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198 lines
7.0 KiB
C
198 lines
7.0 KiB
C
/*
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FreeRTOS.org V4.1.2 - Copyright (C) 2003-2006 Richard Barry.
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This file is part of the FreeRTOS.org distribution.
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FreeRTOS.org is free software; you can redistribute it and/or modify
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it under the terms of the GNU General Public License as published by
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the Free Software Foundation; either version 2 of the License, or
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(at your option) any later version.
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FreeRTOS.org is distributed in the hope that it will be useful,
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but WITHOUT ANY WARRANTY; without even the implied warranty of
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MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE. See the
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GNU General Public License for more details.
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You should have received a copy of the GNU General Public License
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along with FreeRTOS.org; if not, write to the Free Software
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Foundation, Inc., 59 Temple Place, Suite 330, Boston, MA 02111-1307 USA
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A special exception to the GPL can be applied should you wish to distribute
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a combined work that includes FreeRTOS.org, without being obliged to provide
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the source code for any proprietary components. See the licensing section
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of http://www.FreeRTOS.org for full details of how and when the exception
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can be applied.
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***************************************************************************
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See http://www.FreeRTOS.org for documentation, latest information, license
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and contact details. Please ensure to read the configuration and relevant
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port sections of the online documentation.
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***************************************************************************
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*/
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/*-----------------------------------------------------------
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* Components that can be compiled to either ARM or THUMB mode are
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* contained in port.c The ISR routines, which can only be compiled
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* to ARM mode, are contained in this file.
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*----------------------------------------------------------*/
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/*
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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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/* Constants required to handle interrupts. */
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#define portTIMER_MATCH_ISR_BIT ( ( unsigned portCHAR ) 0x01 )
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#define portCLEAR_VIC_INTERRUPT ( ( unsigned portLONG ) 0 )
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/* Constants required to handle critical sections. */
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#define portNO_CRITICAL_NESTING ( ( unsigned portLONG ) 0 )
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volatile unsigned portLONG ulCriticalNesting = 9999UL;
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/*-----------------------------------------------------------*/
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/*
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* The scheduler can only be started from ARM mode, hence the inclusion of this
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* function here.
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*/
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void vPortISRStartFirstTask( void );
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/*-----------------------------------------------------------*/
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void vPortISRStartFirstTask( void )
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{
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/* Simply start the scheduler. This is included here as it can only be
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called from ARM mode. */
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asm volatile ( \
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"LDR R0, =pxCurrentTCB \n\t" \
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"LDR R0, [R0] \n\t" \
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"LDR LR, [R0] \n\t" \
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\
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/* The critical nesting depth is the first item on the stack. */ \
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/* Load it into the ulCriticalNesting variable. */ \
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"LDR R0, =ulCriticalNesting \n\t" \
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"LDMFD LR!, {R1} \n\t" \
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"STR R1, [R0] \n\t" \
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\
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/* Get the SPSR from the stack. */ \
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"LDMFD LR!, {R0} \n\t" \
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"MSR SPSR, R0 \n\t" \
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\
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/* Restore all system mode registers for the task. */ \
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"LDMFD LR, {R0-R14}^ \n\t" \
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"NOP \n\t" \
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\
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/* Restore the return address. */ \
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"LDR LR, [LR, #+60] \n\t" \
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\
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/* And return - correcting the offset in the LR to obtain the */ \
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/* correct address. */ \
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"SUBS PC, LR, #4 \n\t" \
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); \
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}
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/*-----------------------------------------------------------*/
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/* The preemptive scheduler is defined as "naked" as the full context is
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saved on entry as part of the context switch. */
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void vPortTickISR( void )
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{
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/* Increment the RTOS tick count, then look for the highest priority
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task that is ready to run. */
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vTaskIncrementTick();
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#if configUSE_PREEMPTION == 1
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vTaskSwitchContext();
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#endif
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/* Ready for the next interrupt. */
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TB_ClearITPendingBit( TB_IT_Update );
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}
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/*-----------------------------------------------------------*/
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/*
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* The interrupt management utilities can only be called from ARM mode. When
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* THUMB_INTERWORK is defined the utilities are defined as functions here to
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* ensure a switch to ARM mode. When THUMB_INTERWORK is not defined then
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* the utilities are defined as macros in portmacro.h - as per other ports.
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*/
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#ifdef THUMB_INTERWORK
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void vPortDisableInterruptsFromThumb( void ) __attribute__ ((naked));
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void vPortEnableInterruptsFromThumb( void ) __attribute__ ((naked));
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void vPortDisableInterruptsFromThumb( void )
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{
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asm volatile (
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"STMDB SP!, {R0} \n\t" /* Push R0. */
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"MRS R0, CPSR \n\t" /* Get CPSR. */
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"ORR R0, R0, #0xC0 \n\t" /* Disable IRQ, FIQ. */
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"MSR CPSR, R0 \n\t" /* Write back modified value. */
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"LDMIA SP!, {R0} \n\t" /* Pop R0. */
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"BX R14" ); /* Return back to thumb. */
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}
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void vPortEnableInterruptsFromThumb( void )
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{
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asm volatile (
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"STMDB SP!, {R0} \n\t" /* Push R0. */
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"MRS R0, CPSR \n\t" /* Get CPSR. */
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"BIC R0, R0, #0xC0 \n\t" /* Enable IRQ, FIQ. */
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"MSR CPSR, R0 \n\t" /* Write back modified value. */
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"LDMIA SP!, {R0} \n\t" /* Pop R0. */
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"BX R14" ); /* Return back to thumb. */
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}
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#endif /* THUMB_INTERWORK */
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/* The code generated by the GCC compiler uses the stack in different ways at
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different optimisation levels. The interrupt flags can therefore not always
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be saved to the stack. Instead the critical section nesting level is stored
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in a variable, which is then saved as part of the stack context. */
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void vPortEnterCritical( void )
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{
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/* Disable interrupts as per portDISABLE_INTERRUPTS(); */
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asm volatile (
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"STMDB SP!, {R0} \n\t" /* Push R0. */
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"MRS R0, CPSR \n\t" /* Get CPSR. */
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"ORR R0, R0, #0xC0 \n\t" /* Disable IRQ, FIQ. */
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"MSR CPSR, R0 \n\t" /* Write back modified value. */
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"LDMIA SP!, {R0}" ); /* Pop R0. */
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/* Now interrupts are disabled ulCriticalNesting can be accessed
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directly. Increment ulCriticalNesting to keep a count of how many times
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portENTER_CRITICAL() has been called. */
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ulCriticalNesting++;
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}
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void vPortExitCritical( void )
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{
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if( ulCriticalNesting > portNO_CRITICAL_NESTING )
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{
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/* Decrement the nesting count as we are leaving a critical section. */
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ulCriticalNesting--;
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/* If the nesting level has reached zero then interrupts should be
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re-enabled. */
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if( ulCriticalNesting == portNO_CRITICAL_NESTING )
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{
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/* Enable interrupts as per portEXIT_CRITICAL(). */
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asm volatile (
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"STMDB SP!, {R0} \n\t" /* Push R0. */
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"MRS R0, CPSR \n\t" /* Get CPSR. */
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"BIC R0, R0, #0xC0 \n\t" /* Enable IRQ, FIQ. */
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"MSR CPSR, R0 \n\t" /* Write back modified value. */
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"LDMIA SP!, {R0}" ); /* Pop R0. */
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}
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}
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}
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