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x6502.cpp

/* FCE Ultra - NES/Famicom Emulator
 *
 * Copyright notice for this file:
 *  Copyright (C) 2002 Xodnizel
 *
 * This program is free software; you can redistribute it and/or modify
 * it under the terms of the GNU General Public License as published by
 * the Free Software Foundation; either version 2 of the License, or
 * (at your option) any later version.
 *
 * This program is distributed in the hope that it will be useful,
 * but WITHOUT ANY WARRANTY; without even the implied warranty of
 * MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE.  See the
 * GNU General Public License for more details.
 *
 * You should have received a copy of the GNU General Public License
 * along with this program; if not, write to the Free Software
 * Foundation, Inc., 59 Temple Place, Suite 330, Boston, MA  02111-1307  USA
 */

#include <string.h>
#include "types.h"
#include "x6502.h"
#include "fceu.h"
#include "debug.h"
#include "sound.h"
#ifdef _S9XLUA_H
#include "fceulua.h"
#endif

#include "x6502abbrev.h"
X6502 X;
uint32 timestamp;
void (*MapIRQHook)(int a);

#define ADDCYC(x) \
{     \
 int __x=x;       \
 _tcount+=__x;    \
 _count-=__x*48;  \
 timestamp+=__x;  \
}

//normal memory read
static INLINE uint8 RdMem(unsigned int A)
{
 return(_DB=ARead[A](A));
}

//normal memory write
static INLINE void WrMem(unsigned int A, uint8 V)
{
      BWrite[A](A,V);
      #ifdef _S9XLUA_H
      CallRegisteredLuaMemHook(A, 1, V, LUAMEMHOOK_WRITE);
      #endif
}

static INLINE uint8 RdRAM(unsigned int A) 
{
  //bbit edited: this was changed so cheat substituion would work
  return(_DB=ARead[A](A));
  // return(_DB=RAM[A]); 
}

static INLINE void WrRAM(unsigned int A, uint8 V)
{
      RAM[A]=V;
      #ifdef _S9XLUA_H
      CallRegisteredLuaMemHook(A, 1, V, LUAMEMHOOK_WRITE);
      #endif
}

uint8 X6502_DMR(uint32 A)
{
 ADDCYC(1);
 return(X.DB=ARead[A](A));
}

void X6502_DMW(uint32 A, uint8 V)
{
 ADDCYC(1);
 BWrite[A](A,V);
 #ifdef _S9XLUA_H
 CallRegisteredLuaMemHook(A, 1, V, LUAMEMHOOK_WRITE);
 #endif
}

#define PUSH(V) \
{       \
 uint8 VTMP=V;  \
 WrRAM(0x100+_S,VTMP);  \
 _S--;  \
}       

#define POP() RdRAM(0x100+(++_S))

static uint8 ZNTable[256];
/* Some of these operations will only make sense if you know what the flag
   constants are. */

#define X_ZN(zort)      _P&=~(Z_FLAG|N_FLAG);_P|=ZNTable[zort]
#define X_ZNT(zort)  _P|=ZNTable[zort]

#define JR(cond);  \
{    \
 if(cond)  \
 {  \
  uint32 tmp;  \
  int32 disp;  \
  disp=(int8)RdMem(_PC);  \
  _PC++;  \
  ADDCYC(1);  \
  tmp=_PC;  \
  _PC+=disp;  \
  if((tmp^_PC)&0x100)  \
  ADDCYC(1);  \
 }  \
 else _PC++;  \
}


#define LDA     _A=x;X_ZN(_A)
#define LDX     _X=x;X_ZN(_X)
#define LDY  _Y=x;X_ZN(_Y)

/*  All of the freaky arithmetic operations. */
#define AND  _A&=x;X_ZN(_A)
#define BIT  _P&=~(Z_FLAG|V_FLAG|N_FLAG);_P|=ZNTable[x&_A]&Z_FLAG;_P|=x&(V_FLAG|N_FLAG)
#define EOR  _A^=x;X_ZN(_A)
#define ORA  _A|=x;X_ZN(_A)

#define ADC  {  \
        uint32 l=_A+x+(_P&1);  \
        _P&=~(Z_FLAG|C_FLAG|N_FLAG|V_FLAG);  \
        _P|=((((_A^x)&0x80)^0x80) & ((_A^l)&0x80))>>1;  \
        _P|=(l>>8)&C_FLAG;  \
        _A=l;  \
        X_ZNT(_A);  \
       }

