dsp3emu.cpp

SFC游戏模拟器 snes9x 1.43 的原代码

			break;
		}
	case 6:
		{
			DSP3_DR = DSP3_X;
			break;
		}
	case 7:
		{
			DSP3_DR = DSP3_Y;
			DSP3_Index = 0;
			break;
		}
	}
}

uint8  DSP3_Bitmap[8];
uint8  DSP3_Bitplane[8];
uint16 DSP3_BMIndex;
uint16 DSP3_BPIndex;
uint16 DSP3_Count;

void DSP3_Convert_A()
{
	if (DSP3_BMIndex < 8)
	{
		DSP3_Bitmap[DSP3_BMIndex++] = (uint8) (DSP3_DR);
		DSP3_Bitmap[DSP3_BMIndex++] = (uint8) (DSP3_DR >> 8);

		if (DSP3_BMIndex == 8)
		{
			for (short i=0; i < 8; i++)
				for (short j=0; j < 8; j++)
				{
					DSP3_Bitplane[j] <<= 1;
					DSP3_Bitplane[j] |= (DSP3_Bitmap[i] >> j) & 1;
				}

			DSP3_BPIndex = 0;
			DSP3_Count--;
		}
	}

	if (DSP3_BMIndex == 8)
	{
		if (DSP3_BPIndex == 8)
		{
			if (!DSP3_Count) DSP3_Reset();
			DSP3_BMIndex = 0;
		}
		else
		{
			DSP3_DR = DSP3_Bitplane[DSP3_BPIndex++];
			DSP3_DR |= DSP3_Bitplane[DSP3_BPIndex++] << 8;
		}
	}
}

void DSP3_Convert()
{
	DSP3_Count = DSP3_DR;
	DSP3_BMIndex = 0;
	SetDSP3 = &DSP3_Convert_A;
}

bool DSP3_GetBits(uint8 Count)
{
	if (!DSP3_BitsLeft)
	{
		DSP3_BitsLeft = Count;
		DSP3_ReqBits = 0;
	}

	do {
		if (!DSP3_BitCount)
		{
			DSP3_SR = 0xC0;
			return false;
		}

		DSP3_ReqBits <<= 1;
		if (DSP3_ReqData & 0x8000) DSP3_ReqBits++;
		DSP3_ReqData <<= 1;
        
		DSP3_BitCount--;
		DSP3_BitsLeft--;

	} while (DSP3_BitsLeft);

	return true;
}

void DSP3_Decode_Data()
{
	if (!DSP3_BitCount)
	{
		if (DSP3_SR & 0x40)
		{
			DSP3_ReqData = DSP3_DR;
			DSP3_BitCount += 16;
		}
		else
		{
			DSP3_SR = 0xC0;
			return;
		}	
	}

	if (DSP3_LZCode == 1)
	{
		if (!DSP3_GetBits(1))
			return;

		if (DSP3_ReqBits)
			DSP3_LZLength = 12;
		else
			DSP3_LZLength = 8;

		DSP3_LZCode++;
	}

	if (DSP3_LZCode == 2)
	{
		if (!DSP3_GetBits(DSP3_LZLength))
			return;

		DSP3_LZCode = 0;
		DSP3_Outwords--;
		if (!DSP3_Outwords) SetDSP3 = &DSP3_Reset;

		DSP3_SR = 0x80;
		DSP3_DR = DSP3_ReqBits;
		return;
	}

	if (DSP3_BaseCode == 0xffff)
	{
		if (!DSP3_GetBits(DSP3_BaseLength))
			return;

		DSP3_BaseCode = DSP3_ReqBits;
	}

	if (!DSP3_GetBits(DSP3_CodeLengths[DSP3_BaseCode]))
		return;

	DSP3_Symbol = DSP3_Codes[DSP3_CodeOffsets[DSP3_BaseCode] + DSP3_ReqBits];
	DSP3_BaseCode = 0xffff;

	if (DSP3_Symbol & 0xff00)
	{
		DSP3_Symbol += 0x7f02;
		DSP3_LZCode++;
	}
	else
	{
		DSP3_Outwords--;
		if (!DSP3_Outwords) 
			SetDSP3 = &DSP3_Reset;
	}

	DSP3_SR = 0x80;
	DSP3_DR = DSP3_Symbol;
}

void DSP3_Decode_Tree()
{
	if (!DSP3_BitCount)
	{
		DSP3_ReqData = DSP3_DR;
		DSP3_BitCount += 16;
	}

	if (!DSP3_BaseCodes)
	{
		DSP3_GetBits(1);
		if (DSP3_ReqBits)
		{
			DSP3_BaseLength = 3;
			DSP3_BaseCodes = 8;
		}
		else
		{
			DSP3_BaseLength = 2;
			DSP3_BaseCodes = 4;
		}
	}

	while (DSP3_BaseCodes)
	{
		if (!DSP3_GetBits(3))
			return;

