fasthash-sys-fork 0.4.2

// Original: metrohash64.cpp
// Port to C: Frank Denis (jedisct1@github) 
// Optimized variants: Paul G (paulie-g@github, paulg@perforge.net)
//
//
// The MIT License (MIT)
//
// Copyright (c) 2015 J. Andrew Rogers
//
// Permission is hereby granted, free of charge, to any person obtaining a copy
// of this software and associated documentation files (the "Software"), to deal
// in the Software without restriction, including without limitation the rights
// to use, copy, modify, merge, publish, distribute, sublicense, and/or sell
// copies of the Software, and to permit persons to whom the Software is
// furnished to do so, subject to the following conditions:
//
// The above copyright notice and this permission notice shall be included in all
// copies or substantial portions of the Software.
//
// THE SOFTWARE IS PROVIDED "AS IS", WITHOUT WARRANTY OF ANY KIND, EXPRESS OR
// IMPLIED, INCLUDING BUT NOT LIMITED TO THE WARRANTIES OF MERCHANTABILITY,
// FITNESS FOR A PARTICULAR PURPOSE AND NONINFRINGEMENT. IN NO EVENT SHALL THE
// AUTHORS OR COPYRIGHT HOLDERS BE LIABLE FOR ANY CLAIM, DAMAGES OR OTHER
// LIABILITY, WHETHER IN AN ACTION OF CONTRACT, TORT OR OTHERWISE, ARISING FROM,
// OUT OF OR IN CONNECTION WITH THE SOFTWARE OR THE USE OR OTHER DEALINGS IN THE
// SOFTWARE.
//

#include "cmetrohash.h"
#include "opt_cmetrohash.h"

#define DO_16 {\
	register uint64_t v0 = hash + (cread_u64(ptr) * k0); ptr += 8; v0 = crotate_right(v0,33) * k1;\
	register uint64_t v1 = hash + (cread_u64(ptr) * k1); ptr += 8; v1 = crotate_right(v1,33) * k2;\
	v0 ^= crotate_right(v0 * k0, 35) + v1;\
	v1 ^= crotate_right(v1 * k3, 35) + v0;\
	hash += v1;\
}

#define DO_8 {\
    hash += cread_u64(ptr) * k3; ptr += 8;\
    hash ^= crotate_right(hash, 33) * k1;\
}

#define DO_4 {\
    hash += cread_u32(ptr) * k3; ptr += 4;\
    hash ^= crotate_right(hash, 15) * k1;\
}

#define DO_2 {\
    hash += cread_u16(ptr) * k3; ptr += 2;\
    hash ^= crotate_right(hash, 13) * k1;\
}

#define DO_1 {\
	hash += cread_u8 (ptr) * k3;\
	hash ^= crotate_right(hash, 25) * k1;\
}

#define OUT {\
    hash ^= crotate_right(hash, 33);\
    hash *= k0;\
    hash ^= crotate_right(hash, 33);\
    memcpy(out, &hash, 8);\
	return;\
}


void cmetrohash64_1_optshort(const uint8_t * key, uint64_t len, uint32_t seed, uint8_t * out)
{
    static const uint64_t k0 = 0xC83A91E1;
    static const uint64_t k1 = 0x8648DBDB;
    static const uint64_t k2 = 0x7BDEC03B;
    static const uint64_t k3 = 0x2F5870A5;

    const uint8_t * ptr = key;
    const uint8_t * const end = ptr + len;
    
    uint64_t hash = ((((uint64_t) seed) + k2) * k0) + len;


	switch (len) {
	default:
		if (len >= 32)
		{
			uint64_t v[4];
			v[0] = hash;
			v[1] = hash;
			v[2] = hash;
			v[3] = hash;

			do
			{
				v[0] += cread_u64(ptr) * k0; ptr += 8; v[0] = crotate_right(v[0], 29) + v[2];
				v[1] += cread_u64(ptr) * k1; ptr += 8; v[1] = crotate_right(v[1], 29) + v[3];
				v[2] += cread_u64(ptr) * k2; ptr += 8; v[2] = crotate_right(v[2], 29) + v[0];
				v[3] += cread_u64(ptr) * k3; ptr += 8; v[3] = crotate_right(v[3], 29) + v[1];
			} while (ptr <= (end - 32));

