gen/nanosleep.c

   1 /*
   2  * Copyright (c) 1999 Apple Computer, Inc. All rights reserved.
   3  *
   4  * @APPLE_LICENSE_HEADER_START@
   5  *
   6  * Copyright (c) 1999-2003 Apple Computer, Inc.  All Rights Reserved.
   7  *
   8  * This file contains Original Code and/or Modifications of Original Code
   9  * as defined in and that are subject to the Apple Public Source License
  10  * Version 2.0 (the 'License'). You may not use this file except in
  11  * compliance with the License. Please obtain a copy of the License at
  12  * http://www.opensource.apple.com/apsl/ and read it before using this
  13  * file.
  14  *
  15  * The Original Code and all software distributed under the License are
  16  * distributed on an 'AS IS' basis, WITHOUT WARRANTY OF ANY KIND, EITHER
  17  * EXPRESS OR IMPLIED, AND APPLE HEREBY DISCLAIMS ALL SUCH WARRANTIES,
  18  * INCLUDING WITHOUT LIMITATION, ANY WARRANTIES OF MERCHANTABILITY,
  19  * FITNESS FOR A PARTICULAR PURPOSE, QUIET ENJOYMENT OR NON-INFRINGEMENT.
  20  * Please see the License for the specific language governing rights and
  21  * limitations under the License.
  22  *
  23  * @APPLE_LICENSE_HEADER_END@
  24  */
  25
  26 #include <errno.h>
  27 #include <sys/time.h>
  28 #include <mach/mach_error.h>
  29 #include <mach/mach_time.h>
  30 #include <stdio.h>
  31
  32 int
  33 nanosleep(const struct timespec *requested_time, struct timespec *remaining_time) {
  34     kern_return_t ret;
  35     mach_timespec_t remain;
  36     mach_timespec_t current;
  37     uint64_t end;
  38     static double ratio = 0.0, rratio;
  39
  40     if ((requested_time == NULL) || (requested_time->tv_sec < 0) || (requested_time->tv_nsec > NSEC_PER_SEC)) {
  41         errno = EINVAL;
  42         return -1;
  43     }
  44
  45     if (ratio == 0.0) {
  46         struct mach_timebase_info info;
  47         ret = mach_timebase_info(&info);
  48         if (ret != KERN_SUCCESS) {
  49             fprintf(stderr, "mach_timebase_info() failed: %s\n", mach_error_string(ret));
  50             errno = EAGAIN;
  51             return -1;
  52         }
  53         ratio = (double)info.numer / ((double)info.denom * NSEC_PER_SEC);
  54         rratio = (double)info.denom / (double)info.numer;
  55     }
  56
  57     /* use rratio to avoid division */
  58     end = mach_absolute_time() + (uint64_t)(((double)requested_time->tv_sec * NSEC_PER_SEC + (double)requested_time->tv_nsec) * rratio);
  59     ret = mach_wait_until(end);
  60     if (ret != KERN_SUCCESS) {
  61         if (ret == KERN_ABORTED) {
  62             errno = EINTR;
  63             if (remaining_time != NULL) {
  64                 uint64_t now = mach_absolute_time();
  65                 double delta;
  66                 if (now > end)
  67                     now = end;
  68                 delta = (end - now) * ratio;
  69                 remaining_time->tv_sec = delta;
  70                 remaining_time->tv_nsec = NSEC_PER_SEC * (delta - remaining_time->tv_sec);
  71             }
  72         } else {
  73             errno = EINVAL;
  74         }
  75         return -1;
  76     }
  77     return 0;
  78 }