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jeremybenn |
/*
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FreeRTOS V6.1.1 - Copyright (C) 2011 Real Time Engineers Ltd.
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***************************************************************************
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* *
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* If you are: *
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* *
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* + New to FreeRTOS, *
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* + Wanting to learn FreeRTOS or multitasking in general quickly *
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* + Looking for basic training, *
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* + Wanting to improve your FreeRTOS skills and productivity *
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* *
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* then take a look at the FreeRTOS books - available as PDF or paperback *
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* *
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* "Using the FreeRTOS Real Time Kernel - a Practical Guide" *
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* http://www.FreeRTOS.org/Documentation *
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* *
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* A pdf reference manual is also available. Both are usually delivered *
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* to your inbox within 20 minutes to two hours when purchased between 8am *
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* and 8pm GMT (although please allow up to 24 hours in case of *
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* exceptional circumstances). Thank you for your support! *
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* *
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***************************************************************************
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This file is part of the FreeRTOS distribution.
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FreeRTOS is free software; you can redistribute it and/or modify it under
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the terms of the GNU General Public License (version 2) as published by the
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Free Software Foundation AND MODIFIED BY the FreeRTOS exception.
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***NOTE*** The exception to the GPL is included to allow you to distribute
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a combined work that includes FreeRTOS without being obliged to provide the
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source code for proprietary components outside of the FreeRTOS kernel.
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FreeRTOS is distributed in the hope that it will be useful, but WITHOUT
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ANY WARRANTY; without even the implied warranty of MERCHANTABILITY or
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FITNESS FOR A PARTICULAR PURPOSE. See the GNU General Public License for
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more details. You should have received a copy of the GNU General Public
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License and the FreeRTOS license exception along with FreeRTOS; if not it
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can be viewed here: http://www.freertos.org/a00114.html and also obtained
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by writing to Richard Barry, contact details for whom are available on the
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FreeRTOS WEB site.
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1 tab == 4 spaces!
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http://www.FreeRTOS.org - Documentation, latest information, license and
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contact details.
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http://www.SafeRTOS.com - A version that is certified for use in safety
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critical systems.
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http://www.OpenRTOS.com - Commercial support, development, porting,
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licensing and training services.
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*/
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/*-----------------------------------------------------------
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* Implementation of functions defined in portable.h for the SH2A port.
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*----------------------------------------------------------*/
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/* Scheduler includes. */
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#include "FreeRTOS.h"
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#include "task.h"
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/* Library includes. */
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#include "string.h"
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/* Hardware specifics. */
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#include "iodefine.h"
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/*-----------------------------------------------------------*/
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/* Tasks should start with interrupts enabled and in Supervisor mode, therefore
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PSW is set with U and I set, and PM and IPL clear. */
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#define portINITIAL_PSW ( ( portSTACK_TYPE ) 0x00030000 )
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#define portINITIAL_FPSW ( ( portSTACK_TYPE ) 0x00000100 )
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/*-----------------------------------------------------------*/
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/*
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* Function to start the first task executing - written in asm code as direct
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* access to registers is required.
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*/
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static void prvStartFirstTask( void );
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/*
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* Software interrupt handler. Performs the actual context switch (saving and
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* restoring of registers). Written in asm code as direct register access is
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* required.
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*/
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static void prvYieldHandler( void );
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/*
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* The entry point for the software interrupt handler. This is the function
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* that calls the inline asm function prvYieldHandler(). It is installed in
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* the vector table, but the code that installs it is in prvYieldHandler rather
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* than using a #pragma.
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*/
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void vSoftwareInterruptISR( void );
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/*-----------------------------------------------------------*/
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/* This is accessed by the inline assembler functions so is file scope for
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convenience. */
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extern void *pxCurrentTCB;
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extern void vTaskSwitchContext( void );
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/*-----------------------------------------------------------*/
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/*
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* See header file for description.
