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C02/lib6502/lib6502.c
Curtis F Kaylor 60ac041bb1 Multiple modifications to run6502.c and file6502.c
2020-10-08 16:43:58 -04:00

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/* lib6502.c -- MOS Technology 6502 emulator -*- C -*- */
/* Copyright (c) 2005 Ian Piumarta
*
* All rights reserved.
*
* Permission is hereby granted, free of charge, to any person obtaining a
* copy of this software and associated documentation files (the 'Software'),
* to deal in the Software without restriction, including without limitation
* the rights to use, copy, modify, merge, publish, distribute, and/or sell
* copies of the Software, and to permit persons to whom the Software is
* furnished to do so, provided that the above copyright notice(s) and this
* permission notice appear in all copies of the Software and that both the
* above copyright notice(s) and this permission notice appear in supporting
* documentation.
*
* THE SOFTWARE IS PROVIDED 'AS IS'. USE ENTIRELY AT YOUR OWN RISK.
*/
/* Last edited: 2013-06-07 23:03:39 by piumarta on emilia.local
*
* BUGS:
* - RTS and RTI do not check the return address for a callback
* - the disassembler cannot be configured to read two bytes for BRK
* - architectural variations (unimplemented/extended instructions) not implemented
* - ANSI versions (from from gcc extensions) of the dispatch macros are missing
* - emulator+disassembler in same object file (library is kind of pointless)
*/
#include <stdio.h>
#include <stdlib.h>
#include "lib6502.h"
typedef uint8_t byte;
typedef uint16_t word;
enum {
flagN= (1<<7), /* negative */
flagV= (1<<6), /* overflow */
flagX= (1<<5), /* unused */
flagB= (1<<4), /* irq from brk */
flagD= (1<<3), /* decimal mode */
flagI= (1<<2), /* irq disable */
flagZ= (1<<1), /* zero */
flagC= (1<<0) /* carry */
};
#define getN() (P & flagN)
#define getV() (P & flagV)
#define getB() (P & flagB)
#define getD() (P & flagD)
#define getI() (P & flagI)
#define getZ() (P & flagZ)
#define getC() (P & flagC)
#define setNVZC(N,V,Z,C) (P= (P & ~(flagN | flagV | flagZ | flagC)) | (N) | ((V)<<6) | ((Z)<<1) | (C))
#define setNZC(N,Z,C) (P= (P & ~(flagN | flagZ | flagC)) | (N) | ((Z)<<1) | (C))
#define setNZ(N,Z) (P= (P & ~(flagN | flagZ )) | (N) | ((Z)<<1) )
#define setZ(Z) (P= (P & ~( flagZ )) | ((Z)<<1) )
#define setC(C) (P= (P & ~( flagC)) | (C))
#define NAND(P, Q) (!((P) & (Q)))
#define tick(n)
#define tickIf(p)
/* memory access (indirect if callback installed) -- ARGUMENTS ARE EVALUATED MORE THAN ONCE! */
#define putMemory(ADDR, BYTE) \
( writeCallback[ADDR] \
? writeCallback[ADDR](mpu, ADDR, BYTE) \
: (memory[ADDR]= BYTE) )
#define getMemory(ADDR) \
( readCallback[ADDR] \
? readCallback[ADDR](mpu, ADDR, 0) \
: memory[ADDR] )
/* stack access (always direct) */
#define push(BYTE) (memory[0x0100 + S--]= (BYTE))
#define pop() (memory[++S + 0x0100])
/* adressing modes (memory access direct) */
#define implied(ticks) \
tick(ticks);
#define immediate(ticks) \
tick(ticks); \
ea= PC++;
#define abs(ticks) \
tick(ticks); \
ea= memory[PC] + (memory[PC + 1] << 8); \
PC += 2;
#define relative(ticks) \
tick(ticks); \
ea= memory[PC++]; \
if (ea & 0x80) ea -= 0x100; \
tickIf((ea >> 8) != (PC >> 8));
