ARM Compiler armasm User Guide : 16.136 SBFX

16.136 SBFX

Signed Bitfield Extract.

This instruction is an alias of SBFM.

The equivalent instruction is SBFM Wd, Wn, #lsb, #(lsb+width-1).

Syntax

SBFX Wd, Wn, #lsb, #width ; 32-bit

SBFX Xd, Xn, #lsb, #width ; 64-bit

Where:

Wd

Is the 32-bit name of the general-purpose destination register.

Wn

Is the 32-bit name of the general-purpose source register.

lsb

Depends on the instruction variant:

32-bit general registers: Is the bit number of the lsb of the source bitfield, in the range 0 to 31.
64-bit general registers: Is the bit number of the lsb of the source bitfield, in the range 0 to 63.

width

Depends on the instruction variant:

32-bit general registers: Is the width of the bitfield, in the range 1 to 32-lsb.
64-bit general registers: Is the width of the bitfield, in the range 1 to 64-lsb.

Xd

Is the 64-bit name of the general-purpose destination register.

Xn

Is the 64-bit name of the general-purpose source register.

Usage

Signed Bitfield Extract extracts any number of adjacent bits at any position from a register, sign-extends them to the size of the register, and writes the result to the destination register.

Related reference

16.1 A64 instructions in alphabetical order

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