2 FreeRTOS V7.5.3 - Copyright (C) 2013 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 ***************************************************************************
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9 * FreeRTOS provides completely free yet professionally developed, *
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10 * robust, strictly quality controlled, supported, and cross *
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11 * platform software that has become a de facto standard. *
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13 * Help yourself get started quickly and support the FreeRTOS *
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14 * project by purchasing a FreeRTOS tutorial book, reference *
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15 * manual, or both from: http://www.FreeRTOS.org/Documentation *
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19 ***************************************************************************
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21 This file is part of the FreeRTOS distribution.
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23 FreeRTOS is free software; you can redistribute it and/or modify it under
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24 the terms of the GNU General Public License (version 2) as published by the
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25 Free Software Foundation >>!AND MODIFIED BY!<< the FreeRTOS exception.
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27 >>! NOTE: The modification to the GPL is included to allow you to distribute
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28 >>! a combined work that includes FreeRTOS without being obliged to provide
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29 >>! the source code for proprietary components outside of the FreeRTOS
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32 FreeRTOS is distributed in the hope that it will be useful, but WITHOUT ANY
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33 WARRANTY; without even the implied warranty of MERCHANTABILITY or FITNESS
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34 FOR A PARTICULAR PURPOSE. Full license text is available from the following
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35 link: http://www.freertos.org/a00114.html
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39 ***************************************************************************
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41 * Having a problem? Start by reading the FAQ "My application does *
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42 * not run, what could be wrong?" *
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44 * http://www.FreeRTOS.org/FAQHelp.html *
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46 ***************************************************************************
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48 http://www.FreeRTOS.org - Documentation, books, training, latest versions,
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49 license and Real Time Engineers Ltd. contact details.
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51 http://www.FreeRTOS.org/plus - A selection of FreeRTOS ecosystem products,
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52 including FreeRTOS+Trace - an indispensable productivity tool, a DOS
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53 compatible FAT file system, and our tiny thread aware UDP/IP stack.
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55 http://www.OpenRTOS.com - Real Time Engineers ltd license FreeRTOS to High
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56 Integrity Systems to sell under the OpenRTOS brand. Low cost OpenRTOS
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57 licenses offer ticketed support, indemnification and middleware.
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59 http://www.SafeRTOS.com - High Integrity Systems also provide a safety
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60 engineered and independently SIL3 certified version for use in safety and
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61 mission critical applications that require provable dependability.
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66 /*-----------------------------------------------------------
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67 * Implementation of functions defined in portable.h for the ARM CM4F port.
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68 *----------------------------------------------------------*/
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70 /* Scheduler includes. */
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71 #include "FreeRTOS.h"
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74 #ifndef __TARGET_FPU_VFP
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75 #error This port can only be used when the project options are configured to enable hardware floating point support.
