Dec Decrement - Samsung S3C80M4/F80M4 User Manual

S3C80M4/F80M4
DEC
— Decrement
DEC dst
dst ← dst – 1
Operation:
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:
opc
Examples: Given: R1 = 03H and register 03H = 10H:
DEC
DEC
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.
dst
→
R1 R1 = 02H
→
@R1 Register 03H = 0FH
Bytes Cycles Opcode
(Hex)
2 4
4
INSTRUCTION SET
Addr Mode
dst
00 R
01 IR
6-35