Operations:

Syntax:

Operation:

Operands:

Program Counter:

Opcode

Comment

Stack

CPI Rd,K

Rd - K

16 <= d <= 31, 0 <= K <= 255

PC = PC + 1

0011KKKKddddKKKK

Description

This instruction performs a compare between register Rd and a constant. The register is not changed. All conditional branches can be used after this instruction.

Status Register (SREG) and Boolean Formula

I

–

T

–

H

⇔

~Rd3 AND K3 OR K3 AND R3 OR R3 AND ~Rd3

Set if there was a borrow from bit 3; cleared otherwise.

S

⇔

N XOR V, for signed tests.

V

⇔

Rd7 AND ~K7 AND ~R7 OR ~Rd7 AND K7 AND R7

Set if two's complement overflow resulted from the operation; cleared otherwise.

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

⇔

~Rd7 AND K7 OR K7 AND R7 OR R7 AND ~Rd7

Set if the absolute value of K is larger than the absolute value of Rd; cleared otherwise.

R (Result)

R (Result) after the operation.

Example: 

      cpi   r19,3  ; Compare r19 with 3
      brne  error  ; Branch if r19<>3
      ...
error: 
      nop          ; Branch destination (do nothing)

Words

1 (2 bytes)

Table Cycles

Name

Cycles

AVRe

1

AVRxm

1

AVRxt

1

AVRrc

1