Operations:

Syntax:

Operation:

Operands:

Program Counter:

Opcode

Comment

Stack

COM Rd

Rd = 0xFF - Rd

0 <= d <= 31

PC = PC + 1

1001010ddddd0000

Description

This instruction performs a One's Complement of register Rd.

Status Register (SREG) and Boolean Formula

I

–

T

–

H

–

S

⇔

N XOR V, for signed tests.

V

0

0

Cleared.

N

⇔

R7

Set if MSB of the result is set; cleared otherwise.

Z

⇔

~R7 AND ~R6 AND ~R5 AND ~R4 AND ~R3 AND ~R2 AND ~R1 AND ~R0

Set if the result is 0x00; cleared otherwise.

C

1

1

Set.

R (Result)

R (Result) equals Rd after the operation.

Example: 

      com   r4     ; Take one’s complement of r4
      breq  zero   ; Branch if zero
      ...
zero: nop          ; Branch destination (do nothing)

Words

1 (2 bytes)

Table Cycles

Name

Cycles

AVRe

1

AVRxm

1

AVRxt

1

AVRrc

1