0x2205:
//	printf ("SA1 NMI vector: %04x\n", byte | (Memory.FillRAM [0x2206] << 8));
	break;
    case 0x2206:
//	printf ("SA1 NMI vector: %04x\n", (byte << 8) | Memory.FillRAM [0x2205]);
	break;

    case 0x2207:
//	printf ("SA1 IRQ vector: %04x\n", byte | (Memory.FillRAM [0x2208] << 8));
	break;
    case 0x2208:
//	printf ("SA1 IRQ vector: %04x\n", (byte << 8) | Memory.FillRAM [0x2207]);
	break;

    case 0x2209:
	Memory.FillRAM [0x2209] = byte;
	if (byte & 0x80)
	    Memory.FillRAM [0x2300] |= 0x80;

	if (byte & Memory.FillRAM [0x2201] & 0x80)
	{
	    S9xSetIRQ (SA1_IRQ_SOURCE);
	}
	break;
    case 0x220a:
	if (((byte ^ Memory.FillRAM [0x220a]) & 0x80) &&
	    (Memory.FillRAM [0x2301] & byte & 0x80))
	{
	    SA1.Flags |= IRQ_PENDING_FLAG;
	    SA1.IRQActive |= SNES_IRQ_SOURCE;
//	    SA1.Executing = !SA1.Waiting;
	}
	if (((byte ^ Memory.FillRAM [0x220a]) & 0x40) &&
	    (Memory.FillRAM [0x2301] & byte & 0x40))
	{
	    SA1.Flags |= IRQ_PENDING_FLAG;
	    SA1.IRQActive |= TIMER_IRQ_SOURCE;
//	    SA1.Executing = !SA1.Waiting;
	}
	if (((byte ^ Memory.FillRAM [0x220a]) & 0x20) &&
	    (Memory.FillRAM [0x2301] & byte & 0x20))
	{
	    SA1.Flags |= IRQ_PENDING_FLAG;
	    SA1.IRQActive |= DMA_IRQ_SOURCE;
//	    SA1.Executing = !SA1.Waiting;
	}
	if (((byte ^ Memory.FillRAM [0x220a]) & 0x10) &&
	    (Memory.FillRAM [0x2301] & byte & 0x10))
	{
#ifdef DEBUGGER
	    printf ("###SA1 NMI\n");
#endif
	}
	break;
    case 0x220b:
	if (byte & 0x80)
	{
	    SA1.IRQActive &= ~SNES_IRQ_SOURCE;
	    Memory.FillRAM [0x2301] &= ~0x80;
	}
	if (byte & 0x40)
	{
	    SA1.IRQActive &= ~TIMER_IRQ_SOURCE;
	    Memory.FillRAM [0x2301] &= ~0x40;
	}
	if (byte & 0x20)
	{
	    SA1.IRQActive &= ~DMA_IRQ_SOURCE;
	    Memory.FillRAM [0x2301] &= ~0x20;
	}
	if (byte & 0x10)
	{
	    // Clear NMI
	    Memory.FillRAM [0x2301] &= ~0x10;
	}
	if (!SA1.IRQActive)
	    SA1.Flags &= ~IRQ_PENDING_FLAG;
	break;
    case 0x220c:
//	printf ("SNES NMI vector: %04x\n", byte | (Memory.FillRAM [0x220d] << 8));
	break;
    case 0x220d:
//	printf ("SNES NMI vector: %04x\n", (byte << 8) | Memory.FillRAM [0x220c]);
	break;

    case 0x220e:
//	printf ("SNES IRQ vector: %04x\n", byte | (Memory.FillRAM [0x220f] << 8));
	break;
    case 0x220f:
//	printf ("SNES IRQ vector: %04x\n", (byte << 8) | Memory.FillRAM [0x220e]);
	break;

