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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75 /*-----------------------------------------------------------
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76 * Implementation of functions defined in portable.h for the ARM CM4F port.
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77 *----------------------------------------------------------*/
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79 /* Compiler includes. */
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80 #include <intrinsics.h>
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82 /* Scheduler includes. */
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83 #include "FreeRTOS.h"
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87 #error This port can only be used when the project options are configured to enable hardware floating point support.
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90 #if configMAX_SYSCALL_INTERRUPT_PRIORITY == 0
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91 #error configMAX_SYSCALL_INTERRUPT_PRIORITY must not be set to 0. See http://www.FreeRTOS.org/RTOS-Cortex-M3-M4.html
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94 #ifndef configSYSTICK_CLOCK_HZ
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95 #define configSYSTICK_CLOCK_HZ configCPU_CLOCK_HZ
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98 /* Constants required to manipulate the core. Registers first... */
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99 #define portNVIC_SYSTICK_CTRL_REG ( * ( ( volatile unsigned long * ) 0xe000e010 ) )
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100 #define portNVIC_SYSTICK_LOAD_REG ( * ( ( volatile unsigned long * ) 0xe000e014 ) )
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101 #define portNVIC_SYSTICK_CURRENT_VALUE_REG ( * ( ( volatile unsigned long * ) 0xe000e018 ) )
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102 #define portNVIC_SYSPRI2_REG ( * ( ( volatile unsigned long * ) 0xe000ed20 ) )
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103 /* ...then bits in the registers. */
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104 #define portNVIC_SYSTICK_CLK_BIT ( 1UL << 2UL )
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105 #define portNVIC_SYSTICK_INT_BIT ( 1UL << 1UL )
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106 #define portNVIC_SYSTICK_ENABLE_BIT ( 1UL << 0UL )
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107 #define portNVIC_SYSTICK_COUNT_FLAG_BIT ( 1UL << 16UL )
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108 #define portNVIC_PENDSVCLEAR_BIT ( 1UL << 27UL )
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109 #define portNVIC_PEND_SYSTICK_CLEAR_BIT ( 1UL << 25UL )
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111 #define portNVIC_PENDSV_PRI ( ( ( unsigned long ) configKERNEL_INTERRUPT_PRIORITY ) << 16UL )
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112 #define portNVIC_SYSTICK_PRI ( ( ( unsigned long ) configKERNEL_INTERRUPT_PRIORITY ) << 24UL )
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114 /* Constants required to check the validity of an interrupt prority. */
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115 #define portFIRST_USER_INTERRUPT_NUMBER ( 16 )
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116 #define portNVIC_IP_REGISTERS_OFFSET_16 ( 0xE000E3F0 )
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117 #define portAIRCR_REG ( * ( ( volatile unsigned long * ) 0xE000ED0C ) )
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118 #define portPRIORITY_GROUP_MASK ( 0x07UL << 8UL )
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120 /* Constants required to manipulate the VFP. */
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121 #define portFPCCR ( ( volatile unsigned long * ) 0xe000ef34 ) /* Floating point context control register. */
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122 #define portASPEN_AND_LSPEN_BITS ( 0x3UL << 30UL )
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124 /* Constants required to set up the initial stack. */
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125 #define portINITIAL_XPSR ( 0x01000000 )
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126 #define portINITIAL_EXEC_RETURN ( 0xfffffffd )
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128 /* The systick is a 24-bit counter. */
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129 #define portMAX_24_BIT_NUMBER ( 0xffffffUL )
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131 /* A fiddle factor to estimate the number of SysTick counts that would have
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132 occurred while the SysTick counter is stopped during tickless idle
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134 #define portMISSED_COUNTS_FACTOR ( 45UL )
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137 /* Each task maintains its own interrupt status in the critical nesting
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139 static unsigned portBASE_TYPE uxCriticalNesting = 0xaaaaaaaa;
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142 * Setup the timer to generate the tick interrupts. The implementation in this
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143 * file is weak to allow application writers to change the timer used to
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144 * generate the tick interrupt.
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146 void vPortSetupTimerInterrupt( void );
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149 * Exception handlers.
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151 void xPortSysTickHandler( void );
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154 * Start first task is a separate function so it can be tested in isolation.
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156 extern void vPortStartFirstTask( void );
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161 extern void vPortEnableVFP( void );
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163 /*-----------------------------------------------------------*/
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166 * The number of SysTick increments that make up one tick period.
