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- #include <stdio.h>
- #include <stdlib.h>
- #include <sys/types.h>
- #include <sys/stat.h>
- #include <inttypes.h>
- #include <string.h>
- #define lo8(x) (x & 0xFF)
- #define hi8(x) ((x >> 8) & 0xFF)
- #define xhi8(x) ((x >> 16) & 0xff)
- #define xxhi8(x) ((x >> 24) & 0xff)
- unsigned short crc_ccitt_update (uint16_t crc, uint8_t data)
- {
- data ^= lo8 (crc);
- data ^= data << 4;
- return ((((uint16_t)data << 8) | hi8 (crc)) ^ (uint8_t)(data >> 4) ^ ((uint16_t)data << 3));
- }
- int main(int argc, char *argv[]) {
- if (argc != 5) {
- printf("Usage: crcgen <filename> <length> <signature> <version>\r\n");
- return 1;
- }
- unsigned long length = strtol(argv[2],NULL,0);
- unsigned long devid = strtol(argv[3],NULL,0);
- unsigned long version = strtol(argv[4],NULL,0);
- if (length > length+8) {
- printf("Ha ha, very funny.\n");
- return 1;
- }
- uint8_t *data = malloc(length+8);
- if (!data) {
- perror("malloc");
- return 1;
- }
- memset(data, 0xff, length);
-
- FILE *f;
-
- f = fopen(argv[1], "rb+");
-
- if (f == 0) {
- printf("Unable to open file %s\r\n", argv[1]);
- return 1;
- }
-
- fread(data, 1, length, f);
- data[length-8] = lo8(devid);
- data[length-7] = hi8(devid);
- data[length-6] = xhi8(devid);
- data[length-5] = xxhi8(devid);
- data[length-4] = lo8(version);
- data[length-3] = hi8(version);
- unsigned long l;
- unsigned short crc = 0xFFFF;
-
- for (l=0; l < length-2; l++)
- crc = crc_ccitt_update(crc, data[l]);
-
- data[length-2] = lo8(crc);
- data[length-1] = hi8(crc);
- if (fseek(f, 0, SEEK_SET)) {
- perror("fseek");
- return 1;
- }
- if (fwrite(data, length, 1, f) != 1) {
- perror("fwrite");
- return 1;
- }
-
- fclose(f);
-
- return 0;
- }
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