145 righe
4.3 KiB
C
145 righe
4.3 KiB
C
/*
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* Copyright (c), MM Weiss
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* All rights reserved.
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*
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* Redistribution and use in source and binary forms, with or without modification,
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* are permitted provided that the following conditions are met:
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*
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* 1. Redistributions of source code must retain the above copyright notice,
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* this list of conditions and the following disclaimer.
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*
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* 2. Redistributions in binary form must reproduce the above copyright notice,
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* this list of conditions and the following disclaimer in the documentation
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* and/or other materials provided with the distribution.
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*
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* 3. Neither the name of the MM Weiss nor the names of its contributors
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* may be used to endorse or promote products derived from this software without
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* specific prior written permission.
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*
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* THIS SOFTWARE IS PROVIDED BY THE COPYRIGHT HOLDERS AND CONTRIBUTORS "AS IS" AND ANY
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* EXPRESS OR IMPLIED WARRANTIES, INCLUDING, BUT NOT LIMITED TO, THE IMPLIED WARRANTIES
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* OF MERCHANTABILITY AND FITNESS FOR A PARTICULAR PURPOSE ARE DISCLAIMED. IN NO EVENT
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* SHALL THE COPYRIGHT OWNER OR CONTRIBUTORS BE LIABLE FOR ANY DIRECT, INDIRECT, INCIDENTAL,
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* SPECIAL, EXEMPLARY, OR CONSEQUENTIAL DAMAGES (INCLUDING, BUT NOT LIMITED TO, PROCUREMENT
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* OF SUBSTITUTE GOODS OR SERVICES; LOSS OF USE, DATA, OR PROFITS; OR BUSINESS INTERRUPTION)
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* HOWEVER CAUSED AND ON ANY THEORY OF LIABILITY, WHETHER IN CONTRACT, STRICT LIABILITY, OR
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* TORT (INCLUDING NEGLIGENCE OR OTHERWISE) ARISING IN ANY WAY OUT OF THE USE OF THIS SOFTWARE,
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* EVEN IF ADVISED OF THE POSSIBILITY OF SUCH DAMAGE.
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*/
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/*
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* clock_gettime_stub.c
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* gcc -Wall -c clock_gettime_stub.c
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* posix realtime functions; MacOS user space glue
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*/
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/* @comment
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* other possible implementation using intel builtin rdtsc
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* rdtsc-workaround: http://www.mcs.anl.gov/~kazutomo/rdtsc.html
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*
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* we could get the ticks by doing this
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*
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* __asm __volatile("mov %%ebx, %%esi\n\t"
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* "cpuid\n\t"
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* "xchg %%esi, %%ebx\n\t"
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* "rdtsc"
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* : "=a" (a),
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* "=d" (d)
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* );
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* we could even replace our tricky sched_yield call by assembly code to get a better accurency,
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* anyway the following C stub will satisfy 99% of apps using posix clock_gettime call,
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* moreover, the setter version (clock_settime) could be easly written using mach primitives:
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* http://www.opensource.apple.com/source/xnu/xnu-${VERSION}/osfmk/man/ (clock_[set|get]_time)
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*
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* hackers don't be crackers, don't you use a flush toilet?
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*
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*
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* @see draft: ./posix-realtime-stub/posix-realtime-stub.c
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*
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*/
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#ifdef OS_OSX
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#pragma weak clock_gettime
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#include <sys/time.h>
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#include <sys/resource.h>
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#include <mach/mach.h>
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#include <mach/clock.h>
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#include <mach/mach_time.h>
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#include <errno.h>
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#include <unistd.h>
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#include <sched.h>
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#include "clock_gettime_stub.h"
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/*
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typedef enum {
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CLOCK_REALTIME,
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CLOCK_MONOTONIC,
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CLOCK_PROCESS_CPUTIME_ID,
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CLOCK_THREAD_CPUTIME_ID
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} clockid_t;
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*/
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static mach_timebase_info_data_t __clock_gettime_inf;
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int clock_gettime(clockid_t clk_id, struct timespec *tp) {
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kern_return_t ret;
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clock_serv_t clk;
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clock_id_t clk_serv_id;
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mach_timespec_t tm;
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uint64_t start, end, delta, nano;
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//task_basic_info_data_t tinfo;
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//task_thread_times_info_data_t ttinfo;
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//mach_msg_type_number_t tflag;
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int retval = -1;
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switch (clk_id) {
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case CLOCK_REALTIME:
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case CLOCK_MONOTONIC:
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clk_serv_id = clk_id == CLOCK_REALTIME ? CALENDAR_CLOCK : SYSTEM_CLOCK;
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if (KERN_SUCCESS == (ret = host_get_clock_service(mach_host_self(), clk_serv_id, &clk))) {
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if (KERN_SUCCESS == (ret = clock_get_time(clk, &tm))) {
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tp->tv_sec = tm.tv_sec;
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tp->tv_nsec = tm.tv_nsec;
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retval = 0;
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}
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}
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if (KERN_SUCCESS != ret) {
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errno = EINVAL;
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retval = -1;
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}
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break;
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case CLOCK_PROCESS_CPUTIME_ID:
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case CLOCK_THREAD_CPUTIME_ID:
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start = mach_absolute_time();
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if (clk_id == CLOCK_PROCESS_CPUTIME_ID) {
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getpid();
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} else {
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sched_yield();
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}
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end = mach_absolute_time();
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delta = end - start;
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if (0 == __clock_gettime_inf.denom) {
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mach_timebase_info(&__clock_gettime_inf);
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}
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nano = delta * __clock_gettime_inf.numer / __clock_gettime_inf.denom;
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tp->tv_sec = nano * 1e-9;
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tp->tv_nsec = nano - (tp->tv_sec * 1e9);
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retval = 0;
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break;
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default:
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errno = EINVAL;
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retval = -1;
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}
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return retval;
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}
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#endif // __APPLE__
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/* EOF */
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