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*/
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portSTACK_TYPE *pxPortInitialiseStack( portSTACK_TYPE *pxTopOfStack, pdTASK_CODE pxCode, void *pvParameters )
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{
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/* R0 is not included as it is the stack pointer. */
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*pxTopOfStack = 0xdeadbeef;
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pxTopOfStack--;
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*pxTopOfStack = portINITIAL_PSW;
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pxTopOfStack--;
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*pxTopOfStack = ( portSTACK_TYPE ) pxCode;
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/* When debugging it can be useful if every register is set to a known
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value. Otherwise code space can be saved by just setting the registers
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that need to be set. */
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#ifdef USE_FULL_REGISTER_INITIALISATION
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{
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pxTopOfStack--;
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*pxTopOfStack = 0xffffffff; /* r15. */
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pxTopOfStack--;
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*pxTopOfStack = 0xeeeeeeee;
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pxTopOfStack--;
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*pxTopOfStack = 0xdddddddd;
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pxTopOfStack--;
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*pxTopOfStack = 0xcccccccc;
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pxTopOfStack--;
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*pxTopOfStack = 0xbbbbbbbb;
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pxTopOfStack--;
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*pxTopOfStack = 0xaaaaaaaa;
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pxTopOfStack--;
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*pxTopOfStack = 0x99999999;
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pxTopOfStack--;
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*pxTopOfStack = 0x88888888;
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pxTopOfStack--;
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*pxTopOfStack = 0x77777777;
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pxTopOfStack--;
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*pxTopOfStack = 0x66666666;
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pxTopOfStack--;
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*pxTopOfStack = 0x55555555;
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pxTopOfStack--;
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*pxTopOfStack = 0x44444444;
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pxTopOfStack--;
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*pxTopOfStack = 0x33333333;
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pxTopOfStack--;
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*pxTopOfStack = 0x22222222;
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pxTopOfStack--;
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}
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#else
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{
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pxTopOfStack -= 15;
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}
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#endif
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*pxTopOfStack = ( portSTACK_TYPE ) pvParameters; /* R1 */
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pxTopOfStack--;
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*pxTopOfStack = portINITIAL_FPSW;
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pxTopOfStack--;
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*pxTopOfStack = 0x12345678; /* Accumulator. */
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pxTopOfStack--;
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*pxTopOfStack = 0x87654321; /* Accumulator. */
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return pxTopOfStack;
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}
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/*-----------------------------------------------------------*/
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portBASE_TYPE xPortStartScheduler( void )
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{
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extern void vApplicationSetupTimerInterrupt( void );
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/* Use pxCurrentTCB just so it does not get optimised away. */
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if( pxCurrentTCB != NULL )
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{
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/* Call an application function to set up the timer that will generate the
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tick interrupt. This way the application can decide which peripheral to
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use. A demo application is provided to show a suitable example. */
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vApplicationSetupTimerInterrupt();
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/* Enable the software interrupt. */
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_IEN( _ICU_SWINT ) = 1;
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/* Ensure the software interrupt is clear. */
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_IR( _ICU_SWINT ) = 0;
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/* Ensure the software interrupt is set to the kernel priority. */
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_IPR( _ICU_SWINT ) = configKERNEL_INTERRUPT_PRIORITY;
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/* Start the first task. */
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prvStartFirstTask();
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}
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/* Just to make sure the function is not optimised away. */
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( void ) vSoftwareInterruptISR();
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/* Should not get here. */
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return pdFAIL;
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}
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/*-----------------------------------------------------------*/
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#pragma inline_asm prvStartFirstTask
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static void prvStartFirstTask( void )
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{
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/* When starting the scheduler there is nothing that needs moving to the
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interrupt stack because the function is not called from an interrupt.
