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#include <archive.h>
#include <archive_entry.h>
// iNES header fields
#define INES_HEADER_SIZE 16
#define INES_PRG_SIZE_LSB 4
#define INES_CHR_SIZE_LSB 5
#define INES_FLAGS6 6
#define INES_FLAGS7 7
#define INES_PRG_CHR_MSB 9
#define INES_CHR_EXP 8
#define INES_PRG_EXP 9
// Size units
#define PRG_ROM_UNIT 16384
#define CHR_ROM_UNIT 8192
#define TRAINER_SIZE 512
// Flag masks
#define FLAG6_TRAINER 0x04
#define FLAG6_FOUR_SCREEN 0x08
#define FLAG6_VERTICAL_MIRROR 0x01
// Mirroring modes
#define MIRROR_HORIZONTAL 0
#define MIRROR_VERTICAL 1
#define MIRROR_FOUR_SCREEN 2
static uint8_t *ines2_read_entire_file(const char *path, size_t *out_size) {
FILE *f = fopen(path, "rb");
if(!f) return 0;
fseek(f, 0, SEEK_END);
size_t size = ftell(f);
fseek(f, 0, SEEK_SET);
uint8_t *buffer = (uint8_t *)malloc(size);
size_t read_size = fread(buffer, 1, size, f);
fclose(f);
if(read_size != size) {
free(buffer);
return 0;
}
*out_size = size;
return buffer;
}
uint8_t *ines2_unzip_file_to_memory(const char *zip_path, size_t *out_size) {
struct archive *a = archive_read_new();
struct archive_entry *entry;
uint8_t *buffer = 0;
size_t size = 0;
archive_read_support_format_zip(a);
if(archive_read_open_filename(a, zip_path, 10240) != ARCHIVE_OK) {
fprintf(stderr, "libarchive: failed to open zip: %s\n", archive_error_string(a));
archive_read_free(a);
return 0;
}
if(archive_read_next_header(a, &entry) != ARCHIVE_OK) {
fprintf(stderr, "libarchive: no valid file found in zip\n");
archive_read_free(a);
return 0;
}
const char *name = archive_entry_pathname(entry);
size = archive_entry_size(entry);
buffer = (uint8_t*)malloc(size);
if(!buffer) {
fprintf(stderr, "libarchive: malloc failed\n");
archive_read_free(a);
return 0;
}
ssize_t read_size = archive_read_data(a, buffer, size);
if(read_size != (ssize_t)size) {
fprintf(stderr, "libarchive: failed to read full file\n");
free(buffer);
buffer = 0;
}
archive_read_free(a);
if(buffer && out_size) {
*out_size = size;
}
return buffer;
}
static int ines2_load(struct nes_state *state, const char *path) {
uint8_t *data = 0;
size_t size = 0;
if(strstr(path, ".zip")) {
data = ines2_unzip_file_to_memory(path, &size);
} else {
data = ines2_read_entire_file(path, &size);
}
if(!data || size < INES_HEADER_SIZE) {
free(data);
return -1;
}
uint8_t *ptr = data;
uint8_t *header = ptr; ptr += INES_HEADER_SIZE;
uint8_t prg_lsb = header[INES_PRG_SIZE_LSB];
uint8_t chr_lsb = header[INES_CHR_SIZE_LSB];
uint8_t prg_msb = header[INES_PRG_CHR_MSB] & 0x0f;
uint8_t chr_msb = (header[INES_PRG_CHR_MSB] & 0xf0) >> 4;
uint32_t prg_size = (prg_msb << 8 | prg_lsb) * PRG_ROM_UNIT;
uint32_t chr_size = (chr_msb << 8 | chr_lsb) * CHR_ROM_UNIT;
if(prg_lsb == 0x0f) prg_size = 1 << header[INES_PRG_EXP];
if(chr_lsb == 0x0f) chr_size = 1 << header[INES_CHR_EXP];
uint8_t mapper_low = (header[INES_FLAGS6] >> 4);
uint8_t mapper_high = (header[INES_FLAGS7] & 0xf0);
uint8_t mapper_ext = (header[INES_PRG_CHR_MSB] & 0x0f);
uint8_t mapper_upper = header[8] & 0x0f;
uint8_t submapper = (header[8] >> 4);
state->ines.mapper = mapper_low | mapper_high | (mapper_upper << 8);
state->ines.submapper = submapper;
if(header[INES_FLAGS6] & FLAG6_FOUR_SCREEN) {
state->ines.mirroring = MIRROR_FOUR_SCREEN;
} else if(header[INES_FLAGS6] & FLAG6_VERTICAL_MIRROR) {
state->ines.mirroring = MIRROR_VERTICAL;
} else {
state->ines.mirroring = MIRROR_HORIZONTAL;
}
state->ines.prg_size = prg_size;
state->ines.chr_size = chr_size;
if(header[INES_FLAGS6] & FLAG6_TRAINER) {
ptr += TRAINER_SIZE;
}
memcpy(state->prg_rom, ptr, prg_size);
ptr += prg_size;
if(chr_size > 0) {
memcpy(state->chr_rom, ptr, chr_size);
}
free(data);
return 0;
}
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