[b1783062] | 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.com/license/LICENSE. |
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| 18 | * |
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| 19 | * $Id$ |
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| 20 | * |
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| 21 | * Jukka Pietarinen <jukka.pietarinen@mrf.fi>, 2008, |
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| 22 | * Micro-Research Finland Oy |
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| 23 | */ |
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| 24 | |
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| 25 | #include <rtems.h> |
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| 26 | #include <bsp.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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[5d64375f] | 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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[b1783062] | 35 | return *((int*)(TIMER1_BASE_ADDRESS + reg)); |
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| 36 | #else |
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[5d64375f] | 37 | #warning "Benchmarking timer not available!" |
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[b1783062] | 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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[5d64375f] | 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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[b1783062] | 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 | int 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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