#define indirect(ticks) \
tick(ticks); \
{ \
word tmp; \
tmp= memory[PC] + (memory[PC + 1] << 8); \
ea = memory[tmp] + (memory[tmp + 1] << 8); \
PC += 2; \
}
#define absx(ticks) \
tick(ticks); \
ea= memory[PC] + (memory[PC + 1] << 8); \
PC += 2; \
tickIf((ticks == 4) && ((ea >> 8) != ((ea + X) >> 8))); \
ea += X;
#define absy(ticks) \
tick(ticks); \
ea= memory[PC] + (memory[PC + 1] << 8); \
PC += 2; \
tickIf((ticks == 4) && ((ea >> 8) != ((ea + Y) >> 8))); \
ea += Y
#define zp(ticks) \
tick(ticks); \
ea= memory[PC++];
#define zpx(ticks) \
tick(ticks); \
ea= memory[PC++] + X; \
ea &= 0x00ff;
#define zpy(ticks) \
tick(ticks); \
ea= memory[PC++] + Y; \
ea &= 0x00ff;
#define indx(ticks) \
tick(ticks); \
{ \
byte tmp= memory[PC++] + X; \
ea= memory[tmp] + (memory[tmp + 1] << 8); \
}
#define indy(ticks) \
tick(ticks); \
{ \
byte tmp= memory[PC++]; \
ea= memory[tmp] + (memory[tmp + 1] << 8); \
tickIf((ticks == 5) && ((ea >> 8) != ((ea + Y) >> 8))); \
ea += Y; \
}
#define indabsx(ticks) \
tick(ticks); \
{ \
word tmp; \
tmp= memory[PC ] + (memory[PC + 1] << 8) + X; \
ea = memory[tmp] + (memory[tmp + 1] << 8); \
}
#define indzp(ticks) \
tick(ticks); \
{ \
byte tmp; \
tmp= memory[PC++]; \
ea = memory[tmp] + (memory[tmp + 1] << 8); \
}
/* insns */
#define adc(ticks, adrmode) \
adrmode(ticks); \
{ \
byte B= getMemory(ea); \
if (!getD()) \
{ \
int c= A + B + getC(); \
int v= (int8_t)A + (int8_t)B + getC(); \
fetch(); \
A= c; \
setNVZC((A & 0x80), (((A & 0x80) > 0) ^ (v < 0)), (A == 0), ((c & 0x100) > 0)); \
next(); \
} \
else \
{ \
int l, h, s; \
/* inelegant & slow, but consistent with the hw for illegal digits */ \
l= (A & 0x0F) + (B & 0x0F) + getC(); \
h= (A & 0xF0) + (B & 0xF0); \
if (l >= 0x0A) { l += 0x06; h += 0x10; } \
if (h >= 0xA0) { h += 0x60; } \
fetch(); \
s= (h & 0xF0) | (l & 0x0F); \
/* only C is valid on NMOS 6502 */ \
setNVZC(s & 0x80, !(((A ^ B) & 0x80) && ((A ^ s) & 0x80)), (s==0), ((h & 0x100) > 0)); \
A= s; \
tick(1); \
next(); \
} \
}
#define sbc(ticks, adrmode) \
adrmode(ticks); \
{ \
byte B= getMemory(ea); \
if (!getD()) \
{ \
int b= 1 - (P &0x01); \
int c= A - B - b; \
int v= (int8_t)A - (int8_t) B - b; \
fetch(); \
A= c; \
setNVZC(A & 0x80, ((A & 0x80) > 0) ^ ((v & 0x100) != 0), A == 0, c >= 0); \
next(); \
} \
else \
{ \
/* this is verbatim ADC, with a 10's complemented operand */ \
int l, h, s; \
B= 0x99 - B; \
l= (A & 0x0F) + (B & 0x0F) + getC(); \
h= (A & 0xF0) + (B & 0xF0); \
if (l >= 0x0A) { l -= 0x0A; h += 0x10; } \
if (h >= 0xA0) { h -= 0xA0; } \
fetch(); \
s= h | (l & 0x0F); \
/* only C is valid on NMOS 6502 */ \
setNVZC(s & 0x80, !(((A ^ B) & 0x80) && ((A ^ s) & 0x80)), !s, !!(h & 0x80)); \
A= s; \
tick(1); \
next(); \
} \
}
#define cmpR(ticks, adrmode, R) \
adrmode(ticks); \
fetch(); \
{ \
byte B= getMemory(ea); \
byte d= R - B; \
setNZC(d & 0x80, !d, R >= B); \
} \
next();
#define cmp(ticks, adrmode) cmpR(ticks, adrmode, A)
#define cpx(ticks, adrmode) cmpR(ticks, adrmode, X)
#define cpy(ticks, adrmode) cmpR(ticks, adrmode, Y)
#define dec(ticks, adrmode) \
adrmode(ticks); \
fetch(); \
{ \
byte B= getMemory(ea); \
--B; \
putMemory(ea, B); \
setNZ(B & 0x80, !B); \
} \
next();
#define decR(ticks, adrmode, R) \
fetch(); \
tick(ticks); \
--R; \
