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puce6502/puce6502.c

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/*
puce6502 - MOS 6502 cpu emulator
Last modified 21st of June 2021
Copyright (c) 2018 Arthur Ferreira (arthur.ferreira2@gmail.com)
This version has been modified for reinette II plus, a french Apple II plus
emulator using SDL2 (https://github.com/ArthurFerreira2/reinette-II-plus).
Please download the latest version from
https://github.com/ArthurFerreira2/puce6502
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.
*/
// set to zero for 'normal' use
// or to 1 if you want to run the functionnal tests
#define _FUNCTIONNAL_TESTS 1
#include "puce6502.h"
#define CARRY 0x01
#define ZERO 0x02
#define INTR 0x04
#define DECIM 0x08
#define BREAK 0x10
#define UNDEF 0x20
#define OFLOW 0x40
#define SIGN 0x80
#if _FUNCTIONNAL_TESTS
// for functionnal tests, see main()
uint8_t RAM[65536];
inline uint8_t readMem(uint16_t address) { return RAM[address]; }
inline void writeMem(uint16_t address, uint8_t value) { RAM[address] = value; }
#else
// user provided functions
extern uint8_t readMem(uint16_t address);
extern void writeMem(uint16_t address, uint8_t value);
#endif
#define CARRY 0x01
#define ZERO 0x02
#define INTR 0x04
#define DECIM 0x08
#define BREAK 0x10
#define UNDEF 0x20
#define OFLOW 0x40
#define SIGN 0x80
static struct Operand {
uint8_t code;
bool setAcc;
uint8_t value;
uint16_t address;
} ope;
static struct Register {
uint8_t A,X,Y,SR,SP;
uint16_t PC;
} reg;
unsigned long long int ticks; // exportable to user modules
static const int cycles[256] = { // cycles per instruction
7,6,0,0,0,3,5,0,3,2,2,0,0,4,6,0,3,5,0,0,0,4,6,0,2,4,0,0,0,4,7,0,
6,6,0,0,3,3,5,0,4,2,2,0,4,4,6,0,3,5,0,0,0,4,6,0,2,4,0,0,0,4,7,0,
6,6,0,0,0,3,5,0,3,2,2,0,3,4,6,0,3,5,0,0,0,4,6,0,2,4,0,0,0,4,7,0,
6,6,0,0,0,3,5,0,4,2,2,0,5,4,6,0,3,5,0,0,0,4,6,0,2,4,0,0,0,4,7,0,
0,6,0,0,3,3,3,0,2,0,2,0,4,4,4,0,3,6,0,0,4,4,4,0,2,5,2,0,0,5,0,0,
2,6,2,0,3,3,3,0,2,2,2,0,4,4,4,0,3,5,0,0,4,4,4,0,2,4,2,0,4,4,4,0,
2,6,0,0,3,3,5,0,2,2,2,0,4,4,6,0,3,5,0,0,0,4,6,0,2,4,0,0,0,4,7,0,
2,6,0,0,3,3,5,0,2,2,2,0,4,4,6,0,3,5,0,0,0,4,6,0,2,4,0,0,0,4,7,0
};
//=============================================== STACK, SIGN AND OTHER ROUTINES
inline static void push(uint8_t value){
writeMem(0x100 + reg.SP--, value);
}
inline static uint8_t pull(){
return(readMem(0x100 + ++reg.SP));
}
inline static void setSZ(uint8_t value){ // updates both the Sign & Zero FLAGS
if (value & 0x00FF) reg.SR &= ~ZERO;
else reg.SR |= ZERO;
if (value & 0x80) reg.SR |= SIGN;
else reg.SR &= ~SIGN;
}