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78 #if configMAX_SYSCALL_INTERRUPT_PRIORITY == 0
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79 #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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82 #ifndef configSYSTICK_CLOCK_HZ
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83 #define configSYSTICK_CLOCK_HZ configCPU_CLOCK_HZ
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86 /* The __weak attribute does not work as you might expect with the Keil tools
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87 so the configOVERRIDE_DEFAULT_TICK_CONFIGURATION constant must be set to 1 if
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88 the application writer wants to provide their own implementation of
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89 vPortSetupTimerInterrupt(). Ensure configOVERRIDE_DEFAULT_TICK_CONFIGURATION
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91 #ifndef configOVERRIDE_DEFAULT_TICK_CONFIGURATION
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92 #define configOVERRIDE_DEFAULT_TICK_CONFIGURATION 0
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95 /* Constants required to manipulate the core. Registers first... */
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96 #define portNVIC_SYSTICK_CTRL_REG ( * ( ( volatile unsigned long * ) 0xe000e010 ) )
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97 #define portNVIC_SYSTICK_LOAD_REG ( * ( ( volatile unsigned long * ) 0xe000e014 ) )
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98 #define portNVIC_SYSTICK_CURRENT_VALUE_REG ( * ( ( volatile unsigned long * ) 0xe000e018 ) )
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99 #define portNVIC_SYSPRI2_REG ( * ( ( volatile unsigned long * ) 0xe000ed20 ) )
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100 /* ...then bits in the registers. */
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101 #define portNVIC_SYSTICK_CLK_BIT ( 1UL << 2UL )
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102 #define portNVIC_SYSTICK_INT_BIT ( 1UL << 1UL )
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103 #define portNVIC_SYSTICK_ENABLE_BIT ( 1UL << 0UL )
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104 #define portNVIC_SYSTICK_COUNT_FLAG_BIT ( 1UL << 16UL )
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105 #define portNVIC_PENDSVCLEAR_BIT ( 1UL << 27UL )
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106 #define portNVIC_PEND_SYSTICK_CLEAR_BIT ( 1UL << 25UL )
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108 #define portNVIC_PENDSV_PRI ( ( ( unsigned long ) configKERNEL_INTERRUPT_PRIORITY ) << 16UL )
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109 #define portNVIC_SYSTICK_PRI ( ( ( unsigned long ) configKERNEL_INTERRUPT_PRIORITY ) << 24UL )
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111 /* Constants required to check the validity of an interrupt priority. */
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112 #define portFIRST_USER_INTERRUPT_NUMBER ( 16 )
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113 #define portNVIC_IP_REGISTERS_OFFSET_16 ( 0xE000E3F0 )
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114 #define portAIRCR_REG ( * ( ( volatile unsigned long * ) 0xE000ED0C ) )
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115 #define portMAX_8_BIT_VALUE ( ( unsigned char ) 0xff )
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116 #define portTOP_BIT_OF_BYTE ( ( unsigned char ) 0x80 )
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117 #define portMAX_PRIGROUP_BITS ( ( unsigned char ) 7 )
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118 #define portPRIORITY_GROUP_MASK ( 0x07UL << 8UL )
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119 #define portPRIGROUP_SHIFT ( 8UL )
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121 /* Constants required to manipulate the VFP. */
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122 #define portFPCCR ( ( volatile unsigned long * ) 0xe000ef34 ) /* Floating point context control register. */
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123 #define portASPEN_AND_LSPEN_BITS ( 0x3UL << 30UL )
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125 /* Constants required to set up the initial stack. */
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126 #define portINITIAL_XPSR ( 0x01000000 )
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127 #define portINITIAL_EXEC_RETURN ( 0xfffffffd )
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129 /* Constants used with memory barrier intrinsics. */
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130 #define portSY_FULL_READ_WRITE ( 15 )
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132 /* The systick is a 24-bit counter. */
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133 #define portMAX_24_BIT_NUMBER ( 0xffffffUL )
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135 /* A fiddle factor to estimate the number of SysTick counts that would have
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136 occurred while the SysTick counter is stopped during tickless idle
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138 #define portMISSED_COUNTS_FACTOR ( 45UL )
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140 /* Each task maintains its own interrupt status in the critical nesting
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142 static unsigned portBASE_TYPE uxCriticalNesting = 0xaaaaaaaa;
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145 * Setup the timer to generate the tick interrupts. The implementation in this
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146 * file is weak to allow application writers to change the timer used to
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147 * generate the tick interrupt.
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149 void vPortSetupTimerInterrupt( void );
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152 * Exception handlers.
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154 void xPortPendSVHandler( void );
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155 void xPortSysTickHandler( void );
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156 void vPortSVCHandler( void );
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159 * Start first task is a separate function so it can be tested in isolation.
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161 static void prvStartFirstTask( void );
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164 * Functions defined in portasm.s to enable the VFP.
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166 static void prvEnableVFP( void );
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169 * Used to catch tasks that attempt to return from their implementing function.
