117 lines
2.4 KiB
C
117 lines
2.4 KiB
C
//
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// Created by william on 10/15/23.
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//
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#ifndef CPU_CPU_H
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#define CPU_CPU_H
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#include <stdbool.h>
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#include "memory.h"
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// Reference: https://www.nesdev.org/wiki/Status_flags
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#define CPU_STATUS_CARRY_MASK 0x01
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#define CPU_STATUS_ZERO_MASK 0x02
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#define CPU_STATUS_INTERRUPT_DISABLE_MASK 0x04
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#define CPU_STATUS_DECIMAL_MASK 0x08
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#define CPU_STATUS_B_MASK 0x10
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#define CPU_STATUS_OVERFLOW_MASK 0x40
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#define CPU_STATUS_NEGATIVE_MASK 0x80
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#define CPU_STACK_ADDR 0x0100
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// Reference: https://www.nesdev.org/obelisk-6502-guide/registers.html
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typedef struct cpu {
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address program_counter;
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byte stack_pointer;
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byte accumulator;
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byte x;
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byte y;
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byte status;
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bool oam_dma_triggered;
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bool nmi_requested;
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unsigned int busy_cycle_count;
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} CPU;
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CPU *cpu_get_state();
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/**
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* Gets a flag from the CPU registers.
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*
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* @param system The system
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* @param mask The flag mask
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* @return The value of the flag.
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*/
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bool cpu_get_flag(byte mask);
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/**
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* Sets a flag in the CPU registers.
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*
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* @param system The system
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* @param mask The flag mask
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* @param set If the flag is set or not
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*/
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void cpu_set_flag(byte mask, bool set);
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/**
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* Gets the next byte in the program.
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* Increases the system program counter.
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*
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* @param system The system
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* @return The value of the next byte.
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*/
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byte cpu_get_next_byte();
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/**
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* Gets the next word in the program.
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* Increases the system program counter by 2.
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*
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* @param system The system
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* @return The value of the next word.
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*/
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word cpu_get_next_word();
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/**
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* Pushes a byte in to the stack.
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*
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* @param system The system
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* @param value The value to push to the stack
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*/
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void cpu_stack_push(byte value);
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/**
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* Pushes the execution context to the stack.
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* This includes the program counter and the CPU status.
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*
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* @param system The system
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*/
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void cpu_stack_push_context();
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/**
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* Pops a byte from the stack.
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*
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* @param system The system
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* @return The value of the byte
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*/
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byte cpu_stack_pop();
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/**
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* Pops an execution context from the stack and overwrite the current context.
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* This includes the program counter and the CPU status.
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*
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* @param system The system
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*/
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void cpu_stack_pop_context();
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/**
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* Adds wait cycles to the CPU.
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*
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* @param cycle_count The number of cycle to wait
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*/
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void cpu_add_cycles(unsigned int cycle_count);
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void cpu_trigger_oam_dma();
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void cpu_trigger_nmi();
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#endif //CPU_CPU_H
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