inline static void branch(){ // used by the 8 branch instructions
ticks++;
if (((reg.PC & 0xFF) + ope.address) & 0xFF00) ticks++;
reg.PC += ope.address;
}
inline static void makeUpdates(uint8_t val){ // used by ASL, LSR, ROL and ROR
if (ope.setAcc){
reg.A = val;
ope.setAcc = false;
}
else writeMem(ope.address, val);
setSZ(val);
}
//============================================================= ADDRESSING MODES
static void IMP(){ // IMPlicit
}
static void ACC(){ // ACCumulator
ope.value = reg.A;
ope.setAcc = true;
}
static void IMM(){ // IMMediate
ope.address = reg.PC++;
ope.value = readMem(ope.address);
}
static void ZPG(){ // Zero PaGe
ope.address = readMem(reg.PC++);
ope.value = readMem(ope.address);
}
static void ZPX(){ // Zero Page,X
ope.address = (readMem(reg.PC++) + reg.X) & 0xFF;
ope.value = readMem(ope.address);
}
static void ZPY(){ // Zero Page,Y
if (readMem(reg.PC) + reg.Y > 0xFF) ticks++;
ope.address = (readMem(reg.PC++) + reg.Y) & 0xFF;
ope.value = readMem(ope.address);
}
static void REL(){ // RELative (for branch instructions)
ope.address = readMem(reg.PC++);
if (ope.address & 0x80) ope.address |= 0xFF00; // branch backward
}
static void ABS(){ // ABSolute
ope.address = readMem(reg.PC) | (readMem(reg.PC + 1) << 8);
ope.value = readMem(ope.address);
reg.PC += 2;
}
static void ABX(){ // ABsolute,X
if (readMem(reg.PC) + reg.X > 0xFF) ticks++;
ope.address = (readMem(reg.PC) | (readMem(reg.PC + 1) << 8)) + reg.X;
ope.value = readMem(ope.address);
reg.PC += 2;
}
static void ABY(){ // ABsolute,Y
if (readMem(reg.PC) + reg.Y > 0xFF) ticks++;
ope.address = (readMem(reg.PC) | (readMem(reg.PC + 1) << 8)) + reg.Y;
ope.value = readMem(ope.address);
reg.PC += 2;
}
static void IND(){ // INDirect - JMP ($ABCD) with page-boundary wraparound bug
uint16_t vector1 = readMem(reg.PC) | (readMem(reg.PC + 1) << 8);
uint16_t vector2 = (vector1 & 0xFF00) | ((vector1 + 1) & 0x00FF);
ope.address = readMem(vector1) | (readMem(vector2) << 8);
ope.value = readMem(ope.address);
reg.PC += 2;
}
static void IDX(){ // InDexed indirect X
uint16_t vector1 = ((readMem(reg.PC++) + reg.X) & 0xFF);
ope.address = readMem(vector1 & 0x00FF)|(readMem((vector1+1) & 0x00FF) << 8);
ope.value = readMem(ope.address);
}
static void IDY(){ // InDirect Indexed Y
uint16_t vector1 = readMem(reg.PC++);
uint16_t vector2 = (vector1 & 0xFF00) | ((vector1 + 1) & 0x00FF);
ope.address = (readMem(vector1) | (readMem(vector2) << 8)) + reg.Y;
ope.value = readMem(ope.address);
}
//================================================================= INSTRUCTIONS
static void NOP(){ // NO Operation
}