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168 #if configUSE_TICKLESS_IDLE == 1
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169 static unsigned long ulTimerCountsForOneTick = 0;
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170 #endif /* configUSE_TICKLESS_IDLE */
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173 * The maximum number of tick periods that can be suppressed is limited by the
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174 * 24 bit resolution of the SysTick timer.
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176 #if configUSE_TICKLESS_IDLE == 1
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177 static unsigned long xMaximumPossibleSuppressedTicks = 0;
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178 #endif /* configUSE_TICKLESS_IDLE */
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181 * Compensate for the CPU cycles that pass while the SysTick is stopped (low
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182 * power functionality only.
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184 #if configUSE_TICKLESS_IDLE == 1
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185 static unsigned long ulStoppedTimerCompensation = 0;
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186 #endif /* configUSE_TICKLESS_IDLE */
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189 * Used by the portASSERT_IF_INTERRUPT_PRIORITY_INVALID() macro to ensure
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190 * FreeRTOS API functions are not called from interrupts that have been assigned
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191 * a priority above configMAX_SYSCALL_INTERRUPT_PRIORITY.
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193 #if ( configASSERT_DEFINED == 1 )
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194 static unsigned char ucMaxSysCallPriority = 0;
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195 static const volatile unsigned char * const pcInterruptPriorityRegisters = ( const volatile unsigned char * const ) portNVIC_IP_REGISTERS_OFFSET_16;
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196 #endif /* configASSERT_DEFINED */
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198 /*-----------------------------------------------------------*/
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201 * See header file for description.
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203 portSTACK_TYPE *pxPortInitialiseStack( portSTACK_TYPE *pxTopOfStack, pdTASK_CODE pxCode, void *pvParameters )
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205 /* Simulate the stack frame as it would be created by a context switch
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208 /* Offset added to account for the way the MCU uses the stack on entry/exit
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209 of interrupts, and to ensure alignment. */
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212 *pxTopOfStack = portINITIAL_XPSR; /* xPSR */
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214 *pxTopOfStack = ( portSTACK_TYPE ) pxCode; /* PC */
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216 *pxTopOfStack = 0; /* LR */
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218 /* Save code space by skipping register initialisation. */
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219 pxTopOfStack -= 5; /* R12, R3, R2 and R1. */
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220 *pxTopOfStack = ( portSTACK_TYPE ) pvParameters; /* R0 */
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222 /* A save method is being used that requires each task to maintain its
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223 own exec return value. */
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225 *pxTopOfStack = portINITIAL_EXEC_RETURN;
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227 pxTopOfStack -= 8; /* R11, R10, R9, R8, R7, R6, R5 and R4. */
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229 return pxTopOfStack;
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231 /*-----------------------------------------------------------*/
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234 * See header file for description.
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236 portBASE_TYPE xPortStartScheduler( void )
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238 #if( configASSERT_DEFINED == 1 )
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240 volatile unsigned long ulOriginalPriority;
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241 volatile char * const pcFirstUserPriorityRegister = ( volatile char * const ) ( portNVIC_IP_REGISTERS_OFFSET_16 + portFIRST_USER_INTERRUPT_NUMBER );
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243 /* Determine the maximum priority from which ISR safe FreeRTOS API
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244 functions can be called. ISR safe functions are those that end in
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245 "FromISR". FreeRTOS maintains separate thread and ISR API functions to
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246 ensure interrupt entry is as fast and simple as possible.
