TBNZ
Test bit and branch if nonzero
This instruction compares the value of a bit in a
general-purpose register with zero, and conditionally branches to
a label at a PC-relative offset if the comparison is not equal.
This instruction provides a hint that this is not a subroutine call or return.
This instruction does not affect condition flags.
0
1
1
0
1
1
1
TBNZ <R><t>, #<imm>, <label>
let t : integer = UInt(Rt);
let datasize : integer{} = 32 << UInt(b5);
let bit_pos : integer = UInt(b5::b40);
let offset : bits(64) = SignExtend{}(imm14::'00');
<R>
Is a width specifier,
In assembler source code an 'X' specifier is always permitted, but a 'W' specifier is only permitted when the bit number is less than 32.
<t>
Is the number [0-30] of the general-purpose register to be tested or the name ZR (31), encoded in the "Rt" field.
<imm>
Is the bit number to be tested, in the range 0 to 63, encoded in "b5:b40".
<label>
Is the program label to be conditionally branched to. Its offset from the address of this instruction, in the range +/-32KB, is encoded as "imm14" times 4.
let operand : bits(datasize) = X{}(t);
let branch_conditional : boolean = TRUE;
if operand[bit_pos] != '0' then
BranchTo{64}(PC64() + offset, BranchType_DIR, branch_conditional);
else
BranchNotTaken(BranchType_DIR, branch_conditional);
end;
2026-03-12 12:23:09
2025-09_rel_asl1