Created
November 1, 2016 09:35
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#include <stdint.h> | |
#include <stdio.h> | |
int ones_count(uint32_t i) { | |
i = i - ((i >> 1) & 0x55555555); | |
i = (i & 0x33333333) + ((i >> 2) & 0x33333333); | |
return (((i + (i >> 4)) & 0x0F0F0F0F) * 0x01010101) >> 24; | |
} | |
int main (int argc, char *argv[]) { | |
const char *filename = argv[1]; | |
FILE *fp = fopen(filename, "r"); | |
if ((fp = fopen(filename, "r" )) == NULL) { | |
perror("error opening file"); | |
return 1; | |
} | |
long total = 0; | |
long total_ones = 0; | |
long total_zeros = 0; | |
long l = 0; | |
while (!feof(fp)) { | |
uint32_t buffer; | |
int count = fread(&buffer, 1, 4, fp); | |
if (ferror(fp)) { | |
perror("read error"); | |
break; | |
} | |
total += count; | |
if (count == 4) { | |
int ones = ones_count(buffer); | |
int zeros = 32 - ones; | |
total_ones += ones; | |
total_zeros += zeros; | |
} | |
if (!(l % (1024 * 1024))) { | |
printf("read %ld mb\n", total / 1024 / 1024); | |
printf("total ones: %ld\n", total_ones); | |
printf("total zeros: %ld\n", total_zeros); | |
printf("1/0: %f\n", (double)total_ones / (double)total_zeros); | |
printf("\n"); | |
} | |
l++; | |
} | |
printf("read %ld bytes\n", total); | |
printf("total ones: %ld\n", total_ones); | |
printf("total zeros: %ld\n", total_zeros); | |
printf("1/0: %f\n", (double)total_ones / (double)total_zeros); | |
fclose(fp); | |
return 0; | |
} |
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