| /* | |
| FreeRTOS V7.2.0 - Copyright (C) 2012 Real Time Engineers Ltd. | |
| *************************************************************************** | |
| * * | |
| * FreeRTOS tutorial books are available in pdf and paperback. * | |
| * Complete, revised, and edited pdf reference manuals are also * | |
| * available. * | |
| * * | |
| * Purchasing FreeRTOS documentation will not only help you, by * | |
| * ensuring you get running as quickly as possible and with an * | |
| * in-depth knowledge of how to use FreeRTOS, it will also help * | |
| * the FreeRTOS project to continue with its mission of providing * | |
| * professional grade, cross platform, de facto standard solutions * | |
| * for microcontrollers - completely free of charge! * | |
| * * | |
| * >>> See http://www.FreeRTOS.org/Documentation for details. <<< * | |
| * * | |
| * Thank you for using FreeRTOS, and thank you for your support! * | |
| * * | |
| *************************************************************************** | |
| This file is part of the FreeRTOS distribution. | |
| FreeRTOS is free software; you can redistribute it and/or modify it under | |
| the terms of the GNU General Public License (version 2) as published by the | |
| Free Software Foundation AND MODIFIED BY the FreeRTOS exception. | |
| >>>NOTE<<< The modification to the GPL is included to allow you to | |
| distribute a combined work that includes FreeRTOS without being obliged to | |
| provide the source code for proprietary components outside of the FreeRTOS | |
| kernel. FreeRTOS is distributed in the hope that it will be useful, but | |
| WITHOUT ANY WARRANTY; without even the implied warranty of MERCHANTABILITY | |
| or FITNESS FOR A PARTICULAR PURPOSE. See the GNU General Public License for | |
| more details. You should have received a copy of the GNU General Public | |
| License and the FreeRTOS license exception along with FreeRTOS; if not it | |
| can be viewed here: http://www.freertos.org/a00114.html and also obtained | |
| by writing to Richard Barry, contact details for whom are available on the | |
| FreeRTOS WEB site. | |
| 1 tab == 4 spaces! | |
| *************************************************************************** | |
| * * | |
| * Having a problem? Start by reading the FAQ "My application does * | |
| * not run, what could be wrong? * | |
| * * | |
| * http://www.FreeRTOS.org/FAQHelp.html * | |
| * * | |
| *************************************************************************** | |
| http://www.FreeRTOS.org - Documentation, training, latest information, | |
| license and contact details. | |
| http://www.FreeRTOS.org/plus - A selection of FreeRTOS ecosystem products, | |
| including FreeRTOS+Trace - an indispensable productivity tool. | |
| Real Time Engineers ltd license FreeRTOS to High Integrity Systems, who sell | |
| the code with commercial support, indemnification, and middleware, under | |
| the OpenRTOS brand: http://www.OpenRTOS.com. High Integrity Systems also | |
| provide a safety engineered and independently SIL3 certified version under | |
| the SafeRTOS brand: http://www.SafeRTOS.com. | |
| */ | |
| /*----------------------------------------------------------- | |
| * Components that can be compiled to either ARM or THUMB mode are | |
| * contained in port.c The ISR routines, which can only be compiled | |
| * to ARM mode, are contained in this file. | |
| *----------------------------------------------------------*/ | |
| /* Scheduler includes. */ | |
| #include "FreeRTOS.h" | |
| #include "task.h" | |
| /* Constants required to handle interrupts. */ | |
| #define portTIMER_MATCH_ISR_BIT ( ( unsigned portCHAR ) 0x01 ) | |
| #define portCLEAR_VIC_INTERRUPT ( ( unsigned portLONG ) 0 ) | |
| /* Constants required to handle critical sections. */ | |
| #define portNO_CRITICAL_NESTING ( ( unsigned portLONG ) 0 ) | |
| volatile unsigned portLONG ulCriticalNesting = 9999UL; | |
| /*-----------------------------------------------------------*/ | |
| /* ISR to handle manual context switches (from a call to taskYIELD()). */ | |
| void vPortYieldProcessor( void ) __attribute__((interrupt("SWI"), naked)); | |
| /* | |
| * The scheduler can only be started from ARM mode, hence the inclusion of this | |
| * function here. | |
| */ | |
| void vPortISRStartFirstTask( void ); | |
| /*-----------------------------------------------------------*/ | |
| void vPortISRStartFirstTask( void ) | |
| { | |
| /* Simply start the scheduler. This is included here as it can only be | |
| called from ARM mode. */ | |
| portRESTORE_CONTEXT(); | |
| } | |
| /*-----------------------------------------------------------*/ | |
| /* | |
| * Called by portYIELD() or taskYIELD() to manually force a context switch. | |
| * | |
| * When a context switch is performed from the task level the saved task | |
| * context is made to look as if it occurred from within the tick ISR. This | |
| * way the same restore context function can be used when restoring the context | |
