2 FreeRTOS.org V4.5.0 - Copyright (C) 2003-2007 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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27 See http://www.FreeRTOS.org for documentation, latest information, license
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28 and contact details. Please ensure to read the configuration and relevant
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29 port sections of the online documentation.
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31 Also see http://www.SafeRTOS.com for an IEC 61508 compliant version along
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32 with commercial development and support options.
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33 ***************************************************************************
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39 + Introduced usage of configKERNEL_INTERRUPT_PRIORITY macro to set the
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40 interrupt priority used by the kernel.
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43 /*-----------------------------------------------------------
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44 * Implementation of functions defined in portable.h for the ARM CM3 port.
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45 *----------------------------------------------------------*/
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47 /* Scheduler includes. */
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48 #include "FreeRTOS.h"
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51 /* Constants required to manipulate the NVIC. */
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52 #define portNVIC_SYSTICK_CTRL ( ( volatile unsigned portLONG *) 0xe000e010 )
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53 #define portNVIC_SYSTICK_LOAD ( ( volatile unsigned portLONG *) 0xe000e014 )
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54 #define portNVIC_INT_CTRL ( ( volatile unsigned portLONG *) 0xe000ed04 )
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55 #define portNVIC_SYSPRI2 ( ( volatile unsigned portLONG *) 0xe000ed20 )
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56 #define portNVIC_SYSPRI1 ( ( volatile unsigned portLONG *) 0xe000ed1c )
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57 #define portNVIC_SYSTICK_CLK 0x00000004
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58 #define portNVIC_SYSTICK_INT 0x00000002
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59 #define portNVIC_SYSTICK_ENABLE 0x00000001
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60 #define portNVIC_PENDSVSET 0x10000000
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61 #define portNVIC_PENDSV_PRI ( ( ( unsigned portLONG ) configKERNEL_INTERRUPT_PRIORITY ) << 16 )
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62 #define portNVIC_SYSTICK_PRI ( ( ( unsigned portLONG ) configKERNEL_INTERRUPT_PRIORITY ) << 24 )
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64 /* Constants required to set up the initial stack. */
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65 #define portINITIAL_XPSR ( 0x01000000 )
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67 /* For backward compatibility, ensure configKERNEL_INTERRUPT_PRIORITY is
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68 defined. The value 255 should also ensure backward compatibility.
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69 FreeRTOS.org versions prior to V4.3.0 did not include this definition. */
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70 #ifndef configKERNEL_INTERRUPT_PRIORITY
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71 #define configKERNEL_INTERRUPT_PRIORITY 255
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74 /* Each task maintains its own interrupt status in the critical nesting
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76 unsigned portBASE_TYPE uxCriticalNesting = 0xaaaaaaaa;
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79 * Setup the timer to generate the tick interrupts.
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81 static void prvSetupTimerInterrupt( void );
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84 * Set the MSP/PSP to a known value.
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86 extern void vSetMSP( unsigned long ulValue );
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87 extern void vSetPSP( unsigned long ulValue );
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90 * Utilities called from the assembler code.
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92 void vPortSwitchContext( void );
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93 void vPortIncrementTick( void );
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95 /*-----------------------------------------------------------*/
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98 * See header file for description.
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100 portSTACK_TYPE *pxPortInitialiseStack( portSTACK_TYPE *pxTopOfStack, pdTASK_CODE pxCode, void *pvParameters )
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102 /* Simulate the stack frame as it would be created by a context switch
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104 *pxTopOfStack = portINITIAL_XPSR; /* xPSR */
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106 *pxTopOfStack = ( portSTACK_TYPE ) pxCode; /* PC */
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108 *pxTopOfStack = 0xfffffffd; /* LR */
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109 pxTopOfStack -= 5; /* R12, R3, R2 and R1. */
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110 *pxTopOfStack = ( portSTACK_TYPE ) pvParameters; /* R0 */
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111 pxTopOfStack -= 9; /* R11, R10, R9, R8, R7, R6, R5 and R4. */
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112 *pxTopOfStack = 0x00000000; /* uxCriticalNesting. */
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114 return pxTopOfStack;
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116 /*-----------------------------------------------------------*/
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119 * See header file for description.
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121 portBASE_TYPE xPortStartScheduler( void )
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123 /* Make PendSV and SysTick the lowest priority interrupts. */
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124 *(portNVIC_SYSPRI2) |= portNVIC_PENDSV_PRI;
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125 *(portNVIC_SYSPRI2) |= portNVIC_SYSTICK_PRI;
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127 /* Start the timer that generates the tick ISR. Interrupts are disabled
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129 prvSetupTimerInterrupt();
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131 /* Start the first task. */
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133 vSetMSP( *((unsigned portLONG *) 0 ) );
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134 *(portNVIC_INT_CTRL) |= portNVIC_PENDSVSET;
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136 /* Enable interrupts */
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137 portENABLE_INTERRUPTS();
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139 /* Should not get here! */
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142 /*-----------------------------------------------------------*/
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144 void vPortEndScheduler( void )
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146 /* It is unlikely that the CM3 port will require this function as there
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147 is nothing to return to. */
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149 /*-----------------------------------------------------------*/
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151 void vPortYieldFromISR( void )
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153 /* Set a PendSV to request a context switch. */
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154 *(portNVIC_INT_CTRL) |= portNVIC_PENDSVSET;
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156 /* This function is also called in response to a Yield(), so we want
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157 the yield to occur immediately. */
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158 portENABLE_INTERRUPTS();
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160 /*-----------------------------------------------------------*/
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162 void vPortEnterCritical( void )
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164 portDISABLE_INTERRUPTS();
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165 uxCriticalNesting++;
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167 /*-----------------------------------------------------------*/
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169 void vPortExitCritical( void )
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171 uxCriticalNesting--;
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172 if( uxCriticalNesting == 0 )
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174 portENABLE_INTERRUPTS();
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177 /*-----------------------------------------------------------*/
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181 * Setup the systick timer to generate the tick interrupts at the required
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184 void prvSetupTimerInterrupt( void )
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186 /* Configure SysTick to interrupt at the requested rate. */
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187 *(portNVIC_SYSTICK_LOAD) = configCPU_CLOCK_HZ / configTICK_RATE_HZ;
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188 *(portNVIC_SYSTICK_CTRL) = portNVIC_SYSTICK_CLK | portNVIC_SYSTICK_INT | portNVIC_SYSTICK_ENABLE;
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190 /*-----------------------------------------------------------*/
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192 void vPortSwitchContext( void )
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194 vPortSetInterruptMask();
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195 vTaskSwitchContext();
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196 vPortClearInterruptMask();
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198 /*-----------------------------------------------------------*/
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200 void vPortIncrementTick( void )
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202 vPortSetInterruptMask();
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203 vTaskIncrementTick();
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204 vPortClearInterruptMask();
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