43 lines
945 B
C
43 lines
945 B
C
/* QEMU and x86 hardware with PCI support (and up) require that BIOS options
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* rom have a valid checksum, that the sum of all their bytes equals zero.
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* This script edits a rom binary in-place so it fits that criteria.
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*/
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#include <stdio.h>
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#include <sys/types.h>
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#include <sys/stat.h>
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#include <unistd.h>
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#include <stdlib.h>
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#include <stdint.h>
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struct stat sbuf;
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int main(int argc, char** argv) {
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FILE* fd = fopen(argv[1], "r+");
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fstat(fileno(fd), &sbuf);
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if (sbuf.st_size & 0x1F) {
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fprintf(stderr, "Filesize is not a multiple of 512 bytes\n");
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exit(1);
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}
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// Fill out filesize flag
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fseek(fd, 2, SEEK_SET);
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fputc(sbuf.st_size >> 9, fd);
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// Calculate checksum
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fseek(fd, 0, SEEK_SET);
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off_t i;
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uint8_t s;
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for (i=0; i<sbuf.st_size; i++) {
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s+=fgetc(fd);
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}
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// Edit last byte so that checksum is 0
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fseek(fd, -1, SEEK_END);
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s=fgetc(fd)-s;
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fseek(fd, -1, SEEK_END);
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fputc(s, fd);
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fclose(fd);
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}
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