nese/src/cart.c

#include "cart.h"
#include "filemap.h"
#include "ines.h"
#include "mapper.h"
#include "save.h"


int nes_cart_init_mem(nes_cart* cart, void* mem, int len) {
    int status = 0;
    ines_Header *hdr = (ines_Header*)mem;
    void* ptr = &hdr[1];

    cart->ines_mem  = mem;
    cart->ines_size = len;

    status = ines_check_mem(hdr);

    if (0 == status && (hdr->flags_6 & ines_Flag_Trainer)) {
        // Skip trainer
        ptr += ines_trainer_size;
    }

    if (0 == status) {
        int prg_size = nes_prg_rom_page_size * hdr->prg_size_lsb;
        if (prg_size <= 0) {
            INES_ERR("Bad program ROM size: %#x", prg_size);
            status = -1;
        } else {
            INES_INFO("%d KB PRG ROM", prg_size / 1024);
            cart->prg_rom = ptr;
            cart->prg_rom_banks = hdr->prg_size_lsb;
        }
        ptr += prg_size;
    }

    if (0 == status) {
        int chr_size = nes_chr_page_size * hdr->chr_size_lsb;
        INES_INFO("%d KB CHR ROM", chr_size / 1024);
        cart->chr_rom = ptr;
        cart->chr_rom_banks = hdr->chr_size_lsb * 2;
        ptr += chr_size;

        int index = (hdr->flags_6 & ines_Mapper_Nibble_Lo) >> 4 |
                    (hdr->flags_7 & ines_Mapper_Nibble_Hi);
        cart->mapper = nes_mappers[index];
        if (NULL == cart->mapper) {
            INES_ERR("No mapper found for type %d", index);
            status = -1;
        } else if (NULL != cart->mapper->name) {
            INES_INFO("Mapper: %s", cart->mapper->name);
        }
    }

    if (0 == status) {
        if (hdr->flags_6 & ines_Flag_Horizontal) {
            cart->flags |= Cart_Flag_Horizontal;
        } else {
            cart->flags &= ~Cart_Flag_Horizontal;
        }

        if (hdr->flags_6 & ines_Flag_Battery) {
            cart->flags |= Cart_Flag_Battery;
        }

        // Don't initialize the mapper until all flags are set!
        status = nes_map_init(cart->mapper, cart);
    }

    return status;
}

void nes_cart_done(nes_cart* cart) {
    if (NULL != cart->ines_mem) {
        unmap_file(cart->ines_mem, cart->ines_size);
        cart->ines_mem = NULL;
    }
}

int nes_cart_init_file(nes_cart* cart, FILE* file) {
    int status = 0;
    int size = -1;
    void* mem = NULL;

    // Get file size
    status = fseek(file, 0, SEEK_END);
    if (0 != status) {
        INES_ERR("Failed to check file size");
    } else {
        size = ftell(file);
    }

    // Map file
    if (0 == status) {
        mem = map_file(file, size, Filemap_Mode_Read);
        if (NULL == mem) {
            INES_ERR("Failed to map file (%d bytes)", size);
            status = -1;
        }
    }

    // Check in memory; unmap on failure
    if (0 == status) {
        status = nes_cart_init_mem(cart, mem, size);
        if (0 != status) {
            unmap_file(file, size);
        }
    }

    return status;
}


FILE* nes_load_cart(nes_cart* cart, const char* cart_filename) {
    int status = 0;

    FILE* cart_file = fopen(cart_filename, "rb");
    if (NULL == cart_file) {
        status = -1;
        fprintf(stderr, "Could not open %s\n", cart_filename);
    }

    if (status == 0) {
        status = nes_cart_init_file(cart, cart_file);
    }

    if (status == 0) {
        // Failure might mean there's nothing to load
        load_sram(cart, cart_filename);
    }

    if (status != 0 && NULL != cart_file) {
        fclose(cart_file);
        cart_file = NULL;
    }

    return cart_file;
}