dma.cpp

SFC游戏模拟器 snes9x 1.43 的原代码

							*(p +  0) = (*(p +  0) << 1) | ((r >> 4) & 1);
							*(p +  1) = (*(p +  1) << 1) | ((r >> 5) & 1);
							*(p + 16) = (*(p + 16) << 1) | ((r >> 6) & 1);
							*(p + 17) = (*(p + 17) << 1) | ((r >> 7) & 1);
						}
						p += 2;
					}
					p += 32 - 16;
				}
			}
			break;
		case 8:
			for (i = 0; i < count; i += inc, base += char_line_bytes, 
				inc = char_line_bytes, char_count = num_chars)
			{
				uint8 *line = base + (num_chars - char_count) * 8;
				for (uint32 j = 0; j < char_count && p - buffer < count; 
				j++, line += 8)
				{
					uint8 *q = line;
					for (int l = 0; l < 8; l++, q += bytes_per_line)
					{
						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;
					}
					p += 64 - 16;
				}
			}
			break;
		}
    }
	
#ifdef DEBUGGER
    if (Settings.TraceDMA)
    {
		sprintf (String, "DMA[%d]: %s Mode: %d 0x%02X%04X->0x21%02X Bytes: %d (%s) V-Line:%ld",
			Channel, d->TransferDirection ? "read" : "write",
			d->TransferMode, d->ABank, d->AAddress,
			d->BAddress, d->TransferBytes,
			d->AAddressFixed ? "fixed" :
		(d->AAddressDecrement ? "dec" : "inc"),
			CPU.V_Counter);
		if (d->BAddress == 0x18 || d->BAddress == 0x19 || d->BAddress == 0x39 || d->BAddress == 0x3a)
			sprintf (String, "%s VRAM: %04X (%d,%d) %s", String,
				PPU.VMA.Address,
				PPU.VMA.Increment, PPU.VMA.FullGraphicCount,
				PPU.VMA.High ? "word" : "byte");

		else
			if (d->BAddress == 0x22 || d->BAddress == 0x3b)
			
				sprintf (String, "%s CGRAM: %02X (%x)", String, PPU.CGADD,
					PPU.CGFLIP);			
			else
				if (d->BAddress == 0x04 || d->BAddress == 0x38)
					sprintf (String, "%s OBJADDR: %04X", String, PPU.OAMAddr);
				S9xMessage (S9X_TRACE, S9X_DMA_TRACE, String);
    }
#endif
	
    if (!d->TransferDirection)
    {
		/* XXX: DMA is potentially broken here for cases where we DMA across
		 * XXX: memmap boundries. A possible solution would be to re-call
		 * XXX: GetBasePointer whenever we cross a boundry, and when
		 * XXX: GetBasePointer returns (0) to take the 'slow path' and use
		 * XXX: S9xGetByte instead of *base. GetBasePointer() would want to
		 * XXX: return (0) for MAP_PPU and whatever else is a register range
		 * XXX: rather than a RAM/ROM block, and we'd want to detect MAP_PPU
		 * XXX: (or specifically, Address Bus B addresses $2100-$21FF in
		 * XXX: banks $00-$3F) specially and treat it as MAP_NONE (since
		 * XXX: PPU->PPU transfers don't work).
		 */

		//reflects extra cycle used by DMA
		CPU.Cycles += SLOW_ONE_CYCLE * (count+1);
		S9xUpdateAPUTimer();

		uint8 *base = GetBasePointer ((d->ABank << 16) + d->AAddress);
		uint16 p = d->AAddress;
		
		if (!base)
			base = Memory.ROM;
		
		if (in_sa1_dma)
		{
			base = &Memory.ROM [CMemory::MAX_ROM_SIZE - 0x10000];
			p = 0;
		}
		
		if (in_sdd1_dma)
		{
			base = in_sdd1_dma;
			p = 0;
		}
		if(spc7110_dma)
		{
			base=spc7110_dma;
			p = 0;
		}
		if (inc > 0)
			d->AAddress += count;
		else
			if (inc < 0)
				d->AAddress -= count;
			
			if (d->TransferMode == 0 || d->TransferMode == 2 || d->TransferMode == 6)
			{
				switch (d->BAddress)
				{
				case 0x04:
					do
					{
						Work = *(base + p);
						REGISTER_2104(Work);
						p += inc;
						CHECK_SOUND();
					} while (--count > 0);
					break;
				case 0x18:
#ifndef CORRECT_VRAM_READS
					IPPU.FirstVRAMRead = TRUE;
#endif
					if (!PPU.VMA.FullGraphicCount)
					{
						do
						{
							Work = *(base + p);
							REGISTER_2118_linear(Work);
							p += inc;
							CHECK_SOUND();
						} while (--count > 0);
					}
					else
					{
						do
						{
							Work = *(base + p);
							REGISTER_2118_tile(Work);
							p += inc;
							CHECK_SOUND();
						} while (--count > 0);
					}
					break;
				case 0x19:
#ifndef CORRECT_VRAM_READS
					IPPU.FirstVRAMRead = TRUE;
#endif
					if (!PPU.VMA.FullGraphicCount)
					{
						do
						{
							Work = *(base + p);
							REGISTER_2119_linear(Work);
							p += inc;
							CHECK_SOUND();
						} while (--count > 0);
					}
					else
					{
						do
						{
							Work = *(base + p);
							REGISTER_2119_tile(Work);
							p += inc;
							CHECK_SOUND();
						} while (--count > 0);
					}
					break;
				case 0x22:
					do
					{
						Work = *(base + p);
						REGISTER_2122(Work);
						p += inc;
						CHECK_SOUND();
					} while (--count > 0);
					break;
				case 0x80:
					do
					{
						Work = *(base + p);
						REGISTER_2180(Work);
						p += inc;
						CHECK_SOUND();
					} while (--count > 0);
					break;
				default:
					do
					{
						Work = *(base + p);
						S9xSetPPU (Work, 0x2100 + d->BAddress);
						p += inc;
						CHECK_SOUND();
					} while (--count > 0);
					break;
				}
			}
			else
				if (d->TransferMode == 1 || d->TransferMode == 5)
				{
					if (d->BAddress == 0x18)
					{
						// Write to V-RAM
#ifndef CORRECT_VRAM_READS
						IPPU.FirstVRAMRead = TRUE;
#endif
						if (!PPU.VMA.FullGraphicCount)
						{
							while (count > 1)
							{
								Work = *(base + p);
								REGISTER_2118_linear(Work);
								p += inc;
								
