2 FreeRTOS V9.0.1 - Copyright (C) 2017 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 ***************************************************************************
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14 >>! NOTE: The modification to the GPL is included to allow you to !<<
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15 >>! distribute a combined work that includes FreeRTOS without being !<<
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16 >>! obliged to provide the source code for proprietary components !<<
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17 >>! outside of the FreeRTOS kernel. !<<
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18 ***************************************************************************
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20 FreeRTOS is distributed in the hope that it will be useful, but WITHOUT ANY
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21 WARRANTY; without even the implied warranty of MERCHANTABILITY or FITNESS
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22 FOR A PARTICULAR PURPOSE. Full license text is available on the following
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23 link: http://www.freertos.org/a00114.html
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25 ***************************************************************************
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27 * FreeRTOS provides completely free yet professionally developed, *
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28 * robust, strictly quality controlled, supported, and cross *
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29 * platform software that is more than just the market leader, it *
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30 * is the industry's de facto standard. *
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32 * Help yourself get started quickly while simultaneously helping *
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33 * to support the FreeRTOS project by purchasing a FreeRTOS *
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34 * tutorial book, reference manual, or both: *
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35 * http://www.FreeRTOS.org/Documentation *
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37 ***************************************************************************
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39 http://www.FreeRTOS.org/FAQHelp.html - Having a problem? Start by reading
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40 the FAQ page "My application does not run, what could be wrong?". Have you
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41 defined configASSERT()?
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43 http://www.FreeRTOS.org/support - In return for receiving this top quality
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44 embedded software for free we request you assist our global community by
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45 participating in the support forum.
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47 http://www.FreeRTOS.org/training - Investing in training allows your team to
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48 be as productive as possible as early as possible. Now you can receive
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49 FreeRTOS training directly from Richard Barry, CEO of Real Time Engineers
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50 Ltd, and the world's leading authority on the world's leading RTOS.
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52 http://www.FreeRTOS.org/plus - A selection of FreeRTOS ecosystem products,
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53 including FreeRTOS+Trace - an indispensable productivity tool, a DOS
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54 compatible FAT file system, and our tiny thread aware UDP/IP stack.
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56 http://www.FreeRTOS.org/labs - Where new FreeRTOS products go to incubate.
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57 Come and try FreeRTOS+TCP, our new open source TCP/IP stack for FreeRTOS.
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59 http://www.OpenRTOS.com - Real Time Engineers ltd. license FreeRTOS to High
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60 Integrity Systems ltd. to sell under the OpenRTOS brand. Low cost OpenRTOS
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61 licenses offer ticketed support, indemnification and commercial middleware.
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63 http://www.SafeRTOS.com - High Integrity Systems also provide a safety
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64 engineered and independently SIL3 certified version for use in safety and
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65 mission critical applications that require provable dependability.
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72 #include "FreeRTOS.h"
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75 /*-----------------------------------------------------------
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76 * Implementation of functions defined in portable.h for the AVR/IAR port.
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77 *----------------------------------------------------------*/
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79 /* Start tasks with interrupts enables. */
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80 #define portFLAGS_INT_ENABLED ( ( StackType_t ) 0x80 )
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82 /* Hardware constants for timer 1. */
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83 #define portCLEAR_COUNTER_ON_MATCH ( ( uint8_t ) 0x08 )
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84 #define portPRESCALE_64 ( ( uint8_t ) 0x03 )
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85 #define portCLOCK_PRESCALER ( ( uint32_t ) 64 )
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86 #define portCOMPARE_MATCH_A_INTERRUPT_ENABLE ( ( uint8_t ) 0x10 )
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88 /* The number of bytes used on the hardware stack by the task start address. */
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89 #define portBYTES_USED_BY_RETURN_ADDRESS ( 2 )
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90 /*-----------------------------------------------------------*/
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92 /* Stores the critical section nesting. This must not be initialised to 0.
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93 It will be initialised when a task starts. */
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94 #define portNO_CRITICAL_NESTING ( ( UBaseType_t ) 0 )
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95 UBaseType_t uxCriticalNesting = 0x50;
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99 * Perform hardware setup to enable ticks from timer 1, compare match A.
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101 static void prvSetupTimerInterrupt( void );
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104 * The IAR compiler does not have full support for inline assembler, so
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105 * these are defined in the portmacro assembler file.
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107 extern void vPortYieldFromTick( void );
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108 extern void vPortStart( void );
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110 /*-----------------------------------------------------------*/
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113 * See header file for description.
