1 | /* |
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2 | * RTL22xx board Timer driver |
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3 | * |
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4 | * This uses Timer1 for timing measurments. |
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5 | * |
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6 | * By Ray xu, modify form Mc9328mxl RTEMS DSP |
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7 | * |
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8 | * The license and distribution terms for this file may be |
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9 | * found in the file LICENSE in this distribution or at |
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10 | * |
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11 | * http://www.rtems.com/license/LICENSE. |
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12 | * |
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13 | * Notes: |
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14 | * This file manages the benchmark timer used by the RTEMS Timing Test |
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15 | * Suite. Each measured time period is demarcated by calls to |
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16 | * Timer_initialize() and Read_timer(). Read_timer() usually returns |
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17 | * the number of microseconds since Timer_initialize() exitted. |
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18 | * |
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19 | * It is important that the timer start/stop overhead be determined |
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20 | * when porting or modifying this code. |
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21 | * |
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22 | * $Id$ |
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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 <lpc22xx.h> |
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28 | #include "lpc_timer.h" |
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29 | uint32_t g_start; |
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30 | uint32_t g_freq; |
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31 | |
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32 | #ifndef __cplusplus |
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33 | #define bool int |
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34 | #define true 1 |
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35 | #define false 0 |
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36 | |
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37 | #endif/* __cplusplus */ |
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38 | |
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39 | rtems_boolean Timer_driver_Find_average_overhead; |
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40 | |
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41 | |
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42 | /* |
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43 | * Set up Timer 1 |
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44 | */ |
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45 | void Timer_initialize( void ) |
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46 | { |
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47 | T1TCR &= 0; /* disable and clear timer 0 */ |
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48 | g_start = (T1TC/(LPC22xx_Fpclk/1000000)); |
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49 | T1PC = 0; /* TC is incrementet on every pclk.*/ |
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50 | T1MR0 = ((LPC22xx_Fpclk/1000* BSP_Configuration.microseconds_per_tick) / 1000); /* initialize the timer period and prescaler */ |
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51 | T1EMR = 0; /*No external match*/ |
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52 | T1TCR = 1; /*enable timer1*/ |
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53 | g_freq = LPC22xx_Fpclk / 1000; |
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54 | } |
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55 | |
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56 | /* |
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57 | * The following controls the behavior of Read_timer(). |
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58 | * |
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59 | * AVG_OVEREHAD is the overhead for starting and stopping the timer. It |
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60 | * is usually deducted from the number returned. |
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61 | * |
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62 | * LEAST_VALID is the lowest number this routine should trust. Numbers |
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63 | * below this are "noise" and zero is returned. |
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64 | */ |
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65 | |
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66 | #define AVG_OVERHEAD 0 /* It typically takes X.X microseconds */ |
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67 | /* (Y countdowns) to start/stop the timer. */ |
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68 | /* This value is in microseconds. */ |
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69 | #define LEAST_VALID 1 /* Don't trust a clicks value lower than this */ |
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70 | |
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71 | int Read_timer( void ) |
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72 | { |
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73 | uint32_t t; |
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74 | unsigned long long total; |
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75 | |
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76 | t = (T1TC/(LPC22xx_Fpclk/1000000)); |
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77 | /* |
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78 | * Total is calculated by taking into account the number of timer overflow |
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79 | * interrupts since the timer was initialized and clicks since the last |
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80 | * interrupts. currently it is not supported |
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81 | */ |
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82 | |
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83 | total = (t - g_start); |
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84 | |
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85 | /* convert to nanoseconds */ |
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86 | |
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87 | if ( Timer_driver_Find_average_overhead == 1 ) { |
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88 | return (int) total; |
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89 | } else if ( total < LEAST_VALID ) { |
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90 | return 0; |
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91 | } |
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92 | /* |
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93 | * Somehow convert total into microseconds |
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94 | */ |
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95 | |
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96 | return (total - AVG_OVERHEAD); |
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97 | } |
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98 | |
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99 | /* |
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100 | * Empty function call used in loops to measure basic cost of looping |
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101 | * in Timing Test Suite. |
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102 | */ |
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103 | |
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104 | rtems_status_code Empty_function( void ) |
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105 | { |
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106 | return RTEMS_SUCCESSFUL; |
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107 | } |
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108 | |
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109 | void Set_find_average_overhead( |
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110 | rtems_boolean find_flag |
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111 | ) |
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112 | { |
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113 | Timer_driver_Find_average_overhead = find_flag; |
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114 | } |
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115 | |
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