Test bit and Branch if Zero.
Is a width specifier, and can be either
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.
- Is the number [0-30] of the general-purpose register to be tested or the name ZR (31).
- Is the bit number to be tested, in the range 0 to 63.
- Is the program label to be conditionally branched to. Its offset from the address of this instruction, in the range ±32KB.
Test bit and Branch if Zero compares the value of a test bit with zero, and conditionally branches to a label at a PC-relative offset if the comparison is equal. It provides a hint that this is not a subroutine call or return. This instruction does not affect condition flags.