mrm332/btimer/btimer.c

0001 /* SPDX-License-Identifier: BSD-2-Clause */
0002
0003 /*
0004  *  COPYRIGHT (c) 1989-1999.
0005  *  On-Line Applications Research Corporation (OAR).
0006  *
0007  * Redistribution and use in source and binary forms, with or without
0008  * modification, are permitted provided that the following conditions
0009  * are met:
0010  * 1. Redistributions of source code must retain the above copyright
0011  *    notice, this list of conditions and the following disclaimer.
0012  * 2. Redistributions in binary form must reproduce the above copyright
0013  *    notice, this list of conditions and the following disclaimer in the
0014  *    documentation and/or other materials provided with the distribution.
0015  *
0016  * THIS SOFTWARE IS PROVIDED BY THE COPYRIGHT HOLDERS AND CONTRIBUTORS "AS IS"
0017  * AND ANY EXPRESS OR IMPLIED WARRANTIES, INCLUDING, BUT NOT LIMITED TO, THE
0018  * IMPLIED WARRANTIES OF MERCHANTABILITY AND FITNESS FOR A PARTICULAR PURPOSE
0019  * ARE DISCLAIMED. IN NO EVENT SHALL THE COPYRIGHT OWNER OR CONTRIBUTORS BE
0020  * LIABLE FOR ANY DIRECT, INDIRECT, INCIDENTAL, SPECIAL, EXEMPLARY, OR
0021  * CONSEQUENTIAL DAMAGES (INCLUDING, BUT NOT LIMITED TO, PROCUREMENT OF
0022  * SUBSTITUTE GOODS OR SERVICES; LOSS OF USE, DATA, OR PROFITS; OR BUSINESS
0023  * INTERRUPTION) HOWEVER CAUSED AND ON ANY THEORY OF LIABILITY, WHETHER IN
0024  * CONTRACT, STRICT LIABILITY, OR TORT (INCLUDING NEGLIGENCE OR OTHERWISE)
0025  * ARISING IN ANY WAY OUT OF THE USE OF THIS SOFTWARE, EVEN IF ADVISED OF THE
0026  * POSSIBILITY OF SUCH DAMAGE.
0027  */
0028
0029 #include <bsp.h>
0030 #include <rtems/btimer.h>
0031
0032 bool benchmark_timer_find_average_overhead;
0033
0034 void benchmark_timer_initialize( void )
0035 {
0036 }
0037
0038 /*
0039  *  The following controls the behavior of benchmark_timer_read().
0040  *
0041  *  FIND_AVG_OVERHEAD *  instructs the routine to return the "raw" count.
0042  *
0043  *  AVG_OVEREHAD is the overhead for starting and stopping the timer.  It
0044  *  is usually deducted from the number returned.
0045  *
0046  *  LEAST_VALID is the lowest number this routine should trust.  Numbers
0047  *  below this are "noise" and zero is returned.
0048  */
0049
0050 #define AVG_OVERHEAD      0  /* It typically takes X.X microseconds */
0051                              /* (Y countdowns) to start/stop the timer. */
0052                              /* This value is in microseconds. */
0053 #define LEAST_VALID       1  /* Don't trust a clicks value lower than this */
0054
0055 /*
0056  * Return timer value in 1/2-microsecond units
0057  */
0058 benchmark_timer_t benchmark_timer_read( void )
0059 {
0060   uint32_t         total;
0061   total = 0;
0062
0063   if ( benchmark_timer_find_average_overhead == true )
0064     return total;          /* in XXX microsecond units */
0065
0066   if ( total < LEAST_VALID )
0067     return 0;            /* below timer resolution */
0068
0069   return (total - AVG_OVERHEAD);
0070 }
0071
0072 void benchmark_timer_disable_subtracting_average_overhead(
0073   bool find_flag
0074 )
0075 {
0076   benchmark_timer_find_average_overhead = find_flag;
0077 }