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171 static void prvTaskExitError( void );
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173 /*-----------------------------------------------------------*/
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176 * The number of SysTick increments that make up one tick period.
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178 #if configUSE_TICKLESS_IDLE == 1
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179 static unsigned long ulTimerCountsForOneTick = 0;
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180 #endif /* configUSE_TICKLESS_IDLE */
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183 * The maximum number of tick periods that can be suppressed is limited by the
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184 * 24 bit resolution of the SysTick timer.
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186 #if configUSE_TICKLESS_IDLE == 1
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187 static unsigned long xMaximumPossibleSuppressedTicks = 0;
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188 #endif /* configUSE_TICKLESS_IDLE */
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191 * Compensate for the CPU cycles that pass while the SysTick is stopped (low
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192 * power functionality only.
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194 #if configUSE_TICKLESS_IDLE == 1
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195 static unsigned long ulStoppedTimerCompensation = 0;
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196 #endif /* configUSE_TICKLESS_IDLE */
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199 * Used by the portASSERT_IF_INTERRUPT_PRIORITY_INVALID() macro to ensure
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200 * FreeRTOS API functions are not called from interrupts that have been assigned
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201 * a priority above configMAX_SYSCALL_INTERRUPT_PRIORITY.
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203 #if ( configASSERT_DEFINED == 1 )
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204 static unsigned char ucMaxSysCallPriority = 0;
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205 static unsigned long ulMaxPRIGROUPValue = 0;
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206 static const volatile unsigned char * const pcInterruptPriorityRegisters = ( unsigned char * ) portNVIC_IP_REGISTERS_OFFSET_16;
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207 #endif /* configASSERT_DEFINED */
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209 /*-----------------------------------------------------------*/
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212 * See header file for description.
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214 portSTACK_TYPE *pxPortInitialiseStack( portSTACK_TYPE *pxTopOfStack, pdTASK_CODE pxCode, void *pvParameters )
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216 /* Simulate the stack frame as it would be created by a context switch
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219 /* Offset added to account for the way the MCU uses the stack on entry/exit
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220 of interrupts, and to ensure alignment. */
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223 *pxTopOfStack = portINITIAL_XPSR; /* xPSR */
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225 *pxTopOfStack = ( portSTACK_TYPE ) pxCode; /* PC */
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227 *pxTopOfStack = ( portSTACK_TYPE ) prvTaskExitError; /* LR */
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229 /* Save code space by skipping register initialisation. */
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230 pxTopOfStack -= 5; /* R12, R3, R2 and R1. */
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231 *pxTopOfStack = ( portSTACK_TYPE ) pvParameters; /* R0 */
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233 /* A save method is being used that requires each task to maintain its
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234 own exec return value. */
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236 *pxTopOfStack = portINITIAL_EXEC_RETURN;
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238 pxTopOfStack -= 8; /* R11, R10, R9, R8, R7, R6, R5 and R4. */
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240 return pxTopOfStack;
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242 /*-----------------------------------------------------------*/
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244 static void prvTaskExitError( void )
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246 /* A function that implements a task must not exit or attempt to return to
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247 its caller as there is nothing to return to. If a task wants to exit it
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248 should instead call vTaskDelete( NULL ).
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250 Artificially force an assert() to be triggered if configASSERT() is
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251 defined, then stop here so application writers can catch the error. */
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252 configASSERT( uxCriticalNesting == ~0UL );
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253 portDISABLE_INTERRUPTS();
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256 /*-----------------------------------------------------------*/
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258 __asm void vPortSVCHandler( void )
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262 /* Get the location of the current TCB. */
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263 ldr r3, =pxCurrentTCB
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266 /* Pop the core registers. */
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267 ldmia r0!, {r4-r11, r14}
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273 /*-----------------------------------------------------------*/
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275 __asm void prvStartFirstTask( void )
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279 /* Use the NVIC offset register to locate the stack. */
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280 ldr r0, =0xE000ED08
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283 /* Set the msp back to the start of the stack. */
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285 /* Globally enable interrupts. */
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287 /* Call SVC to start the first task. */
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291 /*-----------------------------------------------------------*/
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293 __asm void prvEnableVFP( void )
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297 /* The FPU enable bits are in the CPACR. */
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298 ldr.w r0, =0xE000ED88
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301 /* Enable CP10 and CP11 coprocessors, then save back. */
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302 orr r1, r1, #( 0xf << 20 )
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307 /*-----------------------------------------------------------*/
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310 * See header file for description.