void BRK(){ // BReaK
push(((++reg.PC) >> 8) & 0xFF);
push(reg.PC & 0xFF);
push(reg.SR | BREAK);
reg.SR |= INTR;
reg.PC = readMem(0xFFFE) | ((readMem(0xFFFF) << 8)); // IRQ/BRK vect @FFFE/FF
}
static void CLD(){ // CLear Decimal
reg.SR &= ~DECIM;
}
static void SED(){ // SEt Decimal
reg.SR |= DECIM;
}
static void CLC(){ // CLear Carry
reg.SR &= ~CARRY;
}
static void SEC(){ // SEt Carry
reg.SR |= CARRY;
}
static void CLI(){ // CLear Interrupt
reg.SR &= ~INTR;
}
static void SEI(){ // SEt Interrupt
reg.SR |= INTR;
}
static void CLV(){ // CLear oVerflow
reg.SR &= ~OFLOW;
}
static void LDA(){ // LoaD Accumulator
reg.A = ope.value;
setSZ(reg.A);
}
static void LDX(){ // LoaD X
reg.X = ope.value;
setSZ(reg.X);
}
static void LDY(){ // LoaD Y
reg.Y = ope.value;
setSZ(reg.Y);
}
static void STA(){ // STore Accumulator
writeMem(ope.address, reg.A);
}
static void STX(){ // STore X
writeMem(ope.address, reg.X);
}
static void STY(){ // STore Y
writeMem(ope.address, reg.Y);
}
static void DEC(){ // DECrement
writeMem(ope.address, --ope.value);
setSZ(ope.value);
}
static void DEX(){ // DEcrement X
setSZ(--reg.X);
}
static void DEY(){ // DEcrement Y
setSZ(--reg.Y);
}
static void INC(){ // INCrement
writeMem(ope.address, ++ope.value);
setSZ(ope.value);
}
static void INX(){ // INcrement X
setSZ(++reg.X);
}
static void INY(){ // INcrement Y
setSZ(++reg.Y);
}
static void TAX(){ // Transfer Accumulator to X
reg.X = reg.A;
setSZ(reg.X);
}
static void TAY(){ // Transfer Accumulator to Y
reg.Y = reg.A;
setSZ(reg.Y);
}
static void TXA(){ // Transfer X to Accumulator
reg.A = reg.X;
setSZ(reg.A);
}
static void TYA(){ // Transfer Y to Accumulator
reg.A = reg.Y;
setSZ(reg.A);
}
static void TSX(){ // Transfer Sp to X
reg.X = reg.SP;
setSZ(reg.X);
}
static void TXS(){ // Transfer X to Sp
reg.SP = reg.X;
}
static void BEQ(){ // Branch on EQual (zero set)
if (reg.SR & ZERO) branch();
}
static void BNE(){ // Branch on Not Equal (zero clear)
if (!(reg.SR & ZERO)) branch();
}
static void BMI(){ // Branch if MInus : when negative, when SIGN is set
if (reg.SR & SIGN) branch();
}
static void BPL(){ // Branch if PLus : when positive, when SIGN is clear
if (!(reg.SR & SIGN)) branch();
}
static void BVS(){ // Branch on oVerflow Set
if (reg.SR & OFLOW) branch();
}
static void BVC(){ // Branch on oVerflow Clear
if (!(reg.SR & OFLOW)) branch();
}
static void BCS(){ // Branch on Carry Set
if (reg.SR & CARRY) branch();
}
static void BCC(){ // Branch on Carry Clear
if (!(reg.SR & CARRY)) branch();
}
static void PHA(){ // PusH A to the stack
push(reg.A);
}
static void PLA(){ // PulL stack into A
