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/gecko_api/include/prinrval.h

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  1/* -*- Mode: C++; tab-width: 4; indent-tabs-mode: nil; c-basic-offset: 2 -*- */
  2/* ***** BEGIN LICENSE BLOCK *****
  3 * Version: MPL 1.1/GPL 2.0/LGPL 2.1
  4 *
  5 * The contents of this file are subject to the Mozilla Public License Version
  6 * 1.1 (the "License"); you may not use this file except in compliance with
  7 * the License. You may obtain a copy of the License at
  8 * http://www.mozilla.org/MPL/
  9 *
 10 * Software distributed under the License is distributed on an "AS IS" basis,
 11 * WITHOUT WARRANTY OF ANY KIND, either express or implied. See the License
 12 * for the specific language governing rights and limitations under the
 13 * License.
 14 *
 15 * The Original Code is the Netscape Portable Runtime (NSPR).
 16 *
 17 * The Initial Developer of the Original Code is
 18 * Netscape Communications Corporation.
 19 * Portions created by the Initial Developer are Copyright (C) 1998-2000
 20 * the Initial Developer. All Rights Reserved.
 21 *
 22 * Contributor(s):
 23 *
 24 * Alternatively, the contents of this file may be used under the terms of
 25 * either the GNU General Public License Version 2 or later (the "GPL"), or
 26 * the GNU Lesser General Public License Version 2.1 or later (the "LGPL"),
 27 * in which case the provisions of the GPL or the LGPL are applicable instead
 28 * of those above. If you wish to allow use of your version of this file only
 29 * under the terms of either the GPL or the LGPL, and not to allow others to
 30 * use your version of this file under the terms of the MPL, indicate your
 31 * decision by deleting the provisions above and replace them with the notice
 32 * and other provisions required by the GPL or the LGPL. If you do not delete
 33 * the provisions above, a recipient may use your version of this file under
 34 * the terms of any one of the MPL, the GPL or the LGPL.
 35 *
 36 * ***** END LICENSE BLOCK ***** */
 37
 38/*
 39** File:		prinrval.h
 40** Description:	API to interval timing functions of NSPR.
 41**
 42**
 43** NSPR provides interval times that are independent of network time
 44** of day values. Interval times are (in theory) accurate regardless
 45** of host processing requirements and also very cheap to acquire. It
 46** is expected that getting an interval time while in a synchronized
 47** function (holding one's lock).
 48**/
 49
 50#if !defined(prinrval_h)
 51#define prinrval_h
 52
 53#include "prtypes.h"
 54
 55PR_BEGIN_EXTERN_C
 56
 57/**********************************************************************/
 58/************************* TYPES AND CONSTANTS ************************/
 59/**********************************************************************/
 60
 61typedef PRUint32 PRIntervalTime;
 62
 63/***********************************************************************
 64** DEFINES:     PR_INTERVAL_MIN
 65**              PR_INTERVAL_MAX
 66** DESCRIPTION:
 67**  These two constants define the range (in ticks / second) of the
 68**  platform dependent type, PRIntervalTime. These constants bound both
 69**  the period and the resolution of a PRIntervalTime. 
 70***********************************************************************/
 71#define PR_INTERVAL_MIN 1000UL
 72#define PR_INTERVAL_MAX 100000UL
 73
 74/***********************************************************************
 75** DEFINES:     PR_INTERVAL_NO_WAIT
 76**              PR_INTERVAL_NO_TIMEOUT
 77** DESCRIPTION:
 78**  Two reserved constants are defined in the PRIntervalTime namespace.
 79**  They are used to indicate that the process should wait no time (return
 80**  immediately) or wait forever (never time out), respectively.
 81***********************************************************************/
 82#define PR_INTERVAL_NO_WAIT 0UL
 83#define PR_INTERVAL_NO_TIMEOUT 0xffffffffUL
 84
 85/**********************************************************************/
 86/****************************** FUNCTIONS *****************************/
 87/**********************************************************************/
 88
 89/***********************************************************************
 90** FUNCTION:    PR_IntervalNow
 91** DESCRIPTION:
 92**  Return the value of NSPR's free running interval timer. That timer
 93**  can be used to establish epochs and determine intervals (be computing
 94**  the difference between two times).
 95** INPUTS:      void
 96** OUTPUTS:     void
 97** RETURN:      PRIntervalTime
 98**  
 99** SIDE EFFECTS:
100**  None
101** RESTRICTIONS:
102**  The units of PRIntervalTime are platform dependent. They are chosen
103**  such that they are appropriate for the host OS, yet provide sufficient
104**  resolution and period to be useful to clients. 
105** MEMORY:      N/A
106** ALGORITHM:   Platform dependent
107***********************************************************************/
108NSPR_API(PRIntervalTime) PR_IntervalNow(void);
109
110/***********************************************************************
111** FUNCTION:    PR_TicksPerSecond
112** DESCRIPTION:
113**  Return the number of ticks per second for PR_IntervalNow's clock.
114**  The value will be in the range [PR_INTERVAL_MIN..PR_INTERVAL_MAX].
115** INPUTS:      void
116** OUTPUTS:     void
117** RETURN:      PRUint32
118**  
119** SIDE EFFECTS:
120**  None
121** RESTRICTIONS:
122**  None
123** MEMORY:      N/A
124** ALGORITHM:   N/A
125***********************************************************************/
126NSPR_API(PRUint32) PR_TicksPerSecond(void);
127
128/***********************************************************************
129** FUNCTION:    PR_SecondsToInterval
130**              PR_MillisecondsToInterval
131**              PR_MicrosecondsToInterval
132** DESCRIPTION:
133**  Convert standard clock units to platform dependent intervals.
134** INPUTS:      PRUint32
135** OUTPUTS:     void
136** RETURN:      PRIntervalTime
137**  
138** SIDE EFFECTS:
139**  None
140** RESTRICTIONS:
141**  Conversion may cause overflow, which is not reported.
142** MEMORY:      N/A
143** ALGORITHM:   N/A
144***********************************************************************/
145NSPR_API(PRIntervalTime) PR_SecondsToInterval(PRUint32 seconds);
146NSPR_API(PRIntervalTime) PR_MillisecondsToInterval(PRUint32 milli);
147NSPR_API(PRIntervalTime) PR_MicrosecondsToInterval(PRUint32 micro);
148
149/***********************************************************************
150** FUNCTION:    PR_IntervalToSeconds
151**              PR_IntervalToMilliseconds
152**              PR_IntervalToMicroseconds
153** DESCRIPTION:
154**  Convert platform dependent intervals to standard clock units.
155** INPUTS:      PRIntervalTime
156** OUTPUTS:     void
157** RETURN:      PRUint32
158**  
159** SIDE EFFECTS:
160**  None
161** RESTRICTIONS:
162**  Conversion may cause overflow, which is not reported.
163** MEMORY:      N/A
164** ALGORITHM:   N/A
165***********************************************************************/
166NSPR_API(PRUint32) PR_IntervalToSeconds(PRIntervalTime ticks);
167NSPR_API(PRUint32) PR_IntervalToMilliseconds(PRIntervalTime ticks);
168NSPR_API(PRUint32) PR_IntervalToMicroseconds(PRIntervalTime ticks);
169
170PR_END_EXTERN_C
171
172
173#endif /* !defined(prinrval_h) */
174
175/* prinrval.h */