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TST (shifted register)

Test (shifted register).

This instruction is an alias of ANDS (shifted register).

The equivalent instruction is ANDS WZR, Wn, Wm{, shift #amount}.

Syntax

TST Wn, Wm{, shift #amount} ; 32-bit

TST Xn, Xm{, shift #amount} ; 64-bit

Where:

Wn
Is the 32-bit name of the first general-purpose source register.
Wm
Is the 32-bit name of the second general-purpose source register.
amount

Depends on the instruction variant:

32-bit general registers
Is the shift amount, in the range 0 to 31, defaulting to 0.
64-bit general registers
Is the shift amount, in the range 0 to 63, defaulting to 0.
Xn
Is the 64-bit name of the first general-purpose source register.
Xm
Is the 64-bit name of the second general-purpose source register.
shift
Is the optional shift to be applied to the final source, defaulting to LSL, and can be one of LSL, LSR, ASR, or ROR.

Operation

Test (shifted register) performs a bitwise AND operation on a register value and an optionally-shifted register value. It updates the condition flags based on the result, and discards the result.

Rn AND shift(Rm, amount), where R is either W or X.

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