    case 0x2210:
#if 0
	printf ("Timer %s\n", (byte & 0x80) ? "linear" : "HV");
	printf ("Timer H-IRQ %s\n", (byte & 1) ? "enabled" : "disabled");
	printf ("Timer V-IRQ %s\n", (byte & 2) ? "enabled" : "disabled");
#endif
	break;
    case 0x2211:
//	printf ("Timer reset\n");
	break;
    case 0x2212:
//	printf ("H-Timer %04x\n", byte | (Memory.FillRAM [0x2213] << 8));
	break;
    case 0x2213:
//	printf ("H-Timer %04x\n", (byte << 8) | Memory.FillRAM [0x2212]);
	break;
    case 0x2214:
//	printf ("V-Timer %04x\n", byte | (Memory.FillRAM [0x2215] << 8));
	break;
    case 0x2215:
//	printf ("V-Timer %04x\n", (byte << 8) | Memory.FillRAM [0x2214]);
	break;
    case 0x2220:
    case 0x2221:
    case 0x2222:
    case 0x2223:
	S9xSetSA1MemMap (address - 0x2220, byte);
//	printf ("MMC: %02x\n", byte);
	break;
    case 0x2224:
//	printf ("BWRAM image SNES %02x -> 0x6000\n", byte);
	Memory.BWRAM = Memory.SRAM + (byte & 7) * 0x2000;
	break;
    case 0x2225:
//	printf ("BWRAM image SA1 %02x -> 0x6000 (%02x)\n", byte, Memory.FillRAM [address]);
	if (byte != Memory.FillRAM [address])
	    S9xSA1SetBWRAMMemMap (byte);
	break;
    case 0x2226:
//	printf ("BW-RAM SNES write %s\n", (byte & 0x80) ? "enabled" : "disabled");
	break;
    case 0x2227:
//	printf ("BW-RAM SA1 write %s\n", (byte & 0x80) ? "enabled" : "disabled");
	break;

    case 0x2228:
//	printf ("BW-RAM write protect area %02x\n", byte);
	break;
    case 0x2229:
//	printf ("I-RAM SNES write protect area %02x\n", byte);
	break;
    case 0x222a:
//	printf ("I-RAM SA1 write protect area %02x\n", byte);
	break;
    case 0x2230:
#if 0
	printf ("SA1 DMA %s\n", (byte & 0x80) ? "enabled" : "disabled");
	printf ("DMA priority %s\n", (byte & 0x40) ? "DMA" : "SA1");
	printf ("DMA %s\n", (byte & 0x20) ? "char conv" : "normal");
	printf ("DMA type %s\n", (byte & 0x10) ? "BW-RAM -> I-RAM" : "SA1 -> I-RAM");
	printf ("DMA distination %s\n", (byte & 4) ? "BW-RAM" : "I-RAM");
	printf ("DMA source %s\n", DMAsource [byte & 3]);
#endif
	break;
    case 0x2231:
	if (byte & 0x80)
	    SA1.in_char_dma = FALSE;
#if 0
	printf ("CHDEND %s\n", (byte & 0x80) ? "complete" : "incomplete");
	printf ("DMA colour mode %d\n", byte & 3);
	printf ("virtual VRAM width %d\n", (byte >> 2) & 7);
#endif
	break;
    case 0x2232:
    case 0x2233:
    case 0x2234:
	Memory.FillRAM [address] = byte;
#if 0
	printf ("DMA source start %06x\n", 
		Memory.FillRAM [0x2232] | (Memory.FillRAM [0x2233] << 8) |
		(Memory.FillRAM [0x2234] << 16));
#endif
	break;
    case 0x2235:
	Memory.FillRAM [address] = byte;
	break;
    case 0x2236:
	Memory.FillRAM [address] = byte;
	if ((Memory.FillRAM [0x2230] & 0xa4) == 0x80)
	{
	    // Normal DMA to I-RAM
	    S9xSA1DMA ();
	}
	else
	if ((Memory.FillRAM [0x2230] & 0xb0) == 0xb0)
	{
	    Memory.FillRAM [0x2300] |= 0x20;
	    if (Memory.FillRAM [0x2201] & 0x20)
		S9xSetIRQ (SA1_DMA_IRQ_SOURCE);
	    SA1.in_char_dma = TRUE;
	}
	break;
    case 0x2237:
	Memory.FillRAM [address] = byte;
	if ((Memory.FillRAM [0x2230] & 0xa4) == 0x84)
	{
	    // Normal DMA to BW-RAM
	    S9xSA1DMA ();
	}
#if 0
	printf ("DMA dest address %06x\n", 
		Memory.FillRAM [0x2235] | (Memory.FillRAM [0x2236] << 8) |
		(Memory.FillRAM [0x2237] << 16));
#endif
	break;
    case 0x2238:
    case 0x2239:
	Memory.FillRAM [address] = byte;
#if 0
	printf ("DMA length %04x\n", 
		Memory.FillRAM [0x2238] | (Memory.FillRAM [0x2239] << 8));
#endif
	break;
    case 0x223f:
	SA1.VirtualBitmapFormat = (byte & 0x80) ? 2 : 4;
	//printf ("virtual VRAM depth %d\n", (byte & 0x80) ? 2 : 4);
	break;

