14. BRBS – Branch if Bit in SREG is Set
14.1. Description
Conditional relative branch. Tests a single bit in SREG and branches relatively to PC if the bit is set. This
instruction branches relatively to PC in either direction (PC - 63 ≤ destination ≤ PC + 64). Parameter k is
the offset from PC and is represented in two’s complement form.
Operation:
(i) If SREG(s) = 1 then PC ← PC + k + 1, else PC ← PC + 1
Syntax: Operands: Program Counter:
(i) BRBS s,k 0 ≤ s ≤ 7, -64 ≤ k ≤ +63 PC ← PC + k + 1
PC ← PC + 1, if condition is
false
16-bit Opcode:
1111 00kk kkkk ksss
14.2. 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)
Cycles 1 if condition is false
2 if condition is true
Atmel AVR Instruction Set Manual [OTHER]
Atmel-0856L-AVR-Instruction-Set-Manual_Other-11/2016
41
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