HHD Byte Count

bytes.c

#include <stdio.h>
#include <stdlib.h>
#include <stdint.h>
#include <string.h>
#include <inttypes.h>

#define BLOCK_SIZE (4096 * 1024)

typedef struct {
	uint8_t byte;
	uint64_t count;
} ByteCount;

int main(int argc, char* argv[]) {
	FILE* hdd;
	ByteCount counts[UINT8_MAX + 1];
	size_t len, read;
	
	if (argc < 2)
		return 1;
	
	for (int i = 0; i < UINT8_MAX + 1; i++) {
		counts[i].byte = i;
		counts[i].count = 0;
	}

	hdd = fopen(argv[1], "rb");
	if (!hdd)
		return 1;
	
	if (fseeko(hdd, 0, SEEK_END))
		return 1;
	len = ftello(hdd);
	read = 0;
	if (fseek(hdd, 0, SEEK_SET))
		return 1;
	
	printf("Scanning the %zuGB volume %s\n", len / (1024 * 1024 * 1024), argv[1]);
	
	do {
		uint8_t block[BLOCK_SIZE];
		size_t count;
		
		count = fread(block, sizeof(uint8_t), BLOCK_SIZE, hdd);
		
		read += count;
		
		for (size_t i = 0; i < count; i++) {
			counts[block[i]].count++;
		}
		
		if (!(read % (10 * BLOCK_SIZE)))
			printf("%zu MB read\n", read / (1024 * 1024));
	} while (!feof(hdd));
	
	fclose(hdd);
	
	printf("Ordering frequencies\n");
	
	qsort_b(counts, UINT8_MAX + 1, sizeof(ByteCount), ^(const void* a, const void* b) { return (int)(((ByteCount*)a)->count - ((ByteCount*)b)->count); });
	
	for (int i = 0; i < UINT8_MAX + 1; i++) {
		printf("%0.2x : %" PRId64 "\n", counts[i].byte, counts[i].count);
	}
}