2 FreeRTOS.org V4.8.0 - Copyright (C) 2003-2008 Richard Barry.
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4 This file is part of the FreeRTOS.org distribution.
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6 FreeRTOS.org is free software; you can redistribute it and/or modify
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7 it under the terms of the GNU General Public License as published by
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8 the Free Software Foundation; either version 2 of the License, or
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9 (at your option) any later version.
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11 FreeRTOS.org is distributed in the hope that it will be useful,
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12 but WITHOUT ANY WARRANTY; without even the implied warranty of
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13 MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE. See the
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14 GNU General Public License for more details.
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16 You should have received a copy of the GNU General Public License
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17 along with FreeRTOS.org; if not, write to the Free Software
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18 Foundation, Inc., 59 Temple Place, Suite 330, Boston, MA 02111-1307 USA
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20 A special exception to the GPL can be applied should you wish to distribute
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21 a combined work that includes FreeRTOS.org, without being obliged to provide
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22 the source code for any proprietary components. See the licensing section
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23 of http://www.FreeRTOS.org for full details of how and when the exception
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26 ***************************************************************************
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27 ***************************************************************************
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29 * SAVE TIME AND MONEY! We can port FreeRTOS.org to your own hardware, *
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30 * and even write all or part of your application on your behalf. *
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31 * See http://www.OpenRTOS.com for details of the services we provide to *
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32 * expedite your project. *
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34 ***************************************************************************
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35 ***************************************************************************
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37 Please ensure to read the configuration and relevant port sections of the
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38 online documentation.
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40 http://www.FreeRTOS.org - Documentation, latest information, license and
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43 http://www.SafeRTOS.com - A version that is certified for use in safety
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46 http://www.OpenRTOS.com - Commercial support, development, porting,
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47 licensing and training services.
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50 /* High speed timer test as described in main.c. */
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53 /* Scheduler includes. */
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54 #include "FreeRTOS.h"
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56 /* Demo includes. */
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57 #include "partest.h"
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59 /* The number of interrupts to pass before we start looking at the jitter. */
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60 #define timerSETTLE_TIME 200
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62 /* The maximum value the 16bit timer can contain. */
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63 #define timerMAX_COUNT 0xffff
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66 /*-----------------------------------------------------------*/
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68 /* The maximum time (in processor clocks) between two consecutive timer
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69 interrupts so far. */
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70 unsigned portLONG ulMaxJitter = 0;
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72 /*-----------------------------------------------------------*/
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74 void vSetupTimerTest( unsigned portSHORT usFrequencyHz )
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76 /* T2 is used to generate interrupts. The core timer is used to provide an
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77 accurate time measurement. */
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81 /* Timer 2 is going to interrupt at usFrequencyHz Hz. */
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82 PR2 = ( unsigned portSHORT ) ( configPERIPHERAL_CLOCK_HZ / ( unsigned portLONG ) usFrequencyHz );
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84 /* Setup timer 2 interrupt priority to be above the kernel priority so
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85 the timer jitter is not effected by the kernel activity. */
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86 ConfigIntTimer2( T2_INT_ON | ( configKERNEL_INTERRUPT_PRIORITY + 1 ) );
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88 /* Clear the interrupt as a starting condition. */
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91 /* Enable the interrupt. */
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94 /* Start the timer. */
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97 /*-----------------------------------------------------------*/
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99 void __attribute__( (interrupt(ipl0), vector(_TIMER_2_VECTOR))) vT2InterruptHandler( void );
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100 void vT2InterruptHandler( void )
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102 static unsigned portLONG ulLastCount = 0, ulSettleCount = 0;
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103 static unsigned portLONG ulThisCount, ulDifference;
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105 /* Capture the timer value as we enter the interrupt. */
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106 ulThisCount = _CP0_GET_COUNT();
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108 if( ulSettleCount >= timerSETTLE_TIME )
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110 /* What is the difference between the timer value in this interrupt
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111 and the value from the last interrupt. */
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112 ulDifference = ulThisCount - ulLastCount;
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114 /* Store the difference in the timer values if it is larger than the
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115 currently stored largest value. The difference over and above the
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116 expected difference will give the 'jitter' in the processing of these
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118 if( ulDifference > ulMaxJitter )
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120 ulMaxJitter = ulDifference;
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125 /* Don't bother storing any values for the first couple of
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130 /* Remember what the timer value was this time through, so we can calculate
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131 the difference the next time through. */
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132 ulLastCount = ulThisCount;
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134 /* Clear the timer interrupt. */
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