Operations:

Syntax:

Operation:

Operands:

Program Counter:

Opcode

Comment

Stack

BRBS s,k

If SREG(s) == 1 then PC = PC + k + 1, else PC = PC + 1

0 <= s <= 7, -64 <= k <= +63

PC = PC + k + 1

PC = PC + 1, if the condition is false

111100kkkkkkksss

Description

Conditional relative branch. Tests a single bit in SREG and branches relatively to the PC if the bit is set. This instruction branches relatively to the PC in either direction (PC - 63 <= destination <= PC + 64). Parameter k is the offset from the PC and is represented in two's complement form.

Status Register (SREG) and Boolean Formula

I

–

T

–

H

–

S

–

V

–

N

–

Z

–

C

–

Example: 

        bst   r0,3      ; Load T bit with bit 3 of r0
        brbs  6,bitset  ; Branch T bit was set
        ...
bitset: nop             ; Branch destination (do nothing)

Words

1 (2 bytes)

Table Cycles

Name

Cycles

i

ii

AVRe

1

2

AVRxm

1

2

AVRxt

1

2

AVRrc

1

2

i) If the condition is false.

ii) If the condition is true.