134 lines
4.6 KiB
C++
134 lines
4.6 KiB
C++
/*
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* This Source Code Form is subject to the terms of the Mozilla Public
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* License, v. 2.0. If a copy of the MPL was not distributed with this
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* file, You can obtain one at http://mozilla.org/MPL/2.0/.
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*
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* Copyright 2015 Danny Robson <danny@nerdcruft.net>
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*/
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#include "common.hpp"
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#include "../../debug/panic.hpp"
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///////////////////////////////////////////////////////////////////////////////
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namespace cruft::hash::murmur {
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template <>
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uint32_t
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tail<uint32_t> (const uint8_t *restrict bytes, size_t len)
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{
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uint32_t h = 0;
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switch (len % sizeof (uint32_t)) {
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case 3: h += bytes[2] << 16; [[fallthrough]];
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case 2: h += bytes[1] << 8; [[fallthrough]];
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case 1: h += bytes[0];
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break;
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default:
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unreachable ();
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}
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return h;
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}
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}
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//-----------------------------------------------------------------------------
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namespace cruft::hash::murmur {
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template <>
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uint64_t
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tail<uint64_t> (const uint8_t *restrict bytes, size_t len)
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{
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uint64_t h = 0;
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switch (len % sizeof (uint64_t)) {
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case 7: h += uint64_t(bytes[6]) << 48; [[fallthrough]];
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case 6: h += uint64_t(bytes[5]) << 40; [[fallthrough]];
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case 5: h += uint64_t(bytes[4]) << 32; [[fallthrough]];
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case 4: h += uint64_t(bytes[3]) << 24; [[fallthrough]];
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case 3: h += uint64_t(bytes[2]) << 16; [[fallthrough]];
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case 2: h += uint64_t(bytes[1]) << 8; [[fallthrough]];
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case 1: h += uint64_t(bytes[0]);
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break;
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default:
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unreachable ();
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}
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return h;
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}
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}
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//-----------------------------------------------------------------------------
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namespace cruft::hash::murmur {
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template <>
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std::array<uint32_t,4>
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tail_array<uint32_t> (const uint8_t *restrict bytes, size_t len)
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{
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std::array<uint32_t,4> result {0,0,0,0};
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switch (len % 16) {
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case 15: result[3] |= bytes[14] << 16; [[fallthrough]];
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case 14: result[3] |= bytes[13] << 8; [[fallthrough]];
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case 13: result[3] |= bytes[12] << 0; [[fallthrough]];
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case 12: result[2] |= bytes[11] << 24; [[fallthrough]];
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case 11: result[2] |= bytes[10] << 16; [[fallthrough]];
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case 10: result[2] |= bytes[ 9] << 8; [[fallthrough]];
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case 9: result[2] |= bytes[ 8] << 0; [[fallthrough]];
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case 8: result[1] |= bytes[ 7] << 24; [[fallthrough]];
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case 7: result[1] |= bytes[ 6] << 16; [[fallthrough]];
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case 6: result[1] |= bytes[ 5] << 8; [[fallthrough]];
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case 5: result[1] |= bytes[ 4] << 0; [[fallthrough]];
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case 4: result[0] |= bytes[ 3] << 24; [[fallthrough]];
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case 3: result[0] |= bytes[ 2] << 16; [[fallthrough]];
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case 2: result[0] |= bytes[ 1] << 8; [[fallthrough]];
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case 1: result[0] |= bytes[ 0] << 0;
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break;
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default:
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unreachable ();
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}
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return result;
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}
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}
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//-----------------------------------------------------------------------------
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namespace cruft::hash::murmur {
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template <>
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std::array<uint64_t,2>
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tail_array<uint64_t> (const uint8_t *restrict bytes, size_t len)
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{
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std::array<uint64_t,2> result {0, 0};
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switch(len & 15)
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{
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case 15: result[1] |= uint64_t{bytes[14]} << 48; [[fallthrough]];
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case 14: result[1] |= uint64_t{bytes[13]} << 40; [[fallthrough]];
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case 13: result[1] |= uint64_t{bytes[12]} << 32; [[fallthrough]];
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case 12: result[1] |= uint64_t{bytes[11]} << 24; [[fallthrough]];
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case 11: result[1] |= uint64_t{bytes[10]} << 16; [[fallthrough]];
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case 10: result[1] |= uint64_t{bytes[ 9]} << 8; [[fallthrough]];
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case 9: result[1] |= uint64_t{bytes[ 8]} << 0; [[fallthrough]];
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case 8: result[0] |= uint64_t{bytes[ 7]} << 56; [[fallthrough]];
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case 7: result[0] |= uint64_t{bytes[ 6]} << 48; [[fallthrough]];
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case 6: result[0] |= uint64_t{bytes[ 5]} << 40; [[fallthrough]];
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case 5: result[0] |= uint64_t{bytes[ 4]} << 32; [[fallthrough]];
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case 4: result[0] |= uint64_t{bytes[ 3]} << 24; [[fallthrough]];
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case 3: result[0] |= uint64_t{bytes[ 2]} << 16; [[fallthrough]];
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case 2: result[0] |= uint64_t{bytes[ 1]} << 8; [[fallthrough]];
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case 1: result[0] |= uint64_t{bytes[ 0]} << 0;
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break;
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default:
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unreachable ();
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};
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return result;
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}
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}
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