    case 0x2240:    case 0x2241:    case 0x2242:    case 0x2243:
    case 0x2244:    case 0x2245:    case 0x2246:    case 0x2247:
    case 0x2248:    case 0x2249:    case 0x224a:    case 0x224b:
    case 0x224c:    case 0x224d:    case 0x224e:
#if 0
	if (!(SA1.Flags & TRACE_FLAG))
	{
	    TraceSA1 ();
	    Trace ();
	}
#endif
	Memory.FillRAM [address] = byte;
	break;

    case 0x224f:
	Memory.FillRAM [address] = byte;
	if ((Memory.FillRAM [0x2230] & 0xb0) == 0xa0)
	{
	    // Char conversion 2 DMA enabled
	    memmove (&Memory.ROM [CMemory::MAX_ROM_SIZE - 0x10000] + SA1.in_char_dma * 16,
		     &Memory.FillRAM [0x2240], 16);
	    SA1.in_char_dma = (SA1.in_char_dma + 1) & 7;
	    if ((SA1.in_char_dma & 3) == 0)
	    {
		S9xSA1CharConv2 ();
	    }
	}
	break;
    case 0x2250:
	if (byte & 2)
	    SA1.sum = 0;
	SA1.arithmetic_op = byte & 3;
	break;
    
    case 0x2251:
	SA1.op1 = (SA1.op1 & 0xff00) | byte;
	break;
    case 0x2252:
	SA1.op1 = (SA1.op1 & 0xff) | (byte << 8);
	break;
    case 0x2253:
	SA1.op2 = (SA1.op2 & 0xff00) | byte;
	break;
    case 0x2254:
	SA1.op2 = (SA1.op2 & 0xff) | (byte << 8);
	switch (SA1.arithmetic_op)
	{
        case 0:	// multiply
	    SA1.sum = SA1.op1 * SA1.op2;
	    break;
	case 1: // divide
	    if (SA1.op2 == 0)
		SA1.sum = SA1.op1 << 16;
	    else
	    {
		SA1.sum = (SA1.op1 / (int) ((uint16) SA1.op2)) |
			  ((SA1.op1 % (int) ((uint16) SA1.op2)) << 16);
	    }
	    break;
	case 2:
	default: // cumulative sum
	    SA1.sum += SA1.op1 * SA1.op2;
	    if (SA1.sum & ((int64) 0xffffff << 32))
		SA1.overflow = TRUE;
	    break;
	}
	break;
    case 0x2258:    // Variable bit-field length/auto inc/start.
	Memory.FillRAM [0x2258] = byte;
	S9xSA1ReadVariableLengthData (TRUE, FALSE);
	return;
    case 0x2259:
    case 0x225a:
    case 0x225b:    // Variable bit-field start address
	Memory.FillRAM [address] = byte;
	// XXX: ???
	SA1.variable_bit_pos = 0;
	S9xSA1ReadVariableLengthData (FALSE, TRUE);
	return;
    default:
//	printf ("W: %02x->%04x\n", byte, address);
	break;
    }
    if (address >= 0x2200 && address <= 0x22ff)
	Memory.FillRAM [address] = byte;
}

static void S9xSA1CharConv2 ()
{
    uint32 dest = Memory.FillRAM [0x2235] | (Memory.FillRAM [0x2236] << 8);
    uint32 offset = (SA1.in_char_dma & 7) ? 0 : 1;
    int depth = (Memory.FillRAM [0x2231] & 3) == 0 ? 8 :
		(Memory.FillRAM [0x2231] & 3) == 1 ? 4 : 2;
    int bytes_per_char = 8 * depth;
    uint8 *p = &Memory.FillRAM [0x3000] + dest + offset * bytes_per_char;
    uint8 *q = &Memory.ROM [CMemory::MAX_ROM_SIZE - 0x10000] + offset * 64;