setNZ(R & 0x80, !R); \
next();
#define dea(ticks, adrmode) decR(ticks, adrmode, A)
#define dex(ticks, adrmode) decR(ticks, adrmode, X)
#define dey(ticks, adrmode) decR(ticks, adrmode, Y)
#define inc(ticks, adrmode) \
adrmode(ticks); \
fetch(); \
{ \
byte B= getMemory(ea); \
++B; \
putMemory(ea, B); \
setNZ(B & 0x80, !B); \
} \
next();
#define incR(ticks, adrmode, R) \
fetch(); \
tick(ticks); \
++R; \
setNZ(R & 0x80, !R); \
next();
#define ina(ticks, adrmode) incR(ticks, adrmode, A)
#define inx(ticks, adrmode) incR(ticks, adrmode, X)
#define iny(ticks, adrmode) incR(ticks, adrmode, Y)
#define bit(ticks, adrmode) \
adrmode(ticks); \
fetch(); \
{ \
byte B= getMemory(ea); \
P= (P & ~(flagN | flagV | flagZ)) \
| (B & (0xC0)) | (((A & B) == 0) << 1); \
} \
next();
#define tsb(ticks, adrmode) \
adrmode(ticks); \
fetch(); \
{ \
byte b= getMemory(ea); \
b |= A; \
putMemory(ea, b); \
setZ(!b); \
} \
next();
#define trb(ticks, adrmode) \
adrmode(ticks); \
fetch(); \
{ \
byte b= getMemory(ea); \
b |= (A ^ 0xFF); \
putMemory(ea, b); \
setZ(!b); \
} \
next();
#define bitwise(ticks, adrmode, op) \
adrmode(ticks); \
fetch(); \
A op##= getMemory(ea); \
setNZ(A & 0x80, !A); \
next();
#define and(ticks, adrmode) bitwise(ticks, adrmode, &)
#define eor(ticks, adrmode) bitwise(ticks, adrmode, ^)
#define ora(ticks, adrmode) bitwise(ticks, adrmode, |)
#define asl(ticks, adrmode) \
adrmode(ticks); \
{ \
unsigned int i= getMemory(ea) << 1; \
putMemory(ea, i); \
fetch(); \
setNZC(i & 0x80, !i, i >> 8); \
} \
next();
#define asla(ticks, adrmode) \
tick(ticks); \
fetch(); \
{ \
int c= A >> 7; \
A <<= 1; \
setNZC(A & 0x80, !A, c); \
} \
next();
#define lsr(ticks, adrmode) \
adrmode(ticks); \
{ \
byte b= getMemory(ea); \
int c= b & 1; \
fetch(); \
b >>= 1; \
putMemory(ea, b); \
setNZC(0, !b, c); \
} \
next();
#define lsra(ticks, adrmode) \
tick(ticks); \
fetch(); \
{ \
int c= A & 1; \
A >>= 1; \
setNZC(0, !A, c); \
} \
next();
#define rol(ticks, adrmode) \
adrmode(ticks); \
{ \
word b= (getMemory(ea) << 1) | getC(); \
fetch(); \
putMemory(ea, b); \
setNZC(b & 0x80, !(b & 0xFF), b >> 8); \
} \
next();
#define rola(ticks, adrmode) \
tick(ticks); \
fetch(); \
{ \
word b= (A << 1) | getC(); \
A= b; \
setNZC(A & 0x80, !A, b >> 8); \
} \
next();
#define ror(ticks, adrmode) \
adrmode(ticks); \
{ \
int c= getC(); \
byte m= getMemory(ea); \
byte b= (c << 7) | (m >> 1); \
fetch(); \
putMemory(ea, b); \
setNZC(b & 0x80, !b, m & 1); \
} \
next();
#define rora(ticks, adrmode) \
adrmode(ticks); \
{ \
int ci= getC(); \
int co= A & 1; \
fetch(); \
A= (ci << 7) | (A >> 1); \
setNZC(A & 0x80, !A, co); \
} \
next();
#define tRS(ticks, adrmode, R, S) \
fetch(); \
tick(ticks); \
S= R; \
setNZ(S & 0x80, !S); \
next();
#define tax(ticks, adrmode) tRS(ticks, adrmode, A, X)
#define txa(ticks, adrmode) tRS(ticks, adrmode, X, A)
#define tay(ticks, adrmode) tRS(ticks, adrmode, A, Y)
#define tya(ticks, adrmode) tRS(ticks, adrmode, Y, A)
#define tsx(ticks, adrmode) tRS(ticks, adrmode, S, X)
#define txs(ticks, adrmode) \
fetch(); \
tick(ticks); \
S= X; \
next();
#define ldR(ticks, adrmode, R) \
adrmode(ticks); \
fetch(); \
R= getMemory(ea); \
setNZ(R & 0x80, !R); \
next();
#define lda(ticks, adrmode) ldR(ticks, adrmode, A)