reg.A = pull();
setSZ(reg.A);
}
static void PHP(){ // PusH Programm (Status) register to the stack
push(reg.SR | BREAK);
}
static void PLP(){ // PulL stack into Programm (SR) register
reg.SR = pull() | UNDEF;
}
static void JMP(){ // JuMP
reg.PC = ope.address;
}
static void JSR(){ // Jump Sub-Routine
push((--reg.PC >> 8) & 0xFF);
push(reg.PC & 0xFF);
reg.PC = ope.address;
}
static void RTS(){ // ReTurn from Sub-routine
reg.PC = (pull() | (pull() << 8)) + 1;
}
static void RTI(){ // ReTurn from Interrupt
reg.SR = pull();
reg.PC = pull() | (pull() << 8);
}
static void CMP(){ // Compare with A
setSZ(reg.A - ope.value);
if (reg.A >= ope.value) reg.SR |= CARRY;
else reg.SR &= ~CARRY;
}
static void CPX(){ // Compare with X
setSZ(reg.X - ope.value);
if (reg.X >= ope.value) reg.SR |= CARRY;
else reg.SR &= ~CARRY;
}
static void CPY(){ // Compare with Y
setSZ(reg.Y - ope.value);
if (reg.Y >= ope.value) reg.SR |= CARRY;
else reg.SR &= ~CARRY;
}
static void AND(){ // AND with A
reg.A &= ope.value;
setSZ(reg.A);
}
static void ORA(){ // OR with A
reg.A |= ope.value;
setSZ(reg.A);
}
static void EOR(){ // Exclusive Or with A
reg.A ^= ope.value;
setSZ(reg.A);
}
static void BIT(){ // BIT with A - http://www.6502.org/tutorials/vflag.html
if (reg.A & ope.value) reg.SR &= ~ZERO;
else reg.SR |= ZERO;
reg.SR = (reg.SR & 0x3F) | (ope.value & 0xC0); // update SIGN & OFLOW
}
static void ASL(){ // Arithmetic Shift Left
uint16_t result = (ope.value << 1);
if (result & 0xFF00) reg.SR |= CARRY;
else reg.SR &= ~CARRY;
makeUpdates((uint8_t)(result & 0xFF));
}
static void LSR(){ // Logical Shift Right
if (ope.value & 1) reg.SR |= CARRY;
else reg.SR &= ~CARRY;
makeUpdates((uint8_t)((ope.value >> 1) & 0xFF));
}
static void ROL(){ // ROtate Left
uint16_t result = ((ope.value << 1) | (reg.SR & CARRY));
if (result & 0x100) reg.SR |= CARRY;
else reg.SR &= ~CARRY;
makeUpdates((uint8_t)(result & 0xFF));
}
static void ROR(){ // ROtate Right
uint16_t result = (ope.value >> 1) | ((reg.SR & CARRY) << 7);
if (ope.value & 0x1) reg.SR |= CARRY;
else reg.SR &= ~CARRY;
makeUpdates((uint8_t)(result & 0xFF));
}
static void ADC(){ // ADd with Carry
uint16_t result = reg.A + ope.value + (reg.SR & CARRY);
setSZ(result);
if (((result)^(reg.A))&((result)^(ope.value))&0x0080) reg.SR |= OFLOW;
else reg.SR &= ~OFLOW;
if (reg.SR&DECIM) result += ((((result+0x66)^reg.A^ope.value)>>3)&0x22)*3;
if (result & 0xFF00) reg.SR |= CARRY;
else reg.SR &= ~CARRY;
reg.A = (result & 0xFF);
}
static void SBC(){ // SuBtract with Carry
ope.value ^= 0xFF;
if (reg.SR & DECIM) ope.value -= 0x0066;
