38. CBR – Clear Bits in Register
38.1. Description
Clears the specified bits in register Rd. Performs the logical AND between the contents of register Rd and
the complement of the constant mask K. The result will be placed in register Rd.
Operation:
(i) Rd ← Rd • ($FF - K)
Syntax: Operands: Program Counter:
(i) CBR Rd,K 16 ≤ d ≤ 31, 0 ≤ K ≤ 255 PC ← PC + 1
16-bit Opcode: (see ANDI with K complemented)
38.2. Status Register (SREG) and Boolean Formula
I T H S V N Z C
– – – ⇔ 0 ⇔ ⇔ –
S N ⊕ V, for signed tests.
V 0
Cleared.
N R7
Set if MSB of the result is set; cleared otherwise.
Z R7 • R6 • R5 • R4 • R3 • R2 • R1 • R0
Set if the result is $00; cleared otherwise.
R (Result) equals Rd after the operation.
Example:
cbr r16,$F0 ; Clear upper nibble of r16
cbr r18,1 ; Clear bit 0 in r18
Words 1 (2 bytes)
Cycles 1
Atmel AVR Instruction Set Manual [OTHER]
Atmel-0856L-AVR-Instruction-Set-Manual_Other-11/2016
66
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