[ac7d5ef0] | 1 | /* 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 | * $Id$ |
---|
| 20 | */ |
---|
| 21 | |
---|
| 22 | #include <rtems.h> |
---|
| 23 | #include <bsp.h> |
---|
| 24 | |
---|
| 25 | rtems_unsigned32 Timer_interrupts; |
---|
| 26 | rtems_boolean Timer_driver_Find_average_overhead; |
---|
| 27 | |
---|
| 28 | void Timer_initialize( void ) |
---|
| 29 | { |
---|
| 30 | |
---|
| 31 | /* |
---|
| 32 | * Timer has never overflowed. This may not be necessary on some |
---|
| 33 | * implemenations of timer but .... |
---|
| 34 | */ |
---|
| 35 | |
---|
| 36 | Timer_interrupts = 0; |
---|
| 37 | |
---|
| 38 | /* |
---|
| 39 | * Somehow start the timer |
---|
| 40 | */ |
---|
| 41 | } |
---|
| 42 | |
---|
| 43 | /* |
---|
| 44 | * The following controls the behavior of Read_timer(). |
---|
| 45 | * |
---|
| 46 | * AVG_OVEREHAD is the overhead for starting and stopping the timer. It |
---|
| 47 | * is usually deducted from the number returned. |
---|
| 48 | * |
---|
| 49 | * LEAST_VALID is the lowest number this routine should trust. Numbers |
---|
| 50 | * below this are "noise" and zero is returned. |
---|
| 51 | */ |
---|
| 52 | |
---|
| 53 | #define AVG_OVERHEAD 0 /* It typically takes X.X microseconds */ |
---|
| 54 | /* (Y countdowns) to start/stop the timer. */ |
---|
| 55 | /* This value is in microseconds. */ |
---|
| 56 | #define LEAST_VALID 1 /* Don't trust a clicks value lower than this */ |
---|
| 57 | |
---|
| 58 | int Read_timer( void ) |
---|
| 59 | { |
---|
| 60 | rtems_unsigned32 clicks; |
---|
| 61 | rtems_unsigned32 total; |
---|
| 62 | |
---|
| 63 | /* |
---|
| 64 | * Read the timer and see how many clicks it has been since we started. |
---|
| 65 | */ |
---|
| 66 | |
---|
| 67 | clicks = 0; /* XXX: read some HW here */ |
---|
| 68 | |
---|
| 69 | /* |
---|
| 70 | * Total is calculated by taking into account the number of timer overflow |
---|
| 71 | * interrupts since the timer was initialized and clicks since the last |
---|
| 72 | * interrupts. |
---|
| 73 | */ |
---|
| 74 | |
---|
| 75 | total = clicks * 0; |
---|
| 76 | |
---|
| 77 | if ( Timer_driver_Find_average_overhead == 1 ) |
---|
| 78 | return total; /* in XXX microsecond units */ |
---|
| 79 | else { |
---|
| 80 | if ( total < LEAST_VALID ) |
---|
| 81 | return 0; /* below timer resolution */ |
---|
| 82 | /* |
---|
| 83 | * Somehow convert total into microseconds |
---|
| 84 | */ |
---|
| 85 | return (total - AVG_OVERHEAD); |
---|
| 86 | } |
---|
| 87 | } |
---|
| 88 | |
---|
| 89 | /* |
---|
| 90 | * Empty function call used in loops to measure basic cost of looping |
---|
| 91 | * in Timing Test Suite. |
---|
| 92 | */ |
---|
| 93 | |
---|
| 94 | rtems_status_code Empty_function( void ) |
---|
| 95 | { |
---|
| 96 | return RTEMS_SUCCESSFUL; |
---|
| 97 | } |
---|
| 98 | |
---|
| 99 | void Set_find_average_overhead( |
---|
| 100 | rtems_boolean find_flag |
---|
| 101 | ) |
---|
| 102 | { |
---|
| 103 | Timer_driver_Find_average_overhead = find_flag; |
---|
| 104 | } |
---|
| 105 | |
---|