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mos6502.cpp
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mos6502.cpp
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/*
MIT License
Copyright (c) 2017 Gianluca Ghettini
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, sublicense, and/or sell
copies of the Software, and to permit persons to whom the Software is
furnished to do so, subject to the following conditions:
The above copyright notice and this permission notice shall be included in all
copies or substantial portions of the Software.
THE SOFTWARE IS PROVIDED "AS IS", WITHOUT WARRANTY OF ANY KIND, EXPRESS OR
IMPLIED, INCLUDING BUT NOT LIMITED TO THE WARRANTIES OF MERCHANTABILITY,
FITNESS FOR A PARTICULAR PURPOSE AND NONINFRINGEMENT. IN NO EVENT SHALL THE
AUTHORS OR COPYRIGHT HOLDERS BE LIABLE FOR ANY CLAIM, DAMAGES OR OTHER
LIABILITY, WHETHER IN AN ACTION OF CONTRACT, TORT OR OTHERWISE, ARISING FROM,
OUT OF OR IN CONNECTION WITH THE SOFTWARE OR THE USE OR OTHER DEALINGS IN THE
SOFTWARE.
*/
//minor mods for breakpoint mechanism and other things...
// !!!! MAKE SURE you call 'init_opcodes()', straight after calling constructor
#include "mos6502.h"
extern mtx_tag mtx; //structure used for mutex access to vars
// !!! MAKE SURE you call 'init_opcodes()', straight after calling this constructor
mos6502::mos6502(BusRead r, BusWrite w)
{
Write = (BusWrite)w;
Read = (BusRead)r;
}
void mos6502::init_opcodes()
{
Instr instr;
// fill jump table with ILLEGALs
instr.addr = &mos6502::Addr_IMP;
instr.code = &mos6502::Op_ILLEGAL;
for(int i = 0; i < 256; i++)
{
InstrTable[i] = instr;
}
// insert opcodes
instr.addr = &mos6502::Addr_IMM;
instr.code = &mos6502::Op_ADC;
InstrTable[0x69] = instr;
instr.addr = &mos6502::Addr_ABS;
instr.code = &mos6502::Op_ADC;
InstrTable[0x6D] = instr;
instr.addr = &mos6502::Addr_ZER;
instr.code = &mos6502::Op_ADC;
InstrTable[0x65] = instr;
instr.addr = &mos6502::Addr_INX;
instr.code = &mos6502::Op_ADC;
InstrTable[0x61] = instr;
instr.addr = &mos6502::Addr_INY;
instr.code = &mos6502::Op_ADC;
InstrTable[0x71] = instr;
instr.addr = &mos6502::Addr_ZEX;
instr.code = &mos6502::Op_ADC;
InstrTable[0x75] = instr;
instr.addr = &mos6502::Addr_ABX;
instr.code = &mos6502::Op_ADC;
InstrTable[0x7D] = instr;
instr.addr = &mos6502::Addr_ABY;
instr.code = &mos6502::Op_ADC;
InstrTable[0x79] = instr;
instr.addr = &mos6502::Addr_IMM;
instr.code = &mos6502::Op_AND;
InstrTable[0x29] = instr;
instr.addr = &mos6502::Addr_ABS;
instr.code = &mos6502::Op_AND;
InstrTable[0x2D] = instr;
instr.addr = &mos6502::Addr_ZER;
instr.code = &mos6502::Op_AND;
InstrTable[0x25] = instr;
instr.addr = &mos6502::Addr_INX;