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312 portBASE_TYPE xPortStartScheduler( void )
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314 #if( configASSERT_DEFINED == 1 )
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316 volatile unsigned long ulOriginalPriority;
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317 volatile char * const pcFirstUserPriorityRegister = ( char * ) ( portNVIC_IP_REGISTERS_OFFSET_16 + portFIRST_USER_INTERRUPT_NUMBER );
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318 volatile unsigned char ucMaxPriorityValue;
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320 /* Determine the maximum priority from which ISR safe FreeRTOS API
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321 functions can be called. ISR safe functions are those that end in
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322 "FromISR". FreeRTOS maintains separate thread and ISR API functions to
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323 ensure interrupt entry is as fast and simple as possible.
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325 Save the interrupt priority value that is about to be clobbered. */
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326 ulOriginalPriority = *pcFirstUserPriorityRegister;
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328 /* Determine the number of priority bits available. First write to all
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330 *pcFirstUserPriorityRegister = portMAX_8_BIT_VALUE;
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332 /* Read the value back to see how many bits stuck. */
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333 ucMaxPriorityValue = *pcFirstUserPriorityRegister;
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335 /* Use the same mask on the maximum system call priority. */
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336 ucMaxSysCallPriority = configMAX_SYSCALL_INTERRUPT_PRIORITY & ucMaxPriorityValue;
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338 /* Calculate the maximum acceptable priority group value for the number
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339 of bits read back. */
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340 ulMaxPRIGROUPValue = portMAX_PRIGROUP_BITS;
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341 while( ( ucMaxPriorityValue & portTOP_BIT_OF_BYTE ) == portTOP_BIT_OF_BYTE )
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343 ulMaxPRIGROUPValue--;
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344 ucMaxPriorityValue <<= ( unsigned char ) 0x01;
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347 /* Shift the priority group value back to its position within the AIRCR
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349 ulMaxPRIGROUPValue <<= portPRIGROUP_SHIFT;
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350 ulMaxPRIGROUPValue &= portPRIORITY_GROUP_MASK;
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352 /* Restore the clobbered interrupt priority register to its original
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354 *pcFirstUserPriorityRegister = ulOriginalPriority;
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356 #endif /* conifgASSERT_DEFINED */
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358 /* Make PendSV and SysTick the lowest priority interrupts. */
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359 portNVIC_SYSPRI2_REG |= portNVIC_PENDSV_PRI;
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360 portNVIC_SYSPRI2_REG |= portNVIC_SYSTICK_PRI;
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362 /* Start the timer that generates the tick ISR. Interrupts are disabled
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364 vPortSetupTimerInterrupt();
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366 /* Initialise the critical nesting count ready for the first task. */
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367 uxCriticalNesting = 0;
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369 /* Ensure the VFP is enabled - it should be anyway. */
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372 /* Lazy save always. */
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373 *( portFPCCR ) |= portASPEN_AND_LSPEN_BITS;
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375 /* Start the first task. */
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376 prvStartFirstTask();
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378 /* Should not get here! */
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381 /*-----------------------------------------------------------*/
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383 void vPortEndScheduler( void )
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385 /* It is unlikely that the CM4F port will require this function as there
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386 is nothing to return to. */
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388 /*-----------------------------------------------------------*/
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390 void vPortYield( void )
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392 /* Set a PendSV to request a context switch. */
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393 portNVIC_INT_CTRL_REG = portNVIC_PENDSVSET_BIT;
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395 /* Barriers are normally not required but do ensure the code is completely
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396 within the specified behaviour for the architecture. */
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397 __dsb( portSY_FULL_READ_WRITE );
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398 __isb( portSY_FULL_READ_WRITE );
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400 /*-----------------------------------------------------------*/
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402 void vPortEnterCritical( void )
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404 portDISABLE_INTERRUPTS();
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405 uxCriticalNesting++;