#define ldx(ticks, adrmode) ldR(ticks, adrmode, X)
#define ldy(ticks, adrmode) ldR(ticks, adrmode, Y)
#define stR(ticks, adrmode, R) \
adrmode(ticks); \
fetch(); \
putMemory(ea, R); \
next();
#define sta(ticks, adrmode) stR(ticks, adrmode, A)
#define stx(ticks, adrmode) stR(ticks, adrmode, X)
#define sty(ticks, adrmode) stR(ticks, adrmode, Y)
#define stz(ticks, adrmode) stR(ticks, adrmode, 0)
#define branch(ticks, adrmode, cond) \
if (cond) \
{ \
adrmode(ticks); \
PC += ea; \
tick(1); \
} \
else \
{ \
tick(ticks); \
PC++; \
} \
fetch(); \
next();
#define bcc(ticks, adrmode) branch(ticks, adrmode, !getC())
#define bcs(ticks, adrmode) branch(ticks, adrmode, getC())
#define bne(ticks, adrmode) branch(ticks, adrmode, !getZ())
#define beq(ticks, adrmode) branch(ticks, adrmode, getZ())
#define bpl(ticks, adrmode) branch(ticks, adrmode, !getN())
#define bmi(ticks, adrmode) branch(ticks, adrmode, getN())
#define bvc(ticks, adrmode) branch(ticks, adrmode, !getV())
#define bvs(ticks, adrmode) branch(ticks, adrmode, getV())
#define bra(ticks, adrmode) \
adrmode(ticks); \
PC += ea; \
fetch(); \
tick(1); \
next();
#define jmp(ticks, adrmode) \
adrmode(ticks); \
PC= ea; \
if (mpu->callbacks->call[ea]) \
{ \
word addr; \
externalise(); \
if ((addr= mpu->callbacks->call[ea](mpu, ea, 0))) \
{ \
internalise(); \
PC= addr; \
} \
} \
fetch(); \
next();
#define jsr(ticks, adrmode) \
PC++; \
push(PC >> 8); \
push(PC & 0xff); \
PC--; \
adrmode(ticks); \
if (mpu->callbacks->call[ea]) \
{ \
word addr; \
externalise(); \
if ((addr= mpu->callbacks->call[ea](mpu, ea, 0))) \
{ \
internalise(); \
PC= addr; \
fetch(); \
next(); \
} \
} \
PC=ea; \
fetch(); \
next();
#define rts(ticks, adrmode) \
tick(ticks); \
PC = pop(); \
PC |= (pop() << 8); \
PC++; \
fetch(); \
next();
#define brk(ticks, adrmode) \
tick(ticks); \
PC++; \
push(PC >> 8); \
push(PC & 0xff); \
P |= flagB; \
push(P | flagX); \
P |= flagI; \
{ \
word hdlr= getMemory(0xfffe) + (getMemory(0xffff) << 8); \
if (mpu->callbacks->call[hdlr]) \
{ \
word addr; \
externalise(); \
if ((addr= mpu->callbacks->call[hdlr](mpu, PC - 2, 0))) \
{ \
internalise(); \
hdlr= addr; \
} \
} \
PC= hdlr; \
} \
fetch(); \
next();
#define rti(ticks, adrmode) \
tick(ticks); \
P= pop(); \
PC= pop(); \
PC |= (pop() << 8); \
fetch(); \
next();
#define nop(ticks, adrmode) \
fetch(); \
tick(ticks); \
next();
#define ill(ticks, adrmode) \
fetch(); \
tick(ticks); \
fflush(stdout); \
fprintf(stderr, "\nundefined instruction %02X at address %04x\n", memory[PC-1], PC-1); \
return;
#define phR(ticks, adrmode, R) \
fetch(); \
tick(ticks); \
push(R); \
next();
#define pha(ticks, adrmode) phR(ticks, adrmode, A)
#define phx(ticks, adrmode) phR(ticks, adrmode, X)
#define phy(ticks, adrmode) phR(ticks, adrmode, Y)
#define php(ticks, adrmode) phR(ticks, adrmode, P | flagX | flagB)
#define plR(ticks, adrmode, R) \
fetch(); \
tick(ticks); \
R= pop(); \
setNZ(R & 0x80, !R); \
next();
#define pla(ticks, adrmode) plR(ticks, adrmode, A)
#define plx(ticks, adrmode) plR(ticks, adrmode, X)
#define ply(ticks, adrmode) plR(ticks, adrmode, Y)
#define plp(ticks, adrmode) \
fetch(); \
tick(ticks); \
P= pop(); \
next();
#define clF(ticks, adrmode, F) \
fetch(); \
tick(ticks); \
P &= ~F; \
next();