instr.code = &mos6502::Op_AND;
InstrTable[0x21] = instr;
instr.addr = &mos6502::Addr_INY;
instr.code = &mos6502::Op_AND;
InstrTable[0x31] = instr;
instr.addr = &mos6502::Addr_ZEX;
instr.code = &mos6502::Op_AND;
InstrTable[0x35] = instr;
instr.addr = &mos6502::Addr_ABX;
instr.code = &mos6502::Op_AND;
InstrTable[0x3D] = instr;
instr.addr = &mos6502::Addr_ABY;
instr.code = &mos6502::Op_AND;
InstrTable[0x39] = instr;
instr.addr = &mos6502::Addr_ABS;
instr.code = &mos6502::Op_ASL;
InstrTable[0x0E] = instr;
instr.addr = &mos6502::Addr_ZER;
instr.code = &mos6502::Op_ASL;
InstrTable[0x06] = instr;
instr.addr = &mos6502::Addr_ACC;
instr.code = &mos6502::Op_ASL_ACC;
InstrTable[0x0A] = instr;
instr.addr = &mos6502::Addr_ZEX;
instr.code = &mos6502::Op_ASL;
InstrTable[0x16] = instr;
instr.addr = &mos6502::Addr_ABX;
instr.code = &mos6502::Op_ASL;
InstrTable[0x1E] = instr;
instr.addr = &mos6502::Addr_REL;
instr.code = &mos6502::Op_BCC;
InstrTable[0x90] = instr;
instr.addr = &mos6502::Addr_REL;
instr.code = &mos6502::Op_BCS;
InstrTable[0xB0] = instr;
instr.addr = &mos6502::Addr_REL;
instr.code = &mos6502::Op_BEQ;
InstrTable[0xF0] = instr;
instr.addr = &mos6502::Addr_ABS;
instr.code = &mos6502::Op_BIT;
InstrTable[0x2C] = instr;
instr.addr = &mos6502::Addr_ZER;
instr.code = &mos6502::Op_BIT;
InstrTable[0x24] = instr;
instr.addr = &mos6502::Addr_REL;
instr.code = &mos6502::Op_BMI;
InstrTable[0x30] = instr;
instr.addr = &mos6502::Addr_REL;
instr.code = &mos6502::Op_BNE;
InstrTable[0xD0] = instr;
instr.addr = &mos6502::Addr_REL;
instr.code = &mos6502::Op_BPL;
InstrTable[0x10] = instr;
instr.addr = &mos6502::Addr_IMP;
instr.code = &mos6502::Op_BRK;
InstrTable[0x00] = instr;
instr.addr = &mos6502::Addr_REL;
instr.code = &mos6502::Op_BVC;
InstrTable[0x50] = instr;
instr.addr = &mos6502::Addr_REL;
instr.code = &mos6502::Op_BVS;
InstrTable[0x70] = instr;
instr.addr = &mos6502::Addr_IMP;
instr.code = &mos6502::Op_CLC;
InstrTable[0x18] = instr;
instr.addr = &mos6502::Addr_IMP;
instr.code = &mos6502::Op_CLD;
InstrTable[0xD8] = instr;
instr.addr = &mos6502::Addr_IMP;
instr.code = &mos6502::Op_CLI;
InstrTable[0x58] = instr;
instr.addr = &mos6502::Addr_IMP;
instr.code = &mos6502::Op_CLV;
InstrTable[0xB8] = instr;
instr.addr = &mos6502::Addr_IMM;
instr.code = &mos6502::Op_CMP;
InstrTable[0xC9] = instr;
instr.addr = &mos6502::Addr_ABS;
instr.code = &mos6502::Op_CMP;
InstrTable[0xCD] = instr;
instr.addr = &mos6502::Addr_ZER;
instr.code = &mos6502::Op_CMP;
InstrTable[0xC5] = instr;
instr.addr = &mos6502::Addr_INX;
instr.code = &mos6502::Op_CMP;
InstrTable[0xC1] = instr;
instr.addr = &mos6502::Addr_INY;
instr.code = &mos6502::Op_CMP;
InstrTable[0xD1] = instr;
instr.addr = &mos6502::Addr_ZEX;
