pal-beta: Get ROM fully matching

tools/mkrom/main.c

@@ -28,19 +28,25 @@ struct state state;
  * piracy checks.
  *
  * <zipmagic>
- * This is a two byte value which is used when zipping the game segments.
+ * This is a two byte hex value which is used when zipping the game segments.
  * The original code was influenced by uninitialised data. These two bytes are
  * just setting that uninitialised data.
  *
+ * <copylen>
+ * This is used for copying some redundant data at the end of the gamezips
+ * segment. The value is the number of bytes to copy. Copying this data makes
+ * no functional difference but is required for a match. This parameter can be
+ * removed if a formula is found for calculating the copy amount.
+ *
  * <outfile>
  * The file to write the final ROM file to.
  *
- * eg. mkrom stage1.bin pd.map 1 0x1234 pd.z64
+ * eg. mkrom stage1.bin pd.map 1 0x1234 2 pd.z64
  */
 int main(int argc, char **argv)
 {
-	if (argc < 6) {
-		fprintf(stderr, "Usage: mkrom <romfile> <mapfile> <piracychecks> <zipmagic> <outfile>\n");
+	if (argc < 7) {
+		fprintf(stderr, "Usage: mkrom <romfile> <mapfile> <piracychecks> <zipmagic> <copylen> <outfile>\n");
 		exit(1);
 	}
 
@@ -49,6 +55,7 @@ int main(int argc, char **argv)
 
 	state.piracychecks = atoi(argv[3]);
 	state.zipmagic = strtol(argv[4], NULL, 16);
+	state.copylen = atoi(argv[5]);
 
 	// Compute piracy checksums if requested
 	if (state.piracychecks) {
@@ -66,7 +73,7 @@ int main(int argc, char **argv)
 
 	rom_update_crc();
 
-	rom_write(argv[5]);
+	rom_write(argv[6]);
 
 	return 0;
 }

tools/mkrom/mkrom.h

@@ -28,6 +28,11 @@ struct state {
 	 */
 	unsigned short zipmagic;
 
+	/**
+	 * Number of bytes to copy after building gamezips.
+	 */
+	unsigned char copylen;
+
 	/**
 	 * File descriptor for the linker map.
 	 */

tools/mkrom/pack.c

@@ -83,9 +83,10 @@ void pack_game(void)
 		memcpy(&state.rom[gamezipstart + state.gamezipslen], state.gamezips, truncatedlen);
 
 		// The final two bytes from the real segment are duplicated into
-		// the first two bytes of the second segment's offset table
-		state.rom[gamezipstart + state.gamezipslen + 0] = state.rom[gamezipstart + state.gamezipslen - 2];
-		state.rom[gamezipstart + state.gamezipslen + 1] = state.rom[gamezipstart + state.gamezipslen - 1];
+		// the first two bytes of the second segment's offset table...
+		// though for some versions the copy length can vary for unknown reasons
+		// so we take the copy length as an argument to mkrom.
+		memcpy(&state.rom[gamezipstart + state.gamezipslen], &state.rom[gamezipstart + state.gamezipslen - state.copylen], state.copylen);
 	}
 }