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[/] [openrisc/] [trunk/] [rtos/] [rtems/] [c/] [src/] [lib/] [libcpu/] [a29k/] [timer/] [timer.c] - Blame information for rev 228

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/*  timer.c
 *
 *  This file manages the benchmark timer used by the RTEMS Timing Test
 *  Suite.  Each measured time period is demarcated by calls to
 *  Timer_initialize() and Read_timer().  Read_timer() usually returns
 *  the number of microseconds since Timer_initialize() exitted.
 *
 *  NOTE: It is important that the timer start/stop overhead be
 *        determined when porting or modifying this code.
 *
 *  COPYRIGHT (c) 1989, 1990, 1991, 1992, 1993, 1994.
 *  On-Line Applications Research Corporation (OAR).
 *  All rights assigned to U.S. Government, 1994.
 *
 *  This material may be reproduced by or for the U.S. Government pursuant
 *  to the copyright license under the clause at DFARS 252.227-7013.  This
 *  notice must appear in all copies of this file and its derivatives.
 *
 *  $Id: timer.c,v 1.2 2001-09-27 12:01:20 chris Exp $
 */
 
#ifndef lint
static char _sccsid[] = "@(#)timer.c 05/07/96     1.4\n";
#endif
 
#include <rtems.h>
#include <bsp.h>
 
#define CLOCKS_PER_MICROSECOND ( CPU_CLOCK_RATE_MHZ )
#define TIMER_MAX_VALUE 0xffffffff
 
static unsigned32 read_timer( void )
{
  return 0; /* do something with real hardware here */
}
 
static rtems_boolean Timer_driver_Find_average_overhead;
static unsigned32 Timer_initial_value = 0;
 
void Timer_initialize( void )
{
   Timer_initial_value = read_timer();
 
  /*
   *  Somehow start the timer
   */
 
  /* Timer on 4650 is always running */
}
 
/*
 *  The following controls the behavior of Read_timer().
 *
 *  AVG_OVEREHAD is the overhead for starting and stopping the timer.  It
 *  is usually deducted from the number returned.
 *
 *  LEAST_VALID is the lowest number this routine should trust.  Numbers
 *  below this are "noise" and zero is returned.
 */
 
#define AVG_OVERHEAD      8  /* It typically takes X.X microseconds */
                             /* (Y countdowns) to start/stop the timer. */
                             /* This value is in cycles. */
#define LEAST_VALID       1  /* Don't trust a clicks value lower than this */
 
int Read_timer( void )
{
  unsigned64 clicks;
  unsigned32 total;
 
  /*
   *  Read the timer and see how many clicks it has been since we started.
   */
 
  clicks = read_timer();   /* XXX: read some HW here */
  if (clicks < Timer_initial_value)
  {
      clicks += TIMER_MAX_VALUE;
  }
  clicks -= Timer_initial_value;
 
  /*
   *  Total is calculated by taking into account the number of timer overflow
   *  interrupts since the timer was initialized and clicks since the last
   *  interrupts.
   */
#if 0 /* leave total in number of cycles */
   total = clicks / CLOCKS_PER_MICROSECOND;
#else
   total = clicks;
#endif
 
  if ( Timer_driver_Find_average_overhead == 1 )
    return total;          /* in # cycles units */
  else {
    if ( total < LEAST_VALID )
      return 0;            /* below timer resolution */
  /*
   *  leave total in cycles
   */
      return (total - AVG_OVERHEAD);
    }
}
 
/*
 *  Empty function call used in loops to measure basic cost of looping
 *  in Timing Test Suite.
 */
 
rtems_status_code Empty_function( void )
{
  return RTEMS_SUCCESSFUL;
}
 
void Set_find_average_overhead(
  rtems_boolean find_flag
)
{
  Timer_driver_Find_average_overhead = find_flag;
}
 

