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/*-
 *   BSD LICENSE
 * 
 *   Copyright(c) 2010-2012 Intel Corporation. All rights reserved.
 *   All rights reserved.
 * 
 *   Redistribution and use in source and binary forms, with or without 
 *   modification, are permitted provided that the following conditions 
 *   are met:
 * 
 *     * Redistributions of source code must retain the above copyright 
 *       notice, this list of conditions and the following disclaimer.
 *     * Redistributions in binary form must reproduce the above copyright 
 *       notice, this list of conditions and the following disclaimer in 
 *       the documentation and/or other materials provided with the 
 *       distribution.
 *     * Neither the name of Intel Corporation nor the names of its 
 *       contributors may be used to endorse or promote products derived 
 *       from this software without specific prior written permission.
 * 
 *   THIS SOFTWARE IS PROVIDED BY THE COPYRIGHT HOLDERS AND CONTRIBUTORS 
 *   "AS IS" AND ANY EXPRESS OR IMPLIED WARRANTIES, INCLUDING, BUT NOT 
 *   LIMITED TO, THE IMPLIED WARRANTIES OF MERCHANTABILITY AND FITNESS FOR 
 *   A PARTICULAR PURPOSE ARE DISCLAIMED. IN NO EVENT SHALL THE COPYRIGHT 
 *   OWNER OR CONTRIBUTORS BE LIABLE FOR ANY DIRECT, INDIRECT, INCIDENTAL, 
 *   SPECIAL, EXEMPLARY, OR CONSEQUENTIAL DAMAGES (INCLUDING, BUT NOT 
 *   LIMITED TO, PROCUREMENT OF SUBSTITUTE GOODS OR SERVICES; LOSS OF USE, 
 *   DATA, OR PROFITS; OR BUSINESS INTERRUPTION) HOWEVER CAUSED AND ON ANY 
 *   THEORY OF LIABILITY, WHETHER IN CONTRACT, STRICT LIABILITY, OR TORT 
 *   (INCLUDING NEGLIGENCE OR OTHERWISE) ARISING IN ANY WAY OUT OF THE USE 
 *   OF THIS SOFTWARE, EVEN IF ADVISED OF THE POSSIBILITY OF SUCH DAMAGE.
 * 
 */

#ifndef _RTE_HASH_CRC_H_
#define _RTE_HASH_CRC_H_

/**
 * @file
 *
 * RTE CRC Hash
 */

#ifdef __cplusplus
extern "C" {
#endif

#include <stdint.h>

/**
 * Use single crc32 instruction to perform a hash on a 4 byte value.
 *
 * @param data
 *   Data to perform hash on.
 * @param init_val
 *   Value to initialise hash generator.
 * @return
 *   32bit calculated hash value.
 */
static inline uint32_t
rte_hash_crc_4byte(uint32_t data, uint32_t init_val)
{
	asm volatile("crc32 %[data], %[init_val]"
	             : [init_val]"=r" (init_val)
	             : [data]"r" (data), "[init_val]" (init_val));
	return init_val;
}

/**
 * Use crc32 instruction to perform a hash.
 *
 * @param data
 *   Data to perform hash on.
 * @param data_len
 *   How many bytes to use to calculate hash value.
 * @param init_val
 *   Value to initialise hash generator.
 * @return
 *   32bit calculated hash value.
 */
static inline uint32_t
rte_hash_crc(const void *data, uint32_t data_len, uint32_t init_val)
{
	unsigned i;
	uint32_t temp = 0;
	const uint32_t *p32 = (const uint32_t *)data;

	for (i = 0; i < data_len / 4; i++) {
		init_val = rte_hash_crc_4byte(*p32++, init_val);
	}

	switch (3 - (data_len & 0x03)) {
	case 0:
		temp |= *((const uint8_t *)p32 + 2) << 16;
		/* Fallthrough */
	case 1:
		temp |= *((const uint8_t *)p32 + 1) << 8;
		/* Fallthrough */
	case 2:
		temp |= *((const uint8_t *)p32);
		init_val = rte_hash_crc_4byte(temp, init_val);
	default:
		break;
	}

	return init_val;
}

#ifdef __cplusplus
}
#endif

#endif /* _RTE_HASH_CRC_H_ */