2 FreeRTOS V8.2.0rc1 - Copyright (C) 2014 Real Time Engineers Ltd.
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5 VISIT http://www.FreeRTOS.org TO ENSURE YOU ARE USING THE LATEST VERSION.
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7 This file is part of the FreeRTOS distribution.
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9 FreeRTOS is free software; you can redistribute it and/or modify it under
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10 the terms of the GNU General Public License (version 2) as published by the
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11 Free Software Foundation >>!AND MODIFIED BY!<< the FreeRTOS exception.
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13 >>! NOTE: The modification to the GPL is included to allow you to !<<
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14 >>! distribute a combined work that includes FreeRTOS without being !<<
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15 >>! obliged to provide the source code for proprietary components !<<
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16 >>! outside of the FreeRTOS kernel. !<<
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18 FreeRTOS is distributed in the hope that it will be useful, but WITHOUT ANY
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19 WARRANTY; without even the implied warranty of MERCHANTABILITY or FITNESS
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20 FOR A PARTICULAR PURPOSE. Full license text is available on the following
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21 link: http://www.freertos.org/a00114.html
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25 ***************************************************************************
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27 * Having a problem? Start by reading the FAQ "My application does *
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28 * not run, what could be wrong?". Have you defined configASSERT()? *
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30 * http://www.FreeRTOS.org/FAQHelp.html *
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32 ***************************************************************************
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34 ***************************************************************************
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36 * FreeRTOS provides completely free yet professionally developed, *
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37 * robust, strictly quality controlled, supported, and cross *
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38 * platform software that is more than just the market leader, it *
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39 * is the industry's de facto standard. *
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41 * Help yourself get started quickly while simultaneously helping *
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42 * to support the FreeRTOS project by purchasing a FreeRTOS *
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43 * tutorial book, reference manual, or both: *
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44 * http://www.FreeRTOS.org/Documentation *
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46 ***************************************************************************
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48 ***************************************************************************
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50 * Investing in training allows your team to be as productive as *
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51 * possible as early as possible, lowering your overall development *
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52 * cost, and enabling you to bring a more robust product to market *
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53 * earlier than would otherwise be possible. Richard Barry is both *
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54 * the architect and key author of FreeRTOS, and so also the world's *
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55 * leading authority on what is the world's most popular real time *
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56 * kernel for deeply embedded MCU designs. Obtaining your training *
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57 * from Richard ensures your team will gain directly from his in-depth *
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58 * product knowledge and years of usage experience. Contact Real Time *
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59 * Engineers Ltd to enquire about the FreeRTOS Masterclass, presented *
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60 * by Richard Barry: http://www.FreeRTOS.org/contact
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62 ***************************************************************************
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64 ***************************************************************************
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66 * You are receiving this top quality software for free. Please play *
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67 * fair and reciprocate by reporting any suspected issues and *
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68 * participating in the community forum: *
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69 * http://www.FreeRTOS.org/support *
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73 ***************************************************************************
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75 http://www.FreeRTOS.org - Documentation, books, training, latest versions,
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76 license and Real Time Engineers Ltd. contact details.
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78 http://www.FreeRTOS.org/plus - A selection of FreeRTOS ecosystem products,
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79 including FreeRTOS+Trace - an indispensable productivity tool, a DOS
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80 compatible FAT file system, and our tiny thread aware UDP/IP stack.
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82 http://www.FreeRTOS.org/labs - Where new FreeRTOS products go to incubate.
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83 Come and try FreeRTOS+TCP, our new open source TCP/IP stack for FreeRTOS.
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85 http://www.OpenRTOS.com - Real Time Engineers ltd license FreeRTOS to High
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86 Integrity Systems ltd. to sell under the OpenRTOS brand. Low cost OpenRTOS
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87 licenses offer ticketed support, indemnification and commercial middleware.
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89 http://www.SafeRTOS.com - High Integrity Systems also provide a safety
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90 engineered and independently SIL3 certified version for use in safety and
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91 mission critical applications that require provable dependability.
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99 + usCriticalNesting now has a volatile qualifier.
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102 /* Standard includes. */
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103 #include <stdlib.h>
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104 #include <signal.h>
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106 /* Scheduler includes. */
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107 #include "FreeRTOS.h"
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110 /*-----------------------------------------------------------
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111 * Implementation of functions defined in portable.h for the MSP430 port.
