2 FreeRTOS V7.4.1 - 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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75 /*-----------------------------------------------------------
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76 * Implementation of functions defined in portable.h for the Philips ARM7 port.
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77 *----------------------------------------------------------*/
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82 + Bug fix - The prescale value for the timer setup is now written to T0PR
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83 instead of T0PC. This bug would have had no effect unless a prescale
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84 value was actually used.
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87 /* Standard includes. */
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89 #include <intrinsics.h>
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91 /* Scheduler includes. */
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92 #include "FreeRTOS.h"
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95 /* Constants required to setup the tick ISR. */
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96 #define portENABLE_TIMER ( ( unsigned char ) 0x01 )
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97 #define portPRESCALE_VALUE 0x00
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98 #define portINTERRUPT_ON_MATCH ( ( unsigned long ) 0x01 )
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99 #define portRESET_COUNT_ON_MATCH ( ( unsigned long ) 0x02 )
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101 /* Constants required to setup the initial stack. */
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102 #define portINITIAL_SPSR ( ( portSTACK_TYPE ) 0x1f ) /* System mode, ARM mode, interrupts enabled. */
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103 #define portTHUMB_MODE_BIT ( ( portSTACK_TYPE ) 0x20 )
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104 #define portINSTRUCTION_SIZE ( ( portSTACK_TYPE ) 4 )
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106 /* Constants required to setup the PIT. */
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107 #define portPIT_CLOCK_DIVISOR ( ( unsigned long ) 16 )
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108 #define portPIT_COUNTER_VALUE ( ( ( configCPU_CLOCK_HZ / portPIT_CLOCK_DIVISOR ) / 1000UL ) * portTICK_RATE_MS )
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110 /* Constants required to handle interrupts. */
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111 #define portTIMER_MATCH_ISR_BIT ( ( unsigned char ) 0x01 )
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112 #define portCLEAR_VIC_INTERRUPT ( ( unsigned long ) 0 )
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114 /* Constants required to handle critical sections. */
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115 #define portNO_CRITICAL_NESTING ( ( unsigned long ) 0 )
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118 #define portINT_LEVEL_SENSITIVE 0
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119 #define portPIT_ENABLE ( ( unsigned short ) 0x1 << 24 )
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120 #define portPIT_INT_ENABLE ( ( unsigned short ) 0x1 << 25 )
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122 /* Constants required to setup the VIC for the tick ISR. */
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123 #define portTIMER_VIC_CHANNEL ( ( unsigned long ) 0x0004 )
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124 #define portTIMER_VIC_CHANNEL_BIT ( ( unsigned long ) 0x0010 )
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125 #define portTIMER_VIC_ENABLE ( ( unsigned long ) 0x0020 )
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127 /*-----------------------------------------------------------*/
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129 /* Setup the PIT to generate the tick interrupts. */
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130 static void prvSetupTimerInterrupt( void );
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132 /* ulCriticalNesting will get set to zero when the first task starts. It
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133 cannot be initialised to 0 as this will cause interrupts to be enabled
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134 during the kernel initialisation process. */
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135 unsigned long ulCriticalNesting = ( unsigned long ) 9999;
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137 /*-----------------------------------------------------------*/
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140 * Initialise the stack of a task to look exactly as if a call to
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141 * portSAVE_CONTEXT had been called.
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143 * See header file for description.
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145 portSTACK_TYPE *pxPortInitialiseStack( portSTACK_TYPE *pxTopOfStack, pdTASK_CODE pxCode, void *pvParameters )
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147 portSTACK_TYPE *pxOriginalTOS;
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149 pxOriginalTOS = pxTopOfStack;
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151 /* Setup the initial stack of the task. The stack is set exactly as
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152 expected by the portRESTORE_CONTEXT() macro. */
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154 /* First on the stack is the return address - which in this case is the
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155 start of the task. The offset is added to make the return address appear
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156 as it would within an IRQ ISR. */
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157 *pxTopOfStack = ( portSTACK_TYPE ) pxCode + portINSTRUCTION_SIZE;
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160 *pxTopOfStack = ( portSTACK_TYPE ) 0xaaaaaaaa; /* R14 */
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162 *pxTopOfStack = ( portSTACK_TYPE ) pxOriginalTOS; /* Stack used when task starts goes in R13. */
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164 *pxTopOfStack = ( portSTACK_TYPE ) 0x12121212; /* R12 */
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166 *pxTopOfStack = ( portSTACK_TYPE ) 0x11111111; /* R11 */
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168 *pxTopOfStack = ( portSTACK_TYPE ) 0x10101010; /* R10 */
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170 *pxTopOfStack = ( portSTACK_TYPE ) 0x09090909; /* R9 */
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172 *pxTopOfStack = ( portSTACK_TYPE ) 0x08080808; /* R8 */
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174 *pxTopOfStack = ( portSTACK_TYPE ) 0x07070707; /* R7 */
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176 *pxTopOfStack = ( portSTACK_TYPE ) 0x06060606; /* R6 */
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178 *pxTopOfStack = ( portSTACK_TYPE ) 0x05050505; /* R5 */
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180 *pxTopOfStack = ( portSTACK_TYPE ) 0x04040404; /* R4 */
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182 *pxTopOfStack = ( portSTACK_TYPE ) 0x03030303; /* R3 */
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184 *pxTopOfStack = ( portSTACK_TYPE ) 0x02020202; /* R2 */
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186 *pxTopOfStack = ( portSTACK_TYPE ) 0x01010101; /* R1 */
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189 /* When the task starts is will expect to find the function parameter in
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191 *pxTopOfStack = ( portSTACK_TYPE ) pvParameters; /* R0 */
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194 /* The status register is set for system mode, with interrupts enabled. */
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195 *pxTopOfStack = ( portSTACK_TYPE ) portINITIAL_SPSR;
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197 if( ( ( unsigned long ) pxCode & 0x01UL ) != 0x00UL )
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199 /* We want the task to start in thumb mode. */
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200 *pxTopOfStack |= portTHUMB_MODE_BIT;
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205 /* Interrupt flags cannot always be stored on the stack and will
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206 instead be stored in a variable, which is then saved as part of the
