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checksummer.c
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77 lines (63 loc) · 2.36 KB
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/*
* Copyright 2012 The Emscripten Authors. All rights reserved.
* Emscripten is available under two separate licenses, the MIT license and the
* University of Illinois/NCSA Open Source License. Both these licenses can be
* found in the LICENSE file.
*/
#include <stdint.h>
#include <stdio.h>
#include <stdlib.h>
const int MOD_ADLER = 65521;
uint64_t adler32(unsigned char *data, int32_t len) /* where data is the location of the data in physical memory and
len is the length of the data in bytes */
{
uint64_t a = 1, b = 0;
int32_t index;
/* Process each byte of the data in order */
for (index = 0; index < len; ++index)
{
a = (a + data[index]) % MOD_ADLER;
b = (b + a) % MOD_ADLER;
}
return (b << 16) | a;
}
int main(int argc, char* argv[]) {
long bufsize;
if (argc != 2) {
fputs("Need 1 argument\n", stderr);
return (EXIT_FAILURE);
}
unsigned char *source = NULL;
FILE *fp = fopen(argv[1], "rb");
if (fp != NULL) {
/* Go to the end of the file. */
if (fseek(fp, 0L, SEEK_END) == 0) {
/* Get the size of the file. */
bufsize = ftell(fp);
if (bufsize == -1) { fputs("Couldn't get size\n", stderr); return (EXIT_FAILURE); }
/* Allocate our buffer to that size. */
source = malloc(sizeof(char) * (bufsize + 1));
if (source == NULL) { fputs("Couldn't allocate\n", stderr); return (EXIT_FAILURE); }
/* Go back to the start of the file. */
if (fseek(fp, 0L, SEEK_SET) == -1) { fputs("Couldn't seek\n", stderr); return (EXIT_FAILURE); }
/* Read the entire file into memory. */
size_t newLen = fread(source, sizeof(char), bufsize, fp);
if (newLen == 0) {
fputs("Error reading file\n", stderr);
//return (EXIT_FAILURE);
} else {
source[++newLen] = '\0'; /* Just to be safe. */
}
} else {
fputs("Couldn't seek to end\n", stderr);
return (EXIT_FAILURE);
}
fclose(fp);
} else {
fputs("Couldn't open\n", stderr);
return (EXIT_FAILURE);
}
printf("%u\n", (uint32_t) adler32(source, bufsize));
free(source); /* Don't forget to call free() later! */
return (EXIT_SUCCESS);
}