ref: 2c4de3dc497a89027aed78548436e64c3631499e
dir: /snes/snes_other.c/
#include <stdio.h>
#include <stdlib.h>
#include <string.h>
#include <stdint.h>
#include <stdbool.h>
#include "snes.h"
#include "cart.h"
#include "ppu.h"
#include "dsp.h"
typedef struct CartHeader {
// normal header
uint8_t headerVersion; // 1, 2, 3
char name[22]; // $ffc0-$ffd4 (max 21 bytes + \0), $ffd4=$00: header V2
uint8_t speed; // $ffd5.7-4 (always 2 or 3)
uint8_t type; // $ffd5.3-0
uint8_t coprocessor; // $ffd6.7-4
uint8_t chips; // $ffd6.3-0
uint32_t romSize; // $ffd7 (0x400 << x)
uint32_t ramSize; // $ffd8 (0x400 << x)
uint8_t region; // $ffd9 (also NTSC/PAL)
uint8_t maker; // $ffda ($33: header V3)
uint8_t version; // $ffdb
uint16_t checksumComplement; // $ffdc,$ffdd
uint16_t checksum; // $ffde,$ffdf
// v2/v3 (v2 only exCoprocessor)
char makerCode[3]; // $ffb0,$ffb1: (2 chars + \0)
char gameCode[5]; // $ffb2-$ffb5: (4 chars + \0)
uint32_t flashSize; // $ffbc (0x400 << x)
uint32_t exRamSize; // $ffbd (0x400 << x) (used for GSU?)
uint8_t specialVersion; // $ffbe
uint8_t exCoprocessor; // $ffbf (if coprocessor = $f)
// calculated stuff
int16_t score; // score for header, to see which mapping is most likely
bool pal; // if this is a rom for PAL regions instead of NTSC
uint8_t cartType; // calculated type
} CartHeader;
static void readHeader(uint8_t* data, int location, CartHeader* header);
bool snes_loadRom(Snes* snes, uint8_t* data, int length) {
// if smaller than smallest possible, don't load
if(length < 0x8000) {
printf("Failed to load rom: rom to small (%d bytes)\n", length);
return false;
}
// check headers
CartHeader headers[4];
memset(headers, 0, sizeof(headers));
for(int i = 0; i < 4; i++) {
headers[i].score = -50;
}
if(length >= 0x8000) readHeader(data, 0x7fc0, &headers[0]);
if(length >= 0x8200) readHeader(data, 0x81c0, &headers[1]);
if(length >= 0x10000) readHeader(data, 0xffc0, &headers[2]);
if(length >= 0x10200) readHeader(data, 0x101c0, &headers[3]);
// see which it is
int max = 0;
int used = 0;
for(int i = 0; i < 4; i++) {
if(headers[i].score > max) {
max = headers[i].score;
used = i;
}
}
if(used & 1) {
// odd-numbered ones are for headered roms
data += 0x200; // move pointer past header
length -= 0x200; // and subtract from size
}
// check if we can load it
if(headers[used].cartType > 2) {
printf("Failed to load rom: unsupported type (%d)\n", headers[used].cartType);
return false;
}
// expand to a power of 2
int newLength = 0x8000;
while(true) {
if(length <= newLength) {
break;
}
newLength *= 2;
}
uint8_t* newData = (uint8_t * )malloc(newLength);
memcpy(newData, data, length);
int test = 1;
while(length != newLength) {
if(length & test) {
memcpy(newData + length, newData + length - test, test);
length += test;
}
test *= 2;
}
// load it
printf("Loaded %s rom\n\"%s\"\n", headers[used].cartType == 2 ? "HiROM" : "LoROM", headers[used].name);
cart_load(
snes->cart, headers[used].cartType,
newData, newLength, headers[used].chips > 0 ? headers[used].ramSize : 0
);
snes_reset(snes, true); // reset after loading
free(newData);
return true;
}
static void readHeader(uint8_t* data, int location, CartHeader* header) {
// read name, TODO: non-ASCII names?
for(int i = 0; i < 21; i++) {
uint8_t ch = data[location + i];
if(ch >= 0x20 && ch < 0x7f) {
header->name[i] = ch;
} else {
header->name[i] = '.';
}
}
header->name[21] = 0;
// read rest
header->speed = data[location + 0x15] >> 4;
header->type = data[location + 0x15] & 0xf;
header->coprocessor = data[location + 0x16] >> 4;
header->chips = data[location + 0x16] & 0xf;
header->romSize = 0x400 << data[location + 0x17];
header->ramSize = 0x400 << data[location + 0x18];
header->region = data[location + 0x19];
header->maker = data[location + 0x1a];
header->version = data[location + 0x1b];
header->checksumComplement = (data[location + 0x1d] << 8) + data[location + 0x1c];
header->checksum = (data[location + 0x1f] << 8) + data[location + 0x1e];
// read v3 and/or v2
header->headerVersion = 1;
if(header->maker == 0x33) {
header->headerVersion = 3;
// maker code
for(int i = 0; i < 2; i++) {
uint8_t ch = data[location - 0x10 + i];
if(ch >= 0x20 && ch < 0x7f) {
header->makerCode[i] = ch;
} else {
header->makerCode[i] = '.';
}
}
header->makerCode[2] = 0;
// game code
for(int i = 0; i < 4; i++) {
uint8_t ch = data[location - 0xe + i];
if(ch >= 0x20 && ch < 0x7f) {
header->gameCode[i] = ch;
} else {
header->gameCode[i] = '.';
}
}
header->gameCode[4] = 0;
header->flashSize = 0x400 << data[location - 4];
header->exRamSize = 0x400 << data[location - 3];
header->specialVersion = data[location - 2];
header->exCoprocessor = data[location - 1];
} else if(data[location + 0x14] == 0) {
header->headerVersion = 2;
header->exCoprocessor = data[location - 1];
}
// get region
header->pal = (header->region >= 0x2 && header->region <= 0xc) || header->region == 0x11;
header->cartType = location < 0x9000 ? 1 : 2;
// get score
// TODO: check name, maker/game-codes (if V3) for ASCII, more vectors,
// more first opcode, rom-sizes (matches?), type (matches header location?)
int score = 0;
score += (header->speed == 2 || header->speed == 3) ? 5 : -4;
score += (header->type <= 3 || header->type == 5) ? 5 : -2;
score += (header->coprocessor <= 5 || header->coprocessor >= 0xe) ? 5 : -2;
score += (header->chips <= 6 || header->chips == 9 || header->chips == 0xa) ? 5 : -2;
score += (header->region <= 0x14) ? 5 : -2;
score += (header->checksum + header->checksumComplement == 0xffff) ? 8 : -6;
uint16_t resetVector = data[location + 0x3c] | (data[location + 0x3d] << 8);
score += (resetVector >= 0x8000) ? 8 : -20;
// check first opcode after reset
uint8_t opcode = data[location + 0x40 - 0x8000 + (resetVector & 0x7fff)];
if(opcode == 0x78 || opcode == 0x18) {
// sei, clc (for clc:xce)
score += 6;
}
if(opcode == 0x4c || opcode == 0x5c || opcode == 0x9c) {
// jmp abs, jml abl, stz abs
score += 3;
}
if(opcode == 0x00 || opcode == 0xff || opcode == 0xdb) {
// brk, sbc alx, stp
score -= 6;
}
header->score = score;
}