uint16_t result = reg.A + ope.value + (reg.SR & CARRY);
setSZ(result);
if (((result)^(reg.A))&((result)^(ope.value))&0x0080) reg.SR |= OFLOW;
else reg.SR &= ~OFLOW;
if (reg.SR&DECIM) result += ((((result+0x66)^reg.A^ope.value)>>3)&0x22)*3;
if (result & 0xFF00) reg.SR |= CARRY;
else reg.SR &= ~CARRY;
reg.A = (result & 0xFF);
}
static void UND(){ // UNDefined (not a valid or supported 6502 opcode)
BRK();
}
//================================================================== JUMP TABLES
static void (*instruction[256])(void) = {
BRK, ORA, UND, UND, UND, ORA, ASL, UND, PHP, ORA, ASL, UND, UND, ORA, ASL, UND,
BPL, ORA, UND, UND, UND, ORA, ASL, UND, CLC, ORA, UND, UND, UND, ORA, ASL, UND,
JSR, AND, UND, UND, BIT, AND, ROL, UND, PLP, AND, ROL, UND, BIT, AND, ROL, UND,
BMI, AND, UND, UND, UND, AND, ROL, UND, SEC, AND, UND, UND, UND, AND, ROL, UND,
RTI, EOR, UND, UND, UND, EOR, LSR, UND, PHA, EOR, LSR, UND, JMP, EOR, LSR, UND,
BVC, EOR, UND, UND, UND, EOR, LSR, UND, CLI, EOR, UND, UND, UND, EOR, LSR, UND,
RTS, ADC, UND, UND, UND, ADC, ROR, UND, PLA, ADC, ROR, UND, JMP, ADC, ROR, UND,
BVS, ADC, UND, UND, UND, ADC, ROR, UND, SEI, ADC, UND, UND, UND, ADC, ROR, UND,
UND, STA, UND, UND, STY, STA, STX, UND, DEY, UND, TXA, UND, STY, STA, STX, UND,
BCC, STA, UND, UND, STY, STA, STX, UND, TYA, STA, TXS, UND, UND, STA, UND, UND,
LDY, LDA, LDX, UND, LDY, LDA, LDX, UND, TAY, LDA, TAX, UND, LDY, LDA, LDX, UND,
BCS, LDA, UND, UND, LDY, LDA, LDX, UND, CLV, LDA, TSX, UND, LDY, LDA, LDX, UND,
CPY, CMP, UND, UND, CPY, CMP, DEC, UND, INY, CMP, DEX, UND, CPY, CMP, DEC, UND,
BNE, CMP, UND, UND, UND, CMP, DEC, UND, CLD, CMP, UND, UND, UND, CMP, DEC, UND,
CPX, SBC, UND, UND, CPX, SBC, INC, UND, INX, SBC, NOP, UND, CPX, SBC, INC, UND,
BEQ, SBC, UND, UND, UND, SBC, INC, UND, SED, SBC, UND, UND, UND, SBC, INC, UND
};
static void (*addressing[256])(void) = {
IMP, IDX, IMP, IMP, IMP, ZPG, ZPG, IMP, IMP, IMM, ACC, IMP, IMP, ABS, ABS, IMP,
REL, IDY, IMP, IMP, IMP, ZPX, ZPX, IMP, IMP, ABY, IMP, IMP, IMP, ABX, ABX, IMP,
ABS, IDX, IMP, IMP, ZPG, ZPG, ZPG, IMP, IMP, IMM, ACC, IMP, ABS, ABS, ABS, IMP,
REL, IDY, IMP, IMP, IMP, ZPX, ZPX, IMP, IMP, ABY, IMP, IMP, IMP, ABX, ABX, IMP,
IMP, IDX, IMP, IMP, IMP, ZPG, ZPG, IMP, IMP, IMM, ACC, IMP, ABS, ABS, ABS, IMP,
REL, IDY, IMP, IMP, IMP, ZPX, ZPX, IMP, IMP, ABY, IMP, IMP, IMP, ABX, ABX, IMP,
IMP, IDX, IMP, IMP, IMP, ZPG, ZPG, IMP, IMP, IMM, ACC, IMP, IND, ABS, ABS, IMP,
REL, IDY, IMP, IMP, IMP, ZPX, ZPX, IMP, IMP, ABY, IMP, IMP, IMP, ABX, ABX, IMP,
IMP, IDX, IMP, IMP, ZPG, ZPG, ZPG, IMP, IMP, IMP, IMP, IMP, ABS, ABS, ABS, IMP,