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248 Save the interrupt priority value that is about to be clobbered. */
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249 ulOriginalPriority = *pcFirstUserPriorityRegister;
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251 /* Write the configMAX_SYSCALL_INTERRUPT_PRIORITY value to an interrupt
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252 priority register. */
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253 *pcFirstUserPriorityRegister = configMAX_SYSCALL_INTERRUPT_PRIORITY;
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255 /* Read back the written priority to obtain its value as seen by the
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256 hardware, which will only implement a subset of the priority bits. */
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257 ucMaxSysCallPriority = *pcFirstUserPriorityRegister;
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259 /* Restore the clobbered interrupt priority register to its original
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261 *pcFirstUserPriorityRegister = ulOriginalPriority;
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263 #endif /* conifgASSERT_DEFINED */
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265 /* Make PendSV and SysTick the lowest priority interrupts. */
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266 portNVIC_SYSPRI2_REG |= portNVIC_PENDSV_PRI;
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267 portNVIC_SYSPRI2_REG |= portNVIC_SYSTICK_PRI;
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269 /* Start the timer that generates the tick ISR. Interrupts are disabled
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271 vPortSetupTimerInterrupt();
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273 /* Initialise the critical nesting count ready for the first task. */
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274 uxCriticalNesting = 0;
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276 /* Ensure the VFP is enabled - it should be anyway. */
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279 /* Lazy save always. */
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280 *( portFPCCR ) |= portASPEN_AND_LSPEN_BITS;
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282 /* Start the first task. */
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283 vPortStartFirstTask();
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285 /* Should not get here! */
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288 /*-----------------------------------------------------------*/
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290 void vPortEndScheduler( void )
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292 /* It is unlikely that the CM4F port will require this function as there
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293 is nothing to return to. */
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295 /*-----------------------------------------------------------*/
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297 void vPortYield( void )
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299 /* Set a PendSV to request a context switch. */
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300 portNVIC_INT_CTRL_REG = portNVIC_PENDSVSET_BIT;
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302 /* Barriers are normally not required but do ensure the code is completely
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303 within the specified behaviour for the architecture. */
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307 /*-----------------------------------------------------------*/
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309 void vPortEnterCritical( void )
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311 portDISABLE_INTERRUPTS();
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312 uxCriticalNesting++;
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316 /*-----------------------------------------------------------*/
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318 void vPortExitCritical( void )
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320 uxCriticalNesting--;
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321 if( uxCriticalNesting == 0 )
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323 portENABLE_INTERRUPTS();
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326 /*-----------------------------------------------------------*/
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328 void xPortSysTickHandler( void )
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330 /* The SysTick runs at the lowest interrupt priority, so when this interrupt
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331 executes all interrupts must be unmasked. There is therefore no need to
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332 save and then restore the interrupt mask value as its value is already
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334 ( void ) portSET_INTERRUPT_MASK_FROM_ISR();
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336 /* Increment the RTOS tick. */
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337 if( xTaskIncrementTick() != pdFALSE )
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339 /* A context switch is required. Context switching is performed in
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340 the PendSV interrupt. Pend the PendSV interrupt. */
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341 portNVIC_INT_CTRL_REG = portNVIC_PENDSVSET_BIT;
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344 portCLEAR_INTERRUPT_MASK_FROM_ISR( 0 );
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346 /*-----------------------------------------------------------*/
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348 #if configUSE_TICKLESS_IDLE == 1
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350 __weak void vPortSuppressTicksAndSleep( portTickType xExpectedIdleTime )
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352 unsigned long ulReloadValue, ulCompleteTickPeriods, ulCompletedSysTickDecrements;
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353 portTickType xModifiableIdleTime;
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355 /* Make sure the SysTick reload value does not overflow the counter. */
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356 if( xExpectedIdleTime > xMaximumPossibleSuppressedTicks )
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358 xExpectedIdleTime = xMaximumPossibleSuppressedTicks;
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361 /* Stop the SysTick momentarily. The time the SysTick is stopped for
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362 is accounted for as best it can be, but using the tickless mode will
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363 inevitably result in some tiny drift of the time maintained by the