#define SBC  {  \
        uint32 l=_A-x-((_P&1)^1);  \
        _P&=~(Z_FLAG|C_FLAG|N_FLAG|V_FLAG);  \
        _P|=((_A^l)&(_A^x)&0x80)>>1;  \
        _P|=((l>>8)&C_FLAG)^C_FLAG;  \
        _A=l;  \
        X_ZNT(_A);  \
       }

#define CMPL(a1,a2) {  \
         uint32 t=a1-a2;  \
         X_ZN(t&0xFF);  \
         _P&=~C_FLAG;  \
         _P|=((t>>8)&C_FLAG)^C_FLAG;  \
                }

/* Special undocumented operation.  Very similar to CMP. */
#define AXS      {  \
                     uint32 t=(_A&_X)-x;    \
                     X_ZN(t&0xFF);      \
                     _P&=~C_FLAG;       \
         _P|=((t>>8)&C_FLAG)^C_FLAG;  \
         _X=t;  \
        }

#define CMP    CMPL(_A,x)
#define CPX    CMPL(_X,x)
#define CPY          CMPL(_Y,x)

/* The following operations modify the byte being worked on. */
#define DEC         x--;X_ZN(x)
#define INC    x++;X_ZN(x)

#define ASL  _P&=~C_FLAG;_P|=x>>7;x<<=1;X_ZN(x)
#define LSR  _P&=~(C_FLAG|N_FLAG|Z_FLAG);_P|=x&1;x>>=1;X_ZNT(x)

/* For undocumented instructions, maybe for other things later... */
#define LSRA  _P&=~(C_FLAG|N_FLAG|Z_FLAG);_P|=_A&1;_A>>=1;X_ZNT(_A)

#define ROL  {  \
     uint8 l=x>>7;  \
     x<<=1;  \
     x|=_P&C_FLAG;  \
     _P&=~(Z_FLAG|N_FLAG|C_FLAG);  \
     _P|=l;  \
     X_ZNT(x);  \
    }
#define ROR  {  \
     uint8 l=x&1;  \
     x>>=1;  \
     x|=(_P&C_FLAG)<<7;  \
     _P&=~(Z_FLAG|N_FLAG|C_FLAG);  \
     _P|=l;  \
     X_ZNT(x);  \
            }
             
/* Icky icky thing for some undocumented instructions.  Can easily be
   broken if names of local variables are changed.
*/

/* Absolute */
#define GetAB(target)   \
{  \
 target=RdMem(_PC);  \
 _PC++;  \
 target|=RdMem(_PC)<<8;  \
 _PC++;  \
}

/* Absolute Indexed(for reads) */
#define GetABIRD(target, i)  \
{  \
 unsigned int tmp;  \
 GetAB(tmp);  \
 target=tmp;  \
 target+=i;  \
 if((target^tmp)&0x100)  \
 {  \
  target&=0xFFFF;  \
  RdMem(target^0x100);  \
  ADDCYC(1);  \
 }  \
}

/* Absolute Indexed(for writes and rmws) */
#define GetABIWR(target, i)  \
{  \
 unsigned int rt;  \
 GetAB(rt);  \
 target=rt;  \
 target+=i;  \
 target&=0xFFFF;  \
 RdMem((target&0x00FF)|(rt&0xFF00));  \
}

/* Zero Page */
#define GetZP(target)  \
{  \
 target=RdMem(_PC);   \
 _PC++;  \
}

/* Zero Page Indexed */
#define GetZPI(target,i)  \
{  \
 target=i+RdMem(_PC);  \
 _PC++;  \
}

/* Indexed Indirect */
#define GetIX(target)  \
{  \
 uint8 tmp;  \
 tmp=RdMem(_PC);  \
 _PC++;  \
 tmp+=_X;  \
 target=RdRAM(tmp);  \
 tmp++;    \
 target|=RdRAM(tmp)<<8;  \
}

/* Indirect Indexed(for reads) */
#define GetIYRD(target)  \
{  \
 unsigned int rt;  \
 uint8 tmp;  \
 tmp=RdMem(_PC);  \
 _PC++;  \
 rt=RdRAM(tmp);  \
 tmp++;  \
 rt|=RdRAM(tmp)<<8;  \
 target=rt;  \
 target+=_Y;  \
 if((target^rt)&0x100)  \
 {  \
  target&=0xFFFF;  \
  RdMem(target^0x100);  \
  ADDCYC(1);  \
 }  \
}

/* Indirect Indexed(for writes and rmws) */
#define GetIYWR(target)  \
{  \
 unsigned int rt;  \
 uint8 tmp;  \
 tmp=RdMem(_PC);  \
 _PC++;  \
 rt=RdRAM(tmp);  \
 tmp++;  \
 rt|=RdRAM(tmp)<<8;  \
 target=rt;  \
 target+=_Y;  \
 target&=0xFFFF; \
 RdMem((target&0x00FF)|(rt&0xFF00));  \
}

