/**
 * Copyright 2016 Yahoo Inc.
 *
 * Licensed under the Apache License, Version 2.0 (the "License");
 * you may not use this file except in compliance with the License.
 * You may obtain a copy of the License at
 *
 *     http://www.apache.org/licenses/LICENSE-2.0
 *
 * Unless required by applicable law or agreed to in writing, software
 * distributed under the License is distributed on an "AS IS" BASIS,
 * WITHOUT WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied.
 * See the License for the specific language governing permissions and
 * limitations under the License.
 */

#include "ChecksumProvider.h"

#include <assert.h>
#include "crc32c_sse42.h"
#include "crc32c_sw.h"

namespace pulsar {
bool isCrc32cSupported = crc32cSupported();

bool crc32cSupported() {
    return crc32c_initialize();
}

/**
 *  computes crc32c checksum: uses sse4.2 hardware-instruction to compute crc32c if machine supports else it computes using sw algo
 *  @param
 *  previousChecksum = in case of incremental-checksum-computation pass previous computed else pass 0 in other case.
 *  data = for which checksum will be computed
 *  length = length of data from offset
 */
uint32_t computeChecksum(uint32_t previousChecksum, const void * data, int length) {
    if (isCrc32cSupported) {
        return crc32cHw(previousChecksum, data, length);
    } else {
        return crc32cSw(previousChecksum, data, length);
    }
}

/**
 * Computes crc32c using hardware sse4.2 instruction
 */
uint32_t crc32cHw(uint32_t previousChecksum, const void * data, int length) {
    assert(isCrc32cSupported);
    return crc32c(previousChecksum, data, length, 0);
}

/**
 * Computes crc32c using sw crc-table algo
 */
uint32_t crc32cSw(uint32_t previousChecksum, const void * data, int length) {
    return crc32c_sw(previousChecksum, data, length);
}

}