| 1 |
30 |
unneback |
/* timer.c
|
| 2 |
|
|
*
|
| 3 |
|
|
* This file contains the initialization code for the IDT 4650 timer driver.
|
| 4 |
|
|
*
|
| 5 |
|
|
* Author: Craig Lebakken <craigl@transition.com>
|
| 6 |
|
|
*
|
| 7 |
|
|
* COPYRIGHT (c) 1996 by Transition Networks Inc.
|
| 8 |
|
|
*
|
| 9 |
|
|
* To anyone who acknowledges that this file is provided "AS IS"
|
| 10 |
|
|
* without any express or implied warranty:
|
| 11 |
|
|
* permission to use, copy, modify, and distribute this file
|
| 12 |
|
|
* for any purpose is hereby granted without fee, provided that
|
| 13 |
|
|
* the above copyright notice and this notice appears in all
|
| 14 |
|
|
* copies, and that the name of Transition Networks not be used in
|
| 15 |
|
|
* advertising or publicity pertaining to distribution of the
|
| 16 |
|
|
* software without specific, written prior permission.
|
| 17 |
|
|
* Transition Networks makes no representations about the suitability
|
| 18 |
|
|
* of this software for any purpose.
|
| 19 |
|
|
*
|
| 20 |
|
|
* derived from src/lib/libbsp/no_cpu/no_bsp/timer/timer.c
|
| 21 |
|
|
*
|
| 22 |
|
|
* This file manages the benchmark timer used by the RTEMS Timing Test
|
| 23 |
|
|
* Suite. Each measured time period is demarcated by calls to
|
| 24 |
|
|
* Timer_initialize() and Read_timer(). Read_timer() usually returns
|
| 25 |
|
|
* the number of microseconds since Timer_initialize() exitted.
|
| 26 |
|
|
*
|
| 27 |
|
|
* NOTE: It is important that the timer start/stop overhead be
|
| 28 |
|
|
* determined when porting or modifying this code.
|
| 29 |
|
|
*
|
| 30 |
|
|
* COPYRIGHT (c) 1989-1999.
|
| 31 |
|
|
* On-Line Applications Research Corporation (OAR).
|
| 32 |
|
|
*
|
| 33 |
|
|
* The license and distribution terms for this file may be
|
| 34 |
|
|
* found in the file LICENSE in this distribution or at
|
| 35 |
|
|
* http://www.OARcorp.com/rtems/license.html.
|
| 36 |
|
|
*
|
| 37 |
|
|
* $Id: timer.c,v 1.2 2001-09-27 12:01:22 chris Exp $
|
| 38 |
|
|
*/
|
| 39 |
|
|
|
| 40 |
|
|
/*
|
| 41 |
|
|
* Rather than deleting this, it is commented out to (hopefully) help
|
| 42 |
|
|
* the submitter send updates.
|
| 43 |
|
|
*
|
| 44 |
|
|
* static char _sccsid[] = "@(#)timer.c 08/20/96 1.5\n";
|
| 45 |
|
|
*/
|
| 46 |
|
|
|
| 47 |
|
|
|
| 48 |
|
|
#include <rtems.h>
|
| 49 |
|
|
|
| 50 |
|
|
#define CLOCKS_PER_MICROSECOND ( CPU_CLOCK_RATE_MHZ )
|
| 51 |
|
|
#define TIMER_MAX_VALUE 0xffffffff
|
| 52 |
|
|
|
| 53 |
|
|
extern unsigned32 mips_read_timer( void );
|
| 54 |
|
|
|
| 55 |
|
|
static rtems_boolean Timer_driver_Find_average_overhead;
|
| 56 |
|
|
static unsigned32 Timer_initial_value = 0;
|
| 57 |
|
|
|
| 58 |
|
|
void Timer_initialize( void )
|
| 59 |
|
|
{
|
| 60 |
|
|
Timer_initial_value = mips_read_timer();
|
| 61 |
|
|
/*
|
| 62 |
|
|
* Somehow start the timer
|
| 63 |
|
|
*/
|
| 64 |
|
|
|
| 65 |
|
|
/* Timer on 4650 is always running */
|
| 66 |
|
|
}
|
| 67 |
|
|
|
| 68 |
|
|
/*
|
| 69 |
|
|
* The following controls the behavior of Read_timer().