								Work = *(base + p);
								REGISTER_2119_linear(Work);
								p += inc;
								CHECK_SOUND();
								count -= 2;
							}
							if (count == 1)
							{
								Work = *(base + p);
								REGISTER_2118_linear(Work);
								p += inc;
							}
						}
						else
						{
							while (count > 1)
							{
								Work = *(base + p);
								REGISTER_2118_tile(Work);
								p += inc;
								
								Work = *(base + p);
								REGISTER_2119_tile(Work);
								p += inc;
								CHECK_SOUND();
								count -= 2;
							}
							if (count == 1)
							{
								Work = *(base + p);
								REGISTER_2118_tile(Work);
								p += inc;
							}
						}
					}
					else
					{
						// DMA mode 1 general case
						while (count > 1)
						{
							Work = *(base + p);
							S9xSetPPU (Work, 0x2100 + d->BAddress);
							p += inc;
							
							Work = *(base + p);
							S9xSetPPU (Work, 0x2101 + d->BAddress);
							p += inc;
							CHECK_SOUND();
							count -= 2;
						}
						if (count == 1)
						{
							Work = *(base + p);
							S9xSetPPU (Work, 0x2100 + d->BAddress);
							p += inc;
						}
					}
				}
				else
					if (d->TransferMode == 3 || d->TransferMode == 7)
					{
						do
						{
							Work = *(base + p);
							S9xSetPPU (Work, 0x2100 + d->BAddress);
							p += inc;
							if (count <= 1)
								break;
							
							Work = *(base + p);
							S9xSetPPU (Work, 0x2100 + d->BAddress);
							p += inc;
							if (count <= 2)
								break;
							
							Work = *(base + p);
							S9xSetPPU (Work, 0x2101 + d->BAddress);
							p += inc;
							if (count <= 3)
								break;
							
							Work = *(base + p);
							S9xSetPPU (Work, 0x2101 + d->BAddress);
							p += inc;
							CHECK_SOUND();
							count -= 4;
						} while (count > 0);
					}
					else
						if (d->TransferMode == 4)
						{
							do
							{
								Work = *(base + p);
								S9xSetPPU (Work, 0x2100 + d->BAddress);
								p += inc;
								if (count <= 1)
									break;
								
								Work = *(base + p);
								S9xSetPPU (Work, 0x2101 + d->BAddress);
								p += inc;
								if (count <= 2)
									break;
								
								Work = *(base + p);
								S9xSetPPU (Work, 0x2102 + d->BAddress);
								p += inc;
								if (count <= 3)
									break;
								
								Work = *(base + p);
								S9xSetPPU (Work, 0x2103 + d->BAddress);
								p += inc;
								CHECK_SOUND();
								count -= 4;
							} while (count > 0);
						}
						else
						{
#ifdef DEBUGGER
							//	    if (Settings.TraceDMA)
							{
								sprintf (String, "Unknown DMA transfer mode: %d on channel %d\n",
									d->TransferMode, Channel);
								S9xMessage (S9X_TRACE, S9X_DMA_TRACE, String);
							}
#endif
						}
    }
    else
    {
		/* XXX: DMA is potentially broken here for cases where the dest is
		 * XXX: in the Address Bus B range. Note that this bad dest may not
		 * XXX: cover the whole range of the DMA though, if we transfer
		 * XXX: 65536 bytes only 256 of them may be Address Bus B.
		 */
		do
		{
			switch (d->TransferMode)
			{
			case 0:
			case 2:
			case 6:
				Work = S9xGetPPU (0x2100 + d->BAddress);
				S9xSetByte (Work, (d->ABank << 16) + d->AAddress);
				d->AAddress += inc;
				--count;
				break;
				
			case 1:
			case 5:
				Work = S9xGetPPU (0x2100 + d->BAddress);
				S9xSetByte (Work, (d->ABank << 16) + d->AAddress);
				d->AAddress += inc;
				if (!--count)
					break;
				
				Work = S9xGetPPU (0x2101 + d->BAddress);
				S9xSetByte (Work, (d->ABank << 16) + d->AAddress);
				d->AAddress += inc;
				count--;
				break;
				
			case 3:
			case 7:
				Work = S9xGetPPU (0x2100 + d->BAddress);
				S9xSetByte (Work, (d->ABank << 16) + d->AAddress);
				d->AAddress += inc;
				if (!--count)
					break;