Samsung S3F80JB manual DEC Decrement, Dst Operation ← dst, R1 = 02H

S3F80JBINSTRUCTION SET

DEC — Decrement

DEC	dst
Operation:	dst	← dst – 1
	The contents of the destination operand are decremented by one.
Flags:	C: Unaffected.
	Z:	Set if the result is "0"; cleared otherwise.
	S:	Set if result is negative; cleared otherwise.
	V:	Set if arithmetic overflow occurred; cleared otherwise.
	D:	Unaffected.
	H:	Unaffected.

Format:
Bytes Cycles Opcode	Addr Mode
(Hex)	dst

opc

dst

2	4	00	R
	4	01	IR

Examples: Given: R1 = 03H and register 03H = 10H:

DEC	R1	→	R1 = 02H
DEC	@R1	→	Register 03H = 0FH

In the first example, if working register R1 contains the value 03H, the statement "DEC R1" decrements the hexadecimal value by one, leaving the value 02H. In the second example, the statement "DEC @R1" decrements the value 10H contained in the destination register 03H by one, leaving the value 0FH.

6-35