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/*
* Copyright (C) 2016 The Android Open Source Project
*
* Licensed under the Apache License, Version 2.0 (the "License");
* you may not use this file except in compliance with the License.
* You may obtain a copy of the License at
*
* http://www.apache.org/licenses/LICENSE-2.0
*
* Unless required by applicable law or agreed to in writing, software
* distributed under the License is distributed on an "AS IS" BASIS,
* WITHOUT WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied.
* See the License for the specific language governing permissions and
* limitations under the License.
*/
#ifndef TIMESPEC_MATH_H_
#define TIMESPEC_MATH_H_
#include <time.h>
namespace profiler {
// Class of Math operations on timespec objects. The operation result is
// formalized, its nanosecond value should be non-negative and less than
// 1e9. See also spec in
// http://www.gnu.org/software/libc/manual/html_node/Elapsed-Time.html
class TimespecMath {
public:
static void Add(const timespec &x, const timespec &y, timespec *result) {
result->tv_sec = x.tv_sec + y.tv_sec;
result->tv_nsec = x.tv_nsec + y.tv_nsec;
formalize(result);
}
static void Subtract(const timespec &x, const timespec &y, timespec *result) {
result->tv_sec = x.tv_sec - y.tv_sec;
result->tv_nsec = x.tv_nsec - y.tv_nsec;
formalize(result);
}
// Returns -1 if x is smaller than y, or 0 if x is equal to y, or 1 if x is
// larger than y.
static int Compare(const timespec &x, const timespec &y) {
timespec x1(x);
timespec y1(y);
formalize(&x1);
formalize(&y1);
if (x1.tv_sec == y1.tv_sec) {
return x1.tv_nsec < y1.tv_nsec ? -1 : x1.tv_nsec == y1.tv_nsec ? 0 : 1;
}
return x1.tv_sec < y1.tv_sec ? -1 : 1;
}
// Formalizes a given timespace, and makes the nanosecond value non-negative
// and no larger than 1e9.
static void formalize(timespec *result) {
// Sequence of these two if clause matters. result->tv_nsec may be equal to
// 1e9 after the first if clause, the second if fixes it.
if (result->tv_nsec < 0) {
int sec = result->tv_nsec / 1e9 - 1;
result->tv_sec += sec;
result->tv_nsec -= 1e9 * sec;
}
if (result->tv_nsec >= 1e9) {
int sec = result->tv_nsec / 1e9;
result->tv_sec += sec;
result->tv_nsec -= 1e9 * sec;
}
}
};
} // namespace profiler
#endif // TIMESPEC_MATH_H_
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