Texas Instruments MSP430x1xx manual Decd.B

Instruction Set

* DECD[.W]	Double-decrement destination
* DECD.B	Double-decrement destination
Syntax	DECD		dst or DECD.W dst
	DECD.B		dst
Operation	dst − 2 −> dst
Emulation	SUB		#2,dst
Emulation	SUB.B		#2,dst
Description	The destination operand is decremented by two. The original contents are lost.
Status Bits	N:	Set if result is negative, reset if positive
	Z:	Set if dst contained 2, reset otherwise
	C:	Reset if dst contained 0 or 1, set otherwise
	V:	Set if an arithmetic overflow occurs, otherwise reset.
		Set if initial value of destination was 08001 or 08000h, otherwise reset.
		Set if initial value of destination was 081 or 080h, otherwise reset.

Mode Bits	OSCOFF, CPUOFF, and GIE are not affected.
Example	R10 is decremented by 2.
	DECD	R10	; Decrement R10 by two

;Move a block of 255 words from memory location starting with EDE to memory location

;starting with TONI

;Tables should not overlap: start of destination address TONI must not be within the

;range EDE to EDE+0FEh

;
		MOV	#EDE,R6
		MOV	#510,R10
	L$1	MOV	@R6+,TONI−EDE−2(R6)
		DECD	R10
		JNZ	L$1
Example	Memory at location LEO is decremented by two.
		DECD.B	LEO	; Decrement MEM(LEO)
	Decrement status byte STATUS by two.
		DECD.B	STATUS

3-38 RISC 16−Bit CPU