/* Now come the macros to wrap up all of the above stuff addressing mode functions
   and operation macros.  Note that operation macros will always operate(redundant
   redundant) on the variable "x".
*/

#define RMW_A(op) {uint8 x=_A; op; _A=x; break; } /* Meh... */
#define RMW_AB(op) {unsigned int A; uint8 x; GetAB(A); x=RdMem(A); WrMem(A,x); op; WrMem(A,x); break; }
#define RMW_ABI(reg,op) {unsigned int A; uint8 x; GetABIWR(A,reg); x=RdMem(A); WrMem(A,x); op; WrMem(A,x); break; }
#define RMW_ABX(op)  RMW_ABI(_X,op)
#define RMW_ABY(op)  RMW_ABI(_Y,op)
#define RMW_IX(op)  {unsigned int A; uint8 x; GetIX(A); x=RdMem(A); WrMem(A,x); op; WrMem(A,x); break; }
#define RMW_IY(op)  {unsigned int A; uint8 x; GetIYWR(A); x=RdMem(A); WrMem(A,x); op; WrMem(A,x); break; }
#define RMW_ZP(op)  {uint8 A; uint8 x; GetZP(A); x=RdRAM(A); op; WrRAM(A,x); break; }
#define RMW_ZPX(op) {uint8 A; uint8 x; GetZPI(A,_X); x=RdRAM(A); op; WrRAM(A,x); break;}

#define LD_IM(op)  {uint8 x; x=RdMem(_PC); _PC++; op; break;}
#define LD_ZP(op)  {uint8 A; uint8 x; GetZP(A); x=RdRAM(A); op; break;}
#define LD_ZPX(op)  {uint8 A; uint8 x; GetZPI(A,_X); x=RdRAM(A); op; break;}
#define LD_ZPY(op)  {uint8 A; uint8 x; GetZPI(A,_Y); x=RdRAM(A); op; break;}
#define LD_AB(op)  {unsigned int A; uint8 x; GetAB(A); x=RdMem(A); op; break; }
#define LD_ABI(reg,op)  {unsigned int A; uint8 x; GetABIRD(A,reg); x=RdMem(A); op; break;}
#define LD_ABX(op)  LD_ABI(_X,op)
#define LD_ABY(op)  LD_ABI(_Y,op)
#define LD_IX(op)  {unsigned int A; uint8 x; GetIX(A); x=RdMem(A); op; break;}
#define LD_IY(op)  {unsigned int A; uint8 x; GetIYRD(A); x=RdMem(A); op; break;}

#define ST_ZP(r)  {uint8 A; GetZP(A); WrRAM(A,r); break;}
#define ST_ZPX(r)  {uint8 A; GetZPI(A,_X); WrRAM(A,r); break;}
#define ST_ZPY(r)  {uint8 A; GetZPI(A,_Y); WrRAM(A,r); break;}
#define ST_AB(r)  {unsigned int A; GetAB(A); WrMem(A,r); break;}
#define ST_ABI(reg,r)  {unsigned int A; GetABIWR(A,reg); WrMem(A,r); break; }
#define ST_ABX(r)  ST_ABI(_X,r)
#define ST_ABY(r)  ST_ABI(_Y,r)
#define ST_IX(r)  {unsigned int A; GetIX(A); WrMem(A,r); break; }
#define ST_IY(r)  {unsigned int A; GetIYWR(A); WrMem(A,r); break; }

static uint8 CycTable[256] =
{                             
/*0x00*/ 7,6,2,8,3,3,5,5,3,2,2,2,4,4,6,6,
/*0x10*/ 2,5,2,8,4,4,6,6,2,4,2,7,4,4,7,7,
/*0x20*/ 6,6,2,8,3,3,5,5,4,2,2,2,4,4,6,6,
/*0x30*/ 2,5,2,8,4,4,6,6,2,4,2,7,4,4,7,7,
/*0x40*/ 6,6,2,8,3,3,5,5,3,2,2,2,3,4,6,6,
/*0x50*/ 2,5,2,8,4,4,6,6,2,4,2,7,4,4,7,7,
/*0x60*/ 6,6,2,8,3,3,5,5,4,2,2,2,5,4,6,6,
/*0x70*/ 2,5,2,8,4,4,6,6,2,4,2,7,4,4,7,7,
/*0x80*/ 2,6,2,6,3,3,3,3,2,2,2,2,4,4,4,4,
/*0x90*/ 2,6,2,6,4,4,4,4,2,5,2,5,5,5,5,5,
/*0xA0*/ 2,6,2,6,3,3,3,3,2,2,2,2,4,4,4,4,
/*0xB0*/ 2,5,2,5,4,4,4,4,2,4,2,4,4,4,4,4,
/*0xC0*/ 2,6,2,8,3,3,5,5,2,2,2,2,4,4,6,6,
/*0xD0*/ 2,5,2,8,4,4,6,6,2,4,2,7,4,4,7,7,
/*0xE0*/ 2,6,3,8,3,3,5,5,2,2,2,2,4,4,6,6,
/*0xF0*/ 2,5,2,8,4,4,6,6,2,4,2,7,4,4,7,7,
};

