2 FreeRTOS V6.1.1 - Copyright (C) 2011 Real Time Engineers Ltd.
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4 ***************************************************************************
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8 * + New to FreeRTOS, *
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9 * + Wanting to learn FreeRTOS or multitasking in general quickly *
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10 * + Looking for basic training, *
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11 * + Wanting to improve your FreeRTOS skills and productivity *
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13 * then take a look at the FreeRTOS books - available as PDF or paperback *
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15 * "Using the FreeRTOS Real Time Kernel - a Practical Guide" *
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16 * http://www.FreeRTOS.org/Documentation *
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18 * A pdf reference manual is also available. Both are usually delivered *
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19 * to your inbox within 20 minutes to two hours when purchased between 8am *
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20 * and 8pm GMT (although please allow up to 24 hours in case of *
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21 * exceptional circumstances). Thank you for your support! *
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23 ***************************************************************************
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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 exception to the GPL is included to allow you to distribute
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31 a combined work that includes FreeRTOS without being obliged to provide the
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32 source code for proprietary components outside of the FreeRTOS kernel.
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33 FreeRTOS is distributed in the hope that it will be useful, but WITHOUT
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34 ANY WARRANTY; without even the implied warranty of MERCHANTABILITY or
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35 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 ST STR71x ARM7
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57 *----------------------------------------------------------*/
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59 /* Library includes. */
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63 /* Standard includes. */
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66 /* Scheduler includes. */
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67 #include "FreeRTOS.h"
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70 /* Constants required to setup the initial stack. */
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71 #define portINITIAL_SPSR ( ( portSTACK_TYPE ) 0x1f ) /* System mode, ARM mode, interrupts enabled. */
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72 #define portTHUMB_MODE_BIT ( ( portSTACK_TYPE ) 0x20 )
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73 #define portINSTRUCTION_SIZE ( ( portSTACK_TYPE ) 4 )
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75 /* Constants required to handle critical sections. */
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76 #define portNO_CRITICAL_NESTING ( ( unsigned long ) 0 )
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78 #define portMICROS_PER_SECOND 1000000
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80 /*-----------------------------------------------------------*/
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82 /* Setup the watchdog to generate the tick interrupts. */
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83 static void prvSetupTimerInterrupt( void );
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85 /* ulCriticalNesting will get set to zero when the first task starts. It
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86 cannot be initialised to 0 as this will cause interrupts to be enabled
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87 during the kernel initialisation process. */
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88 unsigned long ulCriticalNesting = ( unsigned long ) 9999;
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90 /* Tick interrupt routines for cooperative and preemptive operation
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91 respectively. The preemptive version is not defined as __irq as it is called
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92 from an asm wrapper function. */
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93 __arm __irq void vPortNonPreemptiveTick( void );
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94 void vPortPreemptiveTick( void );
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96 /*-----------------------------------------------------------*/
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99 * Initialise the stack of a task to look exactly as if a call to
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100 * portSAVE_CONTEXT had been called.
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102 * See header file for description.
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104 portSTACK_TYPE *pxPortInitialiseStack( portSTACK_TYPE *pxTopOfStack, pdTASK_CODE pxCode, void *pvParameters )
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106 portSTACK_TYPE *pxOriginalTOS;
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108 pxOriginalTOS = pxTopOfStack;
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110 /* Setup the initial stack of the task. The stack is set exactly as
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111 expected by the portRESTORE_CONTEXT() macro. */
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113 /* First on the stack is the return address - which in this case is the
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114 start of the task. The offset is added to make the return address appear
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115 as it would within an IRQ ISR. */
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116 *pxTopOfStack = ( portSTACK_TYPE ) pxCode + portINSTRUCTION_SIZE;
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119 *pxTopOfStack = ( portSTACK_TYPE ) 0xaaaaaaaa; /* R14 */
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121 *pxTopOfStack = ( portSTACK_TYPE ) pxOriginalTOS; /* Stack used when task starts goes in R13. */
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123 *pxTopOfStack = ( portSTACK_TYPE ) 0x12121212; /* R12 */
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125 *pxTopOfStack = ( portSTACK_TYPE ) 0x11111111; /* R11 */
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127 *pxTopOfStack = ( portSTACK_TYPE ) 0x10101010; /* R10 */
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129 *pxTopOfStack = ( portSTACK_TYPE ) 0x09090909; /* R9 */
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131 *pxTopOfStack = ( portSTACK_TYPE ) 0x08080808; /* R8 */
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133 *pxTopOfStack = ( portSTACK_TYPE ) 0x07070707; /* R7 */
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135 *pxTopOfStack = ( portSTACK_TYPE ) 0x06060606; /* R6 */
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137 *pxTopOfStack = ( portSTACK_TYPE ) 0x05050505; /* R5 */
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139 *pxTopOfStack = ( portSTACK_TYPE ) 0x04040404; /* R4 */
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141 *pxTopOfStack = ( portSTACK_TYPE ) 0x03030303; /* R3 */