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112 *----------------------------------------------------------*/
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114 /* Constants required for hardware setup. The tick ISR runs off the ACLK,
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116 #define portACLK_FREQUENCY_HZ ( ( TickType_t ) 32768 )
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117 #define portINITIAL_CRITICAL_NESTING ( ( uint16_t ) 10 )
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118 #define portFLAGS_INT_ENABLED ( ( StackType_t ) 0x08 )
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120 /* We require the address of the pxCurrentTCB variable, but don't want to know
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121 any details of its type. */
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122 typedef void TCB_t;
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123 extern volatile TCB_t * volatile pxCurrentTCB;
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125 /* Most ports implement critical sections by placing the interrupt flags on
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126 the stack before disabling interrupts. Exiting the critical section is then
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127 simply a case of popping the flags from the stack. As mspgcc does not use
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128 a frame pointer this cannot be done as modifying the stack will clobber all
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129 the stack variables. Instead each task maintains a count of the critical
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130 section nesting depth. Each time a critical section is entered the count is
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131 incremented. Each time a critical section is left the count is decremented -
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132 with interrupts only being re-enabled if the count is zero.
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134 usCriticalNesting will get set to zero when the scheduler starts, but must
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135 not be initialised to zero as this will cause problems during the startup
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137 volatile uint16_t usCriticalNesting = portINITIAL_CRITICAL_NESTING;
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138 /*-----------------------------------------------------------*/
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141 * Macro to save a task context to the task stack. This simply pushes all the
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142 * general purpose msp430 registers onto the stack, followed by the
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143 * usCriticalNesting value used by the task. Finally the resultant stack
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144 * pointer value is saved into the task control block so it can be retrieved
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145 * the next time the task executes.
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147 #define portSAVE_CONTEXT() \
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148 asm volatile ( "push r4 \n\t" \
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160 "mov.w usCriticalNesting, r14 \n\t" \
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162 "mov.w pxCurrentTCB, r12 \n\t" \
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163 "mov.w r1, @r12 \n\t" \
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167 * Macro to restore a task context from the task stack. This is effectively
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168 * the reverse of portSAVE_CONTEXT(). First the stack pointer value is
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169 * loaded from the task control block. Next the value for usCriticalNesting
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170 * used by the task is retrieved from the stack - followed by the value of all
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171 * the general purpose msp430 registers.
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173 * The bic instruction ensures there are no low power bits set in the status
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174 * register that is about to be popped from the stack.
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176 #define portRESTORE_CONTEXT() \
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177 asm volatile ( "mov.w pxCurrentTCB, r12 \n\t" \
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178 "mov.w @r12, r1 \n\t" \
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180 "mov.w r15, usCriticalNesting \n\t" \
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193 "bic #(0xf0),0(r1) \n\t" \
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196 /*-----------------------------------------------------------*/
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199 * Sets up the periodic ISR used for the RTOS tick. This uses timer 0, but
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200 * could have alternatively used the watchdog timer or timer 1.
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202 static void prvSetupTimerInterrupt( void );
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203 /*-----------------------------------------------------------*/
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206 * Initialise the stack of a task to look exactly as if a call to
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207 * portSAVE_CONTEXT had been called.
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209 * See the header file portable.h.
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211 StackType_t *pxPortInitialiseStack( StackType_t *pxTopOfStack, TaskFunction_t pxCode, void *pvParameters )
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214 Place a few bytes of known values on the bottom of the stack.
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215 This is just useful for debugging and can be included if required.
