262 lines
6.5 KiB
C++
262 lines
6.5 KiB
C++
//
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// Created by Palindromic Bread Loaf on 7/21/25.
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//
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#ifndef CPU_H
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#define CPU_H
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#include "bus.h"
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// 65816 CPU implementation
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class CPU {
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// Registers
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uint16_t A; // Accumulator
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uint16_t X, Y; // Index registers
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uint16_t SP; // Stack pointer
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uint32_t PC; // Program counter (24-bit)
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uint8_t P; // Processor status
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uint8_t DB; // Data bank
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uint8_t PB; // Program bank
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uint16_t D; // Direct page
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Bus* bus;
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uint64_t cycles;
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bool emulation_mode = false;
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// Status flags
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enum Flags {
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FLAG_C = 0x01, // Carry
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FLAG_Z = 0x02, // Zero
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FLAG_I = 0x04, // IRQ disable
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FLAG_D = 0x08, // Decimal mode
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FLAG_X = 0x10, // Index register size (0=16-bit, 1=8-bit)
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FLAG_M = 0x20, // Memory/Accumulator size (0=16-bit, 1=8-bit)
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FLAG_V = 0x40, // Overflow
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FLAG_N = 0x80 // Negative
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// FLAG_E = ??? // 6502 Emulation Mode
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// FLAG_B = 0x10 //Break
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};
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public:
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explicit CPU(Bus* memory_bus) : bus(memory_bus) {
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Reset();
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}
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void Reset();
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void Step();
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void ExecuteInstruction();
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[[nodiscard]] uint64_t GetCycles() const { return cycles; }
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// Addressing mode helpers
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//uint32_t GetEffectiveAddress(uint8_t mode);
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uint8_t ReadByte(uint32_t address);
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uint16_t ReadWord(uint32_t address);
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void UpdateNZ8(uint8_t value);
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void UpdateNZ16(uint16_t value);
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// Memory write helpers
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void WriteByte(uint32_t address, uint8_t value) const;
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void WriteWord(uint32_t address, uint16_t value) const;
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// Helper methods for compare operations
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void UpdateCompareFlags8(uint8_t reg_value, uint8_t compare_value);
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void UpdateCompareFlags16(uint16_t reg_value, uint16_t compare_value);
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// Branching helper method
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void DoBranch(bool condition);
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// Helper methods for stack operations
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void PushByte(uint8_t value);
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void PushWord(uint16_t value);
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uint8_t PopByte();
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uint16_t PopWord();
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// Helper method for ADC instructions
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void DoADC(uint16_t value);
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// Helper method to check for decimal mode adjustment
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static uint16_t AdjustDecimal(uint16_t binary_result, bool is_16bit);
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// Helper methods for ASL stuff
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void UpdateASLFlags8(uint8_t original_value, uint8_t result);
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void UpdateASLFlags16(uint16_t original_value, uint16_t result);
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// Helper methods for BIT
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void UpdateBITFlags8(uint8_t memory_value, uint8_t acc_value);
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void UpdateBITFlags16(uint16_t memory_value, uint16_t acc_value);
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void UpdateBITImmediateFlags8(uint8_t memory_value, uint8_t acc_value);
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void UpdateBITImmediateFlags16(uint16_t memory_value, uint16_t acc_value);
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// Instruction implementations
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// TODO: Implement remaining instructions
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void CMP_Immediate();
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void CMP_Absolute();
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void CMP_AbsoluteX();
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void CMP_AbsoluteY();
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void CMP_DirectPage();
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void CMP_DirectPageX();
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void CMP_IndirectDirectPage();
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void CMP_IndirectDirectPageY();
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void CMP_DirectPageIndirectX();
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void CMP_Long();
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void CMP_LongX();
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void CPX_Immediate();
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void CPX_Absolute();
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void CPX_DirectPage();
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void CPY_Immediate();
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void CPY_Absolute();
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void CPY_DirectPage();
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static void NOP();
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void LDA_Immediate();
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void LDA_Absolute();
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void LDA_AbsoluteX();
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void LDA_AbsoluteY();
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void LDA_DirectPage();
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void LDA_DirectPageX();
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void LDA_IndirectDirectPage();
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void LDA_IndirectDirectPageY();
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void LDA_DirectPageIndirectX();
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void LDA_Long();
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void LDA_LongX();
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void LDX_Immediate();
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void LDX_Absolute();
