nesemu/cpu/cpu.h

//
// Created by william on 10/15/23.
//

#ifndef CPU_CPU_H
#define CPU_CPU_H

#include <stdbool.h>
#include "memory.h"

// Reference: https://www.nesdev.org/wiki/Status_flags
#define CPU_STATUS_CARRY_MASK 0x01
#define CPU_STATUS_ZERO_MASK 0x02
#define CPU_STATUS_INTERRUPT_DISABLE_MASK 0x04
#define CPU_STATUS_DECIMAL_MASK 0x08
#define CPU_STATUS_B_MASK 0x10
#define CPU_STATUS_OVERFLOW_MASK 0x40
#define CPU_STATUS_NEGATIVE_MASK 0x80

#define CPU_STACK_ADDR 0x0100

/**
 * Gets a flag from the CPU registers.
 * 
 * @param system The system
 * @param mask The flag mask
 * @return The value of the flag.
 */
bool system_get_flag(System *system, byte mask);

static inline bool cpu_get_flag(CPU *cpu, byte mask) {
    return cpu->status & mask;
}

/**
 * Sets a flag in the CPU registers.
 * 
 * @param system The system
 * @param mask The flag mask
 * @param set If the flag is set or not
 */
void system_set_flag(System *system, byte mask, bool set);

/**
 * Gets the next byte in the program.
 * Increases the system program counter.
 * 
 * @param system The system 
 * @return The value of the next byte.
 */
byte cpu_get_next_byte(System *system);

/**
 * Gets the next word in the program.
 * Increases the system program counter by 2.
 * 
 * @param system The system
 * @return The value of the next word.
 */
word cpu_get_next_word(System *system);

/**
 * Pushes a byte in to the stack.
 * 
 * @param system The system 
 * @param value The value to push to the stack
 */
void cpu_stack_push(System *system, byte value);

/**
 * Pushes the execution context to the stack.
 * This includes the program counter and the CPU status.
 * 
 * @param system The system
 */
void cpu_stack_push_context(System *system);

/**
 * Pops a byte from the stack.
 * 
 * @param system The system 
 * @return The value of the byte
 */
byte cpu_stack_pop(System *system);

/**
 * Pops an execution context from the stack and overwrite the current context.
 * This includes the program counter and the CPU status.
 * 
 * @param system The system 
 */
void cpu_stack_pop_context(System *system);

/**
 * Adds wait cycles to the CPU.
 * 
 * @param cycle_count The number of cycle to wait 
 */
void cpu_add_cycles(System *system, unsigned int cycle_count);

#endif //CPU_CPU_H