2 FreeRTOS.org V4.1.0 - Copyright (C) 2003-2006 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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30 ***************************************************************************
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33 /*-----------------------------------------------------------
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34 * Implementation of functions defined in portable.h for the PIC24 port.
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35 *----------------------------------------------------------*/
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37 /* Scheduler include files. */
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38 #include "FreeRTOS.h"
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41 /* Hardware specifics. */
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42 #define portBIT_SET 1
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43 #define portTIMER_PRESCALE 8
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44 #define portINITIAL_SR 0
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46 /* The program counter is only 23 bits. */
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47 #define portUNUSED_PR_BITS 0x7f
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49 /* Records the nesting depth of calls to portENTER_CRITICAL(). */
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50 unsigned portBASE_TYPE uxCriticalNesting = 0xef;
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52 #ifdef MPLAB_PIC24_PORT
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54 #define portRESTORE_CONTEXT() \
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55 asm volatile( "MOV _pxCurrentTCB, W0 \n" /* Restore the stack pointer for the task. */ \
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56 "MOV [W0], W15 \n" \
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57 "POP W0 \n" /* Restore the critical nesting counter for the task. */ \
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58 "MOV W0, _uxCriticalNesting \n" \
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62 "POP RCOUNT \n" /* Restore the registers from the stack. */ \
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74 #define portSAVE_CONTEXT() \
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75 asm volatile( "PUSH SR \n" /* Save the SR used by the task.... */ \
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76 "PUSH W0 \n" /* ....then disable interrupts. */ \
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79 "PUSH W1 \n" /* Save registers to the stack. */ \
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91 "MOV _uxCriticalNesting, W0 \n" /* Save the critical nesting counter for the task. */ \
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93 "MOV _pxCurrentTCB, W0 \n" /* Save the new top of stack into the TCB. */ \
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96 #endif /* MPLAB_PIC24_PORT */
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98 #ifdef MPLAB_DSPIC_PORT
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100 #define portRESTORE_CONTEXT() \
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101 asm volatile( "MOV _pxCurrentTCB, W0 \n" /* Restore the stack pointer for the task. */ \
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102 "MOV [W0], W15 \n" \
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103 "POP W0 \n" /* Restore the critical nesting counter for the task. */ \
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104 "MOV W0, _uxCriticalNesting \n" \
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109 "POP DOSTARTH \n" \
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110 "POP DOSTARTL \n" \
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119 "POP RCOUNT \n" /* Restore the registers from the stack. */ \
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131 #define portSAVE_CONTEXT() \
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132 asm volatile( "PUSH SR \n" /* Save the SR used by the task.... */ \
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133 "PUSH W0 \n" /* ....then disable interrupts. */ \
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134 "MOV #224, W0 \n" \
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136 "PUSH W1 \n" /* Save registers to the stack. */ \
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153 "PUSH DOSTARTL \n" \
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154 "PUSH DOSTARTH \n" \
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159 "MOV _uxCriticalNesting, W0 \n" /* Save the critical nesting counter for the task. */ \
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161 "MOV _pxCurrentTCB, W0 \n" /* Save the new top of stack into the TCB. */ \
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162 "MOV W15, [W0] " );
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164 #endif /* MPLAB_DSPIC_PORT */
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167 * Setup the timer used to generate the tick interrupt.
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169 static void prvSetupTimerInterrupt( void );
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172 * See header file for description.
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174 portSTACK_TYPE *pxPortInitialiseStack( portSTACK_TYPE *pxTopOfStack, pdTASK_CODE pxCode, void *pvParameters )
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176 unsigned portSHORT usCode;
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179 const portSTACK_TYPE xInitialStack[] =
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195 0xcdce, /* RCOUNT */
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196 0xabac, /* TBLPAG */
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198 /* dsPIC specific registers. */
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199 #ifdef MPLAB_DSPIC_PORT
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200 0x0202, /* ACCAL */
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201 0x0303, /* ACCAH */
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202 0x0404, /* ACCAU */
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203 0x0505, /* ACCBL */
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204 0x0606, /* ACCBH */
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205 0x0707, /* ACCBU */
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206 0x0808, /* DCOUNT */
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207 0x090a, /* DOSTARTL */
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208 0x1010, /* DOSTARTH */
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209 0x1110, /* DOENDL */
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210 0x1212, /* DOENDH */
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214 /* Setup the stack as if a yield had occurred.
