73 lines
2.4 KiB
C
73 lines
2.4 KiB
C
/****************************************************************************
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* libs/libc/time/lib_difftime.c
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*
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* Licensed to the Apache Software Foundation (ASF) under one or more
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* contributor license agreements. See the NOTICE file distributed with
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* this work for additional information regarding copyright ownership. The
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* ASF licenses this file to you under the Apache License, Version 2.0 (the
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* "License"); you may not use this file except in compliance with the
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* License. You may obtain a copy of the License at
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*
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* http://www.apache.org/licenses/LICENSE-2.0
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*
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* Unless required by applicable law or agreed to in writing, software
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* distributed under the License is distributed on an "AS IS" BASIS, WITHOUT
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* WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied. See the
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* License for the specific language governing permissions and limitations
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* under the License.
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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.
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* 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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