REL, IDY, IMP, IMP, ZPX, ZPX, ZPY, IMP, IMP, ABY, IMP, IMP, IMP, ABX, IMP, IMP,
IMM, IDX, IMM, IMP, ZPG, ZPG, ZPG, IMP, IMP, IMM, IMP, IMP, ABS, ABS, ABS, IMP,
REL, IDY, IMP, IMP, ZPX, ZPX, ZPY, IMP, IMP, ABY, IMP, IMP, ABX, ABX, ABY, IMP,
IMM, IDX, IMP, IMP, ZPG, ZPG, ZPG, IMP, IMP, IMM, IMP, IMP, ABS, ABS, ABS, IMP,
REL, IDY, IMP, IMP, IMP, ZPX, ZPX, IMP, IMP, ABY, IMP, IMP, IMP, ABX, ABX, IMP,
IMM, IDX, IMP, IMP, ZPG, ZPG, ZPG, IMP, IMP, IMM, IMP, IMP, ABS, ABS, ABS, IMP,
REL, IDY, IMP, IMP, IMP, ZPX, ZPX, IMP, IMP, ABY, IMP, IMP, IMP, ABX, ABX, IMP
};
//========================================================= USER INTERFACE (API)
uint16_t puce6502Exec(unsigned long long int cycleCount){
cycleCount += ticks; // cycleCount becomes the target ticks value
while (ticks < cycleCount) {
ope.code = readMem(reg.PC++); // FETCH and increment the Program Counter
addressing[ope.code](); // DECODE against the addressing mode
instruction[ope.code](); // EXECUTE the instruction
ticks += cycles[ope.code]; // update ticks count
}
return reg.PC;
}
void puce6502RST() {
reg.PC = readMem(0xFFFC) | (readMem(0xFFFD) << 8);
reg.SP = 0xFF;
reg.SR = (reg.SR | INTR | BREAK | UNDEF) & ~DECIM;
ticks += 7;
}
void puce6502NMI() {
writeMem(0x100 + reg.SP--, ((reg.PC) >> 8) & 0xFF);
writeMem(0x100 + reg.SP--, reg.PC & 0xFF);
writeMem(0x100 + reg.SP--, reg.SR);
reg.PC = readMem(0xFFFA) | (readMem(0xFFFB) << 8);
ticks += 7;
}
void puce6502IRQ() {
if (!(reg.SR & INTR)) return;
writeMem(0x100 + reg.SP--, ((reg.PC) >> 8) & 0xFF);
writeMem(0x100 + reg.SP--, reg.PC & 0xFF);
writeMem(0x100 + reg.SP--, reg.SR);
reg.PC = readMem(0xFFFE) | (readMem(0xFFFF) << 8);
ticks += 7;
}
// ALL the code down below was used during developpment for test and debug
// and is not required for normal operation
#include <stdio.h>
static const char* mn[256] = {
"BRK","ORA","UND","UND","UND","ORA","ASL","UND","PHP","ORA","ASL","UND","UND","ORA","ASL","UND",
"BPL","ORA","UND","UND","UND","ORA","ASL","UND","CLC","ORA","UND","UND","UND","ORA","ASL","UND",
"JSR","AND","UND","UND","BIT","AND","ROL","UND","PLP","AND","ROL","UND","BIT","AND","ROL","UND",
"BMI","AND","UND","UND","UND","AND","ROL","UND","SEC","AND","UND","UND","UND","AND","ROL","UND",
"RTI","EOR","UND","UND","UND","EOR","LSR","UND","PHA","EOR","LSR","UND","JMP","EOR","LSR","UND",
"BVC","EOR","UND","UND","UND","EOR","LSR","UND","CLI","EOR","UND","UND","UND","EOR","LSR","UND",
"RTS","ADC","UND","UND","UND","ADC","ROR","UND","PLA","ADC","ROR","UND","JMP","ADC","ROR","UND",
"BVS","ADC","UND","UND","UND","ADC","ROR","UND","SEI","ADC","UND","UND","UND","ADC","ROR","UND",
