2 FreeRTOS.org V4.7.2 - Copyright (C) 2003-2008 Richard Barry.
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4 This file is part of the FreeRTOS.org distribution.
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6 FreeRTOS.org is free software; you can redistribute it and/or modify
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7 it under the terms of the GNU General Public License as published by
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8 the Free Software Foundation; either version 2 of the License, or
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9 (at your option) any later version.
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11 FreeRTOS.org is distributed in the hope that it will be useful,
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12 but WITHOUT ANY WARRANTY; without even the implied warranty of
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13 MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE. See the
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14 GNU General Public License for more details.
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16 You should have received a copy of the GNU General Public License
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17 along with FreeRTOS.org; if not, write to the Free Software
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18 Foundation, Inc., 59 Temple Place, Suite 330, Boston, MA 02111-1307 USA
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20 A special exception to the GPL can be applied should you wish to distribute
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21 a combined work that includes FreeRTOS.org, without being obliged to provide
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22 the source code for any proprietary components. See the licensing section
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23 of http://www.FreeRTOS.org for full details of how and when the exception
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26 ***************************************************************************
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28 Please ensure to read the configuration and relevant port sections of the
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29 online documentation.
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31 +++ http://www.FreeRTOS.org +++
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32 Documentation, latest information, license and contact details.
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34 +++ http://www.SafeRTOS.com +++
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35 A version that is certified for use in safety critical systems.
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37 +++ http://www.OpenRTOS.com +++
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38 Commercial support, development, porting, licensing and training services.
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40 ***************************************************************************
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46 + Introduced usage of configKERNEL_INTERRUPT_PRIORITY macro to set the
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47 interrupt priority used by the kernel.
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50 /*-----------------------------------------------------------
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51 * Implementation of functions defined in portable.h for the ARM CM3 port.
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52 *----------------------------------------------------------*/
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54 /* Scheduler includes. */
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55 #include "FreeRTOS.h"
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58 /* Constants required to manipulate the NVIC. */
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59 #define portNVIC_SYSTICK_CTRL ( ( volatile unsigned portLONG *) 0xe000e010 )
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60 #define portNVIC_SYSTICK_LOAD ( ( volatile unsigned portLONG *) 0xe000e014 )
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61 #define portNVIC_INT_CTRL ( ( volatile unsigned portLONG *) 0xe000ed04 )
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62 #define portNVIC_SYSPRI2 ( ( volatile unsigned portLONG *) 0xe000ed20 )
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63 #define portNVIC_SYSTICK_CLK 0x00000004
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64 #define portNVIC_SYSTICK_INT 0x00000002
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65 #define portNVIC_SYSTICK_ENABLE 0x00000001
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66 #define portNVIC_PENDSVSET 0x10000000
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67 #define portNVIC_PENDSV_PRI ( ( ( unsigned portLONG ) configKERNEL_INTERRUPT_PRIORITY ) << 16 )
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68 #define portNVIC_SYSTICK_PRI ( ( ( unsigned portLONG ) configKERNEL_INTERRUPT_PRIORITY ) << 24 )
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70 /* Constants required to set up the initial stack. */
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71 #define portINITIAL_XPSR ( 0x01000000 )
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73 /* For backward compatibility, ensure configKERNEL_INTERRUPT_PRIORITY is
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74 defined. The value 255 should also ensure backward compatibility.
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75 FreeRTOS.org versions prior to V4.3.0 did not include this definition. */
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76 #ifndef configKERNEL_INTERRUPT_PRIORITY
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77 #define configKERNEL_INTERRUPT_PRIORITY 0
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80 /* Each task maintains its own interrupt status in the critical nesting
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82 unsigned portBASE_TYPE uxCriticalNesting = 0xaaaaaaaa;
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85 * Setup the timer to generate the tick interrupts.
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87 static void prvSetupTimerInterrupt( void );
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90 * Exception handlers.
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92 void xPortSysTickHandler( void );
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95 * Start first task is a separate function so it can be tested in isolation.
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97 extern void vPortStartFirstTask( unsigned portLONG ulValue );
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99 /*-----------------------------------------------------------*/
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102 * See header file for description.
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104 portSTACK_TYPE *pxPortInitialiseStack( portSTACK_TYPE *pxTopOfStack, pdTASK_CODE pxCode, void *pvParameters )
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106 /* Simulate the stack frame as it would be created by a context switch
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108 *pxTopOfStack = portINITIAL_XPSR; /* xPSR */
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110 *pxTopOfStack = ( portSTACK_TYPE ) pxCode; /* PC */
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112 *pxTopOfStack = 0; /* LR */
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113 pxTopOfStack -= 5; /* R12, R3, R2 and R1. */
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114 *pxTopOfStack = ( portSTACK_TYPE ) pvParameters; /* R0 */
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115 pxTopOfStack -= 9; /* R11, R10, R9, R8, R7, R6, R5 and R4. */
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116 *pxTopOfStack = 0x00000000; /* uxCriticalNesting. */
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118 return pxTopOfStack;
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120 /*-----------------------------------------------------------*/
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123 * See header file for description.
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125 portBASE_TYPE xPortStartScheduler( void )
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127 /* Make PendSV and SysTick the lowest priority interrupts. */
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128 *(portNVIC_SYSPRI2) |= portNVIC_PENDSV_PRI;
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129 *(portNVIC_SYSPRI2) |= portNVIC_SYSTICK_PRI;
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131 /* Start the timer that generates the tick ISR. Interrupts are disabled
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133 prvSetupTimerInterrupt();
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135 /* Start the first task. */
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136 vPortStartFirstTask( *((unsigned portLONG *) 0 ) );
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138 /* Should not get here! */
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141 /*-----------------------------------------------------------*/
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143 void vPortEndScheduler( void )
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145 /* It is unlikely that the CM3 port will require this function as there
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146 is nothing to return to. */
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148 /*-----------------------------------------------------------*/
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150 void vPortYieldFromISR( void )
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152 /* Set a PendSV to request a context switch. */
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153 *(portNVIC_INT_CTRL) |= portNVIC_PENDSVSET;
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155 /* This function is also called in response to a Yield(), so we want
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156 the yield to occur immediately. */
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157 portENABLE_INTERRUPTS();
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159 /*-----------------------------------------------------------*/
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161 void vPortEnterCritical( void )
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163 portDISABLE_INTERRUPTS();
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164 uxCriticalNesting++;
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166 /*-----------------------------------------------------------*/
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168 void vPortExitCritical( void )
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170 uxCriticalNesting--;
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171 if( uxCriticalNesting == 0 )
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173 portENABLE_INTERRUPTS();
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176 /*-----------------------------------------------------------*/
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178 void xPortSysTickHandler( void )
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180 vTaskIncrementTick();
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182 /* If using preemption, also force a context switch. */
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183 #if configUSE_PREEMPTION == 1
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184 *(portNVIC_INT_CTRL) |= portNVIC_PENDSVSET;
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187 /*-----------------------------------------------------------*/
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190 * Setup the systick timer to generate the tick interrupts at the required
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193 void prvSetupTimerInterrupt( void )
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195 /* Configure SysTick to interrupt at the requested rate. */
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196 *(portNVIC_SYSTICK_LOAD) = configCPU_CLOCK_HZ / configTICK_RATE_HZ;
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197 *(portNVIC_SYSTICK_CTRL) = portNVIC_SYSTICK_CLK | portNVIC_SYSTICK_INT | portNVIC_SYSTICK_ENABLE;
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199 /*-----------------------------------------------------------*/
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