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406 __dsb( portSY_FULL_READ_WRITE );
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407 __isb( portSY_FULL_READ_WRITE );
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409 /*-----------------------------------------------------------*/
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411 void vPortExitCritical( void )
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413 uxCriticalNesting--;
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414 if( uxCriticalNesting == 0 )
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416 portENABLE_INTERRUPTS();
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419 /*-----------------------------------------------------------*/
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421 __asm void xPortPendSVHandler( void )
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423 extern uxCriticalNesting;
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424 extern pxCurrentTCB;
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425 extern vTaskSwitchContext;
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431 /* Get the location of the current TCB. */
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432 ldr r3, =pxCurrentTCB
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435 /* Is the task using the FPU context? If so, push high vfp registers. */
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438 vstmdbeq r0!, {s16-s31}
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440 /* Save the core registers. */
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441 stmdb r0!, {r4-r11, r14}
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443 /* Save the new top of stack into the first member of the TCB. */
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446 stmdb sp!, {r3, r14}
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447 mov r0, #configMAX_SYSCALL_INTERRUPT_PRIORITY
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449 bl vTaskSwitchContext
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452 ldmia sp!, {r3, r14}
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454 /* The first item in pxCurrentTCB is the task top of stack. */
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458 /* Pop the core registers. */
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459 ldmia r0!, {r4-r11, r14}
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461 /* Is the task using the FPU context? If so, pop the high vfp registers
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465 vldmiaeq r0!, {s16-s31}
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469 #ifdef WORKAROUND_PMU_CM001 /* XMC4000 specific errata */
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470 #if WORKAROUND_PMU_CM001 == 1
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479 /*-----------------------------------------------------------*/
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481 void xPortSysTickHandler( void )
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483 /* The SysTick runs at the lowest interrupt priority, so when this interrupt
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484 executes all interrupts must be unmasked. There is therefore no need to
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485 save and then restore the interrupt mask value as its value is already
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487 ( void ) portSET_INTERRUPT_MASK_FROM_ISR();
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489 /* Increment the RTOS tick. */
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490 if( xTaskIncrementTick() != pdFALSE )
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492 /* A context switch is required. Context switching is performed in
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493 the PendSV interrupt. Pend the PendSV interrupt. */
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494 portNVIC_INT_CTRL_REG = portNVIC_PENDSVSET_BIT;
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497 portCLEAR_INTERRUPT_MASK_FROM_ISR( 0 );
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499 /*-----------------------------------------------------------*/
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501 #if configUSE_TICKLESS_IDLE == 1
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503 __weak void vPortSuppressTicksAndSleep( portTickType xExpectedIdleTime )
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505 unsigned long ulReloadValue, ulCompleteTickPeriods, ulCompletedSysTickDecrements;
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506 portTickType xModifiableIdleTime;
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508 /* Make sure the SysTick reload value does not overflow the counter. */
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509 if( xExpectedIdleTime > xMaximumPossibleSuppressedTicks )
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511 xExpectedIdleTime = xMaximumPossibleSuppressedTicks;
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514 /* Stop the SysTick momentarily. The time the SysTick is stopped for
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515 is accounted for as best it can be, but using the tickless mode will
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516 inevitably result in some tiny drift of the time maintained by the
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517 kernel with respect to calendar time. */
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518 portNVIC_SYSTICK_CTRL_REG = portNVIC_SYSTICK_CLK_BIT | portNVIC_SYSTICK_INT_BIT;
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520 /* Calculate the reload value required to wait xExpectedIdleTime
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521 tick periods. -1 is used because this code will execute part way
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522 through one of the tick periods. */
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523 ulReloadValue = portNVIC_SYSTICK_CURRENT_VALUE_REG + ( ulTimerCountsForOneTick * ( xExpectedIdleTime - 1UL ) );
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524 if( ulReloadValue > ulStoppedTimerCompensation )
