Simple bitcoin signature hashing benchmark code

megatx-benchmark.c

/* Usage: benchmark-sha256 <numtxs> [<numiterations>] 
 * Benchmark the input signature hashes for a maximum-sized transaction with this many
 * inputs
 *
 * Rusty Russell, <rusty@rustcorp.com.au> GPLv3.
 */
#include <ccan/crypto/sha256/sha256.c>
#include <ccan/time/time.h>
#include <stdio.h>
#include <string.h>

//#define BLOCKSIZE 1000000
#define BLOCKSIZE 8000000

int main(int argc, char *argv[])
{
	struct timeabs start;
	struct timerel diff;
	size_t i, n, num_inputs = atoi(argv[1]);
	union {
		struct sha256 h;
		char rest[BLOCKSIZE - 180 * num_inputs];
	} block;

	n = atoi(argv[2] ? argv[2] : "10000");
	memset(&block, 0, sizeof(block));
	sha256(&block.h, &n, sizeof(n));

	start = time_now();
	for (i = 0; i < n; i++) {
		sha256(&block.h, &block, sizeof(block));
		sha256(&block.h, &block.h, sizeof(block.h));
	}
	diff = time_divide(time_between(time_now(), start), n);

	printf("%zu:%zu:%llu:%02x%02x%02x%02x%02x%02x...\n",
	       num_inputs, sizeof(block),
	       (unsigned long long)time_to_usec(time_multiply(diff, num_inputs)),
	       block.h.u.u8[0], block.h.u.u8[1], block.h.u.u8[2],
	       block.h.u.u8[3], block.h.u.u8[4], block.h.u.u8[5]);
	return 0;
}