void X6502_IRQBegin(int w)
{
 _IRQlow|=w;
}

void X6502_IRQEnd(int w)
{
 _IRQlow&=~w;
}

void TriggerNMI(void)
{
 _IRQlow|=FCEU_IQNMI;
}

void TriggerNMI2(void)
{ 
 _IRQlow|=FCEU_IQNMI2;
}

void X6502_Reset(void)
{
 _IRQlow=FCEU_IQRESET;
}
/**
* Initializes the 6502 CPU
**/
void X6502_Init(void)
{
      unsigned int i;

      // Initialize the CPU structure
      memset((void *)&X,0,sizeof(X));

      for(i = 0; i < sizeof(ZNTable); i++)
      {
            if(!i)
            {
                  ZNTable[i] = Z_FLAG;
            }
            else if ( i & 0x80 )
            {
                  ZNTable[i] = N_FLAG;
            }
            else
            {
                  ZNTable[i] = 0;
            }
      }
}

void X6502_Power(void)
{
 _count=_tcount=_IRQlow=_PC=_A=_X=_Y=_S=_P=_PI=_DB=_jammed=0;
 timestamp=0;
 X6502_Reset();
}

void X6502_Run(int32 cycles)
{
  if(PAL)
   cycles*=15;    // 15*4=60
  else
   cycles*=16;    // 16*4=64

  _count+=cycles;
extern int test; test++;
  while(_count>0)
  {
   int32 temp;
   uint8 b1;

   if(_IRQlow)
   {
    if(_IRQlow&FCEU_IQRESET)
    {
      if(debug_loggingCD) LogCDVectors(0);
     _PC=RdMem(0xFFFC);
     _PC|=RdMem(0xFFFD)<<8;
     _jammed=0;
     _PI=_P=I_FLAG;
     _IRQlow&=~FCEU_IQRESET;
    }
    else if(_IRQlow&FCEU_IQNMI2)
     {
     _IRQlow&=~FCEU_IQNMI2;
     _IRQlow|=FCEU_IQNMI;
    }
    else if(_IRQlow&FCEU_IQNMI)
    {
     if(!_jammed)
     {
      ADDCYC(7);
      PUSH(_PC>>8);
      PUSH(_PC);
      PUSH((_P&~B_FLAG)|(U_FLAG));
      _P|=I_FLAG;
        DEBUG( if(debug_loggingCD) LogCDVectors(1) );
      _PC=RdMem(0xFFFA);
      _PC|=RdMem(0xFFFB)<<8;
      _IRQlow&=~FCEU_IQNMI;
     }
    }
    else
    {
     if(!(_PI&I_FLAG) && !_jammed)
     {
      ADDCYC(7);
      PUSH(_PC>>8);
      PUSH(_PC);
      PUSH((_P&~B_FLAG)|(U_FLAG));
      _P|=I_FLAG;
        DEBUG( if(debug_loggingCD) LogCDVectors(1) );
      _PC=RdMem(0xFFFE);
      _PC|=RdMem(0xFFFF)<<8;
     }
    }
    _IRQlow&=~(FCEU_IQTEMP);
    if(_count<=0)
    {
     _PI=_P;
     return;
     } //Should increase accuracy without a
              //major speed hit.
   }

      //will probably cause a major speed decrease on low-end systems
      DEBUG( DebugCycle() );

   _PI=_P;
   b1=RdMem(_PC);

   ADDCYC(CycTable[b1]);

   temp=_tcount;
   _tcount=0;
   if(MapIRQHook) MapIRQHook(temp);
   FCEU_SoundCPUHook(temp);
   #ifdef _S9XLUA_H
   CallRegisteredLuaMemHook(_PC, 1, 0, LUAMEMHOOK_EXEC);
   #endif
   _PC++;
   switch(b1)
   {
    #include "ops.inc"
   }
  }
}

