2 FreeRTOS.org V4.3.0 - Copyright (C) 2003-2007 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 See http://www.FreeRTOS.org for documentation, latest information, license
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28 and contact details. Please ensure to read the configuration and relevant
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29 port sections of the online documentation.
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31 Also see http://www.SafeRTOS.com for an IEC 61508 compliant version along
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32 with commercial development and support options.
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33 ***************************************************************************
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39 + Introduced the configKERNEL_INTERRUPT_PRIORITY definition.
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42 /*-----------------------------------------------------------
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43 * Implementation of functions defined in portable.h for the PIC24 port.
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44 *----------------------------------------------------------*/
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46 /* Scheduler include files. */
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47 #include "FreeRTOS.h"
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50 /* Hardware specifics. */
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51 #define portBIT_SET 1
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52 #define portTIMER_PRESCALE 8
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53 #define portINITIAL_SR 0
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55 /* Defined for backward compatability with project created prior to
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56 FreeRTOS.org V4.3.0. */
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57 #ifndef configKERNEL_INTERRUPT_PRIORITY
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58 #define configKERNEL_INTERRUPT_PRIORITY 1
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61 /* The program counter is only 23 bits. */
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62 #define portUNUSED_PR_BITS 0x7f
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64 /* Records the nesting depth of calls to portENTER_CRITICAL(). */
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65 unsigned portBASE_TYPE uxCriticalNesting = 0xef;
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67 #if configKERNEL_INTERRUPT_PRIORITY != 1
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68 #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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71 #ifdef MPLAB_PIC24_PORT
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73 #define portRESTORE_CONTEXT() \
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74 asm volatile( "MOV _pxCurrentTCB, W0 \n" /* Restore the stack pointer for the task. */ \
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75 "MOV [W0], W15 \n" \
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76 "POP W0 \n" /* Restore the critical nesting counter for the task. */ \
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77 "MOV W0, _uxCriticalNesting \n" \
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81 "POP RCOUNT \n" /* Restore the registers from the stack. */ \
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93 #define portSAVE_CONTEXT() \
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94 asm volatile( "PUSH SR \n" /* Save the SR used by the task.... */ \
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95 "PUSH W0 \n" /* ....then disable interrupts. */ \
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98 "PUSH W1 \n" /* Save registers to the stack. */ \
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110 "MOV _uxCriticalNesting, W0 \n" /* Save the critical nesting counter for the task. */ \
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112 "MOV _pxCurrentTCB, W0 \n" /* Save the new top of stack into the TCB. */ \
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115 #endif /* MPLAB_PIC24_PORT */
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117 #ifdef MPLAB_DSPIC_PORT
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119 #define portRESTORE_CONTEXT() \
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120 asm volatile( "MOV _pxCurrentTCB, W0 \n" /* Restore the stack pointer for the task. */ \
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121 "MOV [W0], W15 \n" \
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122 "POP W0 \n" /* Restore the critical nesting counter for the task. */ \
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123 "MOV W0, _uxCriticalNesting \n" \
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128 "POP DOSTARTH \n" \
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129 "POP DOSTARTL \n" \
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138 "POP RCOUNT \n" /* Restore the registers from the stack. */ \
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150 #define portSAVE_CONTEXT() \
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151 asm volatile( "PUSH SR \n" /* Save the SR used by the task.... */ \
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152 "PUSH W0 \n" /* ....then disable interrupts. */ \
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155 "PUSH W1 \n" /* Save registers to the stack. */ \
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172 "PUSH DOSTARTL \n" \
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173 "PUSH DOSTARTH \n" \
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178 "MOV _uxCriticalNesting, W0 \n" /* Save the critical nesting counter for the task. */ \
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180 "MOV _pxCurrentTCB, W0 \n" /* Save the new top of stack into the TCB. */ \
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181 "MOV W15, [W0] " );
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183 #endif /* MPLAB_DSPIC_PORT */
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186 * Setup the timer used to generate the tick interrupt.
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188 static void prvSetupTimerInterrupt( void );
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191 * See header file for description.
