95 lines
3.1 KiB
C
95 lines
3.1 KiB
C
/**
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* Copyright (c) 2014 MIT License by 6.172 Staff
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*
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* Permission is hereby granted, free of charge, to any person obtaining a copy
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* of this software and associated documentation files (the "Software"), to
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* deal in the Software without restriction, including without limitation the
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* rights to use, copy, modify, merge, publish, distribute, sublicense, and/or
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* sell copies of the Software, and to permit persons to whom the Software is
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* furnished to do so, subject to the following conditions:
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*
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* The above copyright notice and this permission notice shall be included in
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* all copies or substantial portions of the Software.
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*
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* THE SOFTWARE IS PROVIDED "AS IS", WITHOUT WARRANTY OF ANY KIND, EXPRESS OR
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* IMPLIED, INCLUDING BUT NOT LIMITED TO THE WARRANTIES OF MERCHANTABILITY,
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* FITNESS FOR A PARTICULAR PURPOSE AND NONINFRINGEMENT. IN NO EVENT SHALL THE
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* AUTHORS OR COPYRIGHT HOLDERS BE LIABLE FOR ANY CLAIM, DAMAGES OR OTHER
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* LIABILITY, WHETHER IN AN ACTION OF CONTRACT, TORT OR OTHERWISE, ARISING
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* FROM, OUT OF OR IN CONNECTION WITH THE SOFTWARE OR THE USE OR OTHER DEALINGS
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* IN THE SOFTWARE.
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**/
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#ifndef INCLUDED_FASTTIME_DOT_H
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#define INCLUDED_FASTTIME_DOT_H
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#include <assert.h>
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#ifdef __MACH__
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#include <mach/mach_time.h> // mach_absolute_time
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typedef uint64_t fasttime_t;
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// Return the current time.
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static inline fasttime_t gettime(void) {
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return mach_absolute_time();
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}
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// Return the time different between the start and the end, as a float
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// in units of seconds. This function does not need to be fast.
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// Implementation notes: See
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// https://developer.apple.com/library/mac/qa/qa1398/_index.html
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static inline double tdiff(fasttime_t start, fasttime_t end) {
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static mach_timebase_info_data_t timebase;
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int r = mach_timebase_info(&timebase);
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assert(r == 0);
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fasttime_t elapsed = end-start;
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double ns = (double)elapsed * timebase.numer / timebase.denom;
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return ns*1e-9;
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}
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static inline unsigned int random_seed_from_clock(void) {
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fasttime_t now = gettime();
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return (now & 0xFFFFFFFF) + (now>>32);
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}
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#else // LINUX
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// We need _POSIX_C_SOURCE to pick up 'struct timespec' and clock_gettime.
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// #define _POSIX_C_SOURCE 200809L
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#include <time.h>
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typedef struct timespec fasttime_t;
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// Return the current time.
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static inline fasttime_t gettime(void) {
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struct timespec s;
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#ifdef NDEBUG
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clock_gettime(CLOCK_MONOTONIC, &s);
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#else
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int r = clock_gettime(CLOCK_MONOTONIC, &s);
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assert(r == 0);
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#endif
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return s;
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}
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// Return the time different between the start and the end, as a float
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// in units of seconds. This function does not need to be fast.
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static inline double tdiff(fasttime_t start, fasttime_t end) {
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return end.tv_sec - start.tv_sec + 1e-9*(end.tv_nsec - start.tv_nsec);
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}
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static inline unsigned int random_seed_from_clock(void) {
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fasttime_t now = gettime();
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return now.tv_sec + now.tv_nsec;
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}
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// Poison these symbols to help find portability problems.
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int clock_gettime(clockid_t, struct timespec *) __attribute__((deprecated));
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time_t time(time_t *) __attribute__((deprecated));
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#endif // LINUX
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#endif // INCLUDED_FASTTIME_DOT_H
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