"UND","STA","UND","UND","STY","STA","STX","UND","DEY","UND","TXA","UND","STY","STA","STX","UND",
"BCC","STA","UND","UND","STY","STA","STX","UND","TYA","STA","TXS","UND","UND","STA","UND","UND",
"LDY","LDA","LDX","UND","LDY","LDA","LDX","UND","TAY","LDA","TAX","UND","LDY","LDA","LDX","UND",
"BCS","LDA","UND","UND","LDY","LDA","LDX","UND","CLV","LDA","TSX","UND","LDY","LDA","LDX","UND",
"CPY","CMP","UND","UND","CPY","CMP","DEC","UND","INY","CMP","DEX","UND","CPY","CMP","DEC","UND",
"BNE","CMP","UND","UND","UND","CMP","DEC","UND","CLD","CMP","UND","UND","UND","CMP","DEC","UND",
"CPX","SBC","UND","UND","CPX","SBC","INC","UND","INX","SBC","NOP","UND","CPX","SBC","INC","UND",
"BEQ","SBC","UND","UND","UND","SBC","INC","UND","SED","SBC","UND","UND","UND","SBC","INC","UND"
};
static const int am[256] = {
0x0 , 0xC , 0x0 , 0x0 , 0x0 , 0x3 , 0x3 , 0x0 , 0x0 , 0x2 , 0x1 , 0x0 , 0x0 , 0x7 , 0x7 , 0x0 ,
0x6 , 0xD , 0x0 , 0x0 , 0x0 , 0x4 , 0x4 , 0x0 , 0x0 , 0x9 , 0x0 , 0x0 , 0x0 , 0x8 , 0x8 , 0x0 ,
0x7 , 0xC , 0x0 , 0x0 , 0x3 , 0x3 , 0x3 , 0x0 , 0x0 , 0x2 , 0x1 , 0x0 , 0x7 , 0x7 , 0x7 , 0x0 ,
0x6 , 0xD , 0x0 , 0x0 , 0x0 , 0x4 , 0x4 , 0x0 , 0x0 , 0x9 , 0x0 , 0x0 , 0x0 , 0x8 , 0x8 , 0x0 ,
0x0 , 0xC , 0x0 , 0x0 , 0x0 , 0x3 , 0x3 , 0x0 , 0x0 , 0x2 , 0x1 , 0x0 , 0x7 , 0x7 , 0x7 , 0x0 ,
0x6 , 0xD , 0x0 , 0x0 , 0x0 , 0x4 , 0x4 , 0x0 , 0x0 , 0x9 , 0x0 , 0x0 , 0x0 , 0x8 , 0x8 , 0x0 ,
0x0 , 0xC , 0x0 , 0x0 , 0x0 , 0x3 , 0x3 , 0x0 , 0x0 , 0x2 , 0x1 , 0x0 , 0xA , 0x7 , 0x7 , 0x0 ,
0x6 , 0xD , 0x0 , 0x0 , 0x0 , 0x4 , 0x4 , 0x0 , 0x0 , 0x9 , 0x0 , 0x0 , 0x0 , 0x8 , 0x8 , 0x0 ,
0x0 , 0xC , 0x0 , 0x0 , 0x3 , 0x3 , 0x3 , 0x0 , 0x0 , 0x0 , 0x0 , 0x0 , 0x7 , 0x7 , 0x7 , 0x0 ,
0x6 , 0xD , 0x0 , 0x0 , 0x4 , 0x4 , 0x5 , 0x0 , 0x0 , 0x9 , 0x0 , 0x0 , 0x0 , 0x8 , 0x0 , 0x0 ,
0x2 , 0xC , 0x2 , 0x0 , 0x3 , 0x3 , 0x3 , 0x0 , 0x0 , 0x2 , 0x0 , 0x0 , 0x7 , 0x7 , 0x7 , 0x0 ,
0x6 , 0xD , 0x0 , 0x0 , 0x4 , 0x4 , 0x5 , 0x0 , 0x0 , 0x9 , 0x0 , 0x0 , 0x8 , 0x8 , 0x9 , 0x0 ,
0x2 , 0xC , 0x0 , 0x0 , 0x3 , 0x3 , 0x3 , 0x0 , 0x0 , 0x2 , 0x0 , 0x0 , 0x7 , 0x7 , 0x7 , 0x0 ,
0x6 , 0xD , 0x0 , 0x0 , 0x0 , 0x4 , 0x4 , 0x0 , 0x0 , 0x9 , 0x0 , 0x0 , 0x0 , 0x8 , 0x8 , 0x0 ,
0x2 , 0xC , 0x0 , 0x0 , 0x3 , 0x3 , 0x3 , 0x0 , 0x0 , 0x2 , 0x0 , 0x0 , 0x7 , 0x7 , 0x7 , 0x0 ,
0x6 , 0xD , 0x0 , 0x0 , 0x0 , 0x4 , 0x4 , 0x0 , 0x0 , 0x9 , 0x0 , 0x0 , 0x0 , 0x8 , 0x8 , 0x0
};
void dasm(uint16_t address) {
uint8_t op = readMem(address);
uint8_t b1 = readMem((address + 1) & 0xFFFF);
uint8_t b2 = readMem((address + 2) & 0xFFFF);
printf("%04X %02X ", address, op);
switch(am[op]) {
