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894 lines
44 KiB
C
894 lines
44 KiB
C
/* lib6502.c -- MOS Technology 6502 emulator -*- C -*- */
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/* Copyright (c) 2005 Ian Piumarta
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*
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* All rights reserved.
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*
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* Permission is hereby granted, free of charge, to any person obtaining a
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* copy of this software and associated documentation files (the 'Software'),
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* to deal in the Software without restriction, including without limitation
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* the rights to use, copy, modify, merge, publish, distribute, and/or sell
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* copies of the Software, and to permit persons to whom the Software is
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* furnished to do so, provided that the above copyright notice(s) and this
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* permission notice appear in all copies of the Software and that both the
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* above copyright notice(s) and this permission notice appear in supporting
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* documentation.
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*
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* THE SOFTWARE IS PROVIDED 'AS IS'. USE ENTIRELY AT YOUR OWN RISK.
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*/
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/* Last edited: 2013-06-07 23:03:39 by piumarta on emilia.local
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*
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* BUGS:
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* - RTS and RTI do not check the return address for a callback
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* - the disassembler cannot be configured to read two bytes for BRK
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* - architectural variations (unimplemented/extended instructions) not implemented
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* - ANSI versions (from from gcc extensions) of the dispatch macros are missing
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* - emulator+disassembler in same object file (library is kind of pointless)
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*/
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#include <stdio.h>
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#include <stdlib.h>
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#include "lib6502.h"
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typedef uint8_t byte;
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typedef uint16_t word;
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enum {
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flagN= (1<<7), /* negative */
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flagV= (1<<6), /* overflow */
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flagX= (1<<5), /* unused */
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flagB= (1<<4), /* irq from brk */
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flagD= (1<<3), /* decimal mode */
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flagI= (1<<2), /* irq disable */
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flagZ= (1<<1), /* zero */
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flagC= (1<<0) /* carry */
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};
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#define getN() (P & flagN)
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#define getV() (P & flagV)
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#define getB() (P & flagB)
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#define getD() (P & flagD)
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#define getI() (P & flagI)
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#define getZ() (P & flagZ)
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#define getC() (P & flagC)
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#define setNVZC(N,V,Z,C) (P= (P & ~(flagN | flagV | flagZ | flagC)) | (N) | ((V)<<6) | ((Z)<<1) | (C))
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#define setNZC(N,Z,C) (P= (P & ~(flagN | flagZ | flagC)) | (N) | ((Z)<<1) | (C))
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#define setNZ(N,Z) (P= (P & ~(flagN | flagZ )) | (N) | ((Z)<<1) )
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#define setZ(Z) (P= (P & ~( flagZ )) | ((Z)<<1) )
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#define setC(C) (P= (P & ~( flagC)) | (C))
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#define NAND(P, Q) (!((P) & (Q)))
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#define tick(n)
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#define tickIf(p)
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/* memory access (indirect if callback installed) -- ARGUMENTS ARE EVALUATED MORE THAN ONCE! */
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#define putMemory(ADDR, BYTE) \
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( writeCallback[ADDR] \
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? writeCallback[ADDR](mpu, ADDR, BYTE) \
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: (memory[ADDR]= BYTE) )
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#define getMemory(ADDR) \
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( readCallback[ADDR] \
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? readCallback[ADDR](mpu, ADDR, 0) \
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: memory[ADDR] )
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/* stack access (always direct) */
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#define push(BYTE) (memory[0x0100 + S--]= (BYTE))
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#define pop() (memory[++S + 0x0100])
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/* adressing modes (memory access direct) */
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#define implied(ticks) \
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tick(ticks);
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#define immediate(ticks) \
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tick(ticks); \
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ea= PC++;
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#define abs(ticks) \
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tick(ticks); \
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ea= memory[PC] + (memory[PC + 1] << 8); \
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PC += 2;
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#define relative(ticks) \
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tick(ticks); \
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ea= memory[PC++]; \
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if (ea & 0x80) ea -= 0x100; \
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tickIf((ea >> 8) != (PC >> 8));
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#define indirect(ticks) \
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tick(ticks); \
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{ \
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word tmp; \
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tmp= memory[PC] + (memory[PC + 1] << 8); \
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ea = memory[tmp] + (memory[tmp + 1] << 8); \
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PC += 2; \
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}
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#define absx(ticks) \
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tick(ticks); \
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ea= memory[PC] + (memory[PC + 1] << 8); \
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PC += 2; \
