Get NES mapper

get_mapper.c

#include <stdio.h>
#include <stdint.h>

#define HEADER_SIZE 16

int IsNES20(uint8_t* header)
{
    return (header[7] & 0x0C) == 0x08;
}

unsigned GetMapper(uint8_t* header)
{
    unsigned mapper = 0;
    mapper = (header[7] & 0xF0) | ((header[6] & 0xF0) >> 4);
    if (IsNES20(header)) {
        mapper |= (header[8] & 0x0F) << 8;
    }
    return mapper;
}

unsigned GetSubmapper(uint8_t* header)
{
    unsigned submapper = 0xFF;
    if (IsNES20(header)) {
        submapper = (header[8] & 0xF0) >> 4;
    }
    return submapper;
}

int main(int argc, char* argv[])
{
    if (argc != 2) {
        return 1;
    }

    FILE* fp = NULL;
    fp = fopen(argv[1], "rb");
    if (fp == NULL) {
        return 2;
    }
    uint8_t header[HEADER_SIZE] = {};
    if (fread(header, sizeof(uint8_t), HEADER_SIZE, fp) != HEADER_SIZE) {
        fclose(fp);
        return 3;
    }
    fclose(fp);

    printf("Mapper: %u", GetMapper(header));
    if (IsNES20(header)) {
        printf("\nSubmapper: %u", GetSubmapper(header));
    }
    return 0;
}

get_mapper.py

#!/usr/bin/env python3
# -*- coding: utf-8 -*-

import sys

def get_mapper(header):
    mapper = (header[7] & 0xF0) | ((header[6] & 0xF0) >> 4)
    if (header[7] & 0x0C) == 0x08:
        mapper |= (header[8] & 0x0F) << 8
    return mapper

if __name__ == '__main__':
    if len(sys.argv) > 1:
        with open(sys.argv[1], "rb") as f:
            print(get_mapper(f.read(16)))
        input("Press any key...")