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143 *pxTopOfStack = ( portSTACK_TYPE ) 0x02020202; /* R2 */
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145 *pxTopOfStack = ( portSTACK_TYPE ) 0x01010101; /* R1 */
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148 /* When the task starts is will expect to find the function parameter in
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150 *pxTopOfStack = ( portSTACK_TYPE ) pvParameters; /* R0 */
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153 /* The status register is set for system mode, with interrupts enabled. */
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154 *pxTopOfStack = ( portSTACK_TYPE ) portINITIAL_SPSR;
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156 if( ( ( unsigned long ) pxCode & 0x01UL ) != 0x00UL )
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158 /* We want the task to start in thumb mode. */
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159 *pxTopOfStack |= portTHUMB_MODE_BIT;
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164 /* Interrupt flags cannot always be stored on the stack and will
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165 instead be stored in a variable, which is then saved as part of the
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167 *pxTopOfStack = portNO_CRITICAL_NESTING;
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169 return pxTopOfStack;
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171 /*-----------------------------------------------------------*/
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173 portBASE_TYPE xPortStartScheduler( void )
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175 extern void vPortStartFirstTask( void );
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177 /* Start the timer that generates the tick ISR. Interrupts are disabled
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179 prvSetupTimerInterrupt();
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181 /* Start the first task. */
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182 vPortStartFirstTask();
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184 /* Should not get here! */
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187 /*-----------------------------------------------------------*/
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189 void vPortEndScheduler( void )
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191 /* It is unlikely that the ARM port will require this function as there
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192 is nothing to return to. */
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194 /*-----------------------------------------------------------*/
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196 /* The cooperative scheduler requires a normal IRQ service routine to
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197 simply increment the system tick. */
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198 __arm __irq void vPortNonPreemptiveTick( void )
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200 /* Increment the tick count - which may wake some tasks but as the
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201 preemptive scheduler is not being used any woken task is not given
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202 processor time no matter what its priority. */
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203 vTaskIncrementTick();
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205 /* Clear the interrupt in the watchdog and EIC. */
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209 /*-----------------------------------------------------------*/
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211 /* This function is called from an asm wrapper, so does not require the __irq
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213 void vPortPreemptiveTick( void )
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215 /* Increment the tick counter. */
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216 vTaskIncrementTick();
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218 /* The new tick value might unblock a task. Ensure the highest task that
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219 is ready to execute is the task that will execute when the tick ISR
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221 vTaskSwitchContext();
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223 /* Clear the interrupt in the watchdog and EIC. */
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227 /*-----------------------------------------------------------*/
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229 static void prvSetupTimerInterrupt( void )
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231 /* Set the watchdog up to generate a periodic tick. */
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232 WDG_ECITConfig( DISABLE );
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233 WDG_CntOnOffConfig( DISABLE );
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234 WDG_PeriodValueConfig( portMICROS_PER_SECOND / configTICK_RATE_HZ );
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236 /* Setup the tick interrupt in the EIC. */
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237 EIC_IRQChannelPriorityConfig( WDG_IRQChannel, 1 );
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238 EIC_IRQChannelConfig( WDG_IRQChannel, ENABLE );
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239 EIC_IRQConfig( ENABLE );
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240 WDG_ECITConfig( ENABLE );
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242 /* Start the timer - interrupts are actually disabled at this point so
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243 it is safe to do this here. */
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244 WDG_CntOnOffConfig( ENABLE );
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246 /*-----------------------------------------------------------*/
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248 __arm __interwork void vPortEnterCritical( void )
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250 /* Disable interrupts first! */
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251 __disable_interrupt();
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253 /* Now interrupts are disabled ulCriticalNesting can be accessed
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254 directly. Increment ulCriticalNesting to keep a count of how many times
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255 portENTER_CRITICAL() has been called. */
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256 ulCriticalNesting++;
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258 /*-----------------------------------------------------------*/
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260 __arm __interwork void vPortExitCritical( void )
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262 if( ulCriticalNesting > portNO_CRITICAL_NESTING )
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264 /* Decrement the nesting count as we are leaving a critical section. */
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265 ulCriticalNesting--;
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267 /* If the nesting level has reached zero then interrupts should be
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269 if( ulCriticalNesting == portNO_CRITICAL_NESTING )
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271 __enable_interrupt();
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275 /*-----------------------------------------------------------*/
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