cannam@226: /*
cannam@226:   Copyright 2012-2014 David Robillard <http://drobilla.net>
cannam@226: 
cannam@226:   Permission to use, copy, modify, and/or distribute this software for any
cannam@226:   purpose with or without fee is hereby granted, provided that the above
cannam@226:   copyright notice and this permission notice appear in all copies.
cannam@226: 
cannam@226:   THIS SOFTWARE IS PROVIDED "AS IS" AND THE AUTHOR DISCLAIMS ALL WARRANTIES
cannam@226:   WITH REGARD TO THIS SOFTWARE INCLUDING ALL IMPLIED WARRANTIES OF
cannam@226:   MERCHANTABILITY AND FITNESS. IN NO EVENT SHALL THE AUTHOR BE LIABLE FOR
cannam@226:   ANY SPECIAL, DIRECT, INDIRECT, OR CONSEQUENTIAL DAMAGES OR ANY DAMAGES
cannam@226:   WHATSOEVER RESULTING FROM LOSS OF USE, DATA OR PROFITS, WHETHER IN AN
cannam@226:   ACTION OF CONTRACT, NEGLIGENCE OR OTHER TORTIOUS ACTION, ARISING OUT OF
cannam@226:   OR IN CONNECTION WITH THE USE OR PERFORMANCE OF THIS SOFTWARE.
cannam@226: */
cannam@226: 
cannam@245: #include "digest.h"
cannam@226: 
cannam@226: #ifdef __SSE4_2__
cannam@226: #    include <smmintrin.h>
cannam@226: #endif
cannam@226: 
cannam@226: ZIX_API uint32_t
cannam@226: zix_digest_start(void)
cannam@226: {
cannam@226: #ifdef __SSE4_2__
cannam@226: 	return 1;  // CRC32 initial value
cannam@226: #else
cannam@226: 	return 5381;  // DJB hash initial value
cannam@226: #endif
cannam@226: }
cannam@226: 
cannam@226: ZIX_API uint32_t
cannam@226: zix_digest_add(uint32_t hash, const void* const buf, const size_t len)
cannam@226: {
cannam@226: 	const uint8_t* str = (const uint8_t*)buf;
cannam@226: #ifdef __SSE4_2__
cannam@226: 	// SSE 4.2 CRC32
cannam@226: 	for (size_t i = 0; i < (len / sizeof(uint32_t)); ++i) {
cannam@226: 		hash = _mm_crc32_u32(hash, *(const uint32_t*)str);
cannam@226: 		str += sizeof(uint32_t);
cannam@226: 	}
cannam@226: 	if (len & sizeof(uint16_t)) {
cannam@226: 		hash = _mm_crc32_u16(hash, *(const uint16_t*)str);
cannam@226: 		str += sizeof(uint16_t);
cannam@226: 	}
cannam@226: 	if (len & sizeof(uint8_t)) {
cannam@226: 		hash = _mm_crc32_u8(hash, *(const uint8_t*)str);
cannam@226: 	}
cannam@226: #else
cannam@226: 	// Classic DJB hash
cannam@226: 	for (size_t i = 0; i < len; ++i) {
cannam@226: 		hash = (hash << 5) + hash + str[i];
cannam@226: 	}
cannam@226: #endif
cannam@226: 	return hash;
cannam@226: }