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Just ensure the current stack is the user stack. */
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SETPSW U
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/* Obtain the location of the stack associated with which ever task
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pxCurrentTCB is currently pointing to. */
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MOV.L #_pxCurrentTCB, R15
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MOV.L [R15], R15
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MOV.L [R15], R0
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/* Restore the registers from the stack of the task pointed to by
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pxCurrentTCB. */
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POP R15
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MVTACLO R15 /* Accumulator low 32 bits. */
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POP R15
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MVTACHI R15 /* Accumulator high 32 bits. */
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POP R15
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MVTC R15,FPSW /* Floating point status word. */
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POPM R1-R15 /* R1 to R15 - R0 is not included as it is the SP. */
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RTE /* This pops the remaining registers. */
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NOP
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NOP
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}
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/*-----------------------------------------------------------*/
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#pragma interrupt ( vTickISR( vect = _VECT( configTICK_VECTOR ), enable ) )
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void vTickISR( void )
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{
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/* Increment the tick, and perform any processing the new tick value
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necessitates. */
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set_ipl( configMAX_SYSCALL_INTERRUPT_PRIORITY );
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{
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vTaskIncrementTick();
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}
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set_ipl( configKERNEL_INTERRUPT_PRIORITY );
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/* Only select a new task if the preemptive scheduler is being used. */
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#if( configUSE_PREEMPTION == 1 )
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taskYIELD();
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#endif
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}
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/*-----------------------------------------------------------*/
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void vSoftwareInterruptISR( void )
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{
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prvYieldHandler();
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}
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/*-----------------------------------------------------------*/
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#pragma inline_asm prvYieldHandler
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static void prvYieldHandler( void )
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{
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/* Install as the software interrupt handler. */
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.RVECTOR _VECT( _ICU_SWINT ), _vSoftwareInterruptISR
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/* Re-enable interrupts. */
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SETPSW I
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/* Move the data that was automatically pushed onto the interrupt stack when
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the interrupt occurred from the interrupt stack to the user stack.
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R15 is saved before it is clobbered. */
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PUSH.L R15
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/* Read the user stack pointer. */
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MVFC USP, R15
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/* Move the address down to the data being moved. */
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SUB #12, R15
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MVTC R15, USP
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/* Copy the data across. */
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MOV.L [ R0 ], [ R15 ] ; R15
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MOV.L 4[ R0 ], 4[ R15 ] ; PC
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MOV.L 8[ R0 ], 8[ R15 ] ; PSW
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/* Move the interrupt stack pointer to its new correct position. */
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ADD #12, R0
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/* All the rest of the registers are saved directly to the user stack. */
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SETPSW U
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/* Save the rest of the general registers (R15 has been saved already). */
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PUSHM R1-R14
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/* Save the FPSW and accumulator. */
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MVFC FPSW, R15
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PUSH.L R15
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MVFACHI R15
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PUSH.L R15
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MVFACMI R15 ; Middle order word.
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SHLL #16, R15 ; Shifted left as it is restored to the low order word.
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PUSH.L R15
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/* Save the stack pointer to the TCB. */
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MOV.L #_pxCurrentTCB, R15
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MOV.L [ R15 ], R15
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MOV.L R0, [ R15 ]
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/* Ensure the interrupt mask is set to the syscall priority while the kernel
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structures are being accessed. */
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MVTIPL #configMAX_SYSCALL_INTERRUPT_PRIORITY
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/* Select the next task to run. */
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BSR.A _vTaskSwitchContext
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/* Reset the interrupt mask as no more data structure access is required. */
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MVTIPL #configKERNEL_INTERRUPT_PRIORITY
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/* Load the stack pointer of the task that is now selected as the Running
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state task from its TCB. */
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MOV.L #_pxCurrentTCB,R15
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MOV.L [ R15 ], R15
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MOV.L [ R15 ], R0
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/* Restore the context of the new task. The PSW (Program Status Word) and
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PC will be popped by the RTE instruction. */
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POP R15
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MVTACLO R15
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POP R15
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MVTACHI R15
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POP R15
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MVTC R15,FPSW
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POPM R1-R15
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RTE
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NOP
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| 336 |
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NOP
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| 337 |
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}
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| 338 |
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/*-----------------------------------------------------------*/
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| 339 |
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| 340 |
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void vPortEndScheduler( void )
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| 341 |
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{
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| 342 |
|
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/* Not implemented as there is nothing to return to. */
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| 343 |
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| 344 |
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/* The following line is just to prevent the symbol getting optimised away. */
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| 345 |
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( void ) vTaskSwitchContext();
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| 346 |
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}
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| 347 |
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/*-----------------------------------------------------------*/
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| 348 |
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| 349 |
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