[ac7d5ef0] | 1 | /* timer.c |
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| 2 | * |
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| 3 | * This file manages the interval timer on the PA-RISC. |
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| 4 | * |
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| 5 | * NOTE: It is important that the timer start/stop overhead be |
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| 6 | * determined when porting or modifying this code. |
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| 7 | * |
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| 8 | * COPYRIGHT (c) 1989, 1990, 1991, 1992, 1993, 1994. |
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| 9 | * On-Line Applications Research Corporation (OAR). |
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| 10 | * All rights assigned to U.S. Government, 1994. |
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| 11 | * |
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| 12 | * This material may be reproduced by or for the U.S. Government pursuant |
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| 13 | * to the copyright license under the clause at DFARS 252.227-7013. This |
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| 14 | * notice must appear in all copies of this file and its derivatives. |
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| 15 | * |
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| 16 | * $Id$ |
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| 17 | */ |
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| 18 | |
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| 19 | #include <rtems.h> |
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| 20 | |
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| 21 | volatile rtems_unsigned32 Timer_starting; |
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| 22 | rtems_boolean Timer_driver_Find_average_overhead; |
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| 23 | |
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| 24 | void Timer_initialize() |
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| 25 | { |
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| 26 | Timer_starting = get_itimer(); |
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| 27 | } |
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| 28 | |
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| 29 | #define AVG_OVERHEAD 0 /* It typically takes 3.0 microseconds */ |
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| 30 | /* (6 countdowns) to start/stop the timer. */ |
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| 31 | #define LEAST_VALID 1 /* Don't trust a value lower than this */ |
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| 32 | |
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| 33 | int Read_timer() |
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| 34 | { |
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| 35 | rtems_unsigned32 clicks; |
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| 36 | rtems_unsigned32 total; |
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| 37 | |
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| 38 | clicks = get_itimer(); |
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| 39 | |
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| 40 | total = clicks - Timer_starting; |
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| 41 | |
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| 42 | if ( Timer_driver_Find_average_overhead == 1 ) |
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| 43 | return total; /* in XXX microsecond units */ |
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| 44 | |
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| 45 | else { |
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| 46 | if ( total < LEAST_VALID ) |
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| 47 | return 0; /* below timer resolution */ |
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| 48 | return (total - AVG_OVERHEAD); |
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| 49 | } |
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| 50 | } |
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| 51 | |
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| 52 | rtems_status_code Empty_function( void ) |
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| 53 | { |
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| 54 | return RTEMS_SUCCESSFUL; |
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| 55 | } |
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| 56 | |
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| 57 | void Set_find_average_overhead( |
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| 58 | rtems_boolean find_flag |
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| 59 | ) |
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| 60 | { |
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| 61 | Timer_driver_Find_average_overhead = find_flag; |
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| 62 | } |
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