crc.c

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/* -*- C -*- */
/*
 * Copyright (c) 2013-2020 Seagate Technology LLC and/or its Affiliates
 *
 * 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.
 *
 * For any questions about this software or licensing,
 * please email opensource@seagate.com or cortx-questions@seagate.com.
 *
 */


#include "lib/misc.h"

static uint64_t md_crc32_cksum(void *data, uint64_t len, uint64_t *cksum);

#define CRC_POLY        0x04C11DB7
#define CRC_WIDTH       32
#define CRC_SLICE_SIZE  8
#define CRC_TABLE_SIZE  256

uint32_t crc_table[CRC_TABLE_SIZE];
static bool is_table = false;

static void crc_mktable(void)
{
        int      i;
        int      j;
        uint32_t hibit = M0_BITS(CRC_WIDTH - 1);
        uint32_t crc;

        for (i = 0; i < CRC_TABLE_SIZE; i++) {
                crc = (uint32_t)i <<  (CRC_WIDTH - CRC_SLICE_SIZE);
                for(j = 0; j < CRC_SLICE_SIZE; j++) {
                        crc <<= 1;
                        if (crc &  hibit)
                                crc ^= CRC_POLY;
                }
                crc_table[i] = crc;
        }
}

static uint32_t crc32(uint32_t crc, unsigned char const *data, m0_bcount_t len)
{
        M0_PRE(data != NULL);
        M0_PRE(len > 0);

        if (!is_table) {
                crc_mktable();
                is_table = true;
        }

        while (len--)
                crc = ((crc << CRC_SLICE_SIZE) | *data++) ^
                        crc_table[crc >> (CRC_WIDTH - CRC_SLICE_SIZE) & 0xFF];

        return crc;
}

M0_INTERNAL void m0_crc32(const void *data, uint64_t len,
                          uint64_t *cksum)
{
        M0_PRE(data != NULL);
        M0_PRE(len > 0);
        M0_PRE(cksum != NULL);

        cksum[0] = crc32(~0, data, len);
}

M0_INTERNAL bool m0_crc32_chk(const void *data, uint64_t len,
                              const uint64_t *cksum)
{
        M0_PRE(data != NULL);
        M0_PRE(len > 0);
        M0_PRE(cksum != NULL);

        return cksum[0] == (uint64_t) crc32(~0, data, len);
}

static void md_crc32_cksum_set(void *data, uint64_t len, uint64_t *cksum)
{
        *cksum = md_crc32_cksum(data, len, cksum);
}

static uint64_t md_crc32_cksum(void *data, uint64_t len, uint64_t *cksum)
{
        uint64_t crc = ~0;
        uint64_t old_cksum = *cksum;

        *cksum = 0;
        crc = crc32(crc, data, len);
        *cksum = old_cksum;

        return crc;
}

static bool md_crc32_cksum_check(void *data, uint64_t len, uint64_t *cksum)
{
        return *cksum == md_crc32_cksum(data, len, cksum);
}

/*
 *  Local variables:
 *  c-indentation-style: "K&R"
 *  c-basic-offset: 8
 *  tab-width: 8
 *  fill-column: 79
 *  scroll-step: 1
 *  End:
 */