instr.code = &mos6502::Op_CMP;
InstrTable[0xD5] = instr;
instr.addr = &mos6502::Addr_ABX;
instr.code = &mos6502::Op_CMP;
InstrTable[0xDD] = instr;
instr.addr = &mos6502::Addr_ABY;
instr.code = &mos6502::Op_CMP;
InstrTable[0xD9] = instr;
instr.addr = &mos6502::Addr_IMM;
instr.code = &mos6502::Op_CPX;
InstrTable[0xE0] = instr;
instr.addr = &mos6502::Addr_ABS;
instr.code = &mos6502::Op_CPX;
InstrTable[0xEC] = instr;
instr.addr = &mos6502::Addr_ZER;
instr.code = &mos6502::Op_CPX;
InstrTable[0xE4] = instr;
instr.addr = &mos6502::Addr_IMM;
instr.code = &mos6502::Op_CPY;
InstrTable[0xC0] = instr;
instr.addr = &mos6502::Addr_ABS;
instr.code = &mos6502::Op_CPY;
InstrTable[0xCC] = instr;
instr.addr = &mos6502::Addr_ZER;
instr.code = &mos6502::Op_CPY;
InstrTable[0xC4] = instr;
instr.addr = &mos6502::Addr_ABS;
instr.code = &mos6502::Op_DEC;
InstrTable[0xCE] = instr;
instr.addr = &mos6502::Addr_ZER;
instr.code = &mos6502::Op_DEC;
InstrTable[0xC6] = instr;
instr.addr = &mos6502::Addr_ZEX;
instr.code = &mos6502::Op_DEC;
InstrTable[0xD6] = instr;
instr.addr = &mos6502::Addr_ABX;
instr.code = &mos6502::Op_DEC;
InstrTable[0xDE] = instr;
instr.addr = &mos6502::Addr_IMP;
instr.code = &mos6502::Op_DEX;
InstrTable[0xCA] = instr;
instr.addr = &mos6502::Addr_IMP;
instr.code = &mos6502::Op_DEY;
InstrTable[0x88] = instr;
instr.addr = &mos6502::Addr_IMM;
instr.code = &mos6502::Op_EOR;
InstrTable[0x49] = instr;
instr.addr = &mos6502::Addr_ABS;
instr.code = &mos6502::Op_EOR;
InstrTable[0x4D] = instr;
instr.addr = &mos6502::Addr_ZER;
instr.code = &mos6502::Op_EOR;
InstrTable[0x45] = instr;
instr.addr = &mos6502::Addr_INX;
instr.code = &mos6502::Op_EOR;
InstrTable[0x41] = instr;
instr.addr = &mos6502::Addr_INY;
instr.code = &mos6502::Op_EOR;
InstrTable[0x51] = instr;
instr.addr = &mos6502::Addr_ZEX;
instr.code = &mos6502::Op_EOR;
InstrTable[0x55] = instr;
instr.addr = &mos6502::Addr_ABX;
instr.code = &mos6502::Op_EOR;
InstrTable[0x5D] = instr;
instr.addr = &mos6502::Addr_ABY;
instr.code = &mos6502::Op_EOR;
InstrTable[0x59] = instr;
instr.addr = &mos6502::Addr_ABS;
instr.code = &mos6502::Op_INC;
InstrTable[0xEE] = instr;
instr.addr = &mos6502::Addr_ZER;
instr.code = &mos6502::Op_INC;
InstrTable[0xE6] = instr;
instr.addr = &mos6502::Addr_ZEX;
instr.code = &mos6502::Op_INC;
InstrTable[0xF6] = instr;
instr.addr = &mos6502::Addr_ABX;
instr.code = &mos6502::Op_INC;
InstrTable[0xFE] = instr;
instr.addr = &mos6502::Addr_IMP;
instr.code = &mos6502::Op_INX;
InstrTable[0xE8] = instr;
instr.addr = &mos6502::Addr_IMP;
instr.code = &mos6502::Op_INY;
InstrTable[0xC8] = instr;
instr.addr = &mos6502::Addr_ABS;
instr.code = &mos6502::Op_JMP;
InstrTable[0x4C] = instr;
