;********************************************************************************************************
; CODE GENERATION DIRECTIVES
;********************************************************************************************************
AREA _CPU_A_CODE_, CODE, READONLY
ARM
;$PAGE
;********************************************************************************************************
; CRITICAL SECTION FUNCTIONS
;
; Description : Disable/Enable interrupts by preserving the state of interrupts. Generally speaking, the
; state of the interrupt disable flag is stored in the local variable 'cpu_sr' & interrupts
; are then disabled ('cpu_sr' is allocated in all functions that need to disable interrupts).
; The previous interrupt state is restored by copying 'cpu_sr' into the CPU's status register.
;
; Prototypes : CPU_SR CPU_SR_Save (void);
; void CPU_SR_Restore(CPU_SR cpu_sr);
;********************************************************************************************************
CPU_SR_Save
MRS R0, CPSR
CPU_SR_Save_Loop
; Set IRQ & FIQ bits in CPSR to DISABLE all interrupts
ORR R1, R0, #CPU_ARM_CTRL_INT_DIS
MSR CPSR_c, R1
MRS R1, CPSR ; Confirm that CPSR contains the proper interrupt disable flags
AND R1, R1, #CPU_ARM_CTRL_INT_DIS
CMP R1, #CPU_ARM_CTRL_INT_DIS
BNE CPU_SR_Save_Loop ; NOT properly DISABLED (try again)
BX LR ; DISABLED, return the original CPSR contents in R0
CPU_SR_Restore ; See Note #2
MSR CPSR_c, R0
BX LR
;$PAGE
;********************************************************************************************************
; CPU ASSEMBLY PORT FILE END
;********************************************************************************************************
END