| * saved from the ISR or that saved from a call to vPortYieldProcessor. | |
| */ | |
| void vPortYieldProcessor( void ) | |
| { | |
| /* Within an IRQ ISR the link register has an offset from the true return | |
| address, but an SWI ISR does not. Add the offset manually so the same | |
| ISR return code can be used in both cases. */ | |
| __asm volatile ( "ADD LR, LR, #4" ); | |
| /* Perform the context switch. First save the context of the current task. */ | |
| portSAVE_CONTEXT(); | |
| /* Find the highest priority task that is ready to run. */ | |
| __asm volatile( "bl vTaskSwitchContext" ); | |
| /* Restore the context of the new task. */ | |
| portRESTORE_CONTEXT(); | |
| } | |
| /*-----------------------------------------------------------*/ | |
| /* | |
| * The ISR used for the scheduler tick depends on whether the cooperative or | |
| * the preemptive scheduler is being used. | |
| */ | |
| #if configUSE_PREEMPTION == 0 | |
| /* The cooperative scheduler requires a normal IRQ service routine to | |
| simply increment the system tick. */ | |
| void vNonPreemptiveTick( void ) __attribute__ ((interrupt ("IRQ"))); | |
| void vNonPreemptiveTick( void ) | |
| { | |
| vTaskIncrementTick(); | |
| T0IR = 2; | |
| VICVectAddr = portCLEAR_VIC_INTERRUPT; | |
| } | |
| #else | |
| /* The preemptive scheduler is defined as "naked" as the full context is | |
| saved on entry as part of the context switch. */ | |
| void vPreemptiveTick( void ) __attribute__((naked)); | |
| void vPreemptiveTick( void ) | |
| { | |
| /* Save the context of the interrupted task. */ | |
| portSAVE_CONTEXT(); | |
| /* Increment the RTOS tick count, then look for the highest priority | |
| task that is ready to run. */ | |
| __asm volatile( "bl vTaskIncrementTick" ); | |
| __asm volatile( "bl vTaskSwitchContext" ); | |
| /* Ready for the next interrupt. */ | |
| T0IR = 2; | |
| VICVectAddr = portCLEAR_VIC_INTERRUPT; | |
| /* Restore the context of the new task. */ | |
| portRESTORE_CONTEXT(); | |
| } | |
| #endif | |
| /*-----------------------------------------------------------*/ | |
| /* | |
| * The interrupt management utilities can only be called from ARM mode. When | |
| * THUMB_INTERWORK is defined the utilities are defined as functions here to | |
| * ensure a switch to ARM mode. When THUMB_INTERWORK is not defined then | |
| * the utilities are defined as macros in portmacro.h - as per other ports. | |
| */ | |
| #ifdef THUMB_INTERWORK | |
| void vPortDisableInterruptsFromThumb( void ) __attribute__ ((naked)); | |
| void vPortEnableInterruptsFromThumb( void ) __attribute__ ((naked)); | |
| void vPortDisableInterruptsFromThumb( void ) | |
| { | |
| __asm volatile ( | |
| "STMDB SP!, {R0} \n\t" /* Push R0. */ | |
| "MRS R0, CPSR \n\t" /* Get CPSR. */ | |
| "ORR R0, R0, #0xC0 \n\t" /* Disable IRQ, FIQ. */ | |
| "MSR CPSR, R0 \n\t" /* Write back modified value. */ | |
| "LDMIA SP!, {R0} \n\t" /* Pop R0. */ | |
| "BX R14" ); /* Return back to thumb. */ | |
| } | |
| void vPortEnableInterruptsFromThumb( void ) | |
| { | |
| __asm volatile ( | |
| "STMDB SP!, {R0} \n\t" /* Push R0. */ | |
| "MRS R0, CPSR \n\t" /* Get CPSR. */ | |
| "BIC R0, R0, #0xC0 \n\t" /* Enable IRQ, FIQ. */ | |
| "MSR CPSR, R0 \n\t" /* Write back modified value. */ | |
| "LDMIA SP!, {R0} \n\t" /* Pop R0. */ | |
| "BX R14" ); /* Return back to thumb. */ | |
| } | |
| #endif /* THUMB_INTERWORK */ | |
| /* The code generated by the GCC compiler uses the stack in different ways at | |
| different optimisation levels. The interrupt flags can therefore not always | |
| be saved to the stack. Instead the critical section nesting level is stored | |
| in a variable, which is then saved as part of the stack context. */ | |
| void vPortEnterCritical( void ) | |
| { | |
| /* Disable interrupts as per portDISABLE_INTERRUPTS(); */ | |
| __asm volatile ( | |
| "STMDB SP!, {R0} \n\t" /* Push R0. */ | |
| "MRS R0, CPSR \n\t" /* Get CPSR. */ | |
| "ORR R0, R0, #0xC0 \n\t" /* Disable IRQ, FIQ. */ | |
| "MSR CPSR, R0 \n\t" /* Write back modified value. */ | |
| "LDMIA SP!, {R0}" ); /* Pop R0. */ | |
| /* Now interrupts are disabled ulCriticalNesting can be accessed | |
| directly. Increment ulCriticalNesting to keep a count of how many times | |
| portENTER_CRITICAL() has been called. */ | |
| ulCriticalNesting++; | |
| } | |
| void vPortExitCritical( void ) | |
| { | |
| if( ulCriticalNesting > portNO_CRITICAL_NESTING ) | |
| { | |
| /* Decrement the nesting count as we are leaving a critical section. */ | |
| ulCriticalNesting--; | |
| /* If the nesting level has reached zero then interrupts should be | |
| re-enabled. */ | |
| if( ulCriticalNesting == portNO_CRITICAL_NESTING ) | |
| { | |
| /* Enable interrupts as per portEXIT_CRITICAL(). */ | |
| __asm volatile ( | |
| "STMDB SP!, {R0} \n\t" /* Push R0. */ | |
| "MRS R0, CPSR \n\t" /* Get CPSR. */ | |
| "BIC R0, R0, #0xC0 \n\t" /* Enable IRQ, FIQ. */ | |
| "MSR CPSR, R0 \n\t" /* Write back modified value. */ | |
| "LDMIA SP!, {R0}" ); /* Pop R0. */ | |
| } | |
| } | |
| } |