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Don't hardcode CRCs within Crystal base data

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This commit is contained in:
Rangi 2020-11-30 11:32:19 -05:00
parent 4613bcfadf
commit ad6effee82
1 changed files with 38 additions and 25 deletions
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63
tools/stadium.c
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@ -1,9 +1,9 @@
#include <stdio.h>
#include <stdlib.h>
#include <stdbool.h>
#include <getopt.h>
#include <string.h>
#include <stdint.h>
#include <stdbool.h>
#include <getopt.h>
#include "common.h"
@ -17,24 +17,28 @@
#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
// The CRC initial value (also used for checksums)
#define CRC_INIT 0xFEFE
// The CRC initial value for Crystal base data
#define CRC_INIT_BASE 0xACDE
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};
// Base data format: "base", 1, version, CRC (big-endian), 16 unknown bytes
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 us_base[BASESIZE] = {'b', 'a', 's', 'e', 1, 0, 0, 0,
0x40, 0x11, 0x00, 0x22, 0x00, 0x3A, 0xF3, 0x38,
0x18, 0xFF, 0xFF, 0x0F, 0x07, 0x10, 0x68, 0x07};
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 eu_base[BASESIZE] = {'b', 'a', 's', 'e', 1, 1, 0, 0,
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', 1, 0, 0, 0,
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'};
@ -81,6 +85,18 @@ void calculate_checksums(uint8_t *file, int filesize, Base base) {
int DATASIZE = HEADERSIZE + NUMCHECKS * 2; // 2 bytes per checksum
int ORIGIN = filesize - DATASIZE; // Stadium data goes at the end of the file
// 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;
}
// Clear the global checksum
SET_U16BE(file, GLOBALOFF, 0);
@ -94,6 +110,15 @@ void calculate_checksums(uint8_t *file, int filesize, Base base) {
memcpy(file + BASEOFF, dbg_base, BASESIZE);
}
// Calculate the CRC of the base data, or none
if (base) {
uint16_t crc = CRC_INIT_BASE;
for (int i = BASEOFF; i < BASEOFF + BASESIZE; i++) {
crc = (crc >> 8) ^ crc_table[(crc & 0xFF) ^ file[i]];
}
SET_U16BE(file, BASEOFF + 6, crc);
}
// Initialize the Stadium data (this should be free space anyway)
memset(file + ORIGIN, 0, DATASIZE);
memcpy(file + ORIGIN, n64ps3, N64PS3SIZE);
@ -107,18 +132,6 @@ void calculate_checksums(uint8_t *file, int filesize, Base base) {
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++) {