87 lines
3.2 KiB
C
87 lines
3.2 KiB
C
/****************************************************************************
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* libc/time/lib_difftime.c
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*
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* Copyright (C) 2016-2017 Gregory Nutt. All rights reserved.
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* Author: Sebastien Lorquet <sebastien@lorquet.fr>
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*
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* Redistribution and use in source and binary forms, with or without
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* modification, are permitted provided that the following conditions
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* are met:
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*
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* 1. Redistributions of source code must retain the above copyright
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* notice, this list of conditions and the following disclaimer.
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* 2. Redistributions in binary form must reproduce the above copyright
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* notice, this list of conditions and the following disclaimer in
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* the documentation and/or other materials provided with the
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* distribution.
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* 3. Neither the name NuttX nor the names of its contributors may be
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* used to endorse or promote products derived from this software
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* without specific prior written permission.
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*
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* THIS SOFTWARE IS PROVIDED BY THE COPYRIGHT HOLDERS AND CONTRIBUTORS
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* "AS IS" AND ANY EXPRESS OR IMPLIED WARRANTIES, INCLUDING, BUT NOT
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* LIMITED TO, THE IMPLIED WARRANTIES OF MERCHANTABILITY AND FITNESS
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* FOR A PARTICULAR PURPOSE ARE DISCLAIMED. IN NO EVENT SHALL THE
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* COPYRIGHT OWNER OR CONTRIBUTORS BE LIABLE FOR ANY DIRECT, INDIRECT,
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* INCIDENTAL, SPECIAL, EXEMPLARY, OR CONSEQUENTIAL DAMAGES (INCLUDING,
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* BUT NOT LIMITED TO, PROCUREMENT OF SUBSTITUTE GOODS OR SERVICES; LOSS
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* OF USE, DATA, OR PROFITS; OR BUSINESS INTERRUPTION) HOWEVER CAUSED
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* AND ON ANY THEORY OF LIABILITY, WHETHER IN CONTRACT, STRICT
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* LIABILITY, OR TORT (INCLUDING NEGLIGENCE OR OTHERWISE) ARISING IN
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* ANY WAY OUT OF THE USE OF THIS SOFTWARE, EVEN IF ADVISED OF THE
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* POSSIBILITY OF SUCH DAMAGE.
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*
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****************************************************************************/
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/****************************************************************************
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* Included Files
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****************************************************************************/
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#include <nuttx/config.h>
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#include <nuttx/compiler.h>
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#include <stdint.h>
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#include <time.h>
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/****************************************************************************
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* Public Functions
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****************************************************************************/
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/****************************************************************************
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* Name: difftime
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*
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* Description:
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* The difftime() function returns the number of seconds elapsed
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* between time time1 and time time0, represented as a double or a float.
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* Float is used if the platform does not support double. However, when
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* using a float, some precision may be lost for big differences.
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*
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****************************************************************************/
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#ifdef CONFIG_HAVE_DOUBLE
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double difftime(time_t time1, time_t time0)
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{
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return (double)time1 - (double)time0;
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}
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#else
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float difftime(time_t time1, time_t time0)
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{
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if (time1 >= time0)
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{
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/* Result will be positive (even though bit 31 may be set on very large
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* differences!)
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*/
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return (float)((uint32_t)(time1 - time0));
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}
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else
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{
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/* Result will be negative. REVISIT: Am I missing any case where bit 31
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* might not be set?
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*/
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return (float)((int32_t)(time1 - time0));
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}
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}
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#endif
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