os_cpu_a.s

UCOS 在ARM新平台cortex-m3上的移植

;********************************************************************************************************
;                                               uC/OS-II
;                                         The Real-Time Kernel
;
;                          (c) Copyright 1992-2002, Jean J. Labrosse, Weston, FL
;                                          All Rights Reserved
;
; File : OS_CPU_A.ASM
; By   : Jean J. Labrosse
;********************************************************************************************************

;********************************************************************************************************
;                                               ARM Port
;
;                 Target           : ARM (Includes ARM7, ARM9)
;                 Ported by        : Michael Anburaj
;                 URL              : http://geocities.com/michaelanburaj/    Email : [e-mail]
;
;********************************************************************************************************


;Pre-defined constants



        AREA  UCOS_ARM, CODE, READONLY

;*********************************************************************************************************
;                                          START MULTITASKING
;                                       void OSStartHighRdy(void)
;
; Note : OSStartHighRdy() MUST:
;           a) Call OSTaskSwHook() then,
;           b) Set OSRunning to TRUE,
;           c) Switch to the highest priority task.
;*********************************************************************************************************

        IMPORT  OSTaskSwHook
        IMPORT  OSRunning
        IMPORT  OSTCBHighRdy

        EXPORT  OSStartHighRdy

OSStartHighRdy  

        bl OSTaskSwHook             ; Call user defined task switch hook

        ldr r4,=OSRunning           ; Indicate that multitasking has started
        mov r5,#1
        strb r5,[r4]

        ldr r4,=OSTCBHighRdy        ; Get highest priority task TCB address

;*********************************************************************************************************
;                                PERFORM A CONTEXT SWITCH (From task level)
;                                           void OSCtxSw(void)
;
; Note(s):    Upon entry, 
;             OSTCBCur     points to the OS_TCB of the task to suspend
;             OSTCBHighRdy points to the OS_TCB of the task to resume
;
;*********************************************************************************************************

        IMPORT  OSTCBCur
        IMPORT  OSTaskSwHook
        IMPORT  OSTCBHighRdy
        IMPORT  OSPrioCur
        IMPORT  OSPrioHighRdy

        EXPORT  OSCtxSw

OSCtxSw
; Special optimised code below:



		 ; hardware will push r0~r3 r12 pc xpsr
		MRS r12, PSP ; Recover PSP into R12
		STMDB r12!, {r4-r11} ; Push non-stack registers
		
		bl OSTaskSwHook             ; call Task Switch Hook
		LDR r0, =OSTCBCur ; Get pointer to old Thread Control Block
		STR r12, [r0] ; Store SP into Thread Control Block
		LDR r0, =OSTCBHighRdy ; Get pointer to new Thread Control Block




		LDR r12, [r0] ; Acquire new Process SP
		LDMIA r12!, {r4-r11} ; Restore non-stacked registers
		MSR PSP, r12 ; Set PSP to R12
		BX lr ; Return back to Thread


;*********************************************************************************************************
;                                PERFORM A CONTEXT SWITCH (From an ISR)
;                                        void OSIntCtxSw(void)
;
; Note(s): This function only flags a context switch to the ISR Handler
;
;*********************************************************************************************************

        IMPORT  OSIntCtxSwFlag

        EXPORT  OSIntCtxSw

OSIntCtxSw

    
        

;*********************************************************************************************************
;                                            IRQ HANDLER
;
;        This handles all the IRQs
;        Note: FIQ Handler should be written similar to this
;
;*********************************************************************************************************

       
        IMPORT  OSIntEnter
        IMPORT  OSIntExit

        IMPORT  OSIntCtxSwFlag
        IMPORT  OSTCBCur
        IMPORT  OSTaskSwHook
        IMPORT  OSTCBHighRdy
        IMPORT  OSPrioCur
        IMPORT  OSPrioHighRdy

        EXPORT  UCOS_IRQHandler
UCOS_IRQHandler

     


_IntCtxSw
       


;*********************************************************************************************************
;                                   CRITICAL SECTION METHOD 3 FUNCTIONS
;
; Description: Disable/Enable interrupts by preserving the state of interrupts.  Generally speaking you
;              would store the state of the interrupt disable flag in the local variable 'cpu_sr' and then
;              disable interrupts.  'cpu_sr' is allocated in all of uC/OS-II's functions that need to 
;              disable interrupts.  You would restore the interrupt disable state by copying back 'cpu_sr'
;              into the CPU's status register.
;
;              OS_CPU_SR OSCPUSaveSR()
; Arguments  : none
;
; Returns    : OS_CPU_SR
;
;              OSCPURestoreSR(OS_CPU_SR cpu_sr)
; Arguments  : OS_CPU_SR
;
; Returns    : none
;
; Note(s)    : These functions are used in general like this,
;
;            void Task (void *data)
;            {
;                    #if OS_CRITICAL_METHOD == 3 /* Allocate storage for CPU status register */
;                          OS_CPU_SR  cpu_sr;
;                    #endif
;                         :
;                         :
;                    OS_ENTER_CRITICAL(); /* cpu_sr = OSCPUSaveSR(); */
;                         :
;                         :
;                    OS_EXIT_CRITICAL();  /* OSCPURestoreSR(cpu_sr); */
;                         :
;                         :
;            }
;*********************************************************************************************************

        EXPORT  OSCPUSaveSR
OSCPUSaveSR

     


        EXPORT  OSCPURestoreSR
OSCPURestoreSR

      

        END