2 FreeRTOS V6.0.5 - Copyright (C) 2010 Real Time Engineers Ltd.
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4 ***************************************************************************
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8 * + New to FreeRTOS, *
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9 * + Wanting to learn FreeRTOS or multitasking in general quickly *
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10 * + Looking for basic training, *
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11 * + Wanting to improve your FreeRTOS skills and productivity *
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13 * then take a look at the FreeRTOS eBook *
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15 * "Using the FreeRTOS Real Time Kernel - a Practical Guide" *
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16 * http://www.FreeRTOS.org/Documentation *
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18 * A pdf reference manual is also available. Both are usually delivered *
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19 * to your inbox within 20 minutes to two hours when purchased between 8am *
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20 * and 8pm GMT (although please allow up to 24 hours in case of *
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21 * exceptional circumstances). Thank you for your support! *
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23 ***************************************************************************
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25 This file is part of the FreeRTOS distribution.
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27 FreeRTOS is free software; you can redistribute it and/or modify it under
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28 the terms of the GNU General Public License (version 2) as published by the
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29 Free Software Foundation AND MODIFIED BY the FreeRTOS exception.
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30 ***NOTE*** The exception to the GPL is included to allow you to distribute
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31 a combined work that includes FreeRTOS without being obliged to provide the
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32 source code for proprietary components outside of the FreeRTOS kernel.
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33 FreeRTOS is distributed in the hope that it will be useful, but WITHOUT
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34 ANY WARRANTY; without even the implied warranty of MERCHANTABILITY or
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35 FITNESS FOR A PARTICULAR PURPOSE. See the GNU General Public License for
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36 more details. You should have received a copy of the GNU General Public
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37 License and the FreeRTOS license exception along with FreeRTOS; if not it
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38 can be viewed here: http://www.freertos.org/a00114.html and also obtained
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39 by writing to Richard Barry, contact details for whom are available on the
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44 http://www.FreeRTOS.org - Documentation, latest information, license and
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47 http://www.SafeRTOS.com - A version that is certified for use in safety
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50 http://www.OpenRTOS.com - Commercial support, development, porting,
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51 licensing and training services.
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54 /*-----------------------------------------------------------
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55 * Implementation of functions defined in portable.h for the SH2A port.
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56 *----------------------------------------------------------*/
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58 /* Scheduler includes. */
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59 #include "FreeRTOS.h"
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62 /* Library includes. */
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65 /*-----------------------------------------------------------*/
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67 /* Tasks should start with interrupts enabled, therefore PSW is set with U,I,PM
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68 flags set and IPL clear. */
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70 U = 1 User stack pointer.
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71 I = 1 Interrupts enabled.
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72 PM = 0 Supervisor mode.
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73 IPL = 0 All interrupt priorities enabled.
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75 #define portINITIAL_PSW ( ( portSTACK_TYPE ) 0x00030000 )
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76 #define portINITIAL_FPSW ( ( portSTACK_TYPE ) 0x00000100 )
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79 /*-----------------------------------------------------------*/
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84 void vPortYield( void );
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87 * Function to start the first task executing.
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89 void vPortStartFirstTask( void );
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91 void vPortPendContextSwitch( void );
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93 static void prvStartFirstTask( void );
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95 /*-----------------------------------------------------------*/
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97 extern void *pxCurrentTCB;
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99 unsigned char ucIPLToRestore = 0;
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101 /*-----------------------------------------------------------*/
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104 * See header file for description.
