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/*
* Copyright 2010 Google Inc.
*
* Licensed under the Apache License, Version 2.0 (the "License");
* you may not use this file except in compliance with the License.
* You may obtain a copy of the License at
*
* http://www.apache.org/licenses/LICENSE-2.0
*
* Unless required by applicable law or agreed to in writing, software
* distributed under the License is distributed on an "AS IS" BASIS,
* WITHOUT WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied.
* See the License for the specific language governing permissions and
* limitations under the License.
*
* compute rom checksum byte
*/
#include <stdio.h>
#include <unistd.h>
#include <stdlib.h>
#include <fcntl.h>
#include <sys/types.h>
#define MAX_SIZE 65536
unsigned char buf[MAX_SIZE];
int main(int argc, char **argv)
{
ssize_t fsize;
int i, sum, fd;
unsigned char csum;
if (argc < 2) {
fprintf(stderr, "usage: %s filename\n", argv[0]);
exit(1);
}
if ((fd = open(argv[1], O_RDWR)) < 0) {
perror(argv[1]);
exit(1);
}
if ((fsize = read(fd, buf, MAX_SIZE)) < 0) {
perror(argv[1]);
exit(1);
}
if (fsize >= MAX_SIZE && read(fd, &buf[MAX_SIZE - 1], 1) > 0) {
fprintf(stderr, "FAIL: %s is larger than %d bytes\n", argv[1], MAX_SIZE);
exit(1);
}
i = fsize - 2048 * (fsize / 2048);
if (i != 2047) {
fprintf(stderr, "FAIL: %s is %zd bytes, need 2K pad-1\n", argv[1], fsize);
exit(1);
}
for (i = sum = 0; i < fsize; i++) {
sum += buf[i];
}
sum &= 0xff;
csum = -sum & 0xff;
write(fd, &csum, 1);
close(fd);
fprintf(stderr, "%s: sum = 0x%02x, wrote byte 0x%02x\n", argv[1], sum, csum);
return 0;
}
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