1 | /** |
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2 | * @file |
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3 | * @brief |
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4 | * |
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5 | * This file implements a benchmark timer using the PPC Timebase Register. |
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6 | */ |
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7 | |
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8 | /* |
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9 | * COPYRIGHT (c) 1989-2014. |
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10 | * On-Line Applications Research Corporation (OAR). |
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11 | * |
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12 | * The license and distribution terms for this file may in |
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13 | * the file LICENSE in this distribution or at |
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14 | * http://www.rtems.org/license/LICENSE. |
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15 | */ |
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16 | |
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17 | #include <bsp.h> |
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18 | #include <rtems.h> |
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19 | #include <rtems/system.h> |
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20 | #include <rtems/btimer.h> |
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21 | #include <assert.h> |
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22 | #include <libcpu/powerpc-utility.h> |
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23 | |
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24 | #ifndef BSP_Convert_decrementer |
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25 | #define BSP_Convert_decrementer(value) (value) |
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26 | #endif |
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27 | |
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28 | uint64_t Timer_driver_Start_time; |
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29 | |
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30 | bool benchmark_timer_find_average_overhead = false; |
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31 | unsigned clicks_overhead = 0; |
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32 | |
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33 | /* |
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34 | * Timer Get overhead |
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35 | */ |
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36 | static int Timer_get_clicks_overhead(void) |
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37 | { |
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38 | uint64_t clicks; |
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39 | |
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40 | PPC_Set_timebase_register((uint64_t) 0); |
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41 | clicks = PPC_Get_timebase_register(); |
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42 | assert(clicks <= 0xffffffff); |
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43 | clicks_overhead = (unsigned) clicks; |
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44 | return clicks_overhead; |
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45 | } |
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46 | |
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47 | /* |
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48 | * benchmark_timer_initialize |
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49 | */ |
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50 | void benchmark_timer_initialize(void) |
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51 | { |
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52 | |
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53 | /* |
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54 | * Timer runs long and accurate enough not to require an interrupt. |
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55 | */ |
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56 | |
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57 | if (clicks_overhead == 0) clicks_overhead = Timer_get_clicks_overhead(); |
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58 | PPC_Set_timebase_register((uint64_t) 0); |
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59 | } |
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60 | |
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61 | |
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62 | /* |
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63 | * benchmark_timer_read |
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64 | */ |
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65 | |
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66 | benchmark_timer_t benchmark_timer_read(void) |
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67 | { |
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68 | uint64_t total64; |
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69 | uint32_t 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 | total64 = PPC_Get_timebase_register(); |
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74 | |
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75 | assert( total64 <= 0xffffffff ); /* fits into a uint32_t */ |
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76 | |
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77 | total = (uint32_t) total64; |
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78 | |
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79 | if ( benchmark_timer_find_average_overhead == true ) |
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80 | return total; /* in "clicks" of the decrementer units */ |
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81 | |
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82 | return (int) BSP_Convert_decrementer(total - clicks_overhead); |
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83 | } |
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84 | |
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85 | void benchmark_timer_disable_subtracting_average_overhead(bool find_flag) |
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86 | { |
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87 | benchmark_timer_find_average_overhead = find_flag; |
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88 | } |
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