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526 ulReloadValue -= ulStoppedTimerCompensation;
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529 /* Enter a critical section but don't use the taskENTER_CRITICAL()
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530 method as that will mask interrupts that should exit sleep mode. */
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533 /* If a context switch is pending or a task is waiting for the scheduler
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534 to be unsuspended then abandon the low power entry. */
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535 if( eTaskConfirmSleepModeStatus() == eAbortSleep )
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537 /* Restart from whatever is left in the count register to complete
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538 this tick period. */
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539 portNVIC_SYSTICK_LOAD_REG = portNVIC_SYSTICK_CURRENT_VALUE_REG;
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541 /* Restart SysTick. */
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542 portNVIC_SYSTICK_CTRL_REG = portNVIC_SYSTICK_CLK_BIT | portNVIC_SYSTICK_INT_BIT | portNVIC_SYSTICK_ENABLE_BIT;
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544 /* Reset the reload register to the value required for normal tick
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546 portNVIC_SYSTICK_LOAD_REG = ulTimerCountsForOneTick - 1UL;
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548 /* Re-enable interrupts - see comments above __disable_irq() call
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554 /* Set the new reload value. */
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555 portNVIC_SYSTICK_LOAD_REG = ulReloadValue;
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557 /* Clear the SysTick count flag and set the count value back to
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559 portNVIC_SYSTICK_CURRENT_VALUE_REG = 0UL;
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561 /* Restart SysTick. */
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562 portNVIC_SYSTICK_CTRL_REG = portNVIC_SYSTICK_CLK_BIT | portNVIC_SYSTICK_INT_BIT | portNVIC_SYSTICK_ENABLE_BIT;
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564 /* Sleep until something happens. configPRE_SLEEP_PROCESSING() can
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565 set its parameter to 0 to indicate that its implementation contains
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566 its own wait for interrupt or wait for event instruction, and so wfi
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567 should not be executed again. However, the original expected idle
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568 time variable must remain unmodified, so a copy is taken. */
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569 xModifiableIdleTime = xExpectedIdleTime;
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570 configPRE_SLEEP_PROCESSING( xModifiableIdleTime );
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571 if( xModifiableIdleTime > 0 )
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573 __dsb( portSY_FULL_READ_WRITE );
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575 __isb( portSY_FULL_READ_WRITE );
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577 configPOST_SLEEP_PROCESSING( xExpectedIdleTime );
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579 /* Stop SysTick. Again, the time the SysTick is stopped for is
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580 accounted for as best it can be, but using the tickless mode will
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581 inevitably result in some tiny drift of the time maintained by the
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582 kernel with respect to calendar time. */
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583 portNVIC_SYSTICK_CTRL_REG = portNVIC_SYSTICK_CLK_BIT | portNVIC_SYSTICK_INT_BIT;
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585 /* Re-enable interrupts - see comments above __disable_irq() call
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589 if( ( portNVIC_SYSTICK_CTRL_REG & portNVIC_SYSTICK_COUNT_FLAG_BIT ) != 0 )
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591 unsigned long ulCalculatedLoadValue;
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593 /* The tick interrupt has already executed, and the SysTick
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594 count reloaded with ulReloadValue. Reset the
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595 portNVIC_SYSTICK_LOAD_REG with whatever remains of this tick
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597 ulCalculatedLoadValue = ( ulTimerCountsForOneTick - 1UL ) - ( ulReloadValue - portNVIC_SYSTICK_CURRENT_VALUE_REG );
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599 /* Don't allow a tiny value, or values that have somehow
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600 underflowed because the post sleep hook did something
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601 that took too long. */
\r
602 if( ( ulCalculatedLoadValue < ulStoppedTimerCompensation ) || ( ulCalculatedLoadValue > ulTimerCountsForOneTick ) )
\r
604 ulCalculatedLoadValue = ( ulTimerCountsForOneTick - 1UL );
\r
607 portNVIC_SYSTICK_LOAD_REG = ulCalculatedLoadValue;
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609 /* The tick interrupt handler will already have pended the tick
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610 processing in the kernel. As the pending tick will be
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611 processed as soon as this function exits, the tick value
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612 maintained by the tick is stepped forward by one less than the
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613 time spent waiting. */
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614 ulCompleteTickPeriods = xExpectedIdleTime - 1UL;
\r
618 /* Something other than the tick interrupt ended the sleep.
