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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57 + Introduced the configKERNEL_INTERRUPT_PRIORITY definition.
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60 /*-----------------------------------------------------------
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61 * Implementation of functions defined in portable.h for the PIC24 port.
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62 *----------------------------------------------------------*/
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64 /* Scheduler include files. */
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65 #include "FreeRTOS.h"
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68 /* Hardware specifics. */
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69 #define portBIT_SET 1
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70 #define portTIMER_PRESCALE 8
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71 #define portINITIAL_SR 0
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73 /* Defined for backward compatability with project created prior to
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74 FreeRTOS.org V4.3.0. */
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75 #ifndef configKERNEL_INTERRUPT_PRIORITY
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76 #define configKERNEL_INTERRUPT_PRIORITY 1
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79 /* The program counter is only 23 bits. */
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80 #define portUNUSED_PR_BITS 0x7f
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82 /* Records the nesting depth of calls to portENTER_CRITICAL(). */
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83 unsigned portBASE_TYPE uxCriticalNesting = 0xef;
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85 #if configKERNEL_INTERRUPT_PRIORITY != 1
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86 #error If configKERNEL_INTERRUPT_PRIORITY is not 1 then the #32 in the following macros needs changing to equal the portINTERRUPT_BITS value, which is ( configKERNEL_INTERRUPT_PRIORITY << 5 )
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89 #ifdef MPLAB_PIC24_PORT
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91 #define portRESTORE_CONTEXT() \
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92 asm volatile( "MOV _pxCurrentTCB, W0 \n" /* Restore the stack pointer for the task. */ \
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93 "MOV [W0], W15 \n" \
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94 "POP W0 \n" /* Restore the critical nesting counter for the task. */ \
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95 "MOV W0, _uxCriticalNesting \n" \
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99 "POP RCOUNT \n" /* Restore the registers from the stack. */ \
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110 #endif /* MPLAB_PIC24_PORT */
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112 #ifdef MPLAB_DSPIC_PORT
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114 #define portRESTORE_CONTEXT() \
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115 asm volatile( "MOV _pxCurrentTCB, W0 \n" /* Restore the stack pointer for the task. */ \
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116 "MOV [W0], W15 \n" \
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117 "POP W0 \n" /* Restore the critical nesting counter for the task. */ \
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118 "MOV W0, _uxCriticalNesting \n" \
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123 "POP DOSTARTH \n" \
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124 "POP DOSTARTL \n" \
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133 "POP RCOUNT \n" /* Restore the registers from the stack. */ \
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144 #endif /* MPLAB_DSPIC_PORT */
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147 * Setup the timer used to generate the tick interrupt.
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149 static void prvSetupTimerInterrupt( void );
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152 * See header file for description.
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154 portSTACK_TYPE *pxPortInitialiseStack( portSTACK_TYPE *pxTopOfStack, pdTASK_CODE pxCode, void *pvParameters )
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156 unsigned short usCode;
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159 const portSTACK_TYPE xInitialStack[] =
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175 0xcdce, /* RCOUNT */
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176 0xabac, /* TBLPAG */
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178 /* dsPIC specific registers. */
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179 #ifdef MPLAB_DSPIC_PORT
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180 0x0202, /* ACCAL */
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181 0x0303, /* ACCAH */
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182 0x0404, /* ACCAU */
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183 0x0505, /* ACCBL */
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184 0x0606, /* ACCBH */
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185 0x0707, /* ACCBU */
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186 0x0808, /* DCOUNT */
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187 0x090a, /* DOSTARTL */
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188 0x1010, /* DOSTARTH */
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189 0x1110, /* DOENDL */
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190 0x1212, /* DOENDH */
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194 /* Setup the stack as if a yield had occurred.
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196 Save the low bytes of the program counter. */
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197 usCode = ( unsigned short ) pxCode;
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198 *pxTopOfStack = ( portSTACK_TYPE ) usCode;
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201 /* Save the high byte of the program counter. This will always be zero
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202 here as it is passed in a 16bit pointer. If the address is greater than
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203 16 bits then the pointer will point to a jump table. */
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204 *pxTopOfStack = ( portSTACK_TYPE ) 0;
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207 /* Status register with interrupts enabled. */
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208 *pxTopOfStack = portINITIAL_SR;
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211 /* Parameters are passed in W0. */
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212 *pxTopOfStack = ( portSTACK_TYPE ) pvParameters;
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215 for( i = 0; i < ( sizeof( xInitialStack ) / sizeof( portSTACK_TYPE ) ); i++ )
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217 *pxTopOfStack = xInitialStack[ i ];
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221 *pxTopOfStack = CORCON;
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223 *pxTopOfStack = PSVPAG;
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226 /* Finally the critical nesting depth. */
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227 *pxTopOfStack = 0x00;
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230 return pxTopOfStack;
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232 /*-----------------------------------------------------------*/
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234 portBASE_TYPE xPortStartScheduler( void )
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236 /* Setup a timer for the tick ISR. */
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237 prvSetupTimerInterrupt();
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239 /* Restore the context of the first task to run. */
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240 portRESTORE_CONTEXT();
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242 /* Simulate the end of the yield function. */
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243 asm volatile ( "return" );
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245 /* Should not reach here. */
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248 /*-----------------------------------------------------------*/
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250 void vPortEndScheduler( void )
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252 /* It is unlikely that the scheduler for the PIC port will get stopped
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253 once running. If required disable the tick interrupt here, then return
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254 to xPortStartScheduler(). */
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256 /*-----------------------------------------------------------*/
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259 * Setup a timer for a regular tick.
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261 static void prvSetupTimerInterrupt( void )
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263 const unsigned long ulCompareMatch = ( ( configCPU_CLOCK_HZ / portTIMER_PRESCALE ) / configTICK_RATE_HZ ) - 1;
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265 /* Prescale of 8. */
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269 PR1 = ( unsigned short ) ulCompareMatch;
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271 /* Setup timer 1 interrupt priority. */
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272 IPC0bits.T1IP = configKERNEL_INTERRUPT_PRIORITY;
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274 /* Clear the interrupt as a starting condition. */
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277 /* Enable the interrupt. */
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280 /* Setup the prescale value. */
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281 T1CONbits.TCKPS0 = 1;
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282 T1CONbits.TCKPS1 = 0;
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284 /* Start the timer. */
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287 /*-----------------------------------------------------------*/
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289 void vPortEnterCritical( void )
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291 portDISABLE_INTERRUPTS();
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292 uxCriticalNesting++;
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294 /*-----------------------------------------------------------*/
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296 void vPortExitCritical( void )
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298 uxCriticalNesting--;
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299 if( uxCriticalNesting == 0 )
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301 portENABLE_INTERRUPTS();
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304 /*-----------------------------------------------------------*/
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306 void __attribute__((__interrupt__, auto_psv)) _T1Interrupt( void )
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308 /* Clear the timer interrupt. */
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311 vTaskIncrementTick();
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313 #if configUSE_PREEMPTION == 1
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