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lpcchksum.c
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lpcchksum.c
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/*
* calculate+inject LPC1700 vector checksum
*/
#include <stdlib.h>
#include <stdio.h>
#include <stdint.h>
uint32_t getu32(uint8_t *buffer) {
return buffer[0]+(buffer[1]<<8)+(buffer[2]<<16)+(buffer[3]<<24);
}
void putu32(uint8_t *buffer, uint32_t data) {
buffer[0]=(uint8_t)(data&0xff);
buffer[1]=(uint8_t)((data>>8)&0xff);
buffer[2]=(uint8_t)((data>>16)&0xff);
buffer[3]=(uint8_t)((data>>24)&0xff);
}
int main(int argc, char **argv) {
FILE *bin;
uint32_t data;
size_t len;
int count;
uint8_t *buffer;
if(argc<2) {
fprintf(stderr, "Usage: %s <binfile>\nThe original file will be modified!\n", argv[0]);
return 1;
}
if((bin=fopen(argv[1], "rb"))==NULL) {
perror("could not open input file");
return 1;
}
fseek(bin, 0, SEEK_END);
len=ftell(bin);
fseek(bin, 0, SEEK_SET);
if((buffer=malloc(len))==NULL) {
perror("could not reserve memory");
fclose(bin);
return 1;
}
fread(buffer, len, 1, bin);
fclose(bin);
data=0;
for(count=0; count<7; count++) {
data+=getu32(buffer+4*count);
}
printf("data=%x chksum=%x\n", data, ~data+1);
putu32(buffer+28,~data+1);
if((bin=fopen(argv[1], "wb"))==NULL) {
perror("could not open output file");
free(buffer);
return 1;
}
fwrite(buffer, len, 1, bin);
fclose(bin);
printf("done\n");
free(buffer);
return 0;
}