2 FreeRTOS V7.4.2 - Copyright (C) 2013 Real Time Engineers Ltd.
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4 FEATURES AND PORTS ARE ADDED TO FREERTOS ALL THE TIME. PLEASE VISIT
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5 http://www.FreeRTOS.org TO ENSURE YOU ARE USING THE LATEST VERSION.
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7 ***************************************************************************
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9 * FreeRTOS tutorial books are available in pdf and paperback. *
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10 * Complete, revised, and edited pdf reference manuals are also *
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13 * Purchasing FreeRTOS documentation will not only help you, by *
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14 * ensuring you get running as quickly as possible and with an *
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15 * in-depth knowledge of how to use FreeRTOS, it will also help *
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16 * the FreeRTOS project to continue with its mission of providing *
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17 * professional grade, cross platform, de facto standard solutions *
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18 * for microcontrollers - completely free of charge! *
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20 * >>> See http://www.FreeRTOS.org/Documentation for details. <<< *
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22 * Thank you for using FreeRTOS, and thank you for your support! *
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24 ***************************************************************************
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27 This file is part of the FreeRTOS distribution.
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29 FreeRTOS is free software; you can redistribute it and/or modify it under
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30 the terms of the GNU General Public License (version 2) as published by the
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31 Free Software Foundation AND MODIFIED BY the FreeRTOS exception.
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33 >>>>>>NOTE<<<<<< The modification to the GPL is included to allow you to
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34 distribute a combined work that includes FreeRTOS without being obliged to
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35 provide the source code for proprietary components outside of the FreeRTOS
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38 FreeRTOS is distributed in the hope that it will be useful, but WITHOUT ANY
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39 WARRANTY; without even the implied warranty of MERCHANTABILITY or FITNESS
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40 FOR A PARTICULAR PURPOSE. See the GNU General Public License for more
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41 details. You should have received a copy of the GNU General Public License
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42 and the FreeRTOS license exception along with FreeRTOS; if not it can be
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43 viewed here: http://www.freertos.org/a00114.html and also obtained by
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44 writing to Real Time Engineers Ltd., contact details for whom are available
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45 on the FreeRTOS WEB site.
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49 ***************************************************************************
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51 * Having a problem? Start by reading the FAQ "My application does *
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52 * not run, what could be wrong?" *
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54 * http://www.FreeRTOS.org/FAQHelp.html *
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56 ***************************************************************************
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59 http://www.FreeRTOS.org - Documentation, books, training, latest versions,
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60 license and Real Time Engineers Ltd. contact details.
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62 http://www.FreeRTOS.org/plus - A selection of FreeRTOS ecosystem products,
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63 including FreeRTOS+Trace - an indispensable productivity tool, and our new
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64 fully thread aware and reentrant UDP/IP stack.
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66 http://www.OpenRTOS.com - Real Time Engineers ltd license FreeRTOS to High
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67 Integrity Systems, who sell the code with commercial support,
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68 indemnification and middleware, under the OpenRTOS brand.
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70 http://www.SafeRTOS.com - High Integrity Systems also provide a safety
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71 engineered and independently SIL3 certified version for use in safety and
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72 mission critical applications that require provable dependability.
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76 /*-----------------------------------------------------------
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77 * Implementation of functions defined in portable.h for the Tern EE 186
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79 *----------------------------------------------------------*/
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81 /* Library includes. */
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82 #include <embedded.h>
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85 /* Scheduler includes. */
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86 #include "FreeRTOS.h"
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88 #include "portasm.h"
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90 /* The timer increments every four clocks, hence the divide by 4. */
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91 #define portPRESCALE_VALUE ( 16 )
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92 #define portTIMER_COMPARE ( configCPU_CLOCK_HZ / ( configTICK_RATE_HZ * 4UL ) )
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94 /* From the RDC data sheet. */
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95 #define portENABLE_TIMER_AND_INTERRUPT ( unsigned short ) 0xe00b
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96 #define portENABLE_TIMER ( unsigned short ) 0xC001
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98 /* Interrupt control. */
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99 #define portEIO_REGISTER 0xff22
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100 #define portCLEAR_INTERRUPT 0x0008
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102 /* Setup the hardware to generate the required tick frequency. */
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103 static void prvSetupTimerInterrupt( void );
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105 /* The ISR used depends on whether the preemptive or cooperative scheduler
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107 #if( configUSE_PREEMPTION == 1 )
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108 /* Tick service routine used by the scheduler when preemptive scheduling is
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110 static void __interrupt __far prvPreemptiveTick( void );
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112 /* Tick service routine used by the scheduler when cooperative scheduling is
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114 static void __interrupt __far prvNonPreemptiveTick( void );
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117 /* Trap routine used by taskYIELD() to manually cause a context switch. */
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118 static void __interrupt __far prvYieldProcessor( void );
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120 /*-----------------------------------------------------------*/
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121 /* See header file for description. */
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122 portSTACK_TYPE *pxPortInitialiseStack( portSTACK_TYPE *pxTopOfStack, pdTASK_CODE pxCode, void *pvParameters )
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124 portSTACK_TYPE DS_Reg = 0;
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126 /* We need the true data segment. */
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127 __asm{ MOV DS_Reg, DS };
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129 /* Place a few bytes of known values on the bottom of the stack.