instr.addr = &mos6502::Addr_ABI;
instr.code = &mos6502::Op_JMP;
InstrTable[0x6C] = instr;
instr.addr = &mos6502::Addr_ABS;
instr.code = &mos6502::Op_JSR;
InstrTable[0x20] = instr;
instr.addr = &mos6502::Addr_IMM;
instr.code = &mos6502::Op_LDA;
InstrTable[0xA9] = instr;
instr.addr = &mos6502::Addr_ABS;
instr.code = &mos6502::Op_LDA;
InstrTable[0xAD] = instr;
instr.addr = &mos6502::Addr_ZER;
instr.code = &mos6502::Op_LDA;
InstrTable[0xA5] = instr;
instr.addr = &mos6502::Addr_INX;
instr.code = &mos6502::Op_LDA;
InstrTable[0xA1] = instr;
instr.addr = &mos6502::Addr_INY;
instr.code = &mos6502::Op_LDA;
InstrTable[0xB1] = instr;
instr.addr = &mos6502::Addr_ZEX;
instr.code = &mos6502::Op_LDA;
InstrTable[0xB5] = instr;
instr.addr = &mos6502::Addr_ABX;
instr.code = &mos6502::Op_LDA;
InstrTable[0xBD] = instr;
instr.addr = &mos6502::Addr_ABY;
instr.code = &mos6502::Op_LDA;
InstrTable[0xB9] = instr;
instr.addr = &mos6502::Addr_IMM;
instr.code = &mos6502::Op_LDX;
InstrTable[0xA2] = instr;
instr.addr = &mos6502::Addr_ABS;
instr.code = &mos6502::Op_LDX;
InstrTable[0xAE] = instr;
instr.addr = &mos6502::Addr_ZER;
instr.code = &mos6502::Op_LDX;
InstrTable[0xA6] = instr;
instr.addr = &mos6502::Addr_ABY;
instr.code = &mos6502::Op_LDX;
InstrTable[0xBE] = instr;
instr.addr = &mos6502::Addr_ZEY;
instr.code = &mos6502::Op_LDX;
InstrTable[0xB6] = instr;
instr.addr = &mos6502::Addr_IMM;
instr.code = &mos6502::Op_LDY;
InstrTable[0xA0] = instr;
instr.addr = &mos6502::Addr_ABS;
instr.code = &mos6502::Op_LDY;
InstrTable[0xAC] = instr;
instr.addr = &mos6502::Addr_ZER;
instr.code = &mos6502::Op_LDY;
InstrTable[0xA4] = instr;
instr.addr = &mos6502::Addr_ZEX;
instr.code = &mos6502::Op_LDY;
InstrTable[0xB4] = instr;
instr.addr = &mos6502::Addr_ABX;
instr.code = &mos6502::Op_LDY;
InstrTable[0xBC] = instr;
instr.addr = &mos6502::Addr_ABS;
instr.code = &mos6502::Op_LSR;
InstrTable[0x4E] = instr;
instr.addr = &mos6502::Addr_ZER;
instr.code = &mos6502::Op_LSR;
InstrTable[0x46] = instr;
instr.addr = &mos6502::Addr_ACC;
instr.code = &mos6502::Op_LSR_ACC;
InstrTable[0x4A] = instr;
instr.addr = &mos6502::Addr_ZEX;
instr.code = &mos6502::Op_LSR;
InstrTable[0x56] = instr;
instr.addr = &mos6502::Addr_ABX;
instr.code = &mos6502::Op_LSR;
InstrTable[0x5E] = instr;
instr.addr = &mos6502::Addr_IMP;
instr.code = &mos6502::Op_NOP;
InstrTable[0xEA] = instr;
instr.addr = &mos6502::Addr_IMM;
instr.code = &mos6502::Op_ORA;
InstrTable[0x09] = instr;
instr.addr = &mos6502::Addr_ABS;
instr.code = &mos6502::Op_ORA;
InstrTable[0x0D] = instr;
instr.addr = &mos6502::Addr_ZER;
instr.code = &mos6502::Op_ORA;
InstrTable[0x05] = instr;
instr.addr = &mos6502::Addr_INX;
instr.code = &mos6502::Op_ORA;
