2 FreeRTOS V7.0.1 - Copyright (C) 2011 Real Time Engineers Ltd.
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5 ***************************************************************************
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7 * FreeRTOS tutorial books are available in pdf and paperback. *
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8 * Complete, revised, and edited pdf reference manuals are also *
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11 * Purchasing FreeRTOS documentation will not only help you, by *
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12 * ensuring you get running as quickly as possible and with an *
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13 * in-depth knowledge of how to use FreeRTOS, it will also help *
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14 * the FreeRTOS project to continue with its mission of providing *
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15 * professional grade, cross platform, de facto standard solutions *
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16 * for microcontrollers - completely free of charge! *
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18 * >>> See http://www.FreeRTOS.org/Documentation for details. <<< *
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20 * Thank you for using FreeRTOS, and thank you for your support! *
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22 ***************************************************************************
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25 This file is part of the FreeRTOS distribution.
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27 FreeRTOS is free software; you can redistribute it and/or modify it under
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28 the terms of the GNU General Public License (version 2) as published by the
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29 Free Software Foundation AND MODIFIED BY the FreeRTOS exception.
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30 >>>NOTE<<< The modification to the GPL is included to allow you to
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31 distribute a combined work that includes FreeRTOS without being obliged to
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32 provide the source code for proprietary components outside of the FreeRTOS
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33 kernel. FreeRTOS is distributed in the hope that it will be useful, but
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34 WITHOUT ANY WARRANTY; without even the implied warranty of MERCHANTABILITY
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35 or FITNESS FOR A PARTICULAR PURPOSE. See the GNU General Public License for
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36 more details. You should have received a copy of the GNU General Public
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37 License and the FreeRTOS license exception along with FreeRTOS; if not it
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38 can be viewed here: http://www.freertos.org/a00114.html and also obtained
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39 by writing to Richard Barry, contact details for whom are available on the
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44 http://www.FreeRTOS.org - Documentation, latest information, license and
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47 http://www.SafeRTOS.com - A version that is certified for use in safety
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50 http://www.OpenRTOS.com - Commercial support, development, porting,
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51 licensing and training services.
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54 /*-----------------------------------------------------------
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55 * Implementation of functions defined in portable.h for the Atmel ARM7 port.
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56 *----------------------------------------------------------*/
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59 /* Standard includes. */
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62 /* Scheduler includes. */
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63 #include "FreeRTOS.h"
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66 /* Hardware includes. */
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68 #include <pio/pio.h>
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69 #include <pio/pio_it.h>
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70 #include <pit/pit.h>
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71 #include <aic/aic.h>
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73 #include <utility/led.h>
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74 #include <utility/trace.h>
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76 /*-----------------------------------------------------------*/
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78 /* Constants required to setup the initial stack. */
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79 #define portINITIAL_SPSR ( ( portSTACK_TYPE ) 0x1f ) /* System mode, ARM mode, interrupts enabled. */
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80 #define portTHUMB_MODE_BIT ( ( portSTACK_TYPE ) 0x20 )
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81 #define portINSTRUCTION_SIZE ( ( portSTACK_TYPE ) 4 )
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83 /* Constants required to setup the PIT. */
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84 #define port1MHz_IN_Hz ( 1000000ul )
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85 #define port1SECOND_IN_uS ( 1000000.0 )
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87 /* Constants required to handle critical sections. */
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88 #define portNO_CRITICAL_NESTING ( ( unsigned long ) 0 )
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91 #define portINT_LEVEL_SENSITIVE 0
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92 #define portPIT_ENABLE ( ( unsigned short ) 0x1 << 24 )
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93 #define portPIT_INT_ENABLE ( ( unsigned short ) 0x1 << 25 )
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94 /*-----------------------------------------------------------*/
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96 /* Setup the PIT to generate the tick interrupts. */
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97 static void prvSetupTimerInterrupt( void );
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99 /* The PIT interrupt handler - the RTOS tick. */
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100 static void vPortTickISR( void );
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102 /* ulCriticalNesting will get set to zero when the first task starts. It
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103 cannot be initialised to 0 as this will cause interrupts to be enabled
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104 during the kernel initialisation process. */
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105 unsigned long ulCriticalNesting = ( unsigned long ) 9999;
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107 /*-----------------------------------------------------------*/
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110 * Initialise the stack of a task to look exactly as if a call to
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111 * portSAVE_CONTEXT had been called.
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113 * See header file for description.
