;********************************************************************************************************
;                                               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
;
;                                                ARM
;                                           IAR C Compiler
;
; Filename      : cpu_a.s
; Version       : V1.14
; Programmer(s) : JJL
;                 ITJ
;********************************************************************************************************


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

        PUBLIC  CPU_SR_Save
        PUBLIC  CPU_SR_Restore


;********************************************************************************************************
;                                               EQUATES
;********************************************************************************************************

CPU_NO_INT  EQU     0xC0                        ; Mask used to disable interrupts (Both FIR and IRQ)


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

        RSEG CODE:CODE:NOROOT(2)
        CODE32


;$PAGE
;*********************************************************************************************************
;                                      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,CPSR                           ; Set IRQ & FIQ bits in CPSR to dis all ints.
        ORR     R1,R0,#CPU_NO_INT
        MSR     CPSR_c,R1
        MRS     R1,CPSR                           ; Confirm that CPSR contains proper int dis flags.
        AND     R1,R1,#CPU_NO_INT
        CMP     R1,#CPU_NO_INT
        BNE     CPU_SR_Save                       ; Not properly DISABLED; try again.
        BX      LR                                ; DISABLED, rtn original CPSR contents in R0.


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


        END