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tickIf((ticks == 4) && ((ea >> 8) != ((ea + X) >> 8))); \
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ea += X;
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#define absy(ticks) \
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tick(ticks); \
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ea= memory[PC] + (memory[PC + 1] << 8); \
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PC += 2; \
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tickIf((ticks == 4) && ((ea >> 8) != ((ea + Y) >> 8))); \
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ea += Y
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#define zp(ticks) \
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tick(ticks); \
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ea= memory[PC++];
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#define zpx(ticks) \
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tick(ticks); \
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ea= memory[PC++] + X; \
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ea &= 0x00ff;
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#define zpy(ticks) \
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tick(ticks); \
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ea= memory[PC++] + Y; \
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ea &= 0x00ff;
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#define indx(ticks) \
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tick(ticks); \
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{ \
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byte tmp= memory[PC++] + X; \
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ea= memory[tmp] + (memory[tmp + 1] << 8); \
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}
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#define indy(ticks) \
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tick(ticks); \
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{ \
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byte tmp= memory[PC++]; \
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ea= memory[tmp] + (memory[tmp + 1] << 8); \
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tickIf((ticks == 5) && ((ea >> 8) != ((ea + Y) >> 8))); \
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ea += Y; \
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}
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#define indabsx(ticks) \
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tick(ticks); \
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{ \
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word tmp; \
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tmp= memory[PC ] + (memory[PC + 1] << 8) + X; \
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ea = memory[tmp] + (memory[tmp + 1] << 8); \
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}
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#define indzp(ticks) \
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tick(ticks); \
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{ \
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byte tmp; \
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tmp= memory[PC++]; \
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ea = memory[tmp] + (memory[tmp + 1] << 8); \
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}
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/* insns */
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#define adc(ticks, adrmode) \
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adrmode(ticks); \
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{ \
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byte B= getMemory(ea); \
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if (!getD()) \
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{ \
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int c= A + B + getC(); \
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int v= (int8_t)A + (int8_t)B + getC(); \
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fetch(); \
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A= c; \
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setNVZC((A & 0x80), (((A & 0x80) > 0) ^ (v < 0)), (A == 0), ((c & 0x100) > 0)); \
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next(); \
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} \
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else \
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{ \
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int l, h, s; \
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/* inelegant & slow, but consistent with the hw for illegal digits */ \
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l= (A & 0x0F) + (B & 0x0F) + getC(); \
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h= (A & 0xF0) + (B & 0xF0); \
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if (l >= 0x0A) { l += 0x06; h += 0x10; } \
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if (h >= 0xA0) { h += 0x60; } \
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fetch(); \
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s= (h & 0xF0) | (l & 0x0F); \
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/* only C is valid on NMOS 6502 */ \
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setNVZC(s & 0x80, !(((A ^ B) & 0x80) && ((A ^ s) & 0x80)), (s==0), ((h & 0x100) > 0)); \
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A= s; \
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tick(1); \
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next(); \
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} \
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}
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#define sbc(ticks, adrmode) \
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adrmode(ticks); \
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{ \
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byte B= getMemory(ea); \
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if (!getD()) \
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{ \
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int b= 1 - (P &0x01); \
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int c= A - B - b; \
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int v= (int8_t)A - (int8_t) B - b; \
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fetch(); \
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A= c; \
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setNVZC(A & 0x80, ((A & 0x80) > 0) ^ ((v & 0x100) != 0), A == 0, c >= 0); \
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next(); \
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} \
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else \
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{ \
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/* this is verbatim ADC, with a 10's complemented operand */ \
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int l, h, s; \
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B= 0x99 - B; \
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l= (A & 0x0F) + (B & 0x0F) + getC(); \
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h= (A & 0xF0) + (B & 0xF0); \
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if (l >= 0x0A) { l -= 0x0A; h += 0x10; } \
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if (h >= 0xA0) { h -= 0xA0; } \
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fetch(); \
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s= h | (l & 0x0F); \
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/* only C is valid on NMOS 6502 */ \
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setNVZC(s & 0x80, !(((A ^ B) & 0x80) && ((A ^ s) & 0x80)), !s, !!(h & 0x80)); \
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A= s; \
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tick(1); \
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next(); \
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} \
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}
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#define cmpR(ticks, adrmode, R) \