InstrTable[0x01] = instr;
instr.addr = &mos6502::Addr_INY;
instr.code = &mos6502::Op_ORA;
InstrTable[0x11] = instr;
instr.addr = &mos6502::Addr_ZEX;
instr.code = &mos6502::Op_ORA;
InstrTable[0x15] = instr;
instr.addr = &mos6502::Addr_ABX;
instr.code = &mos6502::Op_ORA;
InstrTable[0x1D] = instr;
instr.addr = &mos6502::Addr_ABY;
instr.code = &mos6502::Op_ORA;
InstrTable[0x19] = instr;
instr.addr = &mos6502::Addr_IMP;
instr.code = &mos6502::Op_PHA;
InstrTable[0x48] = instr;
instr.addr = &mos6502::Addr_IMP;
instr.code = &mos6502::Op_PHP;
InstrTable[0x08] = instr;
instr.addr = &mos6502::Addr_IMP;
instr.code = &mos6502::Op_PLA;
InstrTable[0x68] = instr;
instr.addr = &mos6502::Addr_IMP;
instr.code = &mos6502::Op_PLP;
InstrTable[0x28] = instr;
instr.addr = &mos6502::Addr_ABS;
instr.code = &mos6502::Op_ROL;
InstrTable[0x2E] = instr;
instr.addr = &mos6502::Addr_ZER;
instr.code = &mos6502::Op_ROL;
InstrTable[0x26] = instr;
instr.addr = &mos6502::Addr_ACC;
instr.code = &mos6502::Op_ROL_ACC;
InstrTable[0x2A] = instr;
instr.addr = &mos6502::Addr_ZEX;
instr.code = &mos6502::Op_ROL;
InstrTable[0x36] = instr;
instr.addr = &mos6502::Addr_ABX;
instr.code = &mos6502::Op_ROL;
InstrTable[0x3E] = instr;
instr.addr = &mos6502::Addr_ABS;
instr.code = &mos6502::Op_ROR;
InstrTable[0x6E] = instr;
instr.addr = &mos6502::Addr_ZER;
instr.code = &mos6502::Op_ROR;
InstrTable[0x66] = instr;
instr.addr = &mos6502::Addr_ACC;
instr.code = &mos6502::Op_ROR_ACC;
InstrTable[0x6A] = instr;
instr.addr = &mos6502::Addr_ZEX;
instr.code = &mos6502::Op_ROR;
InstrTable[0x76] = instr;
instr.addr = &mos6502::Addr_ABX;
instr.code = &mos6502::Op_ROR;
InstrTable[0x7E] = instr;
instr.addr = &mos6502::Addr_IMP;
instr.code = &mos6502::Op_RTI;
InstrTable[0x40] = instr;
instr.addr = &mos6502::Addr_IMP;
instr.code = &mos6502::Op_RTS;
InstrTable[0x60] = instr;
instr.addr = &mos6502::Addr_IMM;
instr.code = &mos6502::Op_SBC;
InstrTable[0xE9] = instr;
instr.addr = &mos6502::Addr_ABS;
instr.code = &mos6502::Op_SBC;
InstrTable[0xED] = instr;
instr.addr = &mos6502::Addr_ZER;
instr.code = &mos6502::Op_SBC;
InstrTable[0xE5] = instr;
instr.addr = &mos6502::Addr_INX;
instr.code = &mos6502::Op_SBC;
InstrTable[0xE1] = instr;
instr.addr = &mos6502::Addr_INY;
instr.code = &mos6502::Op_SBC;
InstrTable[0xF1] = instr;
instr.addr = &mos6502::Addr_ZEX;
instr.code = &mos6502::Op_SBC;
InstrTable[0xF5] = instr;
instr.addr = &mos6502::Addr_ABX;
instr.code = &mos6502::Op_SBC;
InstrTable[0xFD] = instr;
instr.addr = &mos6502::Addr_ABY;
instr.code = &mos6502::Op_SBC;
InstrTable[0xF9] = instr;
instr.addr = &mos6502::Addr_IMP;
instr.code = &mos6502::Op_SEC;
InstrTable[0x38] = instr;
instr.addr = &mos6502::Addr_IMP;