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217 *pxTopOfStack = ( StackType_t ) 0x1111;
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219 *pxTopOfStack = ( StackType_t ) 0x2222;
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221 *pxTopOfStack = ( StackType_t ) 0x3333;
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225 /* The msp430 automatically pushes the PC then SR onto the stack before
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226 executing an ISR. We want the stack to look just as if this has happened
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227 so place a pointer to the start of the task on the stack first - followed
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228 by the flags we want the task to use when it starts up. */
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229 *pxTopOfStack = ( StackType_t ) pxCode;
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231 *pxTopOfStack = portFLAGS_INT_ENABLED;
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234 /* Next the general purpose registers. */
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235 *pxTopOfStack = ( StackType_t ) 0x4444;
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237 *pxTopOfStack = ( StackType_t ) 0x5555;
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239 *pxTopOfStack = ( StackType_t ) 0x6666;
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241 *pxTopOfStack = ( StackType_t ) 0x7777;
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243 *pxTopOfStack = ( StackType_t ) 0x8888;
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245 *pxTopOfStack = ( StackType_t ) 0x9999;
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247 *pxTopOfStack = ( StackType_t ) 0xaaaa;
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249 *pxTopOfStack = ( StackType_t ) 0xbbbb;
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251 *pxTopOfStack = ( StackType_t ) 0xcccc;
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253 *pxTopOfStack = ( StackType_t ) 0xdddd;
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255 *pxTopOfStack = ( StackType_t ) 0xeeee;
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258 /* When the task starts is will expect to find the function parameter in
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260 *pxTopOfStack = ( StackType_t ) pvParameters;
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263 /* The code generated by the mspgcc compiler does not maintain separate
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264 stack and frame pointers. The portENTER_CRITICAL macro cannot therefore
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265 use the stack as per other ports. Instead a variable is used to keep
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266 track of the critical section nesting. This variable has to be stored
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267 as part of the task context and is initially set to zero. */
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268 *pxTopOfStack = ( StackType_t ) portNO_CRITICAL_SECTION_NESTING;
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270 /* Return a pointer to the top of the stack we have generated so this can
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271 be stored in the task control block for the task. */
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272 return pxTopOfStack;
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274 /*-----------------------------------------------------------*/
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276 BaseType_t xPortStartScheduler( void )
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278 /* Setup the hardware to generate the tick. Interrupts are disabled when
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279 this function is called. */
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280 prvSetupTimerInterrupt();
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282 /* Restore the context of the first task that is going to run. */
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283 portRESTORE_CONTEXT();
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285 /* Should not get here as the tasks are now running! */
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288 /*-----------------------------------------------------------*/
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290 void vPortEndScheduler( void )
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292 /* It is unlikely that the MSP430 port will get stopped. If required simply
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293 disable the tick interrupt here. */
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295 /*-----------------------------------------------------------*/
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298 * Manual context switch called by portYIELD or taskYIELD.
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300 * The first thing we do is save the registers so we can use a naked attribute.
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302 void vPortYield( void ) __attribute__ ( ( naked ) );
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303 void vPortYield( void )
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305 /* We want the stack of the task being saved to look exactly as if the task
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306 was saved during a pre-emptive RTOS tick ISR. Before calling an ISR the
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307 msp430 places the status register onto the stack. As this is a function
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308 call and not an ISR we have to do this manually. */
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309 asm volatile ( "push r2" );
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312 /* Save the context of the current task. */
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313 portSAVE_CONTEXT();
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315 /* Switch to the highest priority task that is ready to run. */
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316 vTaskSwitchContext();
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318 /* Restore the context of the new task. */
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319 portRESTORE_CONTEXT();
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321 /*-----------------------------------------------------------*/
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324 * Hardware initialisation to generate the RTOS tick. This uses timer 0
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325 * but could alternatively use the watchdog timer or timer 1.
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327 static void prvSetupTimerInterrupt( void )
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329 /* Ensure the timer is stopped. */
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332 /* Run the timer of the ACLK. */
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335 /* Clear everything to start with. */
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338 /* Set the compare match value according to the tick rate we want. */
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339 TACCR0 = portACLK_FREQUENCY_HZ / configTICK_RATE_HZ;
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341 /* Enable the interrupts. */
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344 /* Start up clean. */
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350 /*-----------------------------------------------------------*/
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353 * The interrupt service routine used depends on whether the pre-emptive
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354 * scheduler is being used or not.
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357 #if configUSE_PREEMPTION == 1
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360 * Tick ISR for preemptive scheduler. We can use a naked attribute as
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361 * the context is saved at the start of vPortYieldFromTick(). The tick
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362 * count is incremented after the context is saved.
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364 interrupt (TIMERA0_VECTOR) prvTickISR( void ) __attribute__ ( ( naked ) );
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365 interrupt (TIMERA0_VECTOR) prvTickISR( void )
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367 /* Save the context of the interrupted task. */
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368 portSAVE_CONTEXT();
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370 /* Increment the tick count then switch to the highest priority task
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371 that is ready to run. */
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372 if( xTaskIncrementTick() != pdFALSE )
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374 vTaskSwitchContext();
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377 /* Restore the context of the new task. */
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378 portRESTORE_CONTEXT();
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384 * Tick ISR for the cooperative scheduler. All this does is increment the
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385 * tick count. We don't need to switch context, this can only be done by
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386 * manual calls to taskYIELD();
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388 interrupt (TIMERA0_VECTOR) prvTickISR( void );
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389 interrupt (TIMERA0_VECTOR) prvTickISR( void )
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391 xTaskIncrementTick();
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