fxemu.cpp

著名SFC模拟器Snes9x的源代码。

/*
 * Snes9x - Portable Super Nintendo Entertainment System (TM) emulator.
 *
 * (c) Copyright 1996 - 2001 Gary Henderson ([e-mail]) and
 *                           Jerremy Koot ([e-mail])
 *
 * Super FX C emulator code 
 * (c) Copyright 1997 - 1999 Ivar ([e-mail]) and
 *                           Gary Henderson.
 * Super FX assembler emulator code (c) Copyright 1998 zsKnight and _Demo_.
 *
 * DSP1 emulator code (c) Copyright 1998 Ivar, _Demo_ and Gary Henderson.
 * C4 asm and some C emulation code (c) Copyright 2000 zsKnight and _Demo_.
 * C4 C code (c) Copyright 2001 Gary Henderson ([e-mail]).
 *
 * DOS port code contains the works of other authors. See headers in
 * individual files.
 *
 * Snes9x homepage: www.snes9x.com
 *
 * Permission to use, copy, modify and distribute Snes9x in both binary and
 * source form, for non-commercial purposes, is hereby granted without fee,
 * providing that this license information and copyright notice appear with
 * all copies and any derived work.
 *
 * This software is provided 'as-is', without any express or implied
 * warranty. In no event shall the authors be held liable for any damages
 * arising from the use of this software.
 *
 * Snes9x is freeware for PERSONAL USE only. Commercial users should
 * seek permission of the copyright holders first. Commercial use includes
 * charging money for Snes9x or software derived from Snes9x.
 *
 * The copyright holders request that bug fixes and improvements to the code
 * should be forwarded to them so everyone can benefit from the modifications
 * in future versions.
 *
 * Super NES and Super Nintendo Entertainment System are trademarks of
 * Nintendo Co., Limited and its subsidiary companies.
 */
#include "fxemu.h"
#include "fxinst.h"
#include <stdlib.h>
#include <string.h>
#include <stdio.h>

/* The FxChip Emulator's internal variables */
struct FxRegs_s GSU = {0};

uint32 (**fx_ppfFunctionTable)(uint32) = 0;
void (**fx_ppfPlotTable)() = 0;
void (**fx_ppfOpcodeTable)() = 0;

#if 0
void fx_setCache()
{
    uint32 c;
    GSU.bCacheActive = TRUE;
    GSU.pvRegisters[0x3e] &= 0xf0;
    c = (uint32)GSU.pvRegisters[0x3e];
    c |= ((uint32)GSU.pvRegisters[0x3f])<<8;
    if(c == GSU.vCacheBaseReg)
	return;
    GSU.vCacheBaseReg = c;
    GSU.vCacheFlags = 0;
    if(c < (0x10000-512))
    {
	uint8 const* t = &ROM(c);
	memcpy(GSU.pvCache,t,512);
    }
    else
    {
	uint8 const* t1;
	uint8 const* t2;
	uint32 i = 0x10000 - c;
	t1 = &ROM(c);
	t2 = &ROM(0);
	memcpy(GSU.pvCache,t1,i);
	memcpy(&GSU.pvCache[i],t2,512-i);
    }
}
#endif

void FxCacheWriteAccess(uint16 vAddress)
{
#if 0
    if(!GSU.bCacheActive)
    {
	uint8 v = GSU.pvCache[GSU.pvCache[vAddress&0x1ff];
	fx_setCache();
	GSU.pvCache[GSU.pvCache[vAddress&0x1ff] = v;
    }
#endif
    if((vAddress & 0x00f) == 0x00f)
	GSU.vCacheFlags |= 1 << ((vAddress&0x1f0) >> 4);
}

void FxFlushCache()
{
    GSU.vCacheFlags = 0;
    GSU.vCacheBaseReg = 0;
    GSU.bCacheActive = FALSE;
//    GSU.vPipe = 0x1;
}