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115 StackType_t *pxPortInitialiseStack( StackType_t *pxTopOfStack, TaskFunction_t pxCode, void *pvParameters )
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117 uint16_t usAddress;
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118 StackType_t *pxTopOfHardwareStack;
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120 /* Place a few bytes of known values on the bottom of the stack.
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121 This is just useful for debugging. */
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123 *pxTopOfStack = 0x11;
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125 *pxTopOfStack = 0x22;
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127 *pxTopOfStack = 0x33;
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130 /* Remember where the top of the hardware stack is - this is required
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132 pxTopOfHardwareStack = pxTopOfStack;
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135 /* Simulate how the stack would look after a call to vPortYield(). */
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137 /*lint -e950 -e611 -e923 Lint doesn't like this much - but nothing I can do about it. */
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141 /* The IAR compiler requires two stacks per task. First there is the
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142 hardware call stack which uses the AVR stack pointer. Second there is the
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143 software stack (local variables, parameter passing, etc.) which uses the
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146 This function places both stacks within the memory block passed in as the
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147 first parameter. The hardware stack is placed at the bottom of the memory
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148 block. A gap is then left for the hardware stack to grow. Next the software
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149 stack is placed. The amount of space between the software and hardware
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150 stacks is defined by configCALL_STACK_SIZE.
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154 The first part of the stack is the hardware stack. Place the start
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155 address of the task on the hardware stack. */
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156 usAddress = ( uint16_t ) pxCode;
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157 *pxTopOfStack = ( StackType_t ) ( usAddress & ( uint16_t ) 0x00ff );
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161 *pxTopOfStack = ( StackType_t ) ( usAddress & ( uint16_t ) 0x00ff );
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165 /* Leave enough space for the hardware stack before starting the software
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166 stack. The '- 2' is because we have already used two spaces for the
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167 address of the start of the task. */
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168 pxTopOfStack -= ( configCALL_STACK_SIZE - 2 );
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172 /* Next simulate the stack as if after a call to portSAVE_CONTEXT().
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173 portSAVE_CONTEXT places the flags on the stack immediately after r0
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174 to ensure the interrupts get disabled as soon as possible, and so ensuring
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175 the stack use is minimal should a context switch interrupt occur. */
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176 *pxTopOfStack = ( StackType_t ) 0x00; /* R0 */
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178 *pxTopOfStack = portFLAGS_INT_ENABLED;
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181 /* Next place the address of the hardware stack. This is required so
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182 the AVR stack pointer can be restored to point to the hardware stack. */
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183 pxTopOfHardwareStack -= portBYTES_USED_BY_RETURN_ADDRESS;
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184 usAddress = ( uint16_t ) pxTopOfHardwareStack;
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187 *pxTopOfStack = ( StackType_t ) ( usAddress & ( uint16_t ) 0x00ff );
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192 *pxTopOfStack = ( StackType_t ) ( usAddress & ( uint16_t ) 0x00ff );
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198 /* Now the remaining registers. */
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199 *pxTopOfStack = ( StackType_t ) 0x01; /* R1 */
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201 *pxTopOfStack = ( StackType_t ) 0x02; /* R2 */
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203 *pxTopOfStack = ( StackType_t ) 0x03; /* R3 */
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205 *pxTopOfStack = ( StackType_t ) 0x04; /* R4 */
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207 *pxTopOfStack = ( StackType_t ) 0x05; /* R5 */
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209 *pxTopOfStack = ( StackType_t ) 0x06; /* R6 */
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211 *pxTopOfStack = ( StackType_t ) 0x07; /* R7 */
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213 *pxTopOfStack = ( StackType_t ) 0x08; /* R8 */
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215 *pxTopOfStack = ( StackType_t ) 0x09; /* R9 */
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217 *pxTopOfStack = ( StackType_t ) 0x10; /* R10 */
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219 *pxTopOfStack = ( StackType_t ) 0x11; /* R11 */
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221 *pxTopOfStack = ( StackType_t ) 0x12; /* R12 */
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223 *pxTopOfStack = ( StackType_t ) 0x13; /* R13 */
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225 *pxTopOfStack = ( StackType_t ) 0x14; /* R14 */
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227 *pxTopOfStack = ( StackType_t ) 0x15; /* R15 */
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230 /* Place the parameter on the stack in the expected location. */
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231 usAddress = ( uint16_t ) pvParameters;
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232 *pxTopOfStack = ( StackType_t ) ( usAddress & ( uint16_t ) 0x00ff );
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236 *pxTopOfStack = ( StackType_t ) ( usAddress & ( uint16_t ) 0x00ff );
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239 *pxTopOfStack = ( StackType_t ) 0x18; /* R18 */
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241 *pxTopOfStack = ( StackType_t ) 0x19; /* R19 */
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243 *pxTopOfStack = ( StackType_t ) 0x20; /* R20 */
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245 *pxTopOfStack = ( StackType_t ) 0x21; /* R21 */
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247 *pxTopOfStack = ( StackType_t ) 0x22; /* R22 */
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249 *pxTopOfStack = ( StackType_t ) 0x23; /* R23 */
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251 *pxTopOfStack = ( StackType_t ) 0x24; /* R24 */
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253 *pxTopOfStack = ( StackType_t ) 0x25; /* R25 */
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255 *pxTopOfStack = ( StackType_t ) 0x26; /* R26 X */
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257 *pxTopOfStack = ( StackType_t ) 0x27; /* R27 */
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260 /* The Y register is not stored as it is used as the software stack and
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261 gets saved into the task control block. */
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263 *pxTopOfStack = ( StackType_t ) 0x30; /* R30 Z */
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265 *pxTopOfStack = ( StackType_t ) 0x031; /* R31 */
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268 *pxTopOfStack = portNO_CRITICAL_NESTING; /* Critical nesting is zero when the task starts. */
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270 /*lint +e950 +e611 +e923 */
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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. */
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279 prvSetupTimerInterrupt();
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281 /* Restore the context of the first task that is going to run.