    switch (depth)
    {
    case 2:
	break;
    case 4:
	break;
    case 8:
	for (int l = 0; l < 8; l++, q += 8)
	{
	    for (int b = 0; b < 8; b++)
	    {
		uint8 r = *(q + b);
		*(p +  0) = (*(p +  0) << 1) | ((r >> 0) & 1);
		*(p +  1) = (*(p +  1) << 1) | ((r >> 1) & 1);
		*(p + 16) = (*(p + 16) << 1) | ((r >> 2) & 1);
		*(p + 17) = (*(p + 17) << 1) | ((r >> 3) & 1);
		*(p + 32) = (*(p + 32) << 1) | ((r >> 4) & 1);
		*(p + 33) = (*(p + 33) << 1) | ((r >> 5) & 1);
		*(p + 48) = (*(p + 48) << 1) | ((r >> 6) & 1);
		*(p + 49) = (*(p + 49) << 1) | ((r >> 7) & 1);
	    }
	    p += 2;
	}
	break;
    }
}

static void S9xSA1DMA ()
{
    uint32 src =  Memory.FillRAM [0x2232] |
	         (Memory.FillRAM [0x2233] << 8) |
		 (Memory.FillRAM [0x2234] << 16);
    uint32 dst =  Memory.FillRAM [0x2235] |
	         (Memory.FillRAM [0x2236] << 8) |
		 (Memory.FillRAM [0x2237] << 16);
    uint32 len =  Memory.FillRAM [0x2238] |
		 (Memory.FillRAM [0x2239] << 8);

    uint8 *s;
    uint8 *d;

    switch (Memory.FillRAM [0x2230] & 3)
    {
    case 0: // ROM
	s = SA1.Map [(src >> MEMMAP_SHIFT) & MEMMAP_MASK];
	if (s >= (uint8 *) CMemory::MAP_LAST)
	    s += (src & 0xffff);
	else
	    s = Memory.ROM + (src & 0xffff);
	break;
    case 1: // BW-RAM
	src &= Memory.SRAMMask;
	len &= Memory.SRAMMask;
	s = Memory.SRAM + src;
	break;
    default:
    case 2:
	src &= 0x3ff;
	len &= 0x3ff;
	s = &Memory.FillRAM [0x3000] + src;
	break;
    }

    if (Memory.FillRAM [0x2230] & 4)
    {
	dst &= Memory.SRAMMask;
	len &= Memory.SRAMMask;
	d = Memory.SRAM + dst;
    }
    else
    {
	dst &= 0x3ff;
	len &= 0x3ff;
	d = &Memory.FillRAM [0x3000] + dst;
    }
    memmove (d, s, len);
    Memory.FillRAM [0x2301] |= 0x20;
    
    if (Memory.FillRAM [0x220a] & 0x20)
    {
	SA1.Flags |= IRQ_PENDING_FLAG;
	SA1.IRQActive |= DMA_IRQ_SOURCE;
//	SA1.Executing = !SA1.Waiting;
    }
}

void S9xSA1ReadVariableLengthData (bool8 inc, bool8 no_shift)
{
    uint32 addr =  Memory.FillRAM [0x2259] |
		  (Memory.FillRAM [0x225a] << 8) |
		  (Memory.FillRAM [0x225b] << 16);
    uint8 shift = Memory.FillRAM [0x2258] & 15;

    if (no_shift)
	shift = 0;
    else
    if (shift == 0)
	shift = 16;

    uint8 s = shift + SA1.variable_bit_pos;

    if (s >= 16)
    {
	addr += (s >> 4) << 1;
	s &= 15;
    }
    uint32 data = S9xSA1GetWord (addr) |
		  (S9xSA1GetWord (addr + 2) << 16);

    data >>= s;
    Memory.FillRAM [0x230c] = (uint8) data;
    Memory.FillRAM [0x230d] = (uint8) (data >> 8);
    if (inc)
    {
	SA1.variable_bit_pos = (SA1.variable_bit_pos + shift) & 15;
	Memory.FillRAM [0x2259] = (uint8) addr;
	Memory.FillRAM [0x225a] = (uint8) (addr >> 8);
	Memory.FillRAM [0x225b] = (uint8) (addr >> 16);
    }
}