instr.code = &mos6502::Op_SED;
InstrTable[0xF8] = instr;
instr.addr = &mos6502::Addr_IMP;
instr.code = &mos6502::Op_SEI;
InstrTable[0x78] = instr;
instr.addr = &mos6502::Addr_ABS;
instr.code = &mos6502::Op_STA;
InstrTable[0x8D] = instr;
instr.addr = &mos6502::Addr_ZER;
instr.code = &mos6502::Op_STA;
InstrTable[0x85] = instr;
instr.addr = &mos6502::Addr_INX;
instr.code = &mos6502::Op_STA;
InstrTable[0x81] = instr;
instr.addr = &mos6502::Addr_INY;
instr.code = &mos6502::Op_STA;
InstrTable[0x91] = instr;
instr.addr = &mos6502::Addr_ZEX;
instr.code = &mos6502::Op_STA;
InstrTable[0x95] = instr;
instr.addr = &mos6502::Addr_ABX;
instr.code = &mos6502::Op_STA;
InstrTable[0x9D] = instr;
instr.addr = &mos6502::Addr_ABY;
instr.code = &mos6502::Op_STA;
InstrTable[0x99] = instr;
instr.addr = &mos6502::Addr_ABS;
instr.code = &mos6502::Op_STX;
InstrTable[0x8E] = instr;
instr.addr = &mos6502::Addr_ZER;
instr.code = &mos6502::Op_STX;
InstrTable[0x86] = instr;
instr.addr = &mos6502::Addr_ZEY;
instr.code = &mos6502::Op_STX;
InstrTable[0x96] = instr;
instr.addr = &mos6502::Addr_ABS;
instr.code = &mos6502::Op_STY;
InstrTable[0x8C] = instr;
instr.addr = &mos6502::Addr_ZER;
instr.code = &mos6502::Op_STY;
InstrTable[0x84] = instr;
instr.addr = &mos6502::Addr_ZEX;
instr.code = &mos6502::Op_STY;
InstrTable[0x94] = instr;
instr.addr = &mos6502::Addr_IMP;
instr.code = &mos6502::Op_TAX;
InstrTable[0xAA] = instr;
instr.addr = &mos6502::Addr_IMP;
instr.code = &mos6502::Op_TAY;
InstrTable[0xA8] = instr;
instr.addr = &mos6502::Addr_IMP;
instr.code = &mos6502::Op_TSX;
InstrTable[0xBA] = instr;
instr.addr = &mos6502::Addr_IMP;
instr.code = &mos6502::Op_TXA;
InstrTable[0x8A] = instr;
instr.addr = &mos6502::Addr_IMP;
instr.code = &mos6502::Op_TXS;
InstrTable[0x9A] = instr;
instr.addr = &mos6502::Addr_IMP;
instr.code = &mos6502::Op_TYA;
InstrTable[0x98] = instr;
//Reset();
return;
}
//breakpoint monitor mem read
uint8_t mos6502::read_bp( uint16_t addr )
{
if( bp_addr == addr ) bp_hit = 1;
uint8_t data = Read( addr );
//printf( "mos6502::read_bp(): addr: [0x%04x] 0x%02x\n", addr, data );
//getchar();
return data;
}
//breakpoint monitored mem write
void mos6502::write_bp( uint16_t addr, uint8_t data )
{
if( bp_addr == addr ) bp_hit = 1;
Write( addr, data );
}
uint16_t mos6502::Addr_ACC()
{
return 0; // not used
}
uint16_t mos6502::Addr_IMM()
{
return pc++;
}
uint16_t mos6502::Addr_ABS()
{
uint16_t addrL;
uint16_t addrH;
uint16_t addr;
addrL = read_bp(pc++);
addrH = read_bp(pc++);
addr = addrL + (addrH << 8);
return addr;
}
uint16_t mos6502::Addr_ZER()
{
return read_bp(pc++);
}
uint16_t mos6502::Addr_IMP()
{
return 0; // not used
}
uint16_t mos6502::Addr_REL()
{