\r
619 Work out how long the sleep lasted rounded to complete tick
\r
620 periods (not the ulReload value which accounted for part
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622 ulCompletedSysTickDecrements = ( xExpectedIdleTime * ulTimerCountsForOneTick ) - portNVIC_SYSTICK_CURRENT_VALUE_REG;
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624 /* How many complete tick periods passed while the processor
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626 ulCompleteTickPeriods = ulCompletedSysTickDecrements / ulTimerCountsForOneTick;
\r
628 /* The reload value is set to whatever fraction of a single tick
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630 portNVIC_SYSTICK_LOAD_REG = ( ( ulCompleteTickPeriods + 1 ) * ulTimerCountsForOneTick ) - ulCompletedSysTickDecrements;
\r
633 /* Restart SysTick so it runs from portNVIC_SYSTICK_LOAD_REG
\r
634 again, then set portNVIC_SYSTICK_LOAD_REG back to its standard
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635 value. The critical section is used to ensure the tick interrupt
\r
636 can only execute once in the case that the reload register is near
\r
638 portNVIC_SYSTICK_CURRENT_VALUE_REG = 0UL;
\r
639 portENTER_CRITICAL();
\r
641 portNVIC_SYSTICK_CTRL_REG = portNVIC_SYSTICK_CLK_BIT | portNVIC_SYSTICK_INT_BIT | portNVIC_SYSTICK_ENABLE_BIT;
\r
642 vTaskStepTick( ulCompleteTickPeriods );
\r
643 portNVIC_SYSTICK_LOAD_REG = ulTimerCountsForOneTick - 1UL;
\r
645 portEXIT_CRITICAL();
\r
649 #endif /* #if configUSE_TICKLESS_IDLE */
\r
651 /*-----------------------------------------------------------*/
\r
654 * Setup the SysTick timer to generate the tick interrupts at the required
\r
657 #if configOVERRIDE_DEFAULT_TICK_CONFIGURATION == 0
\r
659 void vPortSetupTimerInterrupt( void )
\r
661 /* Calculate the constants required to configure the tick interrupt. */
\r
662 #if configUSE_TICKLESS_IDLE == 1
\r
664 ulTimerCountsForOneTick = ( configSYSTICK_CLOCK_HZ / configTICK_RATE_HZ );
\r
665 xMaximumPossibleSuppressedTicks = portMAX_24_BIT_NUMBER / ulTimerCountsForOneTick;
\r
666 ulStoppedTimerCompensation = portMISSED_COUNTS_FACTOR / ( configCPU_CLOCK_HZ / configSYSTICK_CLOCK_HZ );
\r
668 #endif /* configUSE_TICKLESS_IDLE */
\r
670 /* Configure SysTick to interrupt at the requested rate. */
\r
671 portNVIC_SYSTICK_LOAD_REG = ( configSYSTICK_CLOCK_HZ / configTICK_RATE_HZ ) - 1UL;;
\r
672 portNVIC_SYSTICK_CTRL_REG = portNVIC_SYSTICK_CLK_BIT | portNVIC_SYSTICK_INT_BIT | portNVIC_SYSTICK_ENABLE_BIT;
\r
675 #endif /* configOVERRIDE_DEFAULT_TICK_CONFIGURATION */
\r
676 /*-----------------------------------------------------------*/
\r
678 __asm unsigned long ulPortSetInterruptMask( void )
\r
683 mov r1, #configMAX_SYSCALL_INTERRUPT_PRIORITY
\r
687 /*-----------------------------------------------------------*/
\r
689 __asm void vPortClearInterruptMask( unsigned long ulNewMask )
\r
696 /*-----------------------------------------------------------*/