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115 portSTACK_TYPE *pxPortInitialiseStack( portSTACK_TYPE *pxTopOfStack, pdTASK_CODE pxCode, void *pvParameters )
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117 portSTACK_TYPE *pxOriginalTOS;
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119 pxOriginalTOS = pxTopOfStack;
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121 /* To ensure asserts in tasks.c don't fail, although in this case the assert
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122 is not really required. */
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125 /* Setup the initial stack of the task. The stack is set exactly as
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126 expected by the portRESTORE_CONTEXT() macro. */
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128 /* First on the stack is the return address - which in this case is the
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129 start of the task. The offset is added to make the return address appear
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130 as it would within an IRQ ISR. */
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131 *pxTopOfStack = ( portSTACK_TYPE ) pxCode + portINSTRUCTION_SIZE;
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134 *pxTopOfStack = ( portSTACK_TYPE ) 0xaaaaaaaa; /* R14 */
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136 *pxTopOfStack = ( portSTACK_TYPE ) pxOriginalTOS; /* Stack used when task starts goes in R13. */
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138 *pxTopOfStack = ( portSTACK_TYPE ) 0x12121212; /* R12 */
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140 *pxTopOfStack = ( portSTACK_TYPE ) 0x11111111; /* R11 */
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142 *pxTopOfStack = ( portSTACK_TYPE ) 0x10101010; /* R10 */
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144 *pxTopOfStack = ( portSTACK_TYPE ) 0x09090909; /* R9 */
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146 *pxTopOfStack = ( portSTACK_TYPE ) 0x08080808; /* R8 */
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148 *pxTopOfStack = ( portSTACK_TYPE ) 0x07070707; /* R7 */
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150 *pxTopOfStack = ( portSTACK_TYPE ) 0x06060606; /* R6 */
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152 *pxTopOfStack = ( portSTACK_TYPE ) 0x05050505; /* R5 */
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154 *pxTopOfStack = ( portSTACK_TYPE ) 0x04040404; /* R4 */
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156 *pxTopOfStack = ( portSTACK_TYPE ) 0x03030303; /* R3 */
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158 *pxTopOfStack = ( portSTACK_TYPE ) 0x02020202; /* R2 */
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160 *pxTopOfStack = ( portSTACK_TYPE ) 0x01010101; /* R1 */
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163 /* When the task starts is will expect to find the function parameter in
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165 *pxTopOfStack = ( portSTACK_TYPE ) pvParameters; /* R0 */
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168 /* The status register is set for system mode, with interrupts enabled. */
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169 *pxTopOfStack = ( portSTACK_TYPE ) portINITIAL_SPSR;
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171 #ifdef THUMB_INTERWORK
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173 /* We want the task to start in thumb mode. */
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174 *pxTopOfStack |= portTHUMB_MODE_BIT;
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180 /* Interrupt flags cannot always be stored on the stack and will
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181 instead be stored in a variable, which is then saved as part of the
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183 *pxTopOfStack = portNO_CRITICAL_NESTING;
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185 return pxTopOfStack;
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187 /*-----------------------------------------------------------*/
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189 portBASE_TYPE xPortStartScheduler( void )
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191 extern void vPortStartFirstTask( void );
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193 /* Start the timer that generates the tick ISR. Interrupts are disabled
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195 prvSetupTimerInterrupt();
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197 /* Start the first task. */
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198 vPortStartFirstTask();
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200 /* Should not get here! */
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203 /*-----------------------------------------------------------*/
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205 void vPortEndScheduler( void )
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207 /* It is unlikely that the ARM port will require this function as there
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208 is nothing to return to. */
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210 /*-----------------------------------------------------------*/
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212 static __arm void vPortTickISR( void )
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214 volatile unsigned long ulDummy;
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216 /* Increment the tick count - which may wake some tasks but as the
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217 preemptive scheduler is not being used any woken task is not given
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218 processor time no matter what its priority. */
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219 vTaskIncrementTick();
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221 #if configUSE_PREEMPTION == 1
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222 vTaskSwitchContext();
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225 /* Clear the PIT interrupt. */
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226 ulDummy = AT91C_BASE_PITC->PITC_PIVR;
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228 /* To remove compiler warning. */
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231 /* The AIC is cleared in the asm wrapper, outside of this function. */
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233 /*-----------------------------------------------------------*/
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235 static void prvSetupTimerInterrupt( void )
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237 const unsigned long ulPeriodIn_uS = ( 1.0 / ( double ) configTICK_RATE_HZ ) * port1SECOND_IN_uS;
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239 /* Setup the PIT for the required frequency. */
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240 PIT_Init( ulPeriodIn_uS, BOARD_MCK / port1MHz_IN_Hz );
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242 /* Setup the PIT interrupt. */
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243 AIC_DisableIT( AT91C_ID_SYS );
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244 AIC_ConfigureIT( AT91C_ID_SYS, AT91C_AIC_PRIOR_LOWEST, vPortTickISR );
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245 AIC_EnableIT( AT91C_ID_SYS );
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248 /*-----------------------------------------------------------*/
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250 void vPortEnterCritical( void )
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252 /* Disable interrupts first! */
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255 /* Now interrupts are disabled ulCriticalNesting can be accessed
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256 directly. Increment ulCriticalNesting to keep a count of how many times
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257 portENTER_CRITICAL() has been called. */
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258 ulCriticalNesting++;
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260 /*-----------------------------------------------------------*/
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262 void vPortExitCritical( void )
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264 if( ulCriticalNesting > portNO_CRITICAL_NESTING )
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266 /* Decrement the nesting count as we are leaving a critical section. */
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267 ulCriticalNesting--;
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269 /* If the nesting level has reached zero then interrupts should be
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271 if( ulCriticalNesting == portNO_CRITICAL_NESTING )
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277 /*-----------------------------------------------------------*/
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