uint16_t offset;
uint16_t addr;
offset = (uint16_t)read_bp(pc++);
if (offset & 0x80) offset |= 0xFF00;
addr = pc + (int16_t)offset;
return addr;
}
uint16_t mos6502::Addr_ABI()
{
uint16_t addrL;
uint16_t addrH;
uint16_t effL;
uint16_t effH;
uint16_t abs;
uint16_t addr;
addrL = read_bp(pc++);
addrH = read_bp(pc++);
abs = (addrH << 8) | addrL;
effL = read_bp(abs);
effH = read_bp((abs & 0xFF00) + ((abs + 1) & 0x00FF) );
addr = effL + 0x100 * effH;
return addr;
}
uint16_t mos6502::Addr_ZEX()
{
uint16_t addr = (read_bp(pc++) + X) % 256;
return addr;
}
uint16_t mos6502::Addr_ZEY()
{
uint16_t addr = (read_bp(pc++) + Y) % 256;
return addr;
}
uint16_t mos6502::Addr_ABX()
{
uint16_t addr;
uint16_t addrL;
uint16_t addrH;
addrL = read_bp(pc++);
addrH = read_bp(pc++);
addr = addrL + (addrH << 8) + X;
return addr;
}
uint16_t mos6502::Addr_ABY()
{
uint16_t addr;
uint16_t addrL;
uint16_t addrH;
addrL = read_bp(pc++);
addrH = read_bp(pc++);
addr = addrL + (addrH << 8) + Y;
return addr;
}
uint16_t mos6502::Addr_INX()
{
uint16_t zeroL;
uint16_t zeroH;
uint16_t addr;
zeroL = (read_bp(pc++) + X) % 256;
zeroH = (zeroL + 1) % 256;
addr = read_bp(zeroL) + (read_bp(zeroH) << 8);
return addr;
}
uint16_t mos6502::Addr_INY()
{
uint16_t zeroL;
uint16_t zeroH;
uint16_t addr;
zeroL = read_bp(pc++);
zeroH = (zeroL + 1) % 256;
addr = read_bp(zeroL) + (read_bp(zeroH) << 8) + Y;
return addr;
}
void mos6502::Reset()
{
A = 0x00;
Y = 0x00;
X = 0x00;
pc = (read_bp(rstVectorH) << 8) + read_bp(rstVectorL); // load PC from reset vector
printf( "mos6502::Reset(): pc: 0x%04x\n", pc );
sp = 0xFD;
status |= CONSTANT;
cycles = 6; // according to the datasheet, the reset routine takes 6 clock cycles
illegalOpcode = false;
return;
}
void mos6502::StackPush(uint8_t byte)
{
write_bp(0x0100 + sp, byte);
if(sp == 0x00) sp = 0xFF;
else sp--;
}
uint8_t mos6502::StackPop()
{
if(sp == 0xFF) sp = 0x00;
else sp++;
return read_bp(0x0100 + sp);
}
void mos6502::IRQ()
{
if(!IF_INTERRUPT())
{
SET_BREAK(0);
StackPush((pc >> 8) & 0xFF);
StackPush(pc & 0xFF);
StackPush(status);
SET_INTERRUPT(1);
pc = (read_bp(irqVectorH) << 8) + read_bp(irqVectorL);
}
return;
}
void mos6502::NMI()
{
SET_BREAK(0);
StackPush((pc >> 8) & 0xFF);
StackPush(pc & 0xFF);
StackPush(status);
SET_INTERRUPT(1);
pc = (read_bp(nmiVectorH) << 8) + read_bp(nmiVectorL);
return;
}
void mos6502::Run(uint32_t n)
{
if( cycles > ( 0xffffffff00000000 ) ) //just some arbitrary large number
{
printf( "mos6502::Run() - resetting 'cycles' to prevent overflow; %" PRIu64 "\n", cycles );
cycles = 0;
}
uint64_t start = cycles;
uint8_t opcode;
Instr instr;
bp_addr = -1; //no breakpoint
//printf( "Run: %d, pc: 0x%04x, illegalOpcode: %d\n", n, pc, illegalOpcode );
