libz-sys 1.1.5

Low-level bindings to the system libz library (also known as zlib).
Documentation 
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/* benchmark_crc32.cc -- benchmark crc32 variants
 * Copyright (C) 2022 Nathan Moinvaziri
 * For conditions of distribution and use, see copyright notice in zlib.h
 */

#include <stdio.h>
#include <assert.h>

#include <benchmark/benchmark.h>

extern "C" {
#  include "zbuild.h"
#  include "zutil.h"
#  include "zutil_p.h"
#  include "cpu_features.h"
}

#define MAX_RANDOM_INTS (1024 * 1024)
#define MAX_RANDOM_INTS_SIZE (MAX_RANDOM_INTS * sizeof(uint32_t))

class crc32: public benchmark::Fixture {
private:
    uint32_t *random_ints;

public:
    void SetUp(const ::benchmark::State& state) {
        random_ints = (uint32_t *)zng_alloc(MAX_RANDOM_INTS_SIZE);
        assert(random_ints != NULL);

        for (int32_t i = 0; i < MAX_RANDOM_INTS; i++) {
            random_ints[i] = rand();
        }
    }

    void Bench(benchmark::State& state, crc32_func crc32) {
        uint32_t hash = 0;

        for (auto _ : state) {
            hash = crc32(hash, (const unsigned char *)random_ints, state.range(0));
        }

        benchmark::DoNotOptimize(hash);
    }

    void TearDown(const ::benchmark::State& state) {
        zng_free(random_ints);
    }
};

#define BENCHMARK_CRC32(name, fptr, support_flag) \
    BENCHMARK_DEFINE_F(crc32, name)(benchmark::State& state) { \
        if (!support_flag) { \
            state.SkipWithError("CPU does not support " #name); \
        } \
        Bench(state, fptr); \
    } \
    BENCHMARK_REGISTER_F(crc32, name)->Range(1, MAX_RANDOM_INTS_SIZE);

BENCHMARK_CRC32(byfour, crc32_byfour, 1);

#ifdef ARM_ACLE_CRC_HASH
BENCHMARK_CRC32(acle, crc32_acle, arm_cpu_has_crc32);
#elif defined(POWER8_VSX_CRC32)
BENCHMARK_CRC32(power8, crc32_power8, power_cpu_has_arch_2_07);
#elif defined(S390_CRC32_VX)
BENCHMARK_CRC32(vx, s390_crc32_vx, s390_cpu_has_vx);
#elif defined(X86_PCLMULQDQ_CRC)
/* CRC32 fold does a memory copy while hashing */
uint32_t crc32_pclmulqdq(uint32_t crc32, const unsigned char* buf, uint64_t len) {
    crc32_fold ALIGNED_(16) crc_state;
    crc32_fold_reset_pclmulqdq(&crc_state);
    crc32_fold_copy_pclmulqdq(&crc_state, (uint8_t *)buf, buf, len);
    return crc32_fold_final_pclmulqdq(&crc_state);
}
BENCHMARK_CRC32(pclmulqdq, crc32_pclmulqdq, x86_cpu_has_pclmulqdq);
#endif