cpu_a.asm

基于 Cortex-M3 (ARM) 内核使用之 uC/OS-II 作业系统,此例程可移植于 Cortex-M3 (ARM)内核的微处理器上的应用,于 IAR EWARM V4.41A 工程编译,而

;********************************************************************************************************
;                                               uC/CPU
;                                    CPU CONFIGURATION & PORT LAYER
;
;                          (c) Copyright 1999-2005; Micrium, Inc.; Weston, FL
;
;                   All rights reserved.  Protected by international copyright laws.
;                   Knowledge of the source code may not be used to write a similar
;                   product.  This file may only be used in accordance with a license
;                   and should not be redistributed in any way.
;********************************************************************************************************


;********************************************************************************************************
;
;                                           CPU PORT FILE
;
;                                             Cortex-M3
;                                           IAR C Compiler
;
; Filename      : cpu_a.asm
; Version       : V1.14
; Programmer(s) : JJL
;                 ITJ
;********************************************************************************************************


;********************************************************************************************************
;                                           PUBLIC FUNCTIONS
;********************************************************************************************************

        PUBLIC  CPU_DI
        PUBLIC  CPU_EI

        PUBLIC  CPU_SR_Save
        PUBLIC  CPU_SR_Restore

;********************************************************************************************************
;                                      CODE GENERATION DIRECTIVES
;********************************************************************************************************

        RSEG CODE:CODE:NOROOT(2)


;$PAGE
;*********************************************************************************************************
;                                    DISABLE and ENABLE INTERRUPTS
;
; Description: Disable/Enable interrupts.
;
; Prototypes :     void   OS_CPU_DI(void);
;                  void   OS_CPU_EI(void);
;*********************************************************************************************************

CPU_DI
        CPSID   I
        BX      LR

CPU_EI
        CPSIE   I
        BX      LR


;*********************************************************************************************************
;                                      CRITICAL SECTION FUNCTIONS
;
; Description : Disable/Enable interrupts by preserving the state of interrupts.  Generally speaking, the 
;               state of the interrupt disable flag is stored in the local variable 'cpu_sr' & interrupts
;               are then disabled ('cpu_sr' is allocated in all functions that need to disable interrupts).
;               The previous interrupt state is restored by copying 'cpu_sr' into the CPU's status register.
;
; Prototypes  : CPU_SR  CPU_SR_Save(void);
;               void    CPU_SR_Restore(CPU_SR cpu_sr);
;
;
; Note(s)     : (1) These functions are used in general like this:
;
;                   void  Task (void *p_arg)
;                   {
;                                                               /* Allocate storage for CPU status register */
;                   #if (CPU_CFG_CRITICAL_METHOD == CPU_CRITICAL_METHOD_STATUS_LOCAL)
;                       CPU_SR  cpu_sr;
;                   #endif
;
;                            :
;                            :
;                       CPU_CRITICAL_ENTER();                   /* cpu_sr = CPU_SR_Save();                  */
;                            :
;                            :
;                       CPU_CRITICAL_EXIT();                    /* CPU_SR_Restore(cpu_sr);                  */
;                            :
;                            :
;                   }
;
;               (2) CPU_SR_Restore() is implemented as recommended by Atmel's application note :
;
;                      "Disabling Interrupts at Processor Level"
;*********************************************************************************************************

CPU_SR_Save
        MRS     R0, PRIMASK                 ; set prio int mask to mask all (except faults)
        CPSID   I
        BX      LR


CPU_SR_Restore                                    ; See Note #2.
        MSR     PRIMASK, R0
        BX      LR


        END