CBNZ

Compare and branch on nonzero

This instruction compares the value in a register with zero, and conditionally branches to a label at a PC-relative offset if the comparison is not equal. It provides a hint that this is not a subroutine call or return. This instruction does not affect the condition flags.

31	30	29	28	27	26	25	24	23	22	21	20	19	18	17	16	15	14	13	12	11	10	9	8	7	6	5	4	3	2	1	0
sf	0	1	1	0	1	0	1	imm19																			Rt
							op

Encoding for the 32-bit variant

Applies when (sf == 0)

CBNZ <Wt>, <label>

Encoding for the 64-bit variant

Applies when (sf == 1)

CBNZ <Xt>, <label>

Decode for all variants of this encoding

constant integer t = UInt(Rt); constant integer datasize = 32 << UInt(sf); constant bits(64) offset = SignExtend(imm19:'00', 64);

Assembler Symbols

<Wt>	Is the 32-bit name of the general-purpose register to be tested, encoded in the "Rt" field.

<label>

Is the program label to be conditionally branched to. Its offset from the address of this instruction, in the range +/-1MB, is encoded as "imm19" times 4.

<Xt>	Is the 64-bit name of the general-purpose register to be tested, encoded in the "Rt" field.

Operation

constant boolean branch_conditional = TRUE; constant bits(datasize) operand1 = X[t, datasize]; if !IsZero(operand1) then BranchTo(PC64 + offset, BranchType_DIR, branch_conditional); else BranchNotTaken(BranchType_DIR, branch_conditional);