//--------------------------
//---Called from debuggers
void FCEUI_NMI(void)
{
 _IRQlow|=FCEU_IQNMI;
}

void FCEUI_IRQ(void)
{
 _IRQlow|=FCEU_IQTEMP;
}

void FCEUI_GetIVectors(uint16 *reset, uint16 *irq, uint16 *nmi)
{
 fceuindbg=1;

 *reset=RdMem(0xFFFC);
 *reset|=RdMem(0xFFFD)<<8;
 *nmi=RdMem(0xFFFA);
 *nmi|=RdMem(0xFFFB)<<8;
 *irq=RdMem(0xFFFE);
 *irq|=RdMem(0xFFFF)<<8;
 fceuindbg=0;
}

//the opsize table is used to quickly grab the instruction sizes (in bytes)
const uint8 opsize[256] = {
/*0x00*/    1,2,0,0,0,2,2,0,1,2,1,0,0,3,3,0,
/*0x10*/    2,2,0,0,0,2,2,0,1,3,0,0,0,3,3,0,
/*0x20*/    3,2,0,0,2,2,2,0,1,2,1,0,3,3,3,0,
/*0x30*/    2,2,0,0,0,2,2,0,1,3,0,0,0,3,3,0,
/*0x40*/    1,2,0,0,0,2,2,0,1,2,1,0,3,3,3,0,
/*0x50*/    2,2,0,0,0,2,2,0,1,3,0,0,0,3,3,0,
/*0x60*/    1,2,0,0,0,2,2,0,1,2,1,0,3,3,3,0,
/*0x70*/    2,2,0,0,0,2,2,0,1,3,0,0,0,3,3,0,
/*0x80*/    0,2,0,0,2,2,2,0,1,0,1,0,3,3,3,0,
/*0x90*/    2,2,0,0,2,2,2,0,1,3,1,0,0,3,0,0,
/*0xA0*/    2,2,2,0,2,2,2,0,1,2,1,0,3,3,3,0,
/*0xB0*/    2,2,0,0,2,2,2,0,1,3,1,0,3,3,3,0,
/*0xC0*/    2,2,0,0,2,2,2,0,1,2,1,0,3,3,3,0,
/*0xD0*/    2,2,0,0,0,2,2,0,1,3,0,0,0,3,3,0,
/*0xE0*/    2,2,0,0,2,2,2,0,1,2,1,0,3,3,3,0,
/*0xF0*/    2,2,0,0,0,2,2,0,1,3,0,0,0,3,3,0
};


//the optype table is a quick way to grab the addressing mode for any 6502 opcode
//
//  0 = Implied\Accumulator\Immediate\Branch\NULL
//  1 = (Indirect,X)
//  2 = Zero Page
//  3 = Absolute
//  4 = (Indirect),Y
//  5 = Zero Page,X
//  6 = Absolute,Y
//  7 = Absolute,X
//  8 = Zero Page,Y
//
const uint8 optype[256] = {
/*0x00*/    0,1,0,0,0,2,2,0,0,0,0,0,0,3,3,0,
/*0x10*/    0,4,0,0,0,5,5,0,0,6,0,0,0,7,7,0,
/*0x20*/    0,1,0,0,2,2,2,0,0,0,0,0,3,3,3,0,
/*0x30*/    0,4,0,0,0,5,5,0,0,6,0,0,0,7,7,0,
/*0x40*/    0,1,0,0,0,2,2,0,0,0,0,0,0,3,3,0,
/*0x50*/    0,4,0,0,0,5,5,0,0,6,0,0,0,7,7,0,
/*0x60*/    0,1,0,0,0,2,2,0,0,0,0,0,3,3,3,0,
/*0x70*/    0,4,0,0,0,5,5,0,0,6,0,0,0,7,7,0,
/*0x80*/    0,1,0,0,2,2,2,0,0,0,0,0,3,3,3,0,
/*0x90*/    0,4,0,0,5,5,8,0,0,6,0,0,0,7,0,0,
/*0xA0*/    0,1,0,0,2,2,2,0,0,0,0,0,3,3,3,0,
/*0xB0*/    0,4,0,0,5,5,8,0,0,6,0,0,7,7,6,0,
/*0xC0*/    0,1,0,0,2,2,2,0,0,0,0,0,3,3,3,0,
/*0xD0*/    0,4,0,0,0,5,5,0,0,6,0,0,0,7,7,0,
/*0xE0*/    0,1,0,0,2,2,2,0,0,0,0,0,3,3,3,0,
/*0xF0*/    0,4,0,0,0,5,5,0,0,6,0,0,0,7,7,0
};

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