program to check and correct checksum for SMaL VGA firmware
Sometimes the hardware guy takes a stab a writing software. This program displays the PID, VID, Hardware Version, and checksum info for 0x800a byte long firmware found on the Logitech Pocket Digital and Oregon Scientific DS6618 and probably other SMaL based VGA cameras. Additionally, if the firmware file has been altered, it corrects the checksum stored in the firmware file.
Sometimes the hardware guy takes a stab a writing software. This program displays the PID, VID, Hardware Version, and checksum info for 0x800a byte long firmware found on the Logitech Pocket Digital and Oregon Scientific DS6618 and probably other SMaL based VGA cameras. Additionally, if the firmware file has been altered, it corrects the checksum stored in the firmware file.
#include <stdio.h>
#include <stdlib.h>
int main(int argc,char **argv) {
FILE * pFile;
long fileSize;
unsigned int i;
unsigned char x;
unsigned short int PID, VID, HWVER, sumOffset, someVal, checksum, myChecksum;
if (argc < 2) {
printf("Usage: %s <filename>\\\\\\\\\\n",argv[0]);
printf("Where <filename> is the file to use.\\\\\\\\\\\n");
printf("Example: %s t0402-fw.pack\\\\\\\\\\\n",argv[0]);
exit(1);
}
pFile = fopen (argv[1], "r+b");
if (pFile==NULL) {
printf("Error opening file %s\\\\\\\\\\\n",argv[1]);
exit (1);
}
//check file size and exit if not 0x800a bytes
fseek (pFile,0,SEEK_END);
fileSize = ftell (pFile);
if (fileSize!=0x800a) {
printf("File size 0x%08lX not supported.\\\\\\\\\\\n",fileSize);
exit (1);
}
rewind (pFile);
myChecksum = 0;
fread (&PID,2,1,pFile);
fread (&VID,2,1,pFile);
fread (&HWVER,2,1,pFile);
fread (&sumOffset,2,1,pFile);
fread (&someVal,2,1,pFile);
//calculate checksum from start of code to checksum location
for (i=0; i<sumOffset; i++) {
fread (&x,1,1,pFile);
myChecksum += x;
}
fread (&checksum,2,1,pFile);
printf ("PID is 0x%04x\\\\\\\\\\\n",PID);
printf ("VID is 0x%04x\\\\\\\\\\\n",VID);
printf ("Hardware Version is 0x%04x\\\\\\\\\\\n",HWVER);
printf ("Checksum Offset is 0x%04x\\\\\\\\\\\n",sumOffset);
printf ("Checksum is 0x%04x\\\\\\\\\\\n",checksum);
printf ("Calculated Checksum is 0x%04x\\\\\\\\\\\n",myChecksum);
if (checksum!=myChecksum) {
//update checksum
fseek (pFile,-2,SEEK_CUR);
fwrite (&myChecksum,2,1,pFile);
//update copy of checksum
fseek (pFile,-2,SEEK_END);
fwrite (&myChecksum,2,1,pFile);
printf ("Firmware checksum corrected.\\\\\\\\\\\n");
}
fclose (pFile);
return 0;
}