case 0x0: printf(" %s ", mn[op] ); break; // implied
case 0x1: printf(" %s A ", mn[op] ); break; // accumulator
case 0x2: printf("%02X %s #$%02X ", b1, mn[op],b1 ); break; // immediate
case 0x3: printf("%02X %s $%02X ", b1, mn[op],b1 ); break; // zero page
case 0x4: printf("%02X %s $%02X,X ", b1, mn[op],b1 ); break; // zero page, X indexed
case 0x5: printf("%02X %s $%02X,Y ", b1, mn[op],b1 ); break; // zero page, Y indexed
case 0x6: printf("%02X %s $%02X ", b1, mn[op],b1 ); break; // relative
case 0xC: printf("%02X %s ($%02X,X) ", b1, mn[op],b1 ); break; // X indexed, indirect
case 0xD: printf("%02X %s ($%02X),Y ", b1, mn[op],b1 ); break; // indirect, Y indexed
case 0x7: printf("%02X%02X %s $%02X%02X ",b1,b2,mn[op],b2,b1); break; // absolute
case 0x8: printf("%02X%02X %s $%02X%02X,X ",b1,b2,mn[op],b2,b1); break; // absolute, X indexed
case 0x9: printf("%02X%02X %s $%02X%02X,Y ",b1,b2,mn[op],b2,b1); break; // absolute, Y indexed
case 0xA: printf("%02X%02X %s ($%02X%02X) ",b1,b2,mn[op],b2,b1); break; // indirect
}
}
void printRegs() {
printf("A=%02X X=%02X Y=%02X S=%02X *S=%02X %c%c%c%c%c%c%c%c", \
reg.A, reg.X, reg.Y, reg.SP, readMem(0x100 + reg.SP), \
reg.SR&SIGN?'N':'-', reg.SR&OFLOW?'V':'-',reg.SR&UNDEF?'U':'.',reg.SR&BREAK?'B':'-', \
reg.SR&DECIM?'D':'-',reg.SR&INTR?'I':'-', reg.SR&ZERO?'Z':'-', reg.SR&CARRY?'C':'-');
}
void setPC(uint16_t address) {
reg.PC = address;
}
uint16_t getPC(){
return reg.PC;
}
#if _FUNCTIONNAL_TESTS
// 6502 functonnal tests
// using Klaus Dormann's functonnal tests published at :
// https://github.com/Klaus2m5/6502_65C02_functional_tests
int main(int argc, char* argv[]){
char *filename = "6502_functional_test.bin";
FILE *f = fopen(filename, "rb");
if (!f || fread(RAM, 1, 65536, f) != 65536) {
printf("ERROR : can't load %s\n", filename);
return(0);
}
fclose(f);
puce6502RST(); // reset the CPU
reg.PC = 0x0400; // set Program Counter to start of code
unsigned long long int oldticks = ticks;
uint16_t oldPC = 0x0400, newPC = 0x0400; // to detect the BNE $FE when an error occurs
while(1) {
dasm(newPC);
printf(" ");
newPC = puce6502Exec(1);
printRegs();
printf(" Cycles: %llu Total: %llu\n", ticks - oldticks, ticks);
oldticks = ticks;
if (newPC == 0x3469){ // 6502_functional_test SUCCESS
printf("\nReached end of 6502_functional_test @ 0x3469 : SUCCESS !\n");
break;
}
if (newPC == oldPC ) {
printf("\n\nLoop detected @ %04X - Press ENTER to proceed with next test or CTRL<C> to stop\n\n", newPC);
getchar();
reg.PC = newPC + 2;
}
oldPC = newPC;
}
return(0);
}
#endif
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