#define clc(ticks, adrmode) clF(ticks, adrmode, flagC)
#define cld(ticks, adrmode) clF(ticks, adrmode, flagD)
#define cli(ticks, adrmode) clF(ticks, adrmode, flagI)
#define clv(ticks, adrmode) clF(ticks, adrmode, flagV)
#define seF(ticks, adrmode, F) \
fetch(); \
tick(ticks); \
P |= F; \
next();
#define sec(ticks, adrmode) seF(ticks, adrmode, flagC)
#define sed(ticks, adrmode) seF(ticks, adrmode, flagD)
#define sei(ticks, adrmode) seF(ticks, adrmode, flagI)
#define do_insns(_) \
_(00, brk, implied, 7); _(01, ora, indx, 6); _(02, ill, implied, 2); _(03, ill, implied, 2); \
_(04, tsb, zp, 3); _(05, ora, zp, 3); _(06, asl, zp, 5); _(07, ill, implied, 2); \
_(08, php, implied, 3); _(09, ora, immediate, 3); _(0a, asla,implied, 2); _(0b, ill, implied, 2); \
_(0c, tsb, abs, 4); _(0d, ora, abs, 4); _(0e, asl, abs, 6); _(0f, ill, implied, 2); \
_(10, bpl, relative, 2); _(11, ora, indy, 5); _(12, ora, indzp, 3); _(13, ill, implied, 2); \
_(14, trb, zp, 3); _(15, ora, zpx, 4); _(16, asl, zpx, 6); _(17, ill, implied, 2); \
_(18, clc, implied, 2); _(19, ora, absy, 4); _(1a, ina, implied, 2); _(1b, ill, implied, 2); \
_(1c, trb, abs, 4); _(1d, ora, absx, 4); _(1e, asl, absx, 7); _(1f, ill, implied, 2); \
_(20, jsr, abs, 6); _(21, and, indx, 6); _(22, ill, implied, 2); _(23, ill, implied, 2); \
_(24, bit, zp, 3); _(25, and, zp, 3); _(26, rol, zp, 5); _(27, ill, implied, 2); \
_(28, plp, implied, 4); _(29, and, immediate, 3); _(2a, rola,implied, 2); _(2b, ill, implied, 2); \
_(2c, bit, abs, 4); _(2d, and, abs, 4); _(2e, rol, abs, 6); _(2f, ill, implied, 2); \
_(30, bmi, relative, 2); _(31, and, indy, 5); _(32, and, indzp, 3); _(33, ill, implied, 2); \
_(34, bit, zpx, 4); _(35, and, zpx, 4); _(36, rol, zpx, 6); _(37, ill, implied, 2); \
_(38, sec, implied, 2); _(39, and, absy, 4); _(3a, dea, implied, 2); _(3b, ill, implied, 2); \
_(3c, bit, absx, 4); _(3d, and, absx, 4); _(3e, rol, absx, 7); _(3f, ill, implied, 2); \
_(40, rti, implied, 6); _(41, eor, indx, 6); _(42, ill, implied, 2); _(43, ill, implied, 2); \
_(44, ill, implied, 2); _(45, eor, zp, 3); _(46, lsr, zp, 5); _(47, ill, implied, 2); \
_(48, pha, implied, 3); _(49, eor, immediate, 3); _(4a, lsra,implied, 2); _(4b, ill, implied, 2); \
_(4c, jmp, abs, 3); _(4d, eor, abs, 4); _(4e, lsr, abs, 6); _(4f, ill, implied, 2); \
_(50, bvc, relative, 2); _(51, eor, indy, 5); _(52, eor, indzp, 3); _(53, ill, implied, 2); \
_(54, ill, implied, 2); _(55, eor, zpx, 4); _(56, lsr, zpx, 6); _(57, ill, implied, 2); \
_(58, cli, implied, 2); _(59, eor, absy, 4); _(5a, phy, implied, 3); _(5b, ill, implied, 2); \
_(5c, ill, implied, 2); _(5d, eor, absx, 4); _(5e, lsr, absx, 7); _(5f, ill, implied, 2); \
_(60, rts, implied, 6); _(61, adc, indx, 6); _(62, ill, implied, 2); _(63, ill, implied, 2); \
_(64, stz, zp, 3); _(65, adc, zp, 3); _(66, ror, zp, 5); _(67, ill, implied, 2); \
_(68, pla, implied, 4); _(69, adc, immediate, 3); _(6a, rora,implied, 2); _(6b, ill, implied, 2); \
_(6c, jmp, indirect, 5); _(6d, adc, abs, 4); _(6e, ror, abs, 6); _(6f, ill, implied, 2); \
_(70, bvs, relative, 2); _(71, adc, indy, 5); _(72, adc, indzp, 3); _(73, ill, implied, 2); \
_(74, stz, zpx, 4); _(75, adc, zpx, 4); _(76, ror, zpx, 6); _(77, ill, implied, 2); \