static void fx_backupCache()
{
#if 0
    uint32 i;
    uint32 v = GSU.vCacheFlags;
    uint32 c = USEX16(GSU.vCacheBaseReg);
    if(v)
	for(i=0; i<32; i++)
	{
	    if(v&1)
	    {
		if(c < (0x10000-16))
		{
		    uint8 * t = &GSU.pvPrgBank[c];
		    memcpy(&GSU.avCacheBackup[i<<4],t,16);
		    memcpy(t,&GSU.pvCache[i<<4],16);
		}
		else
		{
		    uint8 * t1;
		    uint8 * t2;
		    uint32 a = 0x10000 - c;
		    t1 = &GSU.pvPrgBank[c];
		    t2 = &GSU.pvPrgBank[0];
		    memcpy(&GSU.avCacheBackup[i<<4],t1,a);
		    memcpy(t1,&GSU.pvCache[i<<4],a);
		    memcpy(&GSU.avCacheBackup[(i<<4)+a],t2,16-a);
		    memcpy(t2,&GSU.pvCache[(i<<4)+a],16-a);
		}		
	    }
	    c = USEX16(c+16);
	    v >>= 1;
	}
#endif
}

static void fx_restoreCache()
{
#if 0
    uint32 i;
    uint32 v = GSU.vCacheFlags;
    uint32 c = USEX16(GSU.vCacheBaseReg);
    if(v)
	for(i=0; i<32; i++)
	{
	    if(v&1)
	    {
		if(c < (0x10000-16))
		{
		    uint8 * t = &GSU.pvPrgBank[c];
		    memcpy(t,&GSU.avCacheBackup[i<<4],16);
		    memcpy(&GSU.pvCache[i<<4],t,16);
		}
		else
		{
		    uint8 * t1;
		    uint8 * t2;
		    uint32 a = 0x10000 - c;
		    t1 = &GSU.pvPrgBank[c];
		    t2 = &GSU.pvPrgBank[0];
		    memcpy(t1,&GSU.avCacheBackup[i<<4],a);
		    memcpy(&GSU.pvCache[i<<4],t1,a);
		    memcpy(t2,&GSU.avCacheBackup[(i<<4)+a],16-a);
		    memcpy(&GSU.pvCache[(i<<4)+a],t2,16-a);
		}		
	    }
	    c = USEX16(c+16);
	    v >>= 1;
	}
#endif
}

void fx_flushCache()
{
    fx_restoreCache();
    GSU.vCacheFlags = 0;
    GSU.bCacheActive = FALSE;
}

static void fx_readRegisterSpace()
{
    int i;
    uint8 *p;
    static uint32 avHeight[] = { 128, 160, 192, 256 };
    static uint32 avMult[] = { 16, 32, 32, 64 };

    GSU.vErrorCode = 0;

    /* Update R0-R15 */
    p = GSU.pvRegisters;
    for(i=0; i<16; i++)
    {
	GSU.avReg[i] = *p++;
	GSU.avReg[i] += ((uint32)(*p++)) << 8;
    }

    /* Update other registers */
    p = GSU.pvRegisters;
    GSU.vStatusReg = (uint32)p[GSU_SFR];
    GSU.vStatusReg |= ((uint32)p[GSU_SFR+1]) << 8;
    GSU.vPrgBankReg = (uint32)p[GSU_PBR];
    GSU.vRomBankReg = (uint32)p[GSU_ROMBR];
    GSU.vRamBankReg = ((uint32)p[GSU_RAMBR]) & (FX_RAM_BANKS-1);
    GSU.vCacheBaseReg = (uint32)p[GSU_CBR];
    GSU.vCacheBaseReg |= ((uint32)p[GSU_CBR+1]) << 8;

    /* Update status register variables */
    GSU.vZero = !(GSU.vStatusReg & FLG_Z);
    GSU.vSign = (GSU.vStatusReg & FLG_S) << 12;
    GSU.vOverflow = (GSU.vStatusReg & FLG_OV) << 16;
    GSU.vCarry = (GSU.vStatusReg & FLG_CY) >> 2;
    
    /* Set bank pointers */
    GSU.pvRamBank = GSU.apvRamBank[GSU.vRamBankReg & 0x3];
    GSU.pvRomBank = GSU.apvRomBank[GSU.vRomBankReg];
    GSU.pvPrgBank = GSU.apvRomBank[GSU.vPrgBankReg];

