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5. Program examples

The program examples are described as follow:

(1) For assembler

Example 1:

INT_SWITCH1:

FCLR I ; Disable interrupts.

AND.B #00h, 0055h ; Clear TA0IC int. priority level and int. request bit.

NOP ;

Four NOP instructions are required when using HOLD function.

NOP

FSET I ; Enable interrupts.

Example 2:

INT_SWITCH2:

FCLR I ; Disable interrupts.

AND.B #00h, 0055h ; Clear TA0IC int. priority level and int. request bit.

MOV.W MEM, R0 ; Dummy read.

FSET I ; Enable interrupts.

Example 3:

INT_SWITCH3:

PUSHC FLG ; Push Flag register onto stack

FCLR I ; Disable interrupts.

AND.B #00h, 0055h ; Clear TA0IC int. priority level and int. request bit.

POPC FLG ; Enable interrupts.

The reason why two NOP instructions (four when using the HOLD function) or dummy read are inserted

before FSET I in Examples 1 and 2 is to prevent the interrupt enable flag I from being set before the

interrupt control register is rewritten due to effects of the instruction queue.

(2) For C language

#pragma ASM

INT_SWITCH:

FCLR I

#pragma ENDASM

TA0IC & =00 ;

/* Clear TA0IC int. priority level and int. request bit. */

#pragma ASM

NOP

; Four NOP instructions are required when using HOLD function.

NOP

FSET I

#pragma ENDASM

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Renesas Single-Chip Microcomputer M37531T-ADS Technical Information Seite 30