_(78, sei, implied, 2); _(79, adc, absy, 4); _(7a, ply, implied, 4); _(7b, ill, implied, 2); \
_(7c, jmp, indabsx, 6); _(7d, adc, absx, 4); _(7e, ror, absx, 7); _(7f, ill, implied, 2); \
_(80, bra, relative, 2); _(81, sta, indx, 6); _(82, ill, implied, 2); _(83, ill, implied, 2); \
_(84, sty, zp, 2); _(85, sta, zp, 2); _(86, stx, zp, 2); _(87, ill, implied, 2); \
_(88, dey, implied, 2); _(89, bit, immediate, 2); _(8a, txa, implied, 2); _(8b, ill, implied, 2); \
_(8c, sty, abs, 4); _(8d, sta, abs, 4); _(8e, stx, abs, 4); _(8f, ill, implied, 2); \
_(90, bcc, relative, 2); _(91, sta, indy, 6); _(92, sta, indzp, 3); _(93, ill, implied, 2); \
_(94, sty, zpx, 4); _(95, sta, zpx, 4); _(96, stx, zpy, 4); _(97, ill, implied, 2); \
_(98, tya, implied, 2); _(99, sta, absy, 5); _(9a, txs, implied, 2); _(9b, ill, implied, 2); \
_(9c, stz, abs, 4); _(9d, sta, absx, 5); _(9e, stz, absx, 5); _(9f, ill, implied, 2); \
_(a0, ldy, immediate, 3); _(a1, lda, indx, 6); _(a2, ldx, immediate, 3); _(a3, ill, implied, 2); \
_(a4, ldy, zp, 3); _(a5, lda, zp, 3); _(a6, ldx, zp, 3); _(a7, ill, implied, 2); \
_(a8, tay, implied, 2); _(a9, lda, immediate, 3); _(aa, tax, implied, 2); _(ab, ill, implied, 2); \
_(ac, ldy, abs, 4); _(ad, lda, abs, 4); _(ae, ldx, abs, 4); _(af, ill, implied, 2); \
_(b0, bcs, relative, 2); _(b1, lda, indy, 5); _(b2, lda, indzp, 3); _(b3, ill, implied, 2); \
_(b4, ldy, zpx, 4); _(b5, lda, zpx, 4); _(b6, ldx, zpy, 4); _(b7, ill, implied, 2); \
_(b8, clv, implied, 2); _(b9, lda, absy, 4); _(ba, tsx, implied, 2); _(bb, ill, implied, 2); \
_(bc, ldy, absx, 4); _(bd, lda, absx, 4); _(be, ldx, absy, 4); _(bf, ill, implied, 2); \
_(c0, cpy, immediate, 3); _(c1, cmp, indx, 6); _(c2, ill, implied, 2); _(c3, ill, implied, 2); \
_(c4, cpy, zp, 3); _(c5, cmp, zp, 3); _(c6, dec, zp, 5); _(c7, ill, implied, 2); \
_(c8, iny, implied, 2); _(c9, cmp, immediate, 3); _(ca, dex, implied, 2); _(cb, ill, implied, 2); \
_(cc, cpy, abs, 4); _(cd, cmp, abs, 4); _(ce, dec, abs, 6); _(cf, ill, implied, 2); \
_(d0, bne, relative, 2); _(d1, cmp, indy, 5); _(d2, cmp, indzp, 3); _(d3, ill, implied, 2); \
_(d4, ill, implied, 2); _(d5, cmp, zpx, 4); _(d6, dec, zpx, 6); _(d7, ill, implied, 2); \
_(d8, cld, implied, 2); _(d9, cmp, absy, 4); _(da, phx, implied, 3); _(db, ill, implied, 2); \
_(dc, ill, implied, 2); _(dd, cmp, absx, 4); _(de, dec, absx, 7); _(df, ill, implied, 2); \
_(e0, cpx, immediate, 3); _(e1, sbc, indx, 6); _(e2, ill, implied, 2); _(e3, ill, implied, 2); \
_(e4, cpx, zp, 3); _(e5, sbc, zp, 3); _(e6, inc, zp, 5); _(e7, ill, implied, 2); \
_(e8, inx, implied, 2); _(e9, sbc, immediate, 3); _(ea, nop, implied, 2); _(eb, ill, implied, 2); \
_(ec, cpx, abs, 4); _(ed, sbc, abs, 4); _(ee, inc, abs, 6); _(ef, ill, implied, 2); \
_(f0, beq, relative, 2); _(f1, sbc, indy, 5); _(f2, sbc, indzp, 3); _(f3, ill, implied, 2); \
_(f4, ill, implied, 2); _(f5, sbc, zpx, 4); _(f6, inc, zpx, 6); _(f7, ill, implied, 2); \
_(f8, sed, implied, 2); _(f9, sbc, absy, 4); _(fa, plx, implied, 4); _(fb, ill, implied, 2); \
_(fc, ill, implied, 2); _(fd, sbc, absx, 4); _(fe, inc, absx, 7); _(ff, ill, implied, 2);
void M6502_irq(M6502 *mpu)
{
if (!(mpu->registers->p & flagI))
{
mpu->memory[0x0100 + mpu->registers->s--] = (byte)(mpu->registers->pc >> 8);
