[486c329] | 1 | /* Timer_init() |
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| 2 | * |
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| 3 | * This routine initializes a timer in efi68k's DP8570A TCP |
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| 4 | * |
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| 5 | * Input parameters: NONE |
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| 6 | * |
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| 7 | * Output parameters: NONE |
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| 8 | * |
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| 9 | * NOTE: It is important that the timer start/stop overhead be |
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| 10 | * determined when porting or modifying this code. |
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| 11 | * |
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[03f2154e] | 12 | * COPYRIGHT (c) 1989-1997. |
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[486c329] | 13 | * On-Line Applications Research Corporation (OAR). |
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[03f2154e] | 14 | * Copyright assigned to U.S. Government, 1994. |
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[486c329] | 15 | * |
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[03f2154e] | 16 | * The license and distribution terms for this file may in |
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| 17 | * the file LICENSE in this distribution or at |
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| 18 | * http://www.OARcorp.com/rtems/license.html. |
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[486c329] | 19 | * |
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| 20 | * $Id$ |
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| 21 | */ |
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| 22 | |
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| 23 | |
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| 24 | #include <bsp.h> |
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| 25 | |
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| 26 | rtems_boolean Timer_driver_Find_average_overhead; |
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| 27 | |
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| 28 | extern rtems_isr Clock_isr(); |
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| 29 | |
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| 30 | void Timer_initialize( void ) |
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| 31 | { |
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| 32 | } |
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| 33 | |
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| 34 | /* |
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| 35 | * The following controls the behavior of Read_timer(). |
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| 36 | * |
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| 37 | * FIND_AVG_OVERHEAD * instructs the routine to return the "raw" count. |
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| 38 | * |
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| 39 | * AVG_OVEREHAD is the overhead for starting and stopping the timer. It |
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| 40 | * is usually deducted from the number returned. |
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| 41 | * |
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| 42 | * LEAST_VALID is the lowest number this routine should trust. Numbers |
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| 43 | * below this are "noise" and zero is returned. |
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| 44 | */ |
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| 45 | |
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| 46 | #define AVG_OVERHEAD 0 /* It typically takes X.X microseconds */ |
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| 47 | /* (Y countdowns) to start/stop the timer. */ |
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| 48 | /* This value is in microseconds. */ |
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| 49 | #define LEAST_VALID 1 /* Don't trust a clicks value lower than this */ |
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| 50 | |
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| 51 | /* |
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| 52 | * Return timer value in 1/2-microsecond units |
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| 53 | */ |
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| 54 | int Read_timer( void ) |
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| 55 | { |
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| 56 | rtems_unsigned32 total; |
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| 57 | total = 0; |
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| 58 | |
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| 59 | if ( Timer_driver_Find_average_overhead == 1 ) |
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| 60 | return total; /* in XXX microsecond units */ |
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| 61 | |
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| 62 | if ( total < LEAST_VALID ) |
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| 63 | return 0; /* below timer resolution */ |
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| 64 | |
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| 65 | return (total - AVG_OVERHEAD); |
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| 66 | } |
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| 67 | |
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| 68 | |
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| 69 | /* |
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| 70 | * Empty function call used in loops to measure basic cost of looping |
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| 71 | * in Timing Test Suite. |
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| 72 | */ |
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| 73 | |
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| 74 | rtems_status_code Empty_function(void) |
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| 75 | { |
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| 76 | return RTEMS_SUCCESSFUL; |
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| 77 | } |
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| 78 | |
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| 79 | void Set_find_average_overhead( |
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| 80 | rtems_boolean find_flag |
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| 81 | ) |
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| 82 | { |
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| 83 | Timer_driver_Find_average_overhead = find_flag; |
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| 84 | } |
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