\r
698 __asm unsigned long vPortGetIPSR( void )
\r
705 /*-----------------------------------------------------------*/
\r
707 #if( configASSERT_DEFINED == 1 )
\r
709 void vPortValidateInterruptPriority( void )
\r
711 unsigned long ulCurrentInterrupt;
\r
712 unsigned char ucCurrentPriority;
\r
714 /* Obtain the number of the currently executing interrupt. */
\r
715 ulCurrentInterrupt = vPortGetIPSR();
\r
717 /* Is the interrupt number a user defined interrupt? */
\r
718 if( ulCurrentInterrupt >= portFIRST_USER_INTERRUPT_NUMBER )
\r
720 /* Look up the interrupt's priority. */
\r
721 ucCurrentPriority = pcInterruptPriorityRegisters[ ulCurrentInterrupt ];
\r
723 /* The following assertion will fail if a service routine (ISR) for
\r
724 an interrupt that has been assigned a priority above
\r
725 configMAX_SYSCALL_INTERRUPT_PRIORITY calls an ISR safe FreeRTOS API
\r
726 function. ISR safe FreeRTOS API functions must *only* be called
\r
727 from interrupts that have been assigned a priority at or below
\r
728 configMAX_SYSCALL_INTERRUPT_PRIORITY.
\r
730 Numerically low interrupt priority numbers represent logically high
\r
731 interrupt priorities, therefore the priority of the interrupt must
\r
732 be set to a value equal to or numerically *higher* than
\r
733 configMAX_SYSCALL_INTERRUPT_PRIORITY.
\r
735 Interrupts that use the FreeRTOS API must not be left at their
\r
736 default priority of zero as that is the highest possible priority,
\r
737 which is guaranteed to be above configMAX_SYSCALL_INTERRUPT_PRIORITY,
\r
738 and therefore also guaranteed to be invalid.
\r
740 FreeRTOS maintains separate thread and ISR API functions to ensure
\r
741 interrupt entry is as fast and simple as possible.
\r
743 The following links provide detailed information:
\r
744 http://www.freertos.org/RTOS-Cortex-M3-M4.html
\r
745 http://www.freertos.org/FAQHelp.html */
\r
746 configASSERT( ucCurrentPriority >= ucMaxSysCallPriority );
\r
749 /* Priority grouping: The interrupt controller (NVIC) allows the bits
\r
750 that define each interrupt's priority to be split between bits that
\r
751 define the interrupt's pre-emption priority bits and bits that define
\r
752 the interrupt's sub-priority. For simplicity all bits must be defined
\r
753 to be pre-emption priority bits. The following assertion will fail if
\r
754 this is not the case (if some bits represent a sub-priority).
\r
756 If the application only uses CMSIS libraries for interrupt
\r
757 configuration then the correct setting can be achieved on all Cortex-M
\r
758 devices by calling NVIC_SetPriorityGrouping( 0 ); before starting the
\r
759 scheduler. Note however that some vendor specific peripheral libraries
\r
760 assume a non-zero priority group setting, in which cases using a value
\r
761 of zero will result in unpredicable behaviour. */
\r
762 configASSERT( ( portAIRCR_REG & portPRIORITY_GROUP_MASK ) <= ulMaxPRIGROUPValue );
\r
765 #endif /* configASSERT_DEFINED */
\r