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adrmode(ticks); \
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fetch(); \
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{ \
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byte B= getMemory(ea); \
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byte d= R - B; \
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setNZC(d & 0x80, !d, R >= B); \
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} \
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next();
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#define cmp(ticks, adrmode) cmpR(ticks, adrmode, A)
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#define cpx(ticks, adrmode) cmpR(ticks, adrmode, X)
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#define cpy(ticks, adrmode) cmpR(ticks, adrmode, Y)
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#define dec(ticks, adrmode) \
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adrmode(ticks); \
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fetch(); \
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{ \
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byte B= getMemory(ea); \
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--B; \
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putMemory(ea, B); \
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setNZ(B & 0x80, !B); \
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} \
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next();
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#define decR(ticks, adrmode, R) \
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fetch(); \
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tick(ticks); \
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--R; \
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setNZ(R & 0x80, !R); \
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next();
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#define dea(ticks, adrmode) decR(ticks, adrmode, A)
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#define dex(ticks, adrmode) decR(ticks, adrmode, X)
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#define dey(ticks, adrmode) decR(ticks, adrmode, Y)
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#define inc(ticks, adrmode) \
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adrmode(ticks); \
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fetch(); \
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{ \
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byte B= getMemory(ea); \
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++B; \
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putMemory(ea, B); \
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setNZ(B & 0x80, !B); \
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} \
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next();
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#define incR(ticks, adrmode, R) \
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fetch(); \
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tick(ticks); \
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++R; \
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setNZ(R & 0x80, !R); \
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next();
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#define ina(ticks, adrmode) incR(ticks, adrmode, A)
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#define inx(ticks, adrmode) incR(ticks, adrmode, X)
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#define iny(ticks, adrmode) incR(ticks, adrmode, Y)
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#define bit(ticks, adrmode) \
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adrmode(ticks); \
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fetch(); \
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{ \
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byte B= getMemory(ea); \
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P= (P & ~(flagN | flagV | flagZ)) \
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| (B & (0xC0)) | (((A & B) == 0) << 1); \
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} \
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next();
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#define tsb(ticks, adrmode) \
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adrmode(ticks); \
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fetch(); \
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{ \
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byte b= getMemory(ea); \
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b |= A; \
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putMemory(ea, b); \
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setZ(!b); \
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} \
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next();
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#define trb(ticks, adrmode) \
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adrmode(ticks); \
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fetch(); \
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{ \
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byte b= getMemory(ea); \
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b |= (A ^ 0xFF); \
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putMemory(ea, b); \
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setZ(!b); \
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} \
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next();
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#define bitwise(ticks, adrmode, op) \
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adrmode(ticks); \
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fetch(); \
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A op##= getMemory(ea); \
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setNZ(A & 0x80, !A); \
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next();
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#define and(ticks, adrmode) bitwise(ticks, adrmode, &)
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#define eor(ticks, adrmode) bitwise(ticks, adrmode, ^)
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#define ora(ticks, adrmode) bitwise(ticks, adrmode, |)
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#define asl(ticks, adrmode) \
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adrmode(ticks); \
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{ \
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unsigned int i= getMemory(ea) << 1; \
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putMemory(ea, i); \
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fetch(); \
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setNZC(i & 0x80, !i, i >> 8); \
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} \
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next();
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#define asla(ticks, adrmode) \
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tick(ticks); \
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fetch(); \
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{ \
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int c= A >> 7; \
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A <<= 1; \
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setNZC(A & 0x80, !A, c); \
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} \
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next();
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#define lsr(ticks, adrmode) \
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adrmode(ticks); \
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{ \
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byte b= getMemory(ea); \
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int c= b & 1; \
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fetch(); \
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b >>= 1; \
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putMemory(ea, b); \