		DSP3_ReqBits++;

		DSP3_CodeLengths[DSP3_Index] = (uint8) DSP3_ReqBits;
		DSP3_CodeOffsets[DSP3_Index] = DSP3_Symbol;
		DSP3_Index++;

		DSP3_Symbol += 1 << DSP3_ReqBits;
		DSP3_BaseCodes--;
	}

	DSP3_BaseCode = 0xffff;
	DSP3_LZCode = 0;

	SetDSP3 = &DSP3_Decode_Data;
	if (DSP3_BitCount) DSP3_Decode_Data();
}

void DSP3_Decode_Symbols()
{
	DSP3_ReqData = DSP3_DR;
	DSP3_BitCount += 16;

	do {

		if (DSP3_BitCommand == 0xffff)
		{
			if (!DSP3_GetBits(2)) return;
			DSP3_BitCommand = DSP3_ReqBits;
		}

		switch (DSP3_BitCommand)
		{
		case 0:
			{
				if (!DSP3_GetBits(9)) return;
				DSP3_Symbol = DSP3_ReqBits;
				break;
			}
		case 1:
			{
				DSP3_Symbol++;
				break;
			}
		case 2:
			{
				if (!DSP3_GetBits(1)) return;
				DSP3_Symbol += 2 + DSP3_ReqBits;
				break;
			}
		case 3:
			{
				if (!DSP3_GetBits(4)) return;
				DSP3_Symbol += 4 + DSP3_ReqBits;
				break;
			}
		}

		DSP3_BitCommand = 0xffff;

		DSP3_Codes[DSP3_Index++] = DSP3_Symbol;
		DSP3_Codewords--;
		
	} while (DSP3_Codewords);

	DSP3_Index = 0;
	DSP3_Symbol = 0;
	DSP3_BaseCodes = 0;

	SetDSP3 = &DSP3_Decode_Tree;
	if (DSP3_BitCount) DSP3_Decode_Tree();
}

void DSP3_Decode_A()
{
	DSP3_Outwords = DSP3_DR;
	SetDSP3 = &DSP3_Decode_Symbols;
	DSP3_BitCount = 0;
	DSP3_BitsLeft = 0;
	DSP3_Symbol = 0;
	DSP3_Index = 0;
	DSP3_BitCommand = 0xffff;
	DSP3_SR = 0xC0;
}

void DSP3_Decode()
{
	DSP3_Codewords = DSP3_DR;
	SetDSP3 = &DSP3_Decode_A;
}

void DSP3_Command()
{
	if (DSP3_DR < 0x40)
	{
		switch (DSP3_DR)
		{
		case 0x02: SetDSP3 = &DSP3_Coordinate; break;
		case 0x03: SetDSP3 = &DSP3_OP03; break;
		case 0x06: SetDSP3 = &DSP3_OP06; break;
		case 0x07: SetDSP3 = &DSP3_OP07; return;									 
		case 0x0f: SetDSP3 = &DSP3_TestMemory; break;
		case 0x18: SetDSP3 = &DSP3_Convert; break;
		case 0x1f: SetDSP3 = &DSP3_MemoryDump; break;
		case 0x2f: SetDSP3 = &DSP3_MemorySize; break;
		case 0x38: SetDSP3 = &DSP3_Decode; break;
		}
		DSP3_SR = 0x0080;
		DSP3_Index = 0;
	}
}

void DSP3_Reset()
{
	DSP3_DR = 0x0080;
	DSP3_SR = 0x0084;
	SetDSP3 = &DSP3_Command;
}

void DSP3SetByte(uint8 byte, uint16 address)
{
	if ((address & 0xC000) == 0x8000)
    {
		if (DSP3_SR & 0x04)
		{
			DSP3_DR = (DSP3_DR & 0xff00) + byte;
			(*SetDSP3)();
		}
		else
		{
			DSP3_SR ^= 0x10;

			if (DSP3_SR & 0x10)	
				DSP3_DR = (DSP3_DR & 0xff00) + byte;
			else
			{
				DSP3_DR = (DSP3_DR & 0x00ff) + (byte << 8);
				(*SetDSP3)();
			}	
		}
	}
}

uint8 DSP3GetByte(uint16 address)
{
	if ((address & 0xC000) == 0x8000)
    {
		uint8 byte;

		if (DSP3_SR & 0x04)
		{
			byte = (uint8) DSP3_DR;
			(*SetDSP3)();
		}
		else
		{
			DSP3_SR ^= 0x10;

			if (DSP3_SR & 0x10)	
				byte = (uint8) (DSP3_DR);
			else
			{
				byte = (uint8) (DSP3_DR >> 8);
				(*SetDSP3)();
			}
		}

		return byte;
	}

	return (uint8) DSP3_SR;
}