cdsa/cdsa_utilities/timeflow.cpp

   1 /*
   2  * Copyright (c) 2000-2001 Apple Computer, Inc. All Rights Reserved.
   3  *
   4  * The contents of this file constitute Original Code as defined in and are
   5  * subject to the Apple Public Source License Version 1.2 (the 'License').
   6  * You may not use this file except in compliance with the License. Please obtain
   7  * a copy of the License at http://www.apple.com/publicsource and read it before
   8  * using this file.
   9  *
  10  * This Original Code and all software distributed under the License are
  11  * distributed on an 'AS IS' basis, WITHOUT WARRANTY OF ANY KIND, EITHER EXPRESS
  12  * OR IMPLIED, AND APPLE HEREBY DISCLAIMS ALL SUCH WARRANTIES, INCLUDING WITHOUT
  13  * LIMITATION, ANY WARRANTIES OF MERCHANTABILITY, FITNESS FOR A PARTICULAR
  14  * PURPOSE, QUIET ENJOYMENT OR NON-INFRINGEMENT. Please see the License for the
  15  * specific language governing rights and limitations under the License.
  16  */
  17
  18
  19 //
  20 // timeflow - abstract view of the flow of time
  21 //
  22 #include "timeflow.h"
  23 #include <sys/time.h>
  24 #include <math.h>
  25
  26
  27 namespace Security {
  28 namespace Time {
  29
  30
  31 //
  32 // Get "now"
  33 //
  34 Absolute now()
  35 {
  36     struct timeval tv;
  37     gettimeofday(&tv, NULL);
  38     return tv.tv_sec + double(tv.tv_usec) / 1E6;
  39 }
  40
  41
  42 //
  43 // OOL Conversions
  44 //
  45 Absolute::Absolute(const struct timeval &tv)
  46 { mValue = tv.tv_sec + double(tv.tv_usec) / 1E6; }
  47
  48 Absolute::operator struct timeval () const
  49 {
  50     struct timeval tv;
  51     if (mValue > LONG_MAX) {
  52         tv.tv_sec = LONG_MAX;
  53         tv.tv_usec = 0;
  54     } else {
  55         tv.tv_sec = int32_t(mValue);
  56         double intPart;
  57         tv.tv_usec = int32_t(modf(mValue, &intPart));
  58     }
  59     return tv;
  60 }
  61
  62 struct timeval Interval::timevalInterval() const
  63 {
  64     struct timeval tv;
  65     if (mValue > LONG_MAX) {
  66         tv.tv_sec = LONG_MAX;
  67         tv.tv_usec = 0;
  68     } else if (mValue < 0) {
  69         tv.tv_sec = tv.tv_usec = 0;
  70     } else {
  71         tv.tv_sec = int32_t(mValue);
  72         double intPart;
  73         tv.tv_usec = int32_t(modf(mValue, &intPart));
  74     }
  75     return tv;
  76 }
  77
  78
  79 //
  80 // Estimate resolution at given time.
  81 //
  82 // BSD select(2) has theoretical microsecond resolution, but the underlying
  83 // Mach system deals with milliseconds, so we report that conservatively.
  84 // Sometime in the future when the sun is near collapse, residual resolution
  85 // of a double will drop under 1E-3, but we won't worry about that just yet.
  86 //
  87 Interval resolution(Absolute)
  88 {
  89     return 0.001;
  90 }
  91
  92
  93 }       // end namespace Time
  94 }       // end namespace Security