			v[2] ^= crotate_right(((v[0] + v[3]) * k0) + v[1], 33) * k1;
			v[3] ^= crotate_right(((v[1] + v[2]) * k1) + v[0], 33) * k0;
			v[0] ^= crotate_right(((v[0] + v[2]) * k0) + v[3], 33) * k1;
			v[1] ^= crotate_right(((v[1] + v[3]) * k1) + v[2], 33) * k0;
			hash += v[0] ^ v[1];
		}

		if ((end - ptr) >= 16)
		{
			uint64_t v0 = hash + (cread_u64(ptr) * k0); ptr += 8; v0 = crotate_right(v0, 33) * k1;
			uint64_t v1 = hash + (cread_u64(ptr) * k1); ptr += 8; v1 = crotate_right(v1, 33) * k2;
			v0 ^= crotate_right(v0 * k0, 35) + v1;
			v1 ^= crotate_right(v1 * k3, 35) + v0;
			hash += v1;
		}

		if ((end - ptr) >= 8)
		{
			hash += cread_u64(ptr) * k3; ptr += 8;
			hash ^= crotate_right(hash, 33) * k1;

		}

		if ((end - ptr) >= 4)
		{
			hash += cread_u32(ptr) * k3; ptr += 4;
			hash ^= crotate_right(hash, 15) * k1;
		}

		if ((end - ptr) >= 2)
		{
			hash += cread_u16(ptr) * k3; ptr += 2;
			hash ^= crotate_right(hash, 13) * k1;
		}

		if ((end - ptr) >= 1)
		{
			hash += cread_u8(ptr) * k3;
			hash ^= crotate_right(hash, 25) * k1;
		}

		hash ^= crotate_right(hash, 33);
		hash *= k0;
		hash ^= crotate_right(hash, 33);

		memcpy(out, &hash, 8);
		return;

	case 31:
		DO_16
			DO_8
			DO_4
			DO_2
			DO_1
			OUT

	case 30:
		DO_16
			DO_8
			DO_4
			DO_2
			OUT

	case 29:
		DO_16
			DO_8
			DO_4
			DO_1
			OUT

	case 28:
		DO_16
			DO_8
			DO_4
			OUT

	case 27:
		DO_16
			DO_8
			DO_2
			DO_1
			OUT

	case 26:
		DO_16
			DO_8
			DO_2
			OUT

	case 25:
		DO_16
			DO_8
			DO_1
			OUT

	case 24:
		DO_16
			DO_8
			OUT

	case 23:
		DO_16
			DO_4
			DO_2
			DO_1
			OUT

	case 22:
		DO_16
			DO_4
			DO_2
			OUT


	case 21:
		DO_16
			DO_4
			DO_1
			OUT

	case 20:
		DO_16
			DO_4
			OUT

	case 19:
		DO_16
			DO_2
			DO_1
			OUT

	case 18:
		DO_16
			DO_2
			OUT

	case 17:
		DO_16
			DO_1
			OUT

	case 16:
		DO_16
			OUT

	case 15:
		DO_8
			DO_4
			DO_2
			DO_1
			OUT

	case 14:
		DO_8
			DO_4
			DO_2
			OUT

	case 13:
		DO_8
			DO_4
			DO_1
			OUT

	case 12:
		DO_8
			DO_4
			OUT

	case 11:
		DO_8
			DO_2
			DO_1
			OUT

	case 10:
		DO_8
			DO_2
			OUT

	case 9:
		DO_8
			DO_1
			OUT

	case 8:
		DO_8
			OUT
	case 7:
		DO_4
			DO_2
			DO_1
			OUT
	case 6:
		DO_4
			DO_2
			OUT
	case 5:
		DO_4
			DO_1
			OUT
	case 4:
		DO_4
			OUT
	case 3:
		DO_2
			DO_1
			OUT
	case 2:
		DO_2
			OUT
	case 1:
		DO_1

	case 0:
		OUT
	}
}