diff options
Diffstat (limited to 'gi/pyp-topics/src/clock_gettime_stub.c')
| -rw-r--r-- | gi/pyp-topics/src/clock_gettime_stub.c | 141 |
1 files changed, 141 insertions, 0 deletions
diff --git a/gi/pyp-topics/src/clock_gettime_stub.c b/gi/pyp-topics/src/clock_gettime_stub.c new file mode 100644 index 00000000..1fb03a18 --- /dev/null +++ b/gi/pyp-topics/src/clock_gettime_stub.c @@ -0,0 +1,141 @@ +/* + * Copyright (c), MM Weiss + * All rights reserved. + * + * Redistribution and use in source and binary forms, with or without modification, + * are permitted provided that the following conditions are met: + * + * 1. Redistributions of source code must retain the above copyright notice, + * this list of conditions and the following disclaimer. + * + * 2. Redistributions in binary form must reproduce the above copyright notice, + * this list of conditions and the following disclaimer in the documentation + * and/or other materials provided with the distribution. + * + * 3. Neither the name of the MM Weiss nor the names of its contributors + * may be used to endorse or promote products derived from this software without + * specific prior written permission. + * + * THIS SOFTWARE IS PROVIDED BY THE COPYRIGHT HOLDERS AND CONTRIBUTORS "AS IS" AND ANY + * EXPRESS OR IMPLIED WARRANTIES, INCLUDING, BUT NOT LIMITED TO, THE IMPLIED WARRANTIES + * OF MERCHANTABILITY AND FITNESS FOR A PARTICULAR PURPOSE ARE DISCLAIMED. IN NO EVENT + * SHALL THE COPYRIGHT OWNER OR CONTRIBUTORS BE LIABLE FOR ANY DIRECT, INDIRECT, INCIDENTAL, + * SPECIAL, EXEMPLARY, OR CONSEQUENTIAL DAMAGES (INCLUDING, BUT NOT LIMITED TO, PROCUREMENT + * OF SUBSTITUTE GOODS OR SERVICES; LOSS OF USE, DATA, OR PROFITS; OR BUSINESS INTERRUPTION) + * HOWEVER CAUSED AND ON ANY THEORY OF LIABILITY, WHETHER IN CONTRACT, STRICT LIABILITY, OR + * TORT (INCLUDING NEGLIGENCE OR OTHERWISE) ARISING IN ANY WAY OUT OF THE USE OF THIS SOFTWARE, + * EVEN IF ADVISED OF THE POSSIBILITY OF SUCH DAMAGE. + */ + +/* + * clock_gettime_stub.c + * gcc -Wall -c clock_gettime_stub.c + * posix realtime functions; MacOS user space glue + */ + +/* @comment + * other possible implementation using intel builtin rdtsc + * rdtsc-workaround: http://www.mcs.anl.gov/~kazutomo/rdtsc.html + * + * we could get the ticks by doing this + * + * __asm __volatile("mov %%ebx, %%esi\n\t" + * "cpuid\n\t" + * "xchg %%esi, %%ebx\n\t" + * "rdtsc" + * : "=a" (a), + * "=d" (d) + * ); + + * we could even replace our tricky sched_yield call by assembly code to get a better accurency, + * anyway the following C stub will satisfy 99% of apps using posix clock_gettime call, + * moreover, the setter version (clock_settime) could be easly written using mach primitives: + * http://www.opensource.apple.com/source/xnu/xnu-${VERSION}/osfmk/man/ (clock_[set|get]_time) + * + * hackers don't be crackers, don't you use a flush toilet? + * + * + * @see draft: ./posix-realtime-stub/posix-realtime-stub.c + * + */ + + +#ifdef __APPLE__ + +#pragma weak clock_gettime + +#include <sys/time.h> +#include <sys/resource.h> +#include <mach/mach.h> +#include <mach/clock.h> +#include <mach/mach_time.h> +#include <errno.h> +#include <unistd.h> +#include <sched.h> + +typedef enum { + CLOCK_REALTIME, + CLOCK_MONOTONIC, + CLOCK_PROCESS_CPUTIME_ID, + CLOCK_THREAD_CPUTIME_ID +} clockid_t; + +static mach_timebase_info_data_t __clock_gettime_inf; + +int clock_gettime(clockid_t clk_id, struct timespec *tp) { + kern_return_t ret; + clock_serv_t clk; + clock_id_t clk_serv_id; + mach_timespec_t tm; + + uint64_t start, end, delta, nano; + + //task_basic_info_data_t tinfo; + //task_thread_times_info_data_t ttinfo; + //mach_msg_type_number_t tflag; + + int retval = -1; + switch (clk_id) { + case CLOCK_REALTIME: + case CLOCK_MONOTONIC: + clk_serv_id = clk_id == CLOCK_REALTIME ? CALENDAR_CLOCK : SYSTEM_CLOCK; + if (KERN_SUCCESS == (ret = host_get_clock_service(mach_host_self(), clk_serv_id, &clk))) { + if (KERN_SUCCESS == (ret = clock_get_time(clk, &tm))) { + tp->tv_sec = tm.tv_sec; + tp->tv_nsec = tm.tv_nsec; + retval = 0; + } + } + if (KERN_SUCCESS != ret) { + errno = EINVAL; + retval = -1; + } + break; + case CLOCK_PROCESS_CPUTIME_ID: + case CLOCK_THREAD_CPUTIME_ID: + start = mach_absolute_time(); + if (clk_id == CLOCK_PROCESS_CPUTIME_ID) { + getpid(); + } else { + sched_yield(); + } + end = mach_absolute_time(); + delta = end - start; + if (0 == __clock_gettime_inf.denom) { + mach_timebase_info(&__clock_gettime_inf); + } + nano = delta * __clock_gettime_inf.numer / __clock_gettime_inf.denom; + tp->tv_sec = nano * 1e-9; + tp->tv_nsec = nano - (tp->tv_sec * 1e9); + retval = 0; + break; + default: + errno = EINVAL; + retval = -1; + } + return retval; +} + +#endif // __APPLE__ + +/* EOF */ |