2 FreeRTOS.org V4.0.4 - Copyright (C) 2003-2006 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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30 ***************************************************************************
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33 /*-----------------------------------------------------------
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34 * Implementation of functions defined in portable.h for the ST STR71x ARM7
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36 *----------------------------------------------------------*/
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38 /* Library includes. */
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42 /* Standard includes. */
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45 /* Scheduler includes. */
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46 #include "FreeRTOS.h"
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49 /* Constants required to setup the initial stack. */
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50 #define portINITIAL_SPSR ( ( portSTACK_TYPE ) 0x3f ) /* System mode, THUMB mode, interrupts enabled. */
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51 #define portINSTRUCTION_SIZE ( ( portSTACK_TYPE ) 4 )
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53 /* Constants required to handle critical sections. */
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54 #define portNO_CRITICAL_NESTING ( ( unsigned portLONG ) 0 )
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56 #define portMICROS_PER_SECOND 1000000
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58 /*-----------------------------------------------------------*/
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60 /* Setup the watchdog to generate the tick interrupts. */
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61 static void prvSetupTimerInterrupt( void );
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63 /* ulCriticalNesting will get set to zero when the first task starts. It
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64 cannot be initialised to 0 as this will cause interrupts to be enabled
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65 during the kernel initialisation process. */
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66 unsigned portLONG ulCriticalNesting = ( unsigned portLONG ) 9999;
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68 /* Tick interrupt routines for cooperative and preemptive operation
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69 respectively. The preemptive version is not defined as __irq as it is called
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70 from an asm wrapper function. */
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71 __arm __irq void vPortNonPreemptiveTick( void );
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72 void vPortPreemptiveTick( void );
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74 /*-----------------------------------------------------------*/
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77 * Initialise the stack of a task to look exactly as if a call to
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78 * portSAVE_CONTEXT had been called.
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80 * See header file for description.
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82 portSTACK_TYPE *pxPortInitialiseStack( portSTACK_TYPE *pxTopOfStack, pdTASK_CODE pxCode, void *pvParameters )
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84 portSTACK_TYPE *pxOriginalTOS;
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86 pxOriginalTOS = pxTopOfStack;
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88 /* Setup the initial stack of the task. The stack is set exactly as
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89 expected by the portRESTORE_CONTEXT() macro. */
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91 /* First on the stack is the return address - which in this case is the
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92 start of the task. The offset is added to make the return address appear
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93 as it would within an IRQ ISR. */
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94 *pxTopOfStack = ( portSTACK_TYPE ) pxCode + portINSTRUCTION_SIZE;
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97 *pxTopOfStack = ( portSTACK_TYPE ) 0xaaaaaaaa; /* R14 */
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99 *pxTopOfStack = ( portSTACK_TYPE ) pxOriginalTOS; /* Stack used when task starts goes in R13. */
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101 *pxTopOfStack = ( portSTACK_TYPE ) 0x12121212; /* R12 */
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103 *pxTopOfStack = ( portSTACK_TYPE ) 0x11111111; /* R11 */
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105 *pxTopOfStack = ( portSTACK_TYPE ) 0x10101010; /* R10 */
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107 *pxTopOfStack = ( portSTACK_TYPE ) 0x09090909; /* R9 */
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109 *pxTopOfStack = ( portSTACK_TYPE ) 0x08080808; /* R8 */
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111 *pxTopOfStack = ( portSTACK_TYPE ) 0x07070707; /* R7 */
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113 *pxTopOfStack = ( portSTACK_TYPE ) 0x06060606; /* R6 */
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115 *pxTopOfStack = ( portSTACK_TYPE ) 0x05050505; /* R5 */
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117 *pxTopOfStack = ( portSTACK_TYPE ) 0x04040404; /* R4 */
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119 *pxTopOfStack = ( portSTACK_TYPE ) 0x03030303; /* R3 */
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121 *pxTopOfStack = ( portSTACK_TYPE ) 0x02020202; /* R2 */
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123 *pxTopOfStack = ( portSTACK_TYPE ) 0x01010101; /* R1 */
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126 /* When the task starts is will expect to find the function parameter in
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128 *pxTopOfStack = ( portSTACK_TYPE ) pvParameters; /* R0 */
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131 /* The status register is set for system mode, with interrupts enabled. */
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132 *pxTopOfStack = ( portSTACK_TYPE ) portINITIAL_SPSR;
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135 /* Interrupt flags cannot always be stored on the stack and will