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216 Save the low bytes of the program counter. */
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217 usCode = ( unsigned portSHORT ) pxCode;
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218 *pxTopOfStack = ( portSTACK_TYPE ) usCode;
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221 /* Save the high byte of the program counter. This will always be zero
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222 here as it is passed in a 16bit pointer. If the address is greater than
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223 16 bits then the pointer will point to a jump table. */
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224 *pxTopOfStack = ( portSTACK_TYPE ) 0;
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227 /* Status register with interrupts enabled. */
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228 *pxTopOfStack = portINITIAL_SR;
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231 /* Parameters are passed in W0. */
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232 *pxTopOfStack = ( portSTACK_TYPE ) pvParameters;
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235 for( i = 0; i < ( sizeof( xInitialStack ) / sizeof( portSTACK_TYPE ) ); i++ )
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237 *pxTopOfStack = xInitialStack[ i ];
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241 *pxTopOfStack = CORCON;
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243 *pxTopOfStack = PSVPAG;
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246 /* Finally the critical nesting depth. */
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247 *pxTopOfStack = 0x00;
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250 return pxTopOfStack;
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252 /*-----------------------------------------------------------*/
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254 portBASE_TYPE xPortStartScheduler( void )
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256 /* Setup a timer for the tick ISR. */
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257 prvSetupTimerInterrupt();
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259 /* Restore the context of the first task to run. */
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260 portRESTORE_CONTEXT();
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262 /* Simulate the end of the yield function. */
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263 asm volatile ( "return" );
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265 /* Should not reach here. */
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268 /*-----------------------------------------------------------*/
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270 void vPortEndScheduler( void )
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272 /* It is unlikely that the scheduler for the PIC port will get stopped
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273 once running. If required disable the tick interrupt here, then return
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274 to xPortStartScheduler(). */
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276 /*-----------------------------------------------------------*/
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279 * Manual context switch. This is similar to the tick context switch,
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280 * but does not increment the tick count. It must be identical to the
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281 * tick context switch in how it stores the stack of a task.
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283 void vPortYield( void )
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285 portSAVE_CONTEXT();
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286 vTaskSwitchContext();
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287 portRESTORE_CONTEXT();
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289 /*-----------------------------------------------------------*/
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292 * Setup a timer for a regular tick.
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294 static void prvSetupTimerInterrupt( void )
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296 const unsigned portLONG ulCompareMatch = ( configCPU_CLOCK_HZ / portTIMER_PRESCALE ) / configTICK_RATE_HZ;
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298 /* Prescale of 8. */
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302 PR1 = ( unsigned portSHORT ) ulCompareMatch;
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304 /* Setup timer 1 interrupt priority. */
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305 IPC0bits.T1IP = portKERNEL_INTERRUPT_PRIORITY;
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307 /* Clear the interrupt as a starting condition. */
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310 /* Enable the interrupt. */
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313 /* Setup the prescale value. */
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314 T1CONbits.TCKPS0 = 1;
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315 T1CONbits.TCKPS1 = 0;
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317 /* Start the timer. */
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320 /*-----------------------------------------------------------*/
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322 void vPortEnterCritical( void )
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324 portDISABLE_INTERRUPTS();
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325 uxCriticalNesting++;
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327 /*-----------------------------------------------------------*/
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329 void vPortExitCritical( void )
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331 uxCriticalNesting--;
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332 if( uxCriticalNesting == 0 )
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334 portENABLE_INTERRUPTS();
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337 /*-----------------------------------------------------------*/
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339 void __attribute__((__interrupt__)) _T1Interrupt( void )
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341 vTaskIncrementTick();
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343 /* Clear the timer interrupt. */
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346 #if configUSE_PREEMPTION == 1
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