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106 portSTACK_TYPE *pxPortInitialiseStack( portSTACK_TYPE *pxTopOfStack, pdTASK_CODE pxCode, void *pvParameters )
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108 /* R0 is not included as it is the stack pointer. */
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110 *pxTopOfStack = 0xdeadbeef;
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112 *pxTopOfStack = portINITIAL_PSW;
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114 *pxTopOfStack = ( portSTACK_TYPE ) pxCode;
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116 *pxTopOfStack = 0xffffffff; /* r15. */
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118 *pxTopOfStack = 0xeeeeeeee;
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120 *pxTopOfStack = 0xdddddddd;
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122 *pxTopOfStack = 0xcccccccc;
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124 *pxTopOfStack = 0xbbbbbbbb;
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126 *pxTopOfStack = 0xaaaaaaaa;
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128 *pxTopOfStack = 0x99999999;
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130 *pxTopOfStack = 0x88888888;
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132 *pxTopOfStack = 0x77777777;
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134 *pxTopOfStack = 0x66666666;
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136 *pxTopOfStack = 0x55555555;
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138 *pxTopOfStack = 0x44444444;
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140 *pxTopOfStack = 0x33333333;
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142 *pxTopOfStack = 0x22222222;
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144 *pxTopOfStack = ( portSTACK_TYPE ) pvParameters; /* R1 */
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146 *pxTopOfStack = portINITIAL_FPSW;
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148 *pxTopOfStack = 0x12345678; /* Accumulator. */
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150 *pxTopOfStack = 0x87654321; /* Accumulator. */
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152 return pxTopOfStack;
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154 /*-----------------------------------------------------------*/
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156 portBASE_TYPE xPortStartScheduler( void )
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158 extern void vApplicationSetupTimerInterrupt( void );
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160 /* Use pxCurrentTCB just so it does not get optimised away. */
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161 if( pxCurrentTCB != NULL )
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163 /* Call an application function to set up the timer that will generate the
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164 tick interrupt. This way the application can decide which peripheral to
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165 use. A demo application is provided to show a suitable example. */
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166 vApplicationSetupTimerInterrupt();
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168 /* Start the first task. */
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169 prvStartFirstTask();
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172 /* Should not get here. */
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175 /*-----------------------------------------------------------*/
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177 void vPortEndScheduler( void )
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179 /* Not implemented as there is nothing to return to. */
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181 /*-----------------------------------------------------------*/
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183 void vPortYield( void )
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186 /*-----------------------------------------------------------*/
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188 #pragma interrupt (vTickISR(vect=configTICK_VECTOR,enable))
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189 void vTickISR( void )
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191 /* Restore previous IPL on exit. */
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192 //set_ipl( configMAX_SYSCALL_INTERRUPT_PRIORITY );
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194 /* Clear the interrupt. */
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195 vTaskIncrementTick();
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197 #if( configUSE_PREEMPTION == 1 )
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201 /*-----------------------------------------------------------*/
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203 void vPortSetInterruptMask( void )
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205 unsigned char ucPreviousIPL;
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207 /* Store the current IPL to ensure it is restored correctly later if it is
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208 not currently 0. This is a stack variable, so there should not be a race
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209 condition even if there is an interrupt or context switch before the new
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210 IPL value gets set. */
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211 ucPreviousIPL = get_ipl();
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213 /* Set the mask up to the max syscall priority. */
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214 set_ipl( configMAX_SYSCALL_INTERRUPT_PRIORITY );
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216 /* Now the mask is set there will not be a context switch, so the previous
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217 and current IPL values can be compared. This ensures against the IPL being
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218 set back to zero too early when critical sections nest. */
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219 if( ucPreviousIPL < configMAX_SYSCALL_INTERRUPT_PRIORITY )
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221 ucIPLToRestore = ucPreviousIPL;
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224 /*-----------------------------------------------------------*/
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226 #pragma inline_asm prvStartFirstTask
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227 static void prvStartFirstTask( void )
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229 /* When starting the scheduler there is nothing that needs moving to the
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230 interrupt stack because the function is not called from an interrupt.
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231 Just ensure the current stack is the user stack. */
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234 /* Obtain the location of the stack associated with which ever task
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235 pxCurrentTCB is currently pointing to. */
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236 MOV.L #_pxCurrentTCB,R15
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240 /* Restore the registers from the stack of the task pointed to by
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243 MVTACLO R15 /* Accumulator low 32 bits. */
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245 MVTACHI R15 /* Accumulator high 32 bits. */
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247 MVTC R15,FPSW /* Floating point status word. */
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248 POPM R1-R15 /* R1 to R15 - R0 is not included as it is the SP. */
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249 RTE /* This pops the remaining registers. */
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