CBNZ, CBZ -- AArch32

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CBNZ, CBZ

Compare and Branch on Nonzero and Compare and Branch on Zero compare the value in a register with zero, and conditionally branch forward a constant value. They do not affect the condition flags.

T1

15	14	13	12	11	10	9	8	7	6	5	4	3	2	1	0
1	0	1	1	op	0	i	1	imm5					Rn

Encoding for the CBNZ variant

Applies when (op == 1)

CBNZ{<q>} <Rn>, <label>

Encoding for the CBZ variant

Applies when (op == 0)

CBZ{<q>} <Rn>, <label>

Decode for all variants of this encoding

let n : integer = UInt(Rn); let imm32 : bits(32) = ZeroExtend{}(i::imm5::'0'); let nonzero : boolean = (op == '1'); if InITBlock() then UnpredictableProcedure(); end;

For more information about the CONSTRAINED UNPREDICTABLE behavior, see Architectural Constraints on UNPREDICTABLE behaviors.

Assembler Symbols

<q>	See Standard assembler syntax fields.

<Rn>	Is the general-purpose register to be tested, encoded in the "Rn" field.

<label>

Is the program label to be conditionally branched to. Its offset from the PC, a multiple of 2 and in the range 0 to 126, is encoded as "i:imm5" times 2.

Operation

EncodingSpecificOperations(); if nonzero != IsZero(R(n)) then CBWritePC(PC32() + imm32); end;

2025-09_rel_asl1 2026-03-12 12:57:38