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Documentation of br_ips and ips_patch

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PikalaxALT
2019-06-24 09:20:15 -04:00
parent 5b7c34096c
commit f18fcb9fbd
2 changed files with 190 additions and 67 deletions
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tools/br_ips/ips_patch.c
+25 -3
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@@ -24,18 +24,36 @@ do { \
static const char SPLASH[] = "Small IPS patch utility\n"
"Created by PikalaxALT on 23 June 2019 All Rights Reserved\n";
static const char HELP[] = "ips_patch [-h] ROM PATCH OUT\n"
"\n"
" ROM - input ROM file\n"
" PATCH - IPS patch file to apply\n"
" OUT - path to write patched ROM\n"
"\n"
"Options:\n"
" -h - show this message and exit\n";
int main(int argc, char ** argv) {
// Show a friendly message
puts(SPLASH);
if (argc != 4) FATAL_ERROR("usage: %s ROM PATCH OUT\n", argv[0]);
// If requested, show help message
if (argc >= 2 && strcmp(argv[1], "-h") == 0) {
puts(HELP);
return 0;
}
// Enforce CLI syntax
if (argc != 4) FATAL_ERROR("usage: %s [-h] ROM PATCH OUT\n", argv[0]);
FILE * rom = fopen(argv[1], "rb");
if (rom == NULL) FATAL_ERROR("failed to open file \"%s\" for reading\n", argv[1]);
FILE * patch = fopen(argv[2], "rb");
if (patch == NULL) FATAL_ERROR("failed to open file \"%s\" for reading\n", argv[2]);
FILE * out = fopen(argv[3], "wb");
if (patch == NULL) FATAL_ERROR("failed to open file \"%s\" for writing\n", argv[3]);
// IPS magic header
char magic[5];
if (fread(magic, 1, 5, patch) != 5) FATAL_ERROR("read magic\n");
if (memcmp(magic, "PATCH", 5) != 0) FATAL_ERROR("malformed IPS patch\n");
// Read the ROM into allocated memory.
fseek(rom, 0, SEEK_END);
size_t romsize = ftell(rom);
fseek(rom, 0, SEEK_SET);
@@ -46,16 +64,20 @@ int main(int argc, char ** argv) {
while (1) {
uint32_t offset;
size_t size;
// Read each hunk into the buffer, overwriting previous data.
// If two or more hunks overlap, the newest one is retained.
// A good IPS patch creator will avoid this.
offset = (unsigned char)getc(patch) << 16;
offset |= (unsigned char)getc(patch) << 8;
offset |= (unsigned char)getc(patch);
if (offset == 0x454F46) break;
if (offset == 0x454F46) break; // end sentinel "EOF"
size = (unsigned char)getc(patch) << 8;
size |= (unsigned char)getc(patch);
if (offset + size > romsize) FATAL_ERROR("segment extends past end of ROM\n");
if (fread(buffer + offset, 1, size, patch) != size) FATAL_ERROR("read segment\n");
}
fclose(patch);
// Write the patched ROM
fwrite(buffer, 1, romsize, out);
fclose(out);
free(buffer);