/fix-pokemon-state.c Secret
Created
January 16, 2024 22:22
-
-
Save RSDuck/3a39d1c71e3a4068849603141c162b3f to your computer and use it in GitHub Desktop.
melonDS Pokémon gen 5 save state fixer
This file contains bidirectional Unicode text that may be interpreted or compiled differently than what appears below. To review, open the file in an editor that reveals hidden Unicode characters.
Learn more about bidirectional Unicode characters
#include <stdio.h> | |
#include <stdlib.h> | |
#include <string.h> | |
#include <stdint.h> | |
#include <errno.h> | |
const char wifi[] = { 'W', 'I', 'F', 'I' }; | |
const char mem_fill[] = { 0xA5, 0xA5, 0x5A, 0x5A }; | |
uint8_t* state; | |
int main(int argc, char** argv) { | |
if (argc > 2) { | |
fprintf(stderr, "Usage: %s <state>\n", argv[0]); | |
return 1; | |
} | |
FILE* f = fopen(argv[1], "rb"); | |
if (!f) { | |
perror(argv[1]); | |
return errno; | |
} | |
fseek(f, 0, SEEK_END); | |
size_t size = ftell(f); | |
fseek(f, 0, SEEK_SET); | |
state = malloc(size); | |
fread(state, size, 1, f); | |
fclose(f); | |
size_t offset = 0; | |
int found = 0; | |
while (!found) { | |
for (size_t i = offset; i < size; i++) { | |
if (memcmp(state + i, wifi, 4) == 0) { | |
offset = i; | |
break; | |
} | |
} | |
if (offset == 0) { | |
fprintf(stderr, "Couldn't find Wi-Fi data.\n"); | |
return 1; | |
} | |
size_t mem_offset = 0; | |
for (size_t i = offset; i < offset + 32; i++) { | |
if (memcmp(state + i, mem_fill, 4) == 0) { | |
mem_offset = i; | |
} | |
} | |
if (mem_offset == 0) { | |
offset++; | |
continue; | |
} | |
found = 1; | |
offset = mem_offset; | |
} | |
size_t fix_offset = offset + 0x2208; | |
if (state[fix_offset] != 1) { | |
fprintf(stderr, "Doesn't look like a save state that needs to be fixed. (%08lx == %02x)\n", fix_offset, state[fix_offset]); | |
return 1; | |
} | |
state[fix_offset] = 0x09; | |
const char* fixed = ".fixed"; | |
char* new_name = malloc(strlen(argv[1]) + strlen(fixed)); | |
sprintf(new_name, "%s%s", argv[1], fixed); | |
FILE* new_file = fopen(new_name, "wb"); | |
if (!new_file) { | |
perror(new_name); | |
return errno; | |
} | |
fwrite(state, size, 1, new_file); | |
fclose(new_file); | |
} |
Sign up for free
to join this conversation on GitHub.
Already have an account?
Sign in to comment