|
| 70 |
|
|
*
|
| 71 |
|
|
* AVG_OVEREHAD is the overhead for starting and stopping the timer. It
|
| 72 |
|
|
* is usually deducted from the number returned.
|
| 73 |
|
|
*
|
| 74 |
|
|
* LEAST_VALID is the lowest number this routine should trust. Numbers
|
| 75 |
|
|
* below this are "noise" and zero is returned.
|
| 76 |
|
|
*/
|
| 77 |
|
|
|
| 78 |
|
|
#define AVG_OVERHEAD 8 /* It typically takes X.X microseconds */
|
| 79 |
|
|
/* (Y countdowns) to start/stop the timer. */
|
| 80 |
|
|
/* This value is in cycles. */
|
| 81 |
|
|
#define LEAST_VALID 1 /* Don't trust a clicks value lower than this */
|
| 82 |
|
|
|
| 83 |
|
|
int Read_timer( void )
|
| 84 |
|
|
{
|
| 85 |
|
|
unsigned64 clicks;
|
| 86 |
|
|
unsigned32 total;
|
| 87 |
|
|
|
| 88 |
|
|
/*
|
| 89 |
|
|
* Read the timer and see how many clicks it has been since we started.
|
| 90 |
|
|
*/
|
| 91 |
|
|
|
| 92 |
|
|
clicks = mips_read_timer(); /* XXX: read some HW here */
|
| 93 |
|
|
if (clicks < Timer_initial_value)
|
| 94 |
|
|
{
|
| 95 |
|
|
clicks += TIMER_MAX_VALUE;
|
| 96 |
|
|
}
|
| 97 |
|
|
clicks -= Timer_initial_value;
|
| 98 |
|
|
|
| 99 |
|
|
/*
|
| 100 |
|
|
* Total is calculated by taking into account the number of timer overflow
|
| 101 |
|
|
* interrupts since the timer was initialized and clicks since the last
|
| 102 |
|
|
* interrupts.
|
| 103 |
|
|
*/
|
| 104 |
|
|
#if 0 /* leave total in number of cycles */
|
| 105 |
|
|
total = clicks / CLOCKS_PER_MICROSECOND;
|
| 106 |
|
|
#else
|
| 107 |
|
|
total = clicks;
|
| 108 |
|
|
#endif
|
| 109 |
|
|
|
| 110 |
|
|
if ( Timer_driver_Find_average_overhead == 1 )
|
| 111 |
|
|
return total; /* in # cycles units */
|
| 112 |
|
|
else {
|
| 113 |
|
|
if ( total < LEAST_VALID )
|
| 114 |
|
|
return 0; /* below timer resolution */
|
| 115 |
|
|
/*
|
| 116 |
|
|
* leave total in cycles
|
| 117 |
|
|
*/
|
| 118 |
|
|
return (total - AVG_OVERHEAD);
|
| 119 |
|
|
}
|
| 120 |
|
|
}
|
| 121 |
|
|
|
| 122 |
|
|
/*
|
| 123 |
|
|
* Empty function call used in loops to measure basic cost of looping
|
| 124 |
|
|
* in Timing Test Suite.
|
| 125 |
|
|
*/
|
| 126 |
|
|
|
| 127 |
|
|
rtems_status_code Empty_function( void )
|
| 128 |
|
|
{
|
| 129 |
|
|
return RTEMS_SUCCESSFUL;
|
| 130 |
|
|
}
|
| 131 |
|
|
|
| 132 |
|
|
void Set_find_average_overhead(
|
| 133 |
|
|
rtems_boolean find_flag
|
| 134 |
|
|
)
|
| 135 |
|
|
{
|
| 136 |
|
|
Timer_driver_Find_average_overhead = find_flag;
|
| 137 |
|
|
}
|
| 138 |
|
|
|
