Description:
This instruction tests a single bit in a register and skips the next instruction if the bit is cleared.
Operation:
(i)If Rr(b) = 0 then PC ← PC + 2 (or 3) else PC ← PC + 1
Syntax: Operands: Program Counter:
(i)SBRC Rr,b 0 ≤ r ≤ 31, 0 ≤ b ≤ 7 PC ← PC + 1, Condition false - no skip
PC ← PC + 2, Skip a one word instruction
PC ← PC + 3, Skip a two word instruction
16-bit Opcode:
|
1111 |
110r |
rrrr |
0bbb |
Status Register (SREG) and Boolean Formula:
|
I |
T |
H |
S |
V |
N |
Z |
C |
|---|---|---|---|---|---|---|---|
|
- |
- |
- |
- |
- |
- |
- |
- |
Example:
sub r0,r1 ; Subtract r1 from r0 sbrc r0,7 ; Skip if bit 7 in r0 cleared sub r0,r1 ; Only executed if bit 7 in r0 not cleared nop ; Continue (do nothing)
Words: 1 (2 bytes)
Cycles: 1 if condition is false (no skip)
2 if condition is true (skip is executed) and the instruction skipped is 1 word
3 if condition is true (skip is executed) and the instruction skipped is 2 words