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void LDX_AbsoluteY();
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void LDX_DirectPage();
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void LDX_DirectPageY();
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void LDY_Immediate();
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void LDY_Absolute();
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void LDY_AbsoluteX();
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void LDY_DirectPage();
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void LDY_DirectPageX();
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void STA_Absolute();
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void STA_AbsoluteX();
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void STA_AbsoluteY();
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void STA_DirectPage();
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void STA_DirectPageX();
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void STA_IndirectDirectPage();
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void STA_IndirectDirectPageY();
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void STA_DirectPageIndirectX();
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void STA_Long();
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void STA_LongX();
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void STX_Absolute();
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void STX_DirectPage();
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void STX_DirectPageY();
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void STY_Absolute();
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void STY_DirectPage();
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void STY_DirectPageX();
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void INC_Accumulator();
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void INC_Absolute();
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void INC_AbsoluteX();
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void INC_DirectPage();
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void INC_DirectPageX();
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void DEC_Accumulator();
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void DEC_Absolute();
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void DEC_AbsoluteX();
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void DEC_DirectPage();
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void DEC_DirectPageX();
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void INX();
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void INY();
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void DEX();
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void DEY();
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void JMP_Absolute();
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void JMP_AbsoluteIndirect();
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void JMP_AbsoluteLong();
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void JMP_AbsoluteIndirectX();
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void BEQ_Relative();
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void BNE_Relative();
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void BCC_Relative();
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void BCS_Relative();
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void BMI_Relative();
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void BPL_Relative();
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void JSR_Absolute();
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void JSR_AbsoluteLong();
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void JSR_AbsoluteIndirectX();
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void RTS();
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void RTL();
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void PHA();
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void PLA();
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void PHX();
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void PLX();
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void PHY();
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void PLY();
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void PHP();
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void PLP();
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void PHB();
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void PLB();
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void PHD();
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void PLD();
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void PHK();
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void ADC_Immediate();
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void ADC_Absolute();
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void ADC_AbsoluteX();
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void ADC_AbsoluteY();
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void ADC_DirectPage();
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void ADC_DirectPageX();
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void ADC_IndirectDirectPage();
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void ADC_IndirectDirectPageY();
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void ADC_DirectPageIndirectX();
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void ADC_AbsoluteLong();
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void ADC_AbsoluteLongX();
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void ADC_DirectPageIndirectLong();
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void ADC_DirectPageIndirectLongY();
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void ADC_StackRelative();
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void ADC_StackRelativeIndirectY();
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void AND_Immediate();
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void AND_Absolute();
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void AND_AbsoluteX();
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void AND_AbsoluteY();
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void AND_DirectPage();
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void AND_DirectPageX();
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void AND_IndirectDirectPage();
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void AND_IndirectDirectPageLong();
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void AND_IndexedIndirectDirectPageX();
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void AND_IndirectDirectPageY();
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void AND_IndirectDirectPageLongY();
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void AND_AbsoluteLong();
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void AND_AbsoluteLongX();
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void AND_StackRelative();
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void AND_StackRelativeIndirectY();
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void ASL_Accumulator();
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void ASL_Absolute();
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void ASL_AbsoluteX();
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void ASL_DirectPage();
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void ASL_DirectPageX();
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void BIT_Immediate();
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void BIT_Absolute();
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void BIT_AbsoluteX();
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void BIT_DirectPage();
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void BIT_DirectPageX();
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void BRA_Relative();
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void BRL_RelativeLong();
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void BVC_Relative();
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void BVS_Relative();
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void BRK();
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void CLC();
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void CLD();
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void CLI();
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void CLV();
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};
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#endif //CPU_H
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