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; FreeRTOS.org V5.3.0 - Copyright (C) 2003-2009 Richard Barry.
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; * *
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; * This is a concise, step by step, 'hands on' guide that describes both *
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IMPORT ulCriticalNesting ;
IMPORT pxCurrentTCB ;
MACRO
portRESTORE_CONTEXT
LDR R0, =pxCurrentTCB ; Set the LR to the task stack. The location was...
LDR R0, [R0] ; ... stored in pxCurrentTCB
LDR LR, [R0]
LDR R0, =ulCriticalNesting ; The critical nesting depth is the first item on...
LDMFD LR!, {R1} ; ...the stack. Load it into the ulCriticalNesting var.
STR R1, [R0] ;
LDMFD LR!, {R0} ; Get the SPSR from the stack.
MSR SPSR_cxsf, R0 ;
LDMFD LR, {R0-R14}^ ; Restore all system mode registers for the task.
NOP ;
LDR LR, [LR, #+60] ; Restore the return address
; And return - correcting the offset in the LR to obtain ...
SUBS PC, LR, #4 ; ...the correct address.
MEND
; /**********************************************************************/
MACRO
portSAVE_CONTEXT
STMDB SP!, {R0} ; Store R0 first as we need to use it.
STMDB SP,{SP}^ ; Set R0 to point to the task stack pointer.
NOP ;
SUB SP, SP, #4 ;
LDMIA SP!,{R0} ;
STMDB R0!, {LR} ; Push the return address onto the stack.
MOV LR, R0 ; Now we have saved LR we can use it instead of R0.
LDMIA SP!, {R0} ; Pop R0 so we can save it onto the system mode stack.
STMDB LR,{R0-LR}^ ; Push all the system mode registers onto the task stack.
NOP ;
SUB LR, LR, #60 ;
MRS R0, SPSR ; Push the SPSR onto the task stack.
STMDB LR!, {R0} ;
LDR R0, =ulCriticalNesting ;
LDR R0, [R0] ;
STMDB LR!, {R0} ;
LDR R0, =pxCurrentTCB ; Store the new top of stack for the task.
LDR R1, [R0] ;
STR LR, [R1] ;
MEND
END