1 | /* timer.c |
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2 | * |
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3 | * This file implements a benchmark timer using the General Purpose Timer on |
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4 | * the MEC. |
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5 | * |
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6 | * The license and distribution terms for this file are in |
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7 | * the file LICENSE in this distribution or at |
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8 | * http://www.OARcorp.com/rtems/license.html. |
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9 | * |
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10 | * $Id$ |
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11 | */ |
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12 | |
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13 | #include <assert.h> |
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14 | |
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15 | #include <bsp.h> |
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16 | |
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17 | rtems_unsigned64 Timer_driver_Start_time; |
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18 | |
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19 | rtems_boolean Timer_driver_Find_average_overhead; |
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20 | |
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21 | /*PAGE |
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22 | * |
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23 | * Timer_initialize |
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24 | * |
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25 | * This routine initializes the timer. |
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26 | * |
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27 | * Input parameters: NONE |
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28 | * |
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29 | * Output parameters: NONE |
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30 | * |
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31 | * Return values: NONE |
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32 | * |
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33 | */ |
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34 | |
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35 | void Timer_initialize() |
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36 | { |
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37 | /* |
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38 | * Timer runs long and accurate enough not to require an interrupt. |
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39 | */ |
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40 | |
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41 | |
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42 | Timer_driver_Start_time = PPC_Get_timebase_register(); |
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43 | |
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44 | |
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45 | } |
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46 | |
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47 | #define AVG_OVERHEAD 24 /* It typically takes 24 instructions */ |
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48 | /* to start/stop the timer. */ |
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49 | #define LEAST_VALID 1 /* Don't trust a value lower than this */ |
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50 | |
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51 | /* PAGE |
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52 | * |
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53 | * Read_timer |
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54 | * |
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55 | * This routine reads the timer. |
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56 | * |
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57 | * Input parameters: NONE |
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58 | * |
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59 | * Output parameters: NONE |
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60 | * |
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61 | * Return values: timer in ms units |
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62 | * |
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63 | */ |
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64 | |
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65 | int Read_timer() |
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66 | { |
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67 | rtems_unsigned64 clicks; |
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68 | rtems_unsigned64 total64; |
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69 | rtems_unsigned32 total; |
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70 | |
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71 | /* approximately CLOCK_SPEED clicks per microsecond */ |
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72 | |
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73 | clicks = PPC_Get_timebase_register(); |
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74 | |
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75 | assert( clicks > Timer_driver_Start_time ); |
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76 | |
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77 | total64 = clicks - Timer_driver_Start_time; |
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78 | |
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79 | assert( total64 <= 0xffffffff ); /* fits into a unsigned32 */ |
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80 | |
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81 | total = (rtems_unsigned32) total64; |
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82 | |
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83 | if ( Timer_driver_Find_average_overhead == 1 ) |
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84 | return total; /* in one microsecond units */ |
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85 | |
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86 | if ( total < LEAST_VALID ) |
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87 | return 0; /* below timer resolution */ |
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88 | |
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89 | return total - AVG_OVERHEAD; |
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90 | } |
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91 | |
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92 | /* PAGE |
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93 | * |
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94 | * Empty_function |
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95 | * |
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96 | * This routine is called during the idle loop. |
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97 | * |
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98 | * Input parameters: NONE |
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99 | * |
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100 | * Output parameters: |
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101 | * status code of successful |
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102 | * |
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103 | * Return values: NONE |
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104 | * |
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105 | */ |
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106 | |
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107 | rtems_status_code Empty_function( void ) |
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108 | { |
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109 | return RTEMS_SUCCESSFUL; |
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110 | } |
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111 | |
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112 | /* PAGE |
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113 | * |
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114 | * Set_find_average_overhead |
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115 | * |
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116 | * This routine sets a global boolean to the value passed in. |
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117 | * |
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118 | * Input parameters: |
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119 | * find_flag - flag to indicate to find the average overhead. |
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120 | * |
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121 | * Output parameters: NONE |
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122 | * |
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123 | * Return values: NONE |
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124 | * |
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125 | */ |
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126 | |
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127 | void Set_find_average_overhead( |
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128 | rtems_boolean find_flag |
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129 | ) |
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130 | { |
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131 | Timer_driver_Find_average_overhead = find_flag; |
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132 | } |
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