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208 *pxTopOfStack = portNO_CRITICAL_NESTING;
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210 return pxTopOfStack;
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212 /*-----------------------------------------------------------*/
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214 portBASE_TYPE xPortStartScheduler( void )
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216 extern void vPortStartFirstTask( void );
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218 /* Start the timer that generates the tick ISR. Interrupts are disabled
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220 prvSetupTimerInterrupt();
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222 /* Start the first task. */
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223 vPortStartFirstTask();
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225 /* Should not get here! */
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228 /*-----------------------------------------------------------*/
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230 void vPortEndScheduler( void )
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232 /* It is unlikely that the ARM port will require this function as there
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233 is nothing to return to. */
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235 /*-----------------------------------------------------------*/
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237 #if configUSE_PREEMPTION == 0
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239 /* The cooperative scheduler requires a normal IRQ service routine to
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240 simply increment the system tick. */
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241 static __arm __irq void vPortNonPreemptiveTick( void );
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242 static __arm __irq void vPortNonPreemptiveTick( void )
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244 /* Increment the tick count - which may wake some tasks but as the
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245 preemptive scheduler is not being used any woken task is not given
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246 processor time no matter what its priority. */
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247 vTaskIncrementTick();
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249 /* Ready for the next interrupt. */
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250 T0IR = portTIMER_MATCH_ISR_BIT;
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251 VICVectAddr = portCLEAR_VIC_INTERRUPT;
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256 /* This function is called from an asm wrapper, so does not require the __irq
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258 void vPortPreemptiveTick( void );
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259 void vPortPreemptiveTick( void )
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261 /* Increment the tick counter. */
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262 vTaskIncrementTick();
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264 /* The new tick value might unblock a task. Ensure the highest task that
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265 is ready to execute is the task that will execute when the tick ISR
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267 vTaskSwitchContext();
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269 /* Ready for the next interrupt. */
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270 T0IR = portTIMER_MATCH_ISR_BIT;
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271 VICVectAddr = portCLEAR_VIC_INTERRUPT;
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276 /*-----------------------------------------------------------*/
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278 static void prvSetupTimerInterrupt( void )
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280 unsigned long ulCompareMatch;
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282 /* A 1ms tick does not require the use of the timer prescale. This is
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283 defaulted to zero but can be used if necessary. */
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284 T0PR = portPRESCALE_VALUE;
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286 /* Calculate the match value required for our wanted tick rate. */
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287 ulCompareMatch = configCPU_CLOCK_HZ / configTICK_RATE_HZ;
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289 /* Protect against divide by zero. Using an if() statement still results
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290 in a warning - hence the #if. */
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291 #if portPRESCALE_VALUE != 0
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293 ulCompareMatch /= ( portPRESCALE_VALUE + 1 );
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297 T0MR0 = ulCompareMatch;
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299 /* Generate tick with timer 0 compare match. */
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300 T0MCR = portRESET_COUNT_ON_MATCH | portINTERRUPT_ON_MATCH;
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302 /* Setup the VIC for the timer. */
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303 VICIntSelect &= ~( portTIMER_VIC_CHANNEL_BIT );
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304 VICIntEnable |= portTIMER_VIC_CHANNEL_BIT;
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306 /* The ISR installed depends on whether the preemptive or cooperative
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307 scheduler is being used. */
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308 #if configUSE_PREEMPTION == 1
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310 extern void ( vPortPreemptiveTickEntry )( void );
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312 VICVectAddr0 = ( unsigned long ) vPortPreemptiveTickEntry;
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316 extern void ( vNonPreemptiveTick )( void );
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318 VICVectAddr0 = ( long ) vPortNonPreemptiveTick;
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322 VICVectCntl0 = portTIMER_VIC_CHANNEL | portTIMER_VIC_ENABLE;
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324 /* Start the timer - interrupts are disabled when this function is called
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325 so it is okay to do this here. */
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326 T0TCR = portENABLE_TIMER;
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328 /*-----------------------------------------------------------*/
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330 void vPortEnterCritical( void )
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332 /* Disable interrupts first! */
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333 __disable_interrupt();
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335 /* Now interrupts are disabled ulCriticalNesting can be accessed
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336 directly. Increment ulCriticalNesting to keep a count of how many times
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337 portENTER_CRITICAL() has been called. */
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338 ulCriticalNesting++;
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340 /*-----------------------------------------------------------*/
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342 void vPortExitCritical( void )
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344 if( ulCriticalNesting > portNO_CRITICAL_NESTING )
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346 /* Decrement the nesting count as we are leaving a critical section. */
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347 ulCriticalNesting--;
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349 /* If the nesting level has reached zero then interrupts should be
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351 if( ulCriticalNesting == portNO_CRITICAL_NESTING )
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353 __enable_interrupt();
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357 /*-----------------------------------------------------------*/
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