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136 instead be stored in a variable, which is then saved as part of the
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138 *pxTopOfStack = portNO_CRITICAL_NESTING;
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140 return pxTopOfStack;
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142 /*-----------------------------------------------------------*/
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144 portBASE_TYPE xPortStartScheduler( void )
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146 extern void vPortStartFirstTask( void );
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148 /* Start the timer that generates the tick ISR. Interrupts are disabled
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150 prvSetupTimerInterrupt();
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152 /* Start the first task. */
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153 vPortStartFirstTask();
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155 /* Should not get here! */
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158 /*-----------------------------------------------------------*/
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160 void vPortEndScheduler( void )
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162 /* It is unlikely that the ARM port will require this function as there
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163 is nothing to return to. */
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165 /*-----------------------------------------------------------*/
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167 /* The cooperative scheduler requires a normal IRQ service routine to
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168 simply increment the system tick. */
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169 __arm __irq void vPortNonPreemptiveTick( void )
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171 /* Increment the tick count - which may wake some tasks but as the
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172 preemptive scheduler is not being used any woken task is not given
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173 processor time no matter what its priority. */
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174 vTaskIncrementTick();
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176 /* Clear the interrupt in the watchdog and EIC. */
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180 /*-----------------------------------------------------------*/
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182 /* This function is called from an asm wrapper, so does not require the __irq
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184 void vPortPreemptiveTick( void )
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186 /* Increment the tick counter. */
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187 vTaskIncrementTick();
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189 /* The new tick value might unblock a task. Ensure the highest task that
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190 is ready to execute is the task that will execute when the tick ISR
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192 vTaskSwitchContext();
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194 /* Clear the interrupt in the watchdog and EIC. */
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198 /*-----------------------------------------------------------*/
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200 static void prvSetupTimerInterrupt( void )
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202 /* Set the watchdog up to generate a periodic tick. */
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203 WDG_ECITConfig( DISABLE );
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204 WDG_CntOnOffConfig( DISABLE );
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205 WDG_PeriodValueConfig( portMICROS_PER_SECOND / configTICK_RATE_HZ );
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207 /* Setup the tick interrupt in the EIC. */
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208 EIC_IRQChannelPriorityConfig( WDG_IRQChannel, 1 );
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209 EIC_IRQChannelConfig( WDG_IRQChannel, ENABLE );
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210 EIC_IRQConfig( ENABLE );
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211 WDG_ECITConfig( ENABLE );
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213 /* Start the timer - interrupts are actually disabled at this point so
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214 it is safe to do this here. */
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215 WDG_CntOnOffConfig( ENABLE );
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217 /*-----------------------------------------------------------*/
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219 __arm __interwork void vPortEnterCritical( void )
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221 /* Disable interrupts first! */
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222 __disable_interrupt();
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224 /* Now interrupts are disabled ulCriticalNesting can be accessed
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225 directly. Increment ulCriticalNesting to keep a count of how many times
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226 portENTER_CRITICAL() has been called. */
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227 ulCriticalNesting++;
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229 /*-----------------------------------------------------------*/
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231 __arm __interwork void vPortExitCritical( void )
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233 if( ulCriticalNesting > portNO_CRITICAL_NESTING )
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235 /* Decrement the nesting count as we are leaving a critical section. */
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236 ulCriticalNesting--;
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238 /* If the nesting level has reached zero then interrupts should be
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240 if( ulCriticalNesting == portNO_CRITICAL_NESTING )
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242 __enable_interrupt();
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246 /*-----------------------------------------------------------*/
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