mpu->memory[0x0100 + mpu->registers->s--] = (byte)(mpu->registers->pc & 0xff);
mpu->memory[0x0100 + mpu->registers->s--] = mpu->registers->p;
mpu->registers->p &= ~flagB;
mpu->registers->p |= flagI;
mpu->registers->pc = M6502_getVector(mpu, IRQ);
}
}
void M6502_nmi(M6502 *mpu)
{
mpu->memory[0x0100 + mpu->registers->s--] = (byte)(mpu->registers->pc >> 8);
mpu->memory[0x0100 + mpu->registers->s--] = (byte)(mpu->registers->pc & 0xff);
mpu->memory[0x0100 + mpu->registers->s--] = mpu->registers->p;
mpu->registers->p &= ~flagB;
mpu->registers->p |= flagI;
mpu->registers->pc = M6502_getVector(mpu, NMI);
}
void M6502_reset(M6502 *mpu)
{
mpu->registers->p &= ~flagD;
mpu->registers->p |= flagI;
mpu->registers->pc = M6502_getVector(mpu, RST);
}
/* the compiler should elminate all call to this function */
static void oops(void)
{
fprintf(stderr, "\noops -- instruction dispatch missing\n");
}
void M6502_run(M6502 *mpu)
{
#if defined(__GNUC__) && !defined(__STRICT_ANSI__)
static void *itab[256]= { &&_00, &&_01, &&_02, &&_03, &&_04, &&_05, &&_06, &&_07, &&_08, &&_09, &&_0a, &&_0b, &&_0c, &&_0d, &&_0e, &&_0f,
&&_10, &&_11, &&_12, &&_13, &&_14, &&_15, &&_16, &&_17, &&_18, &&_19, &&_1a, &&_1b, &&_1c, &&_1d, &&_1e, &&_1f,
&&_20, &&_21, &&_22, &&_23, &&_24, &&_25, &&_26, &&_27, &&_28, &&_29, &&_2a, &&_2b, &&_2c, &&_2d, &&_2e, &&_2f,
&&_30, &&_31, &&_32, &&_33, &&_34, &&_35, &&_36, &&_37, &&_38, &&_39, &&_3a, &&_3b, &&_3c, &&_3d, &&_3e, &&_3f,
&&_40, &&_41, &&_42, &&_43, &&_44, &&_45, &&_46, &&_47, &&_48, &&_49, &&_4a, &&_4b, &&_4c, &&_4d, &&_4e, &&_4f,
&&_50, &&_51, &&_52, &&_53, &&_54, &&_55, &&_56, &&_57, &&_58, &&_59, &&_5a, &&_5b, &&_5c, &&_5d, &&_5e, &&_5f,
&&_60, &&_61, &&_62, &&_63, &&_64, &&_65, &&_66, &&_67, &&_68, &&_69, &&_6a, &&_6b, &&_6c, &&_6d, &&_6e, &&_6f,
&&_70, &&_71, &&_72, &&_73, &&_74, &&_75, &&_76, &&_77, &&_78, &&_79, &&_7a, &&_7b, &&_7c, &&_7d, &&_7e, &&_7f,
&&_80, &&_81, &&_82, &&_83, &&_84, &&_85, &&_86, &&_87, &&_88, &&_89, &&_8a, &&_8b, &&_8c, &&_8d, &&_8e, &&_8f,
&&_90, &&_91, &&_92, &&_93, &&_94, &&_95, &&_96, &&_97, &&_98, &&_99, &&_9a, &&_9b, &&_9c, &&_9d, &&_9e, &&_9f,
&&_a0, &&_a1, &&_a2, &&_a3, &&_a4, &&_a5, &&_a6, &&_a7, &&_a8, &&_a9, &&_aa, &&_ab, &&_ac, &&_ad, &&_ae, &&_af,
&&_b0, &&_b1, &&_b2, &&_b3, &&_b4, &&_b5, &&_b6, &&_b7, &&_b8, &&_b9, &&_ba, &&_bb, &&_bc, &&_bd, &&_be, &&_bf,
&&_c0, &&_c1, &&_c2, &&_c3, &&_c4, &&_c5, &&_c6, &&_c7, &&_c8, &&_c9, &&_ca, &&_cb, &&_cc, &&_cd, &&_ce, &&_cf,
&&_d0, &&_d1, &&_d2, &&_d3, &&_d4, &&_d5, &&_d6, &&_d7, &&_d8, &&_d9, &&_da, &&_db, &&_dc, &&_dd, &&_de, &&_df,
&&_e0, &&_e1, &&_e2, &&_e3, &&_e4, &&_e5, &&_e6, &&_e7, &&_e8, &&_e9, &&_ea, &&_eb, &&_ec, &&_ed, &&_ee, &&_ef,
&&_f0, &&_f1, &&_f2, &&_f3, &&_f4, &&_f5, &&_f6, &&_f7, &&_f8, &&_f9, &&_fa, &&_fb, &&_fc, &&_fd, &&_fe, &&_ff };
register void **itabp= &itab[0];
register void *tpc;
# define begin() fetch(); next()
# define fetch() tpc= itabp[memory[PC++]]
# define next() goto *tpc
# define dispatch(num, name, mode, cycles) _##num: name(cycles, mode) oops(); next()
# define end()
#else /* (!__GNUC__) || (__STRICT_ANSI__) */
# define begin() for (;;) switch (memory[PC++]) {
# define fetch()
# define next() break
# define dispatch(num, name, mode, cycles) case 0x##num: name(cycles, mode); next()
# define end() }
#endif
