nesemu/system.c

//
// Created by william on 12/23/23.
//

#include "include/cpu.h"
#include "include/system.h"
#include "memory.h"
#include <unistd.h>
#include <assert.h>
#include "cpu.h"

System current_sys;

void system_init() {
    byte *registers_base_addr = mem_get_ptr(PPU_REGISTERS_BASE_ADDR);
    byte *oam_dma_register = mem_get_ptr(PPU_REGISTER_OAM_DMA_ADDR);

    cpu_init();
    ppu_init(registers_base_addr, oam_dma_register);

    current_sys.mapper = get_mapper(MAPPER_TYPE_SIMPLE);
    current_sys.cycle_count = 7;
}

void system_start() {
    address pc = mem_get_word(0xfffc);
    cpu_get_state()->program_counter = pc;
}

void system_loop() {
    assert(CPU_CLOCK_DIVISOR > PPU_CLOCK_DIVISOR);

    unsigned int master_cycle_per_frame = MASTER_CLOCK / FRAME_RATE;
    unsigned int cpu_cycle_per_frame = master_cycle_per_frame / CPU_CLOCK_DIVISOR;
    unsigned int ppu_cycle_per_cpu_cycle = CPU_CLOCK_DIVISOR / PPU_CLOCK_DIVISOR;

    long frame = 1;
    long cpu_cycle_count = 0;
    while (true) {
//        log_info("Frame %d", frame);

        while (current_sys.cycle_count < cpu_cycle_per_frame * frame) {
            if (cpu_cycle_count == current_sys.cycle_count) {
                cpu_cycle();
            }
            cpu_cycle_count++;

            for (int ppu_c = 0; ppu_c < ppu_cycle_per_cpu_cycle; ppu_c++) {
                ppu_cycle();
            }
        }

        frame++;
        usleep(17000); // Wait 16.6666ms
    }
}

void system_uninit() {
}

unsigned int system_get_cycles() {
    return current_sys.cycle_count;
}

void system_add_cycles(unsigned int cycles) {
    current_sys.cycle_count += cycles;
}

Mapper *system_get_mapper() {
    return &current_sys.mapper;
}