1 | /* timer.c |
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2 | * |
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3 | * This file implements a benchmark timer using the General Purpose Timer. |
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4 | * |
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5 | * Notes: |
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6 | * |
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7 | * BSP_TIMER_AVG_OVERHEAD and BSP_TIMER_LEAST_VALID are required to be |
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8 | * provided in bsp.h |
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9 | * |
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10 | * COPYRIGHT (c) 1989-1997. |
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11 | * On-Line Applications Research Corporation (OAR). |
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12 | * |
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13 | * The license and distribution terms for this file may in |
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14 | * the file LICENSE in this distribution or at |
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15 | * http://www.OARcorp.com/rtems/license.html. |
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16 | * |
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17 | * $Id$ |
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18 | */ |
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19 | |
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20 | #include <assert.h> |
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21 | |
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22 | #include <bsp.h> |
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23 | |
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24 | rtems_unsigned64 Timer_driver_Start_time; |
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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 | /* |
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29 | * Timer_initialize |
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30 | */ |
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31 | |
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32 | void Timer_initialize() |
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33 | { |
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34 | |
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35 | /* |
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36 | * Timer runs long and accurate enough not to require an interrupt. |
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37 | */ |
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38 | |
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39 | Timer_driver_Start_time = PPC_Get_timebase_register(); |
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40 | } |
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41 | |
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42 | /* |
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43 | * Read_timer |
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44 | */ |
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45 | |
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46 | int Read_timer() |
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47 | { |
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48 | rtems_unsigned64 clicks; |
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49 | rtems_unsigned64 total64; |
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50 | rtems_unsigned32 total; |
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51 | |
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52 | /* approximately CLOCK_SPEED clicks per microsecond */ |
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53 | |
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54 | clicks = PPC_Get_timebase_register(); |
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55 | |
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56 | assert( clicks > Timer_driver_Start_time ); |
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57 | |
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58 | total64 = clicks - Timer_driver_Start_time; |
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59 | |
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60 | assert( total64 <= 0xffffffff ); /* fits into a unsigned32 */ |
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61 | |
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62 | total = (rtems_unsigned32) total64; |
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63 | |
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64 | if ( Timer_driver_Find_average_overhead == 1 ) |
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65 | return total; /* in "clicks" of the decrementer units */ |
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66 | |
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67 | if ( total < BSP_TIMER_LEAST_VALID ) |
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68 | return 0; /* below timer resolution */ |
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69 | |
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70 | return BSP_Convert_decrementer(total - BSP_TIMER_AVG_OVERHEAD); |
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71 | } |
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72 | |
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73 | rtems_status_code Empty_function( void ) |
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74 | { |
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75 | return RTEMS_SUCCESSFUL; |
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76 | } |
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77 | |
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78 | void Set_find_average_overhead( |
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79 | rtems_boolean find_flag |
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80 | ) |
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81 | { |
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82 | Timer_driver_Find_average_overhead = find_flag; |
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83 | } |
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