S3C84E5/C84E9/P84E9

INSTRUCTION SET

 

 

DEC — Decrement

DECdst

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 the 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.

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Samsung S3C84E5 DEC Decrement, DECdst Operation dst ← dst-1, Contents of the destination operand are decremented by one