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setNZC(0, !b, c); \
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} \
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next();
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#define lsra(ticks, adrmode) \
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tick(ticks); \
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fetch(); \
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{ \
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int c= A & 1; \
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A >>= 1; \
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setNZC(0, !A, c); \
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} \
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next();
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#define rol(ticks, adrmode) \
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adrmode(ticks); \
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{ \
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word b= (getMemory(ea) << 1) | getC(); \
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fetch(); \
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putMemory(ea, b); \
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setNZC(b & 0x80, !(b & 0xFF), b >> 8); \
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} \
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next();
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#define rola(ticks, adrmode) \
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tick(ticks); \
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fetch(); \
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{ \
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word b= (A << 1) | getC(); \
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A= b; \
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setNZC(A & 0x80, !A, b >> 8); \
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} \
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next();
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#define ror(ticks, adrmode) \
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adrmode(ticks); \
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{ \
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int c= getC(); \
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byte m= getMemory(ea); \
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byte b= (c << 7) | (m >> 1); \
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fetch(); \
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putMemory(ea, b); \
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setNZC(b & 0x80, !b, m & 1); \
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} \
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next();
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#define rora(ticks, adrmode) \
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adrmode(ticks); \
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{ \
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int ci= getC(); \
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int co= A & 1; \
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fetch(); \
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A= (ci << 7) | (A >> 1); \
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setNZC(A & 0x80, !A, co); \
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} \
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next();
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#define tRS(ticks, adrmode, R, S) \
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fetch(); \
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tick(ticks); \
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S= R; \
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setNZ(S & 0x80, !S); \
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next();
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#define tax(ticks, adrmode) tRS(ticks, adrmode, A, X)
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#define txa(ticks, adrmode) tRS(ticks, adrmode, X, A)
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#define tay(ticks, adrmode) tRS(ticks, adrmode, A, Y)
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#define tya(ticks, adrmode) tRS(ticks, adrmode, Y, A)
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#define tsx(ticks, adrmode) tRS(ticks, adrmode, S, X)
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#define txs(ticks, adrmode) \
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fetch(); \
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tick(ticks); \
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S= X; \
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next();
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#define ldR(ticks, adrmode, R) \
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adrmode(ticks); \
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fetch(); \
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R= getMemory(ea); \
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setNZ(R & 0x80, !R); \
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next();
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#define lda(ticks, adrmode) ldR(ticks, adrmode, A)
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#define ldx(ticks, adrmode) ldR(ticks, adrmode, X)
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#define ldy(ticks, adrmode) ldR(ticks, adrmode, Y)
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#define stR(ticks, adrmode, R) \
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adrmode(ticks); \
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fetch(); \
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putMemory(ea, R); \
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next();
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#define sta(ticks, adrmode) stR(ticks, adrmode, A)
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#define stx(ticks, adrmode) stR(ticks, adrmode, X)
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#define sty(ticks, adrmode) stR(ticks, adrmode, Y)
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#define stz(ticks, adrmode) stR(ticks, adrmode, 0)
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#define branch(ticks, adrmode, cond) \
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if (cond) \
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{ \
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adrmode(ticks); \
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PC += ea; \
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tick(1); \
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} \
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else \
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{ \
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tick(ticks); \
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PC++; \
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} \
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fetch(); \
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next();
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#define bcc(ticks, adrmode) branch(ticks, adrmode, !getC())
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#define bcs(ticks, adrmode) branch(ticks, adrmode, getC())
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#define bne(ticks, adrmode) branch(ticks, adrmode, !getZ())
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#define beq(ticks, adrmode) branch(ticks, adrmode, getZ())
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#define bpl(ticks, adrmode) branch(ticks, adrmode, !getN())
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#define bmi(ticks, adrmode) branch(ticks, adrmode, getN())
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#define bvc(ticks, adrmode) branch(ticks, adrmode, !getV())
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#define bvs(ticks, adrmode) branch(ticks, adrmode, getV())
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#define bra(ticks, adrmode) \
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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);
|
|
}
|