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422987ab04
Validate ascii string by ORing all bytes and check if 7-th bit is 0. Compared with original std::any_of(), which checks ascii string byte by byte, this new approach validates input in 8 bytes and two independent streams. Performance is much higher for normal cases, though slightly slower when string is very short. See table below. Speed(MB/s) of ascii string validation +---------------+-------------+---------+ | String length | std::any_of | u64 x 2 | +---------------+-------------+---------+ | 9 bytes | 1691 | 1635 | +---------------+-------------+---------+ | 31 bytes | 2923 | 3181 | +---------------+-------------+---------+ | 129 bytes | 3377 | 15110 | +---------------+-------------+---------+ | 1039 bytes | 3357 | 31815 | +---------------+-------------+---------+ | 16385 bytes | 3448 | 47983 | +---------------+-------------+---------+ | 1048576 bytes | 3394 | 31391 | +---------------+-------------+---------+ Signed-off-by: Yibo Cai <yibo.cai@arm.com> Message-Id: <1544669646-31881-1-git-send-email-yibo.cai@arm.com>
45 lines
1.1 KiB
C++
45 lines
1.1 KiB
C++
/*
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* Optimized ASCII string validation.
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*
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* Copyright (c) 2018, Arm Limited.
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*/
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/*
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* This file is part of Scylla.
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*
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* Scylla is free software: you can redistribute it and/or modify
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* it under the terms of the GNU Affero General Public License as published by
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* the Free Software Foundation, either version 3 of the License, or
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* (at your option) any later version.
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*
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* Scylla is distributed in the hope that it will be useful,
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* but WITHOUT ANY WARRANTY; without even the implied warranty of
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* MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE. See the
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* GNU General Public License for more details.
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*
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* You should have received a copy of the GNU General Public License
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* along with Scylla. If not, see <http://www.gnu.org/licenses/>.
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*/
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#pragma once
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#include <cstdint>
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#include "bytes.hh"
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namespace utils {
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namespace ascii {
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bool validate(const uint8_t *data, size_t len);
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inline bool validate(bytes_view string) {
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const uint8_t *data = reinterpret_cast<const uint8_t*>(string.data());
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size_t len = string.size();
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return validate(data, len);
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}
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} // namespace ascii
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} // namespace utils
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