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364 kernel with respect to calendar time. */
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365 portNVIC_SYSTICK_CTRL_REG = portNVIC_SYSTICK_CLK_BIT | portNVIC_SYSTICK_INT_BIT;
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367 /* Calculate the reload value required to wait xExpectedIdleTime
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368 tick periods. -1 is used because this code will execute part way
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369 through one of the tick periods. */
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370 ulReloadValue = portNVIC_SYSTICK_CURRENT_VALUE_REG + ( ulTimerCountsForOneTick * ( xExpectedIdleTime - 1UL ) );
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371 if( ulReloadValue > ulStoppedTimerCompensation )
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373 ulReloadValue -= ulStoppedTimerCompensation;
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376 /* Enter a critical section but don't use the taskENTER_CRITICAL()
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377 method as that will mask interrupts that should exit sleep mode. */
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378 __disable_interrupt();
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380 /* If a context switch is pending or a task is waiting for the scheduler
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381 to be unsuspended then abandon the low power entry. */
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382 if( eTaskConfirmSleepModeStatus() == eAbortSleep )
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384 /* Restart SysTick. */
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385 portNVIC_SYSTICK_CTRL_REG = portNVIC_SYSTICK_CLK_BIT | portNVIC_SYSTICK_INT_BIT | portNVIC_SYSTICK_ENABLE_BIT;
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387 /* Re-enable interrupts - see comments above __disable_interrupt()
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389 __enable_interrupt();
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393 /* Set the new reload value. */
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394 portNVIC_SYSTICK_LOAD_REG = ulReloadValue;
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396 /* Clear the SysTick count flag and set the count value back to
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398 portNVIC_SYSTICK_CURRENT_VALUE_REG = 0UL;
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400 /* Restart SysTick. */
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401 portNVIC_SYSTICK_CTRL_REG = portNVIC_SYSTICK_CLK_BIT | portNVIC_SYSTICK_INT_BIT | portNVIC_SYSTICK_ENABLE_BIT;
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403 /* Sleep until something happens. configPRE_SLEEP_PROCESSING() can
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404 set its parameter to 0 to indicate that its implementation contains
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405 its own wait for interrupt or wait for event instruction, and so wfi
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406 should not be executed again. However, the original expected idle
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407 time variable must remain unmodified, so a copy is taken. */
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408 xModifiableIdleTime = xExpectedIdleTime;
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409 configPRE_SLEEP_PROCESSING( xModifiableIdleTime );
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410 if( xModifiableIdleTime > 0 )
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416 configPOST_SLEEP_PROCESSING( xExpectedIdleTime );
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418 /* Stop SysTick. Again, the time the SysTick is stopped for is
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419 accounted for as best it can be, but using the tickless mode will
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420 inevitably result in some tiny drift of the time maintained by the
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421 kernel with respect to calendar time. */
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422 portNVIC_SYSTICK_CTRL_REG = portNVIC_SYSTICK_CLK_BIT | portNVIC_SYSTICK_INT_BIT;
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424 /* Re-enable interrupts - see comments above __disable_interrupt()
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426 __enable_interrupt();
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428 if( ( portNVIC_SYSTICK_CTRL_REG & portNVIC_SYSTICK_COUNT_FLAG_BIT ) != 0 )
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430 /* The tick interrupt has already executed, and the SysTick
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431 count reloaded with ulReloadValue. Reset the
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432 portNVIC_SYSTICK_LOAD_REG with whatever remains of this tick
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434 portNVIC_SYSTICK_LOAD_REG = ( ulTimerCountsForOneTick - 1UL ) - ( ulReloadValue - portNVIC_SYSTICK_CURRENT_VALUE_REG );
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436 /* The tick interrupt handler will already have pended the tick
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437 processing in the kernel. As the pending tick will be
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438 processed as soon as this function exits, the tick value
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439 maintained by the tick is stepped forward by one less than the
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440 time spent waiting. */
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441 ulCompleteTickPeriods = xExpectedIdleTime - 1UL;
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445 /* Something other than the tick interrupt ended the sleep.
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446 Work out how long the sleep lasted rounded to complete tick
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447 periods (not the ulReload value which accounted for part
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449 ulCompletedSysTickDecrements = ( xExpectedIdleTime * ulTimerCountsForOneTick ) - portNVIC_SYSTICK_CURRENT_VALUE_REG;
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451 /* How many complete tick periods passed while the processor
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453 ulCompleteTickPeriods = ulCompletedSysTickDecrements / ulTimerCountsForOneTick;
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455 /* The reload value is set to whatever fraction of a single tick
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457 portNVIC_SYSTICK_LOAD_REG = ( ( ulCompleteTickPeriods + 1 ) * ulTimerCountsForOneTick ) - ulCompletedSysTickDecrements;
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460 /* Restart SysTick so it runs from portNVIC_SYSTICK_LOAD_REG
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461 again, then set portNVIC_SYSTICK_LOAD_REG back to its standard