Line No.	Rev	Author	Line
1	30	unneback	`/* timer.c`
2			`*`
3			`* This file manages the benchmark timer used by the RTEMS Timing Test`
4			`* Suite. Each measured time period is demarcated by calls to`
5			`* Timer_initialize() and Read_timer(). Read_timer() usually returns`
6			`* the number of microseconds since Timer_initialize() exitted.`
7			`*`
8			`* NOTE: It is important that the timer start/stop overhead be`
9			`* determined when porting or modifying this code.`
10			`*`
11			`* COPYRIGHT (c) 1989, 1990, 1991, 1992, 1993, 1994.`
12			`* On-Line Applications Research Corporation (OAR).`
13			`* All rights assigned to U.S. Government, 1994.`
14			`*`
15			`* This material may be reproduced by or for the U.S. Government pursuant`
16			`* to the copyright license under the clause at DFARS 252.227-7013. This`
17			`* notice must appear in all copies of this file and its derivatives.`
18			`*`
19			`* $Id: timer.c,v 1.2 2001-09-27 12:01:20 chris Exp $`
20			`*/`
21
22			`#ifndef lint`
23			`static char _sccsid[] = "@(#)timer.c 05/07/96 1.4\n";`
24			`#endif`
25
26			`#include <rtems.h>`
27			`#include <bsp.h>`
28
29			`#define CLOCKS_PER_MICROSECOND ( CPU_CLOCK_RATE_MHZ )`
30			`#define TIMER_MAX_VALUE 0xffffffff`
31
32			`static unsigned32 read_timer( void )`
33			`{`
34			`return 0; /* do something with real hardware here */`
35			`}`
36
37			`static rtems_boolean Timer_driver_Find_average_overhead;`
38			`static unsigned32 Timer_initial_value = 0;`
39
40			`void Timer_initialize( void )`
41			`{`
42			`Timer_initial_value = read_timer();`
43
44			`/*`
45			`* Somehow start the timer`
46			`*/`
47
48			`/* Timer on 4650 is always running */`
49			`}`
50
51			`/*`
52			`* The following controls the behavior of Read_timer().`
53			`*`
54			`* AVG_OVEREHAD is the overhead for starting and stopping the timer. It`
55			`* is usually deducted from the number returned.`
56			`*`
57			`* LEAST_VALID is the lowest number this routine should trust. Numbers`
58			`* below this are "noise" and zero is returned.`
59			`*/`
60
61			`#define AVG_OVERHEAD 8 /* It typically takes X.X microseconds */`
62			`/* (Y countdowns) to start/stop the timer. */`
63			`/* This value is in cycles. */`
64			`#define LEAST_VALID 1 /* Don't trust a clicks value lower than this */`
65
66			`int Read_timer( void )`
67			`{`
68			`unsigned64 clicks;`
69			`unsigned32 total;`
70
71			`/*`
72			`* Read the timer and see how many clicks it has been since we started.`
73			`*/`
74
75			`clicks = read_timer(); /* XXX: read some HW here */`
76			`if (clicks < Timer_initial_value)`
77			`{`
78			`clicks += TIMER_MAX_VALUE;`
79			`}`
80			`clicks -= Timer_initial_value;`
81
82			`/*`
83			`* Total is calculated by taking into account the number of timer overflow`
84			`* interrupts since the timer was initialized and clicks since the last`
85			`* interrupts.`
86			`*/`
87			`#if 0 /* leave total in number of cycles */`
88			`total = clicks / CLOCKS_PER_MICROSECOND;`
89			`#else`
90			`total = clicks;`
91			`#endif`
92
93			`if ( Timer_driver_Find_average_overhead == 1 )`
94			`return total; /* in # cycles units */`
95			`else {`
96			`if ( total < LEAST_VALID )`
97			`return 0; /* below timer resolution */`
98			`/*`
99			`* leave total in cycles`
100			`*/`
101			`return (total - AVG_OVERHEAD);`
102			`}`
103			`}`
104
105			`/*`
106			`* Empty function call used in loops to measure basic cost of looping`
107			`* in Timing Test Suite.`
108			`*/`
109
110			`rtems_status_code Empty_function( void )`
111			`{`
112			`return RTEMS_SUCCESSFUL;`
113			`}`
114
115			`void Set_find_average_overhead(`
116			`rtems_boolean find_flag`
117			`)`
118			`{`
119			`Timer_driver_Find_average_overhead = find_flag;`
120			`}`
121

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[/] [openrisc/] [trunk/] [rtos/] [rtems/] [c/] [src/] [lib/] [libcpu/] [a29k/] [timer/] [timer.c] - Blame information for rev 228