Generate the Stadium 2 checksum data with pfero's tool instead of raw INCBINs

tools/stadium.c

@@ -0,0 +1,155 @@
+#include <stdio.h>
+#include <stdlib.h>
+#include <stdbool.h>
+#include <getopt.h>
+#include <string.h>
+#include <stdint.h>
+
+#include "common.h"
+
+// The Game Boy cartridge header stores a global checksum at 0x014E-0x014F
+#define GLOBALOFF 0x014E
+// "base" data; Crystal-only
+#define BASESIZE 24
+// ASCII "N64PS3" header
+#define N64PS3SIZE 6
+// N64PS3 + CRC
+#define HEADERSIZE (N64PS3SIZE + 2)
+// Checksum every half-bank
+#define CHECKSIZE 0x2000
+// The CRC initial value (also used for checksums)
+#define CRC_INIT 0xFEFE
+// The CRC polynomial value
+#define CRC_POLY 0xC387
+
+typedef enum Base { BASE_NONE, BASE_US, BASE_EU, BASE_DEBUG } Base;
+
+uint8_t us_base[BASESIZE] = {'b', 'a', 's', 'e',
+	0x01, 0x00, 0xBF, 0x6B, 0x40, 0x11, 0x00, 0x22, 0x00, 0x3A,
+	0xF3, 0x38, 0x18, 0xFF, 0xFF, 0x0F, 0x07, 0x10, 0x68, 0x07};
+
+uint8_t eu_base[BASESIZE] = {'b', 'a', 's', 'e',
+	0x01, 0x01, 0x1E, 0xCF, 0x00, 0x10, 0x00, 0x00, 0x00, 0x0C,
+	0xA3, 0x38, 0x00, 0xFF, 0xFF, 0x07, 0x00, 0x00, 0x00, 0x14};
+
+uint8_t dbg_base[BASESIZE] = {'b', 'a', 's', 'e',
+	0x01, 0x00, 0x07, 0x82, 0x40, 0x10, 0x00, 0x22, 0x00, 0x3A,
+	0xE3, 0x38, 0x00, 0xFF, 0xFF, 0x07, 0x07, 0x10, 0x68, 0x06};
+
+uint8_t n64ps3[N64PS3SIZE] = {'N', '6', '4', 'P', 'S', '3'};
+
+static void usage(void) {
+	fprintf(stderr, "Usage: stadium [-h|--help] [-b|--base us|eu|dbg] romfile\n");
+}
+
+void parse_args(int argc, char *argv[], Base *b) {
+	struct option long_options[] = {
+		{"base", required_argument, 0, 'b'},
+		{"help", no_argument, 0, 'h'},
+		{0}
+	};
+	for (int opt = 0; opt != -1;) {
+		switch (opt = getopt_long(argc, argv, "hb:", long_options)) {
+		case 'h':
+			usage();
+			exit(0);
+			break;
+		case 'b':
+			*b = !strcmp(optarg, "us") ? BASE_US :
+				!strcmp(optarg, "eu") ? BASE_EU :
+				!strcmp(optarg, "dbg") ? BASE_DEBUG :
+				BASE_NONE;
+			break;
+		case 0:
+		case -1:
+			break;
+		default:
+			usage();
+			exit(1);
+			break;
+		}
+	}
+}
+
+#define SET_U16BE(file, off, v) do { \
+	file[(off) + 0] = (uint8_t)(((v) & 0xFF00) >> 8); \
+	file[(off) + 1] = (uint8_t)(((v) & 0x00FF) >> 0); \
+} while (0)
+
+void calculate_checksums(uint8_t *file, int filesize, Base base) {
+	int NUMCHECKS = filesize / CHECKSIZE;
+	int DATASIZE = HEADERSIZE + NUMCHECKS * 2; // 2 bytes per checksum
+	int ORIGIN = filesize - DATASIZE; // Stadium data goes at the end of the file
+
+	// Clear the global checksum
+	SET_U16BE(file, GLOBALOFF, 0);
+
+	// Write the appropriate base data, or none
+	int BASEOFF = ORIGIN - BASESIZE;
+	if (base == BASE_US) {
+		memcpy(file + BASEOFF, us_base, BASESIZE);
+	} else if (base == BASE_EU) {
+		memcpy(file + BASEOFF, eu_base, BASESIZE);
+	} else if (base == BASE_DEBUG) {
+		memcpy(file + BASEOFF, dbg_base, BASESIZE);
+	}
+
+	// Initialize the Stadium data (this should be free space anyway)
+	memset(file + ORIGIN, 0, DATASIZE);
+	memcpy(file + ORIGIN, n64ps3, N64PS3SIZE);
+
+	// Calculate the half-bank checksums
+	for (int i = 0; i < NUMCHECKS; i++) {
+		uint16_t checksum = CRC_INIT;
+		for (int j = 0; j < CHECKSIZE; j++) {
+			checksum += file[i * CHECKSIZE + j];
+		}
+		SET_U16BE(file, ORIGIN + HEADERSIZE + i * 2, checksum);
+	}
+
+	// Initialize the CRC table
+	uint16_t crc_table[256];
+	for (int i = 0; i < 256; i++) {
+		uint16_t c = i;
+		uint16_t rem = 0;
+		for (int y = 0; y < 8; y++) {
+			rem = (rem >> 1) ^ ((rem ^ c) & 1 ? CRC_POLY : 0);
+			c >>= 1;
+		}
+		crc_table[i] = rem;
+	}
+
+	// Calculate the CRC of the half-bank checksums
+	uint16_t crc = CRC_INIT;
+	for (int i = ORIGIN + HEADERSIZE; i < ORIGIN + DATASIZE; i++) {
+		crc = (crc >> 8) ^ crc_table[(crc & 0xFF) ^ file[i]];
+	}
+	SET_U16BE(file, ORIGIN + HEADERSIZE - 2, crc);
+
+	// Calculate the global checksum
+	uint16_t globalsum = 0;
+	for (int i = 0; i < filesize; i++) {
+		globalsum += file[i];
+	}
+	SET_U16BE(file, GLOBALOFF, globalsum);
+}
+
+int main(int argc, char *argv[]) {
+	Base base = BASE_NONE;
+	parse_args(argc, argv, &base);
+
+	argc -= optind;
+	argv += optind;
+	if (argc < 1) {
+		usage();
+		exit(1);
+	}
+
+	char *filename = argv[0];
+	int filesize;
+	uint8_t *file = read_u8(filename, &filesize);
+	calculate_checksums(file, filesize, base);
+	write_u8(filename, file, filesize);
+
+	return 0;
+}