nesemu/rom/rom.c

//
// Created by william on 12/2/23.
//

#include <stdio.h>
#include <stdlib.h>
#include <assert.h>

#include "../include/rom.h"
#include "ines.c"

#define ARRAY_SIZE(arr) (sizeof(arr) / sizeof((arr)[0]))

Rom rom;

void rom_init() {
    rom.header = NULL;
    rom.prg_rom = NULL;
    rom.chr_rom = NULL;
}

int rom_load(char *path) {
    rom_init();

    FILE *file = fopen(path, "r");
    if (!file) {
        log_error("Failed to open ROM");
        return EXIT_FAILURE;
    }

    char header_buffer[ROM_HEADER_SIZE] = {0};
    size_t read_size = fread(header_buffer, sizeof(char), ARRAY_SIZE(header_buffer), file);
    if (read_size < ARRAY_SIZE(header_buffer)) {
        log_error("Failed to read ROM");
        return EXIT_FAILURE;
    }

    if (!rom_is_ines(header_buffer)) {
        log_error("Only iNes ROMs are supported");
        return EXIT_FAILURE;
    }

    log_info("Reading iNes 1.0 ROM at %s", path);
    rom_ines_read(header_buffer, file, &rom);

    if (fclose(file) != 0) {
        log_error("Failed to close ROM file");
        return EXIT_FAILURE;
    }

    return 0;
}

void rom_uninit() {
    assert(rom.prg_rom != NULL);
    assert(rom.chr_rom != NULL);

    free(rom.prg_rom);
    free(rom.chr_rom);
    
    log_info("Cleared ROM data");
}

byte rom_prg_get_byte(address addr) {
    assert(rom.prg_rom != NULL);

    return rom.prg_rom[addr];
}

word rom_prg_get_word(address addr) {
    assert(rom.prg_rom != NULL);

    word word = rom.prg_rom[addr];
    word += rom.prg_rom[addr + 1] << 8;    // Little endian
    return word;
}