1 | /* timer.c |
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2 | * |
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3 | * This file manages the benchmark timer used by the RTEMS Timing |
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4 | * Test Suite. Each measured time period is demarcated by calls to |
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5 | * benchmark_timer_initialize() and benchmark_timer_read(). |
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6 | * benchmark_timer_read() usually returns the number of microseconds |
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7 | * since benchmark_timer_initialize() exitted. |
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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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12 | * COPYRIGHT (c) 1989-1999. |
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13 | * On-Line Applications Research Corporation (OAR). |
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14 | * |
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15 | * The license and distribution terms for this file may be |
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16 | * found in the file LICENSE in this distribution or at |
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17 | * http://www.rtems.org/license/LICENSE. |
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18 | * |
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19 | * Jukka Pietarinen <jukka.pietarinen@mrf.fi>, 2008, |
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20 | * Micro-Research Finland Oy |
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21 | */ |
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22 | |
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23 | #include <rtems.h> |
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24 | #include <bsp.h> |
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25 | #include <rtems/btimer.h> |
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26 | #include <rtems/bspIo.h> |
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27 | #include "../include/system_conf.h" |
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28 | #include "../../shared/clock/clock.h" |
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29 | |
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30 | static inline int timerread(unsigned int reg) |
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31 | { |
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32 | #if ON_SIMULATOR && defined(TIMER0_BASE_ADDRESS) |
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33 | return *((int*)(TIMER0_BASE_ADDRESS + reg)); |
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34 | #elif defined(TIMER1_BASE_ADDRESS) |
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35 | return *((int*)(TIMER1_BASE_ADDRESS + reg)); |
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36 | #else |
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37 | #warning "Benchmarking timer not available!" |
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38 | return 0; |
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39 | #endif |
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40 | } |
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41 | |
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42 | static inline void timerwrite(unsigned int reg, int value) |
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43 | { |
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44 | #if ON_SIMULATOR && defined(TIMER0_BASE_ADDRESS) |
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45 | *((int*)(TIMER0_BASE_ADDRESS + reg)) = value; |
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46 | #elif defined(TIMER1_BASE_ADDRESS) |
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47 | *((int*)(TIMER1_BASE_ADDRESS + reg)) = value; |
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48 | #endif |
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49 | } |
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50 | |
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51 | bool benchmark_timer_find_average_overhead; |
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52 | |
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53 | void benchmark_timer_initialize( void ) |
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54 | { |
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55 | /* Set timer period */ |
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56 | timerwrite(LM32_CLOCK_PERIOD, 0xffffffff); |
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57 | /* Stop timer */ |
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58 | timerwrite(LM32_CLOCK_CR, LM32_CLOCK_CR_STOP); |
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59 | /* Clear status register */ |
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60 | timerwrite(LM32_CLOCK_SR, 0); |
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61 | /* Start timer */ |
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62 | timerwrite(LM32_CLOCK_CR, LM32_CLOCK_CR_START); |
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63 | } |
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64 | |
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65 | /* |
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66 | * The following controls the behavior of benchmark_timer_read(). |
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67 | * |
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68 | * AVG_OVEREHAD is the overhead for starting and stopping the timer. It |
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69 | * is usually deducted from the number returned. |
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70 | * |
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71 | * LEAST_VALID is the lowest number this routine should trust. Numbers |
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72 | * below this are "noise" and zero is returned. |
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73 | */ |
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74 | |
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75 | #define AVG_OVERHEAD 4 /* It typically takes X.X microseconds */ |
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76 | /* (Y countdowns) to start/stop the timer. */ |
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77 | /* This value is in microseconds. */ |
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78 | #define LEAST_VALID 4 /* Don't trust a clicks value lower than this */ |
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79 | |
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80 | benchmark_timer_t benchmark_timer_read( void ) |
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81 | { |
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82 | uint32_t ticks; |
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83 | uint32_t total; |
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84 | uint32_t status; |
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85 | |
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86 | ticks = 0xffffffff - timerread(LM32_CLOCK_SNAPSHOT); |
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87 | status = timerread(LM32_CLOCK_SR); |
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88 | if (status & LM32_CLOCK_SR_TO) |
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89 | printk("Timer overflow!\n"); |
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90 | |
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91 | total = ticks / (CPU_FREQUENCY / 1000000); |
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92 | |
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93 | if ( benchmark_timer_find_average_overhead == true ) |
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94 | return total; /* in XXX microsecond units */ |
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95 | else |
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96 | { |
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97 | if ( total < LEAST_VALID ) |
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98 | return 0; /* below timer resolution */ |
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99 | /* |
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100 | * Somehow convert total into microseconds |
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101 | */ |
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102 | return (total - AVG_OVERHEAD); |
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103 | } |
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104 | } |
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105 | |
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106 | void benchmark_timer_disable_subtracting_average_overhead( |
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107 | bool find_flag |
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108 | ) |
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109 | { |
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110 | benchmark_timer_find_average_overhead = find_flag; |
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111 | } |
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