register byte *memory= mpu->memory;
register word PC;
word ea;
byte A, X, Y, P, S;
M6502_Callback *readCallback= mpu->callbacks->read;
M6502_Callback *writeCallback= mpu->callbacks->write;
# define internalise() A= mpu->registers->a; X= mpu->registers->x; Y= mpu->registers->y; P= mpu->registers->p; S= mpu->registers->s; PC= mpu->registers->pc
# define externalise() mpu->registers->a= A; mpu->registers->x= X; mpu->registers->y= Y; mpu->registers->p= P; mpu->registers->s= S; mpu->registers->pc= PC
internalise();
begin();
do_insns(dispatch);
end();
# undef begin
# undef internalise
# undef externalise
# undef fetch
# undef next
# undef dispatch
# undef end
(void)oops;
}
int M6502_disassemble(M6502 *mpu, word ip, char buffer[64])
{
char *s= buffer;
byte *b= mpu->memory + ip;
switch (b[0])
{
# define _implied return 1;
# define _immediate sprintf(s, "#%02X", b[1]); return 2;
# define _zp sprintf(s, "%02X", b[1]); return 2;
# define _zpx sprintf(s, "%02X,X", b[1]); return 2;
# define _zpy sprintf(s, "%02X,Y", b[1]); return 2;
# define _abs sprintf(s, "%02X%02X", b[2], b[1]); return 3;
# define _absx sprintf(s, "%02X%02X,X", b[2], b[1]); return 3;
# define _absy sprintf(s, "%02X%02X,Y", b[2], b[1]); return 3;
# define _relative sprintf(s, "%04X", ip + 2 + (int8_t)b[1]); return 2;
# define _indirect sprintf(s, "(%02X%02X)", b[2], b[1]); return 3;
# define _indzp sprintf(s, "(%02X)", b[1]); return 2;
# define _indx sprintf(s, "(%02X,X)", b[1]); return 2;
# define _indy sprintf(s, "(%02X),Y", b[1]); return 2;
# define _indabsx sprintf(s, "(%02X%02X,X)", b[2], b[1]); return 3;
# define disassemble(num, name, mode, cycles) case 0x##num: s += sprintf(s, "%s ", #name); _##mode
do_insns(disassemble);
# undef _do
}
return 0;
}
void M6502_dump(M6502 *mpu, char buffer[64])
{
M6502_Registers *r= mpu->registers;
uint8_t p= r->p;
# define P(N,C) (p & (1 << (N)) ? (C) : '-')
sprintf(buffer, "PC=%04X SP=%04X A=%02X X=%02X Y=%02X P=%02X %c%c%c%c%c%c%c%c",
r->pc, 0x0100 + r->s,
r->a, r->x, r->y, r->p,
P(7,'N'), P(6,'V'), P(5,'?'), P(4,'B'), P(3,'D'), P(2,'I'), P(1,'Z'), P(0,'C'));
# undef P
}
static void outOfMemory(void)
{
fflush(stdout);
fprintf(stderr, "\nout of memory\n");
abort();
}
M6502 *M6502_new(M6502_Registers *registers, M6502_Memory memory, M6502_Callbacks *callbacks)
{
M6502 *mpu= calloc(1, sizeof(M6502));
if (!mpu) outOfMemory();
if (!registers) { registers = (M6502_Registers *)calloc(1, sizeof(M6502_Registers)); mpu->flags |= M6502_RegistersAllocated; }
if (!memory ) { memory = (uint8_t *)calloc(1, sizeof(M6502_Memory )); mpu->flags |= M6502_MemoryAllocated; }
if (!callbacks) { callbacks = (M6502_Callbacks *)calloc(1, sizeof(M6502_Callbacks)); mpu->flags |= M6502_CallbacksAllocated; }
if (!registers || !memory || !callbacks) outOfMemory();
mpu->registers = registers;
mpu->memory = memory;
mpu->callbacks = callbacks;
return mpu;
}
void M6502_delete(M6502 *mpu)
{
if (mpu->flags & M6502_CallbacksAllocated) free(mpu->callbacks);
if (mpu->flags & M6502_MemoryAllocated ) free(mpu->memory);
if (mpu->flags & M6502_RegistersAllocated) free(mpu->registers);
free(mpu);
}
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