    /* Set screen pointers */
    GSU.pvScreenBase = &GSU.pvRam[ USEX8(p[GSU_SCBR]) << 10 ];
    i = (int)(!!(p[GSU_SCMR] & 0x04));
    i |= ((int)(!!(p[GSU_SCMR] & 0x20))) << 1;
    GSU.vScreenHeight = GSU.vScreenRealHeight = avHeight[i];
    GSU.vMode = p[GSU_SCMR] & 0x03;
#if 0
    if(GSU.vMode == 2)
	error illegal color depth GSU.vMode;
#endif
    if(i == 3)
	GSU.vScreenSize = (256/8) * (256/8) * 32;
    else
	GSU.vScreenSize = (GSU.vScreenHeight/8) * (256/8) * avMult[GSU.vMode];
    if (GSU.vPlotOptionReg & 0x10)
    {
	/* OBJ Mode (for drawing into sprites) */
	GSU.vScreenHeight = 256;
    }
#if 0
    if(GSU.pvScreenBase + GSU.vScreenSize > GSU.pvRam + (GSU.nRamBanks * 65536))
	error illegal address for screen base register
#else
    if(GSU.pvScreenBase + GSU.vScreenSize > GSU.pvRam + (GSU.nRamBanks * 65536))
	GSU.pvScreenBase =  GSU.pvRam + (GSU.nRamBanks * 65536) - GSU.vScreenSize;
#endif
    GSU.pfPlot = fx_apfPlotTable[GSU.vMode];
    GSU.pfRpix = fx_apfPlotTable[GSU.vMode + 5];

    fx_ppfOpcodeTable[0x04c] = GSU.pfPlot;
    fx_ppfOpcodeTable[0x14c] = GSU.pfRpix;
    fx_ppfOpcodeTable[0x24c] = GSU.pfPlot;
    fx_ppfOpcodeTable[0x34c] = GSU.pfRpix;

    fx_computeScreenPointers ();

    fx_backupCache();
}

void fx_computeScreenPointers ()
{
    if (GSU.vMode != GSU.vPrevMode || 
	GSU.vPrevScreenHeight != GSU.vScreenHeight)
    {
	int i;

	/* Make a list of pointers to the start of each screen column */
	switch (GSU.vScreenHeight)
	{
	    case 128:
		switch (GSU.vMode)
		{
		    case 0:
			for (i = 0; i < 32; i++)
			{
			    GSU.apvScreen[i] = GSU.pvScreenBase + (i << 4);
			    GSU.x[i] = i << 8;
			}
			break;
		    case 1:
			for (i = 0; i < 32; i++)
			{
			    GSU.apvScreen[i] = GSU.pvScreenBase + (i << 5);
			    GSU.x[i] = i << 9;
			}
			break;
		    case 2:
		    case 3:
			for (i = 0; i < 32; i++)
			{
			    GSU.apvScreen[i] = GSU.pvScreenBase + (i << 6);
			    GSU.x[i] = i << 10;
			}
			break;
		}
		break;
	    case 160:
		switch (GSU.vMode)
		{
		    case 0:
			for (i = 0; i < 32; i++)
			{
			    GSU.apvScreen[i] = GSU.pvScreenBase + (i << 4);
			    GSU.x[i] = (i << 8) + (i << 6);
			}
			break;
		    case 1:
			for (i = 0; i < 32; i++)
			{
			    GSU.apvScreen[i] = GSU.pvScreenBase + (i << 5);
			    GSU.x[i] = (i << 9) + (i << 7);
			}
			break;
		    case 2:
		    case 3:
			for (i = 0; i < 32; i++)
			{
			    GSU.apvScreen[i] = GSU.pvScreenBase + (i << 6);
			    GSU.x[i] = (i << 10) + (i << 8);
			}
			break;
		}
		break;
	    case 192:
		switch (GSU.vMode)
		{
		    case 0:
			for (i = 0; i < 32; i++)
			{