/*********************************************************************
* compile postgres first with different crc32c implementation(use arm vmull_p64 or not)
* we should comment out some codes about elog in pg_crc32c_armv8_choose.c to compile correctly and simply.
* $ gcc   -I ../postgres/_install/include -I ../postgres/_install/include/server main.c \
* -L ../postgres/build/src/port -l pgport_srv -O2  -o main

* this test was run on Neoverse-N1
* $ ./main.no_vmull
* data size is 512 bytes, and compute crc cost 139 us totally, 0.135742 us per loop
* data size is 4096 bytes, and compute crc cost 1061 us totally, 1.036133 us per loop

* $ ./main.use_vmull
* data size is 512 bytes, and compute crc cost 101 us totally, 0.098633 us per loop
* data size is 4096 bytes, and compute crc cost 540 us totally, 0.527344 us per loop

* We can see that the cost of computing crc32c without vmull_p64 is about two times than
* the cost that using vmull_p64 when data size is large. and the cost is almost same when 
* data size is small.
*********************************************************************/

#include <stdio.h>
#include <stdint.h>
#include <stdlib.h>
#include <sys/time.h>
#include <memory.h>

#include "c.h"
#include "port/pg_crc32c.h"

uint64_t
GetTickCount()
{
	struct timeval tv;

	gettimeofday(&tv, NULL);
	return tv.tv_sec * 1000000 + tv.tv_usec;
}

int
main()
{
#define CASE_CNT 2
	uint32_t	test_size[CASE_CNT] = {512, 1024 * 4};

	for (int case_cnt = 0; case_cnt < CASE_CNT; case_cnt++)
	{
		uint8_t    *buf = (uint8_t *) malloc(test_size[case_cnt] * sizeof(uint8_t));

		srand(0);
		for (int i = 0; i < test_size[case_cnt]; i++)
		{
			*(buf + i) = (uint8_t) (rand() % 256u);
		}

		static const uint32_t kLoop = 1024;
		uint32_t	crc = 0;
		uint64_t	start = GetTickCount();

		INIT_CRC32C(crc);
		for (int i = 0; i < kLoop; i++)
		{
			COMP_CRC32C(crc, buf, test_size[case_cnt]);
		}
		FIN_CRC32C(crc);
		uint64_t	stop = GetTickCount();

		printf("data size is %d bytes, and compute crc cost %ld us totally, %f us per loop\n", test_size[case_cnt], stop - start, (double) (stop - start) / kLoop);
		
		free(buf);
	}
#undef CASE_CNT
	return 0;
}