isr_support.h

FreeRTOSV4.1.0 安裝文件 FreeRTOS 是一个源码公开的免费的嵌入式实时操作系统

/*
	FreeRTOS.org V4.1.0 - Copyright (C) 2003-2006 Richard Barry.

	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 as published by
	the Free Software Foundation; either version 2 of the License, or
	(at your option) any later version.

	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
	along with FreeRTOS; if not, write to the Free Software
	Foundation, Inc., 59 Temple Place, Suite 330, Boston, MA  02111-1307  USA

	A special exception to the GPL can be applied should you wish to distribute
	a combined work that includes FreeRTOS, without being obliged to provide
	the source code for any proprietary components.  See the licensing section
	of http://www.FreeRTOS.org for full details of how and when the exception
	can be applied.

	***************************************************************************
	See http://www.FreeRTOS.org for documentation, latest information, license
	and contact details.  Please ensure to read the configuration and relevant
	port sections of the online documentation.
	***************************************************************************
*/

	EXTERN pxCurrentTCB
	EXTERN ulCriticalNesting

;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;
; Context save and restore macro definitions
;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;

portSAVE_CONTEXT MACRO

	; Push R0 as we are going to use the register. 					
	STMDB	SP!, {R0}

	; Set R0 to point to the task stack pointer. 					
	STMDB	SP, {SP}^
	NOP
	SUB		SP, SP, #4
	LDMIA	SP!, {R0}

	; Push the return address onto the stack. 						
	STMDB	R0!, {LR}

	; Now we have saved LR we can use it instead of R0. 				
	MOV		LR, R0

	; Pop R0 so we can save it onto the system mode stack. 			
	LDMIA	SP!, {R0}

	; Push all the system mode registers onto the task stack. 		
	STMDB	LR, {R0-LR}^
	NOP
	SUB		LR, LR, #60

	; Push the SPSR onto the task stack. 							
	MRS		R0, SPSR
	STMDB	LR!, {R0}

	LDR		R0, =ulCriticalNesting 
	LDR		R0, [R0]
	STMDB	LR!, {R0}

	; Store the new top of stack for the task. 						
	LDR		R1, =pxCurrentTCB
	LDR		R0, [R1]
	STR		LR, [R0]

	ENDM


portRESTORE_CONTEXT MACRO

	; Set the LR to the task stack. 									
	LDR		R1, =pxCurrentTCB
	LDR		R0, [R1]
	LDR		LR, [R0]

	; The critical nesting depth is the first item on the stack. 	
	; Load it into the ulCriticalNesting variable. 					
	LDR		R0, =ulCriticalNesting
	LDMFD	LR!, {R1}
	STR		R1, [R0]

	; Get the SPSR from the stack. 									
	LDMFD	LR!, {R0}
	MSR		SPSR_cxsf, R0

	; Restore all system mode registers for the task. 				
	LDMFD	LR, {R0-R14}^
	NOP

	; Restore the return address. 									
	LDR		LR, [LR, #+60]

	; And return - correcting the offset in the LR to obtain the 	
	; correct address. 												
	SUBS	PC, LR, #4

	ENDM