57 lines
1.3 KiB
C
57 lines
1.3 KiB
C
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#include <stdint.h>
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#include <stdio.h>
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#include <stdlib.h>
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#include <string.h>
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#include "rom.h"
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void
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parse_rom(const uint8_t *data, size_t data_len, struct Rom *rom)
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{
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size_t prg_rom_offset = 16;
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size_t chr_rom_offset = 0;
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if (data_len < 16) {
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fprintf(stderr, "Invalid ROM: size less than 16 bytes\n");
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exit(1);
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}
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if (data[0] != 'N' || data[1] != 'E' || data[2] != 'S' || data[3] != 0x1A) {
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fprintf(stderr, "Invalid ROM: not in iNES format\n");
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exit(1);
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}
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/* trainer data present */
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if (data[6] & (1 << 2))
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prg_rom_offset += 512;
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rom->prg_rom_size = data[4] * 0x4000;
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rom->prg_rom = calloc(rom->prg_rom_size, 1);
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memcpy(rom->prg_rom, data + prg_rom_offset, rom->prg_rom_size);
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rom->chr_rom_size = data[5] * 0x2000;
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if (rom->chr_rom_size > 0) {
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rom->chr_rom = calloc(rom->chr_rom_size, 1);
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chr_rom_offset = prg_rom_offset + rom->prg_rom_size;
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memcpy(rom->chr_rom, data + chr_rom_offset, rom->chr_rom_size);
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}
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if ((data[6] & (1 << 3)) != 0)
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rom->mirror = M_FOUR;
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else if ((data[6] & 1) == 1)
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rom->mirror = M_VERTICAL;
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else if ((data[6] & 1) == 0)
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rom->mirror = M_HORIZONTAL;
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rom->mapper = (data[6] & (0xF << 4)) >> 4;
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rom->mapper |= data[7] & (0xF << 4);
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}
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void
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free_rom(struct Rom *rom)
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{
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free(rom->prg_rom);
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if (rom->chr_rom_size > 0)
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free(rom->chr_rom);
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}
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