107 lines
3.4 KiB
C
107 lines
3.4 KiB
C
/****************************************************************************
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* arch/z16/src/common/z16_udelay.c
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*
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* SPDX-License-Identifier: Apache-2.0
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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 <sys/types.h>
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#include <nuttx/arch.h>
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#ifdef CONFIG_BOARD_LOOPSPERMSEC
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/****************************************************************************
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* Pre-processor Definitions
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****************************************************************************/
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#define CONFIG_BOARD_LOOPSPER100USEC ((CONFIG_BOARD_LOOPSPERMSEC+5)/10)
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#define CONFIG_BOARD_LOOPSPER10USEC ((CONFIG_BOARD_LOOPSPERMSEC+50)/100)
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#define CONFIG_BOARD_LOOPSPERUSEC ((CONFIG_BOARD_LOOPSPERMSEC+500)/1000)
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/****************************************************************************
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* Public Functions
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****************************************************************************/
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/****************************************************************************
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* Name: up_udelay
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*
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* Description:
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* Delay inline for the requested number of microseconds. NOTE: Because
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* of all of the setup, several microseconds will be lost before the actual
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* timing loop begins. Thus, the delay will always be a few microseconds
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* longer than requested.
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*
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* *** NOT multi-tasking friendly ***
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*
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* ASSUMPTIONS:
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* The setting CONFIG_BOARD_LOOPSPERMSEC has been calibrated
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*
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****************************************************************************/
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void up_udelay(useconds_t microseconds)
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{
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volatile int i;
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/* We'll do this a little at a time because we expect that the
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* CONFIG_BOARD_LOOPSPERUSEC is very inaccurate during to truncation in
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* the divisions of its calculation. We'll use the largest values that
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* we can in order to prevent significant error buildup in the loops.
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*/
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while (microseconds > 1000)
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{
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for (i = 0; i < CONFIG_BOARD_LOOPSPERMSEC; i++)
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{
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}
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microseconds -= 1000;
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}
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while (microseconds > 100)
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{
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for (i = 0; i < CONFIG_BOARD_LOOPSPER100USEC; i++)
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{
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}
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microseconds -= 100;
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}
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while (microseconds > 10)
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{
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for (i = 0; i < CONFIG_BOARD_LOOPSPER10USEC; i++)
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{
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}
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microseconds -= 10;
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}
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while (microseconds > 0)
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{
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for (i = 0; i < CONFIG_BOARD_LOOPSPERUSEC; i++)
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{
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}
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microseconds--;
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}
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}
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#endif /* CONFIG_BOARD_LOOPSPERMSEC */
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