Samsung S3C8275X - Manual (Page 163)

S3C8275X/F8275X/C8278X/F8278X/C8274X/F8274X INSTRUCTION SET
6-29
COM
— Complement
COM dst
Operation: dst
← NOT dst
The contents of the destination location are complemented (one's complement); all "1s" are
changed to "0s", and vice-versa.
Flags: C: Unaffected.
Z: Set if the result is "0"; cleared otherwise.
S: Set if the result bit 7 is set; cleared otherwise.
V: Always reset to "0".
D: Unaffected.
H: Unaffected.
Format:
Bytes Cycles Opcode
(Hex)
Addr Mode
dst
opc dst 2 4 60 R
4 61 IR
Examples: Given: R1 = 07H and register 07H = 0F1H:
COM R1
→
R1 = 0F8H
COM @R1
→
R1 = 07H, register 07H = 0EH
In the first example, destination working register R1 contains the value 07H (00000111B). The
statement "COM R1" complements all the bits in R1: all logic ones are changed to logic zeros,
and vice-versa, leaving the value 0F8H (11111000B).
In the second example, Indirect Register (IR) addressing mode is used to complement the value
of destination register 07H (11110001B), leaving the new value 0EH (00001110B).