jb24

/* Checksum computing for DG834 * * Checksum is computed by adding bytes from 0 to 0x3dfffb. * The 16 bit sum must be equal to the little endian 16 bit word stored at * 0x3dfffc-03dfffd. */#include <stdlib.h>#include <stdio.h>/* load a file in memory */staticint read_file(const char *filename, long *size, void **buffer){  FILE *fp;  /* open file for reading */  fp = fopen(filename, "rb");  if (fp == NULL) {    fprintf(stderr, "Could not open <%s>\n", filename);    return 1;  }  /* compute file size */  if (fseek(fp, 0, SEEK_END) != 0) {    fprintf(stderr, "Could not open <%s>\n", filename);    fclose(fp);    return 1;  }  *size = ftell(fp);  fseek(fp, 0, SEEK_SET);  if (*size == -1) {    fprintf(stderr, "Could not get size of file <%s>\n", filename);    fclose(fp);    return 1;  }  /* allocate memory to read the file */  *buffer = malloc(*size);  if (*buffer == NULL) {    fprintf(stderr, "Could not alloc mem to read file <%s>\n", filename);    fclose(fp);    return 1;  }  /* read the file */  if (fread(*buffer, 1, *size, fp) != *size) {    fprintf(stderr, "Could not read file <%s>\n", filename);    fclose(fp);    return 1;  }  /* we're done */  fclose(fp);  return 0;}/* read 8 bit */staticunsigned short read_8(unsigned char *mem, unsigned int addr){  return mem[addr];}/* read a 16 bit word in little endian */staticunsigned short read_16l(unsigned char *mem, unsigned int addr){  return mem[addr] | (mem[addr+1] << 8);}/* compute check sum */staticunsigned short compute_checksum(unsigned char *mem){  unsigned int   addr;  unsigned short word;  unsigned short checksum;  checksum = 0;  for (addr = 0; addr < 0x3dfffc; addr++) {    word = read_8(mem, addr);    checksum += word;  }  return checksum;}int main(int argc, const char *argv[]){  const char     *filename;  long            size;  void           *mem;  unsigned short  checksum;  /* command line */  if (argc != 2) {    fprintf(stderr, "Usage: %s firmware\n", argv[0]);    return 1;  }  filename = argv[1];  /* read file in memory */  if (read_file(filename, &size, &mem) != 0) {    return 2;  }  if (size != 0x3e0000) {    fprintf(stderr, "File <%s> has wrong size\n", filename);    return 3;  }  /* compute checksum */  checksum = compute_checksum(mem);  /* check it's OK */  printf("Computed checksum is %04x\n", checksum);  printf("Stored checksum is %04x\n", read_16l(mem, 0x3dfffc));  if (checksum != read_16l(mem, 0x3dfffc)) {    printf("WARNING:  checksum does not match!\n");  }  /* time to leave */  free(mem);  return 0;}