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 /* The SR assigned to a newly created task. The only important thing in this
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68 value is for all interrupts to be enabled. */
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69 #define portINITIAL_SR ( 0UL )
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71 /* Dimensions the array into which the floating point context is saved.
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72 Allocate enough space for FPR0 to FPR15, FPUL and FPSCR, each of which is 4
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73 bytes big. If this number is changed then the 72 in portasm.src also needs
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75 #define portFLOP_REGISTERS_TO_STORE ( 18 )
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76 #define portFLOP_STORAGE_SIZE ( portFLOP_REGISTERS_TO_STORE * 4 )
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78 /*-----------------------------------------------------------*/
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81 * The TRAPA handler used to force a context switch.
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83 void vPortYield( void );
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86 * Function to start the first task executing - defined in portasm.src.
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88 extern void vPortStartFirstTask( void );
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91 * Obtains the current GBR value - defined in portasm.src.
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93 extern unsigned long ulPortGetGBR( 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 /* Mark the end of the stack - used for debugging only and can be removed. */
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103 *pxTopOfStack = 0x11111111UL;
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105 *pxTopOfStack = 0x22222222UL;
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107 *pxTopOfStack = 0x33333333UL;
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111 *pxTopOfStack = portINITIAL_SR;
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115 *pxTopOfStack = ( unsigned long ) pxCode;
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119 *pxTopOfStack = 15;
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123 *pxTopOfStack = 14;
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127 *pxTopOfStack = 13;
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131 *pxTopOfStack = 12;
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135 *pxTopOfStack = 11;
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139 *pxTopOfStack = 10;
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163 *pxTopOfStack = ( unsigned long ) pvParameters;
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183 *pxTopOfStack = 16;
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187 *pxTopOfStack = 17;
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191 *pxTopOfStack = ulPortGetGBR();
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193 /* GBR = global base register.
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194 VBR = vector base register.
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195 TBR = jump table base register.
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196 R15 is the stack pointer. */
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198 return pxTopOfStack;
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200 /*-----------------------------------------------------------*/
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202 portBASE_TYPE xPortStartScheduler( void )
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204 extern void vApplicationSetupTimerInterrupt( void );
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206 /* Call an application function to set up the timer that will generate the
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207 tick interrupt. This way the application can decide which peripheral to
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208 use. A demo application is provided to show a suitable example. */
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209 vApplicationSetupTimerInterrupt();
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211 /* Start the first task. This will only restore the standard registers and
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212 not the flop registers. This does not really matter though because the only
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213 flop register that is initialised to a particular value is fpscr, and it is
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214 only initialised to the current value, which will still be the current value
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215 when the first task starts executing. */
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216 trapa( portSTART_SCHEDULER_TRAP_NO );
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218 /* Should not get here. */
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221 /*-----------------------------------------------------------*/
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223 void vPortEndScheduler( void )
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225 /* Not implemented as there is nothing to return to. */
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227 /*-----------------------------------------------------------*/
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229 void vPortYield( void )
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231 long lInterruptMask;
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233 /* Ensure the yield trap runs at the same priority as the other interrupts
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234 that can cause a context switch. */
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235 lInterruptMask = get_imask();
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237 /* taskYIELD() can only be called from a task, not an interrupt, so the
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238 current interrupt mask can only be 0 or portKERNEL_INTERRUPT_PRIORITY and
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239 the mask can be set without risk of accidentally lowering the mask value. */
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240 set_imask( portKERNEL_INTERRUPT_PRIORITY );
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242 trapa( portYIELD_TRAP_NO );
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244 /* Restore the interrupt mask to whatever it was previously (when the
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245 function was entered). */
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246 set_imask( ( int ) lInterruptMask );
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248 /*-----------------------------------------------------------*/
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250 portBASE_TYPE xPortUsesFloatingPoint( xTaskHandle xTask )
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252 unsigned long *pulFlopBuffer;
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253 portBASE_TYPE xReturn;
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254 extern void * volatile pxCurrentTCB;
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256 /* This function tells the kernel that the task referenced by xTask is
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257 going to use the floating point registers and therefore requires the
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258 floating point registers saved as part of its context. */
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260 /* Passing NULL as xTask is used to indicate that the calling task is the
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261 subject task - so pxCurrentTCB is the task handle. */
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262 if( xTask == NULL )
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264 xTask = ( xTaskHandle ) pxCurrentTCB;
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267 /* Allocate a buffer large enough to hold all the flop registers. */
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268 pulFlopBuffer = ( unsigned long * ) pvPortMalloc( portFLOP_STORAGE_SIZE );
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270 if( pulFlopBuffer != NULL )
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272 /* Start with the registers in a benign state. */
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273 memset( ( void * ) pulFlopBuffer, 0x00, portFLOP_STORAGE_SIZE );
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275 /* The first thing to get saved in the buffer is the FPSCR value -
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276 initialise this to the current FPSCR value. */
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277 *pulFlopBuffer = get_fpscr();
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279 /* Use the task tag to point to the flop buffer. Pass pointer to just
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280 above the buffer because the flop save routine uses a pre-decrement. */
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281 vTaskSetApplicationTaskTag( xTask, ( void * ) ( pulFlopBuffer + portFLOP_REGISTERS_TO_STORE ) );
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291 /*-----------------------------------------------------------*/
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