Files
scylladb/utils/array-search.hh
Avi Kivity 6bc6db8037 utils/array-search: document restrictions
Our AVX2 implementation cannot load a partial vector,
or mask unused elements (that can be done with AVX-512/SVE2),
so it has some restrictions. Document them.

Closes #7385
2020-10-11 15:19:54 +03:00

46 lines
1.3 KiB
C++

/*
* Copyright (C) 2020 ScyllaDB
*/
/*
* This file is part of Scylla.
*
* Scylla is free software: you can redistribute it and/or modify
* it under the terms of the GNU Affero General Public License as published by
* the Free Software Foundation, either version 3 of the License, or
* (at your option) any later version.
*
* Scylla is distributed in the hope that it will be useful,
* but WITHOUT ANY WARRANTY; without even the implied warranty of
* MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE. See the
* GNU General Public License for more details.
*
* You should have received a copy of the GNU General Public License
* along with Scylla. If not, see <http://www.gnu.org/licenses/>.
*/
#pragma once
#include <cstdint>
#include <limits>
namespace utils {
static constexpr int64_t simple_key_unused_value = std::numeric_limits<int64_t>::min();
/*
* array_search_gt(value, array, capacity, size)
*
* Returns the index of the first element in the array that's greater
* than the given value.
*
* To accomodate the single-instruction-multiple-data variant, observe
* the following:
* - capacity must be a multiple of 4
* - any items with indexes in [size, capacity) must be initialized
* to std::numeric_limits<int64_t>::min()
*/
int array_search_gt(int64_t val, const int64_t* array, const int capacity, const int size);
}