0eeb06b932
Move existing fast<str*cmp> templates for general use, pulled from the implementation used in logd that dealt with speed through cache locality and subroutine call mitigation. Rename to fastcmp. Test: logd-benchmarks and based on manual profiling from the past Bug: 31456426 Change-Id: Ic62f4a437fc3e06ffdeaae73a6f34e197957a6b0
54 lines
1.9 KiB
C++
54 lines
1.9 KiB
C++
/*
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* Copyright (C) 2014-2016 The Android Open Source Project
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*
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* Licensed under the Apache License, Version 2.0 (the "License");
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* you may not use this file except in compliance with the License.
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* You may obtain a copy of the License at
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*
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* http://www.apache.org/licenses/LICENSE-2.0
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*
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* Unless required by applicable law or agreed to in writing, software
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* distributed under the License is distributed on an "AS IS" BASIS,
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* WITHOUT WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied.
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* See the License for the specific language governing permissions and
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* limitations under the License.
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*/
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#ifndef _ANDROID_UTILS_FASTSTRCMP_H__
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#define _ANDROID_UTILS_FASTSTRCMP_H__
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#ifdef __cplusplus
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// Optimized for instruction cache locality
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//
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// Template class fastcmp used to create more time-efficient str*cmp
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// functions by pre-checking the first character before resorting
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// to calling the underlying string function. Profiled with a
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// measurable speedup when used in hot code. Usage is of the form:
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//
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// fastcmp<strncmp>(str1, str2, len)
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//
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// NB: Does not work for the case insensitive str*cmp functions.
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// NB: Returns boolean, do not use if expecting to check negative value.
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// Thus not semantically identical to the expected function behavior.
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template <int (*cmp)(const char *l, const char *r, const size_t s)>
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static inline int fastcmp(const char *l, const char *r, const size_t s) {
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return (*l != *r) || cmp(l + 1, r + 1, s - 1);
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}
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template <int (*cmp)(const void *l, const void *r, const size_t s)>
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static inline int fastcmp(const void *lv, const void *rv, const size_t s) {
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const char *l = static_cast<const char *>(lv);
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const char *r = static_cast<const char *>(rv);
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return (*l != *r) || cmp(l + 1, r + 1, s - 1);
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}
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template <int (*cmp)(const char *l, const char *r)>
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static inline int fastcmp(const char *l, const char *r) {
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return (*l != *r) || cmp(l + 1, r + 1);
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}
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#endif
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#endif // _ANDROID_UTILS_FASTSTRCMP_H__
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