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130 This is just useful for debugging. */
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132 *pxTopOfStack = 0x1111;
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134 *pxTopOfStack = 0x2222;
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136 *pxTopOfStack = 0x3333;
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139 /* We are going to start the scheduler using a return from interrupt
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140 instruction to load the program counter, so first there would be the
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141 function call with parameters preamble. */
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143 *pxTopOfStack = FP_OFF( pvParameters );
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145 *pxTopOfStack = FP_OFF( pxCode );
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148 /* Next the status register and interrupt return address. */
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149 *pxTopOfStack = portINITIAL_SW;
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151 *pxTopOfStack = FP_SEG( pxCode );
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153 *pxTopOfStack = FP_OFF( pxCode );
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156 /* The remaining registers would be pushed on the stack by our context
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157 switch function. These are loaded with values simply to make debugging
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159 *pxTopOfStack = ( portSTACK_TYPE ) 0xAAAA; /* AX */
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161 *pxTopOfStack = ( portSTACK_TYPE ) 0xBBBB; /* BX */
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163 *pxTopOfStack = ( portSTACK_TYPE ) 0xCCCC; /* CX */
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165 *pxTopOfStack = ( portSTACK_TYPE ) 0xDDDD; /* DX */
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167 *pxTopOfStack = ( portSTACK_TYPE ) 0xEEEE; /* ES */
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170 *pxTopOfStack = DS_Reg; /* DS */
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172 *pxTopOfStack = ( portSTACK_TYPE ) 0x0123; /* SI */
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174 *pxTopOfStack = ( portSTACK_TYPE ) 0xDDDD; /* DI */
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176 *pxTopOfStack = ( portSTACK_TYPE ) 0xBBBB; /* BP */
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178 return pxTopOfStack;
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180 /*-----------------------------------------------------------*/
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182 portBASE_TYPE xPortStartScheduler( void )
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184 /* This is called with interrupts already disabled. */
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186 /* Put our manual switch (yield) function on a known
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188 setvect( portSWITCH_INT_NUMBER, prvYieldProcessor );
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190 /* Setup the tick interrupt. */
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191 prvSetupTimerInterrupt();
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193 /* Kick off the scheduler by setting up the context of the first task. */
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194 portFIRST_CONTEXT();
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196 /* Should not get here! */
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199 /*-----------------------------------------------------------*/
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201 /* The ISR used depends on whether the preemptive or cooperative scheduler
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203 #if( configUSE_PREEMPTION == 1 )
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204 static void __interrupt __far prvPreemptiveTick( void )
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206 /* Get the scheduler to update the task states following the tick. */
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207 vTaskIncrementTick();
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209 /* Switch in the context of the next task to be run. */
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210 portEND_SWITCHING_ISR();
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212 /* Reset interrupt. */
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213 outport( portEIO_REGISTER, portCLEAR_INTERRUPT );
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216 static void __interrupt __far prvNonPreemptiveTick( void )
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218 /* Same as preemptive tick, but the cooperative scheduler is being used
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219 so we don't have to switch in the context of the next task. */
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220 vTaskIncrementTick();
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221 /* Reset interrupt. */
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222 outport( portEIO_REGISTER, portCLEAR_INTERRUPT );
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225 /*-----------------------------------------------------------*/
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227 static void __interrupt __far prvYieldProcessor( void )
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229 /* Switch in the context of the next task to be run. */
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230 portEND_SWITCHING_ISR();
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232 /*-----------------------------------------------------------*/
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234 void vPortEndScheduler( void )
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236 /* Not implemented. */
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238 /*-----------------------------------------------------------*/
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240 static void prvSetupTimerInterrupt( void )
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242 const unsigned long ulCompareValue = portTIMER_COMPARE;
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243 unsigned short usTimerCompare;
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245 usTimerCompare = ( unsigned short ) ( ulCompareValue >> 4 );
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246 t2_init( portENABLE_TIMER, portPRESCALE_VALUE, NULL );
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248 #if( configUSE_PREEMPTION == 1 )
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249 /* Tick service routine used by the scheduler when preemptive scheduling is
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251 t1_init( portENABLE_TIMER_AND_INTERRUPT, usTimerCompare, usTimerCompare, prvPreemptiveTick );
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253 /* Tick service routine used by the scheduler when cooperative scheduling is
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255 t1_init( portENABLE_TIMER_AND_INTERRUPT, usTimerCompare, usTimerCompare, prvNonPreemptiveTick );
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