88 lines
2.7 KiB
C
88 lines
2.7 KiB
C
#include "file.h"
|
|
|
|
#define SIZE_NES_HEADER 16
|
|
#define SIZE_PRG_BANK 16384
|
|
#define SIZE_CHR_BANK 8192
|
|
|
|
int detect_file( rom_image *rom_info, char *filename )
|
|
{
|
|
int rv = 0;
|
|
// int index = 0;
|
|
FILE *fileptr = NULL;
|
|
//warn uint8_t data[128];
|
|
|
|
//first open file
|
|
fileptr = fopen( filename, "rb");
|
|
//returns file ptr on success, NULL on fail
|
|
check( fileptr, "Unable to open file: %s in read binary mode", filename);
|
|
|
|
//then determine file type
|
|
uint8_t header[SIZE_NES_HEADER];
|
|
//size_t fread(void *ptr, size_t size, size_t nmemb, FILE *stream);
|
|
rv = fread( header, sizeof(header[0]), (sizeof(header)/sizeof(header[0])), fileptr);
|
|
check( rv = sizeof(header), "Unable to read NES header");
|
|
|
|
//for ( index = 0; index < SIZE_NES_HEADER; index++ ) {
|
|
// debug("header byte #%d = h%x c%c", index, header[index], header[index]);
|
|
//}
|
|
|
|
//0-3: Constant $4E $45 $53 $1A ("NES" followed by MS-DOS end-of-file)
|
|
if ( (header[0]=='N') && (header[1]=='E') && (header[2]=='S') && (header[3]==0x1A) ) {
|
|
debug("detected ines header");
|
|
rom_info->console = NES_CART;
|
|
} else {
|
|
debug("only ines files currently accepted as input");
|
|
goto error;
|
|
}
|
|
|
|
//4: Size of PRG ROM in 16 KB units
|
|
rom_info->prg_size = header[4] * SIZE_PRG_BANK;
|
|
debug("PRG ROM size= %d", rom_info->prg_size);
|
|
|
|
//5: Size of CHR ROM in 8 KB units (Value 0 means the board uses CHR RAM)
|
|
rom_info->chr_size = header[5] * SIZE_CHR_BANK;
|
|
debug("CHR ROM size= %d", rom_info->chr_size);
|
|
|
|
//6: Flags 6
|
|
// 76543210
|
|
// ||||||||
|
|
// ||||+||+- 0xx0: vertical arrangement/horizontal mirroring (CIRAM A10 = PPU A11)
|
|
// |||| || 0xx1: horizontal arrangement/vertical mirroring (CIRAM A10 = PPU A10)
|
|
// |||| || 1xxx: four-screen VRAM
|
|
// |||| |+-- 1: Cartridge contains battery-backed PRG RAM ($6000-7FFF) or other persistent memory
|
|
// |||| +--- 1: 512-byte trainer at $7000-$71FF (stored before PRG data)
|
|
// ++++----- Lower nybble of mapper number
|
|
rom_info->mapper = (header[6]>>4);
|
|
rom_info->mapper |= (header[7] & 0xF0);
|
|
debug("mapper #%d", rom_info->mapper);
|
|
rom_info->mirroring = header[6] & 0x09; //0b0000 1001
|
|
debug("mirroring:%x", rom_info->mirroring);
|
|
//7: Flags 7
|
|
// 76543210
|
|
// ||||||||
|
|
// |||||||+- VS Unisystem
|
|
// ||||||+-- PlayChoice-10 (8KB of Hint Screen data stored after CHR data)
|
|
// ||||++--- If equal to 2, flags 8-15 are in NES 2.0 format
|
|
// ++++----- Upper nybble of mapper number
|
|
|
|
//8: Size of PRG RAM in 8 KB units (Value 0 infers 8 KB for compatibility; see PRG RAM circuit)
|
|
//9: Flags 9
|
|
//10: Flags 10 (unofficial)
|
|
//11-15: Zero filled
|
|
|
|
//close file
|
|
check( fclose(fileptr) == SUCCESS, "Unable to close file");
|
|
fileptr = NULL;
|
|
|
|
return 0;
|
|
|
|
error:
|
|
|
|
if (fileptr) {
|
|
fclose(fileptr);
|
|
}
|
|
|
|
return -1;
|
|
|
|
}
|