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193 portSTACK_TYPE *pxPortInitialiseStack( portSTACK_TYPE *pxTopOfStack, pdTASK_CODE pxCode, void *pvParameters )
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195 unsigned portSHORT usCode;
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198 const portSTACK_TYPE xInitialStack[] =
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214 0xcdce, /* RCOUNT */
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215 0xabac, /* TBLPAG */
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217 /* dsPIC specific registers. */
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218 #ifdef MPLAB_DSPIC_PORT
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219 0x0202, /* ACCAL */
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220 0x0303, /* ACCAH */
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221 0x0404, /* ACCAU */
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222 0x0505, /* ACCBL */
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223 0x0606, /* ACCBH */
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224 0x0707, /* ACCBU */
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225 0x0808, /* DCOUNT */
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226 0x090a, /* DOSTARTL */
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227 0x1010, /* DOSTARTH */
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228 0x1110, /* DOENDL */
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229 0x1212, /* DOENDH */
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233 /* Setup the stack as if a yield had occurred.
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235 Save the low bytes of the program counter. */
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236 usCode = ( unsigned portSHORT ) pxCode;
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237 *pxTopOfStack = ( portSTACK_TYPE ) usCode;
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240 /* Save the high byte of the program counter. This will always be zero
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241 here as it is passed in a 16bit pointer. If the address is greater than
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242 16 bits then the pointer will point to a jump table. */
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243 *pxTopOfStack = ( portSTACK_TYPE ) 0;
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246 /* Status register with interrupts enabled. */
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247 *pxTopOfStack = portINITIAL_SR;
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250 /* Parameters are passed in W0. */
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251 *pxTopOfStack = ( portSTACK_TYPE ) pvParameters;
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254 for( i = 0; i < ( sizeof( xInitialStack ) / sizeof( portSTACK_TYPE ) ); i++ )
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256 *pxTopOfStack = xInitialStack[ i ];
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260 *pxTopOfStack = CORCON;
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262 *pxTopOfStack = PSVPAG;
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265 /* Finally the critical nesting depth. */
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266 *pxTopOfStack = 0x00;
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269 return pxTopOfStack;
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271 /*-----------------------------------------------------------*/
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273 portBASE_TYPE xPortStartScheduler( void )
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275 /* Setup a timer for the tick ISR. */
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276 prvSetupTimerInterrupt();
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278 /* Restore the context of the first task to run. */
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279 portRESTORE_CONTEXT();
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281 /* Simulate the end of the yield function. */
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282 asm volatile ( "return" );
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284 /* Should not reach here. */
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287 /*-----------------------------------------------------------*/
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289 void vPortEndScheduler( void )
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291 /* It is unlikely that the scheduler for the PIC port will get stopped
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292 once running. If required disable the tick interrupt here, then return
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293 to xPortStartScheduler(). */
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295 /*-----------------------------------------------------------*/
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298 * Manual context switch. This is similar to the tick context switch,
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299 * but does not increment the tick count. It must be identical to the
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300 * tick context switch in how it stores the stack of a task.
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302 void vPortYield( void )
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304 portSAVE_CONTEXT();
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305 vTaskSwitchContext();
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306 portRESTORE_CONTEXT();
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308 /*-----------------------------------------------------------*/
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311 * Setup a timer for a regular tick.
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313 static void prvSetupTimerInterrupt( void )
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315 const unsigned portLONG ulCompareMatch = ( configCPU_CLOCK_HZ / portTIMER_PRESCALE ) / configTICK_RATE_HZ;
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317 /* Prescale of 8. */
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321 PR1 = ( unsigned portSHORT ) ulCompareMatch;
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323 /* Setup timer 1 interrupt priority. */
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324 IPC0bits.T1IP = configKERNEL_INTERRUPT_PRIORITY;
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326 /* Clear the interrupt as a starting condition. */
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329 /* Enable the interrupt. */
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332 /* Setup the prescale value. */
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333 T1CONbits.TCKPS0 = 1;
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334 T1CONbits.TCKPS1 = 0;
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336 /* Start the timer. */
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339 /*-----------------------------------------------------------*/
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341 void vPortEnterCritical( void )
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343 portDISABLE_INTERRUPTS();
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344 uxCriticalNesting++;
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346 /*-----------------------------------------------------------*/
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348 void vPortExitCritical( void )
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350 uxCriticalNesting--;
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351 if( uxCriticalNesting == 0 )
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353 portENABLE_INTERRUPTS();
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356 /*-----------------------------------------------------------*/
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358 void __attribute__((__interrupt__, auto_psv)) _T1Interrupt( void )
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360 vTaskIncrementTick();
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362 /* Clear the timer interrupt. */
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365 #if configUSE_PREEMPTION == 1
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