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282 Normally we would just call portRESTORE_CONTEXT() here, but as the IAR
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283 compiler does not fully support inline assembler we have to make a call.*/
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286 /* Should not get here! */
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289 /*-----------------------------------------------------------*/
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291 void vPortEndScheduler( void )
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293 /* It is unlikely that the AVR port will get stopped. If required simply
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294 disable the tick interrupt here. */
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296 /*-----------------------------------------------------------*/
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299 * Setup timer 1 compare match A to generate a tick interrupt.
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301 static void prvSetupTimerInterrupt( void )
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303 uint32_t ulCompareMatch;
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304 uint8_t ucHighByte, ucLowByte;
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306 /* Using 16bit timer 1 to generate the tick. Correct fuses must be
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307 selected for the configCPU_CLOCK_HZ clock. */
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309 ulCompareMatch = configCPU_CLOCK_HZ / configTICK_RATE_HZ;
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311 /* We only have 16 bits so have to scale to get our required tick rate. */
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312 ulCompareMatch /= portCLOCK_PRESCALER;
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314 /* Adjust for correct value. */
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315 ulCompareMatch -= ( uint32_t ) 1;
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317 /* Setup compare match value for compare match A. Interrupts are disabled
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318 before this is called so we need not worry here. */
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319 ucLowByte = ( uint8_t ) ( ulCompareMatch & ( uint32_t ) 0xff );
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320 ulCompareMatch >>= 8;
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321 ucHighByte = ( uint8_t ) ( ulCompareMatch & ( uint32_t ) 0xff );
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322 OCR1AH = ucHighByte;
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323 OCR1AL = ucLowByte;
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325 /* Setup clock source and compare match behaviour. */
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326 ucLowByte = portCLEAR_COUNTER_ON_MATCH | portPRESCALE_64;
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327 TCCR1B = ucLowByte;
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329 /* Enable the interrupt - this is okay as interrupt are currently globally
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331 TIMSK |= portCOMPARE_MATCH_A_INTERRUPT_ENABLE;
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333 /*-----------------------------------------------------------*/
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335 #if configUSE_PREEMPTION == 1
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338 * Tick ISR for preemptive scheduler. We can use a __task attribute as
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339 * the context is saved at the start of vPortYieldFromTick(). The tick
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340 * count is incremented after the context is saved.
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342 __task void SIG_OUTPUT_COMPARE1A( void )
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344 vPortYieldFromTick();
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351 * Tick ISR for the cooperative scheduler. All this does is increment the
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352 * tick count. We don't need to switch context, this can only be done by
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353 * manual calls to taskYIELD();
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355 * THE INTERRUPT VECTOR IS POPULATED IN portmacro.s90. DO NOT INSTALL
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356 * IT HERE USING THE USUAL PRAGMA.
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358 __interrupt void SIG_OUTPUT_COMPARE1A( void )
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360 xTaskIncrementTick();
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363 /*-----------------------------------------------------------*/
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365 void vPortEnterCritical( void )
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367 portDISABLE_INTERRUPTS();
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368 uxCriticalNesting++;
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370 /*-----------------------------------------------------------*/
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372 void vPortExitCritical( void )
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374 uxCriticalNesting--;
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375 if( uxCriticalNesting == portNO_CRITICAL_NESTING )
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377 portENABLE_INTERRUPTS();
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