if( illegalOpcode )
{
//printf( "mos6502::Run(%d), pc: 0x%04x, illegalOpcode: %d\n", n, pc, illegalOpcode );
// getchar();
}
while( ((start + n) > cycles) && (!illegalOpcode) )
{
// fetch
opcode = read_bp(pc++);
// printf( " mos6502::Run() - opcode: 0x%02x\n", opcode );
// decode
instr = InstrTable[opcode];
// execute
Exec(instr);
cycles++;
}
}
//returns 1 if breakpoint addr was hit (set bp_addr = -1 to ignore bp)
//else 0
bool mos6502::Run_breakpoint( uint32_t n, int bp_addr_in )
{
if( cycles > ( 0xffffffff00000000 ) ) //just some arbitrary large number
{
printf( "mos6502::Run_breakpoint() - resetting 'cycles' to prevent overflow; %" PRIu64 "\n", cycles );
cycles = 0;
}
uint64_t start = cycles;
uint8_t opcode;
Instr instr;
bp_addr = bp_addr_in;
bp_hit = 0;
while( ((start + n) > cycles) && (!illegalOpcode) )
{
printf( " mos6502::Run_breakpoint() - pc: %04x, opcode: 0x%02x, steps: %d, \n", pc - 1, opcode, n );
// if( bp_addr >= 0 )
// {
// bp = bp_addr;
// if( bp_addr == pc ) return 1;
// }
// else{
// bp = -1;
// }
// fetch
if( bp_addr == pc )
{
bp_hit = 1;
return 1;
}
opcode = read_bp(pc++);
// if( bp_hit ) return 1; //bp?
// decode
instr = InstrTable[opcode];
// execute
Exec(instr);
if( bp_hit ) return 1; //bp?
cycles++;
}
return 0;
}
void mos6502::Exec(Instr i)
{
uint16_t src = (this->*i.addr)();
(this->*i.code)(src);
}
void mos6502::Op_ILLEGAL(uint16_t src)
{
printf( "mos6502::Op_ILLEGAL() - pc: 0x%04x\n", pc );
mtx.illegal_opcode_pc = pc;
illegalOpcode = true;
}
void mos6502::Op_ADC(uint16_t src)
{
uint8_t m = read_bp(src);
unsigned int tmp = m + A + (IF_CARRY() ? 1 : 0);
SET_ZERO(!(tmp & 0xFF));
if (IF_DECIMAL())
{
if (((A & 0xF) + (m & 0xF) + (IF_CARRY() ? 1 : 0)) > 9) tmp += 6;
SET_NEGATIVE(tmp & 0x80);
SET_OVERFLOW(!((A ^ m) & 0x80) && ((A ^ tmp) & 0x80));
if (tmp > 0x99)
{
tmp += 96;
}
SET_CARRY(tmp > 0x99);
}
else
{
SET_NEGATIVE(tmp & 0x80);
SET_OVERFLOW(!((A ^ m) & 0x80) && ((A ^ tmp) & 0x80));
SET_CARRY(tmp > 0xFF);
}
A = tmp & 0xFF;
return;
}
void mos6502::Op_AND(uint16_t src)
{
uint8_t m = read_bp(src);
uint8_t res = m & A;
SET_NEGATIVE(res & 0x80);
SET_ZERO(!res);
A = res;
return;
}
void mos6502::Op_ASL(uint16_t src)
{
uint8_t m = read_bp(src);
SET_CARRY(m & 0x80);
m <<= 1;
m &= 0xFF;
SET_NEGATIVE(m & 0x80);
SET_ZERO(!m);
write_bp(src, m);
return;
}
void mos6502::Op_ASL_ACC(uint16_t src)
{
uint8_t m = A;
SET_CARRY(m & 0x80);
m <<= 1;
m &= 0xFF;
SET_NEGATIVE(m & 0x80);
SET_ZERO(!m);
A = m;
return;
}
void mos6502::Op_BCC(uint16_t src)
{
if (!IF_CARRY())
{
pc = src;
}
return;
}
void mos6502::Op_BCS(uint16_t src)
{
if (IF_CARRY())
{
pc = src;
}
return;
}
void mos6502::Op_BEQ(uint16_t src)
{
if (IF_ZERO())