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463 portNVIC_SYSTICK_CURRENT_VALUE_REG = 0UL;
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464 portNVIC_SYSTICK_CTRL_REG = portNVIC_SYSTICK_CLK_BIT | portNVIC_SYSTICK_INT_BIT | portNVIC_SYSTICK_ENABLE_BIT;
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466 vTaskStepTick( ulCompleteTickPeriods );
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468 /* The counter must start by the time the reload value is reset. */
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469 configASSERT( portNVIC_SYSTICK_CURRENT_VALUE_REG );
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470 portNVIC_SYSTICK_LOAD_REG = ulTimerCountsForOneTick - 1UL;
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474 #endif /* #if configUSE_TICKLESS_IDLE */
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475 /*-----------------------------------------------------------*/
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478 * Setup the systick timer to generate the tick interrupts at the required
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481 __weak void vPortSetupTimerInterrupt( void )
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483 /* Calculate the constants required to configure the tick interrupt. */
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484 #if configUSE_TICKLESS_IDLE == 1
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486 ulTimerCountsForOneTick = ( configSYSTICK_CLOCK_HZ / configTICK_RATE_HZ );
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487 xMaximumPossibleSuppressedTicks = portMAX_24_BIT_NUMBER / ulTimerCountsForOneTick;
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488 ulStoppedTimerCompensation = portMISSED_COUNTS_FACTOR / ( configCPU_CLOCK_HZ / configSYSTICK_CLOCK_HZ );
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490 #endif /* configUSE_TICKLESS_IDLE */
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492 /* Configure SysTick to interrupt at the requested rate. */
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493 portNVIC_SYSTICK_LOAD_REG = ( configSYSTICK_CLOCK_HZ / configTICK_RATE_HZ ) - 1UL;;
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494 portNVIC_SYSTICK_CTRL_REG = portNVIC_SYSTICK_CLK_BIT | portNVIC_SYSTICK_INT_BIT | portNVIC_SYSTICK_ENABLE_BIT;
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496 /*-----------------------------------------------------------*/
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498 #if( configASSERT_DEFINED == 1 )
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500 void vPortValidateInterruptPriority( void )
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502 unsigned long ulCurrentInterrupt;
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503 unsigned char ucCurrentPriority;
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505 /* Obtain the number of the currently executing interrupt. */
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506 __asm volatile( "mrs %0, ipsr" : "=r"( ulCurrentInterrupt ) );
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508 /* Is the interrupt number a user defined interrupt? */
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509 if( ulCurrentInterrupt >= portFIRST_USER_INTERRUPT_NUMBER )
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511 /* Look up the interrupt's priority. */
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512 ucCurrentPriority = pcInterruptPriorityRegisters[ ulCurrentInterrupt ];
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514 /* The following assertion will fail if a service routine (ISR) for
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515 an interrupt that has been assigned a priority above
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516 configMAX_SYSCALL_INTERRUPT_PRIORITY calls an ISR safe FreeRTOS API
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517 function. ISR safe FreeRTOS API functions must *only* be called
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518 from interrupts that have been assigned a priority at or below
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519 configMAX_SYSCALL_INTERRUPT_PRIORITY.
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521 Numerically low interrupt priority numbers represent logically high
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522 interrupt priorities, therefore the priority of the interrupt must
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523 be set to a value equal to or numerically *higher* than
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524 configMAX_SYSCALL_INTERRUPT_PRIORITY.
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526 Interrupts that use the FreeRTOS API must not be left at their
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527 default priority of zero as that is the highest possible priority,
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528 which is guaranteed to be above configMAX_SYSCALL_INTERRUPT_PRIORITY,
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529 and therefore also guaranteed to be invalid.
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531 FreeRTOS maintains separate thread and ISR API functions to ensure
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532 interrupt entry is as fast and simple as possible.
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534 The following links provide detailed information:
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535 http://www.freertos.org/RTOS-Cortex-M3-M4.html
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536 http://www.freertos.org/FAQHelp.html */
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537 configASSERT( ucCurrentPriority >= ucMaxSysCallPriority );
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540 /* Priority grouping: The interrupt controller (NVIC) allows the bits
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541 that define each interrupt's priority to be split between bits that
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542 define the interrupt's pre-emption priority bits and bits that define
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543 the interrupt's sub-priority. For simplicity all bits must be defined
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544 to be pre-emption priority bits. The following assertion will fail if
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545 this is not the case (if some bits represent a sub-priority).
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547 If CMSIS libraries are being used then the correct setting can be
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548 achieved by calling NVIC_SetPriorityGrouping( 0 ); before starting the
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550 configASSERT( ( portAIRCR_REG & portPRIORITY_GROUP_MASK ) == 0 );
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553 #endif /* configASSERT_DEFINED */
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