Index

UBFX

Unsigned Bitfield Extract copies a bitfield of <width> bits starting from bit position <lsb> in the source register to the least significant bits of the destination register, and sets destination bits above the bitfield to zero.

This is an alias of UBFM. This means:

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 1 0 1 0 0 1 1 0 N immr imms Rn Rd
opc

32-bit (sf == 0 && N == 0)

UBFX <Wd>, <Wn>, #<lsb>, #<width>

is equivalent to

UBFM <Wd>, <Wn>, #<lsb>, #(<lsb>+<width>-1)

and is the preferred disassembly when BFXPreferred(sf, opc<1>, imms, immr).

64-bit (sf == 1 && N == 1)

UBFX <Xd>, <Xn>, #<lsb>, #<width>

is equivalent to

UBFM <Xd>, <Xn>, #<lsb>, #(<lsb>+<width>-1)

and is the preferred disassembly when BFXPreferred(sf, opc<1>, imms, immr).

Assembler Symbols

<Wd>

Is the 32-bit name of the general-purpose destination register, encoded in the "Rd" field.
<Wn>

Is the 32-bit name of the general-purpose source register, encoded in the "Rn" field.
<Xd>

Is the 64-bit name of the general-purpose destination register, encoded in the "Rd" field.
<Xn>

Is the 64-bit name of the general-purpose source register, encoded in the "Rn" field.
<lsb>

For the 32-bit variant: is the bit number of the lsb of the source bitfield, in the range 0 to 31.

For the 64-bit variant: is the bit number of the lsb of the source bitfield, in the range 0 to 63.
<width>

For the 32-bit variant: is the width of the bitfield, in the range 1 to 32-<lsb>.

For the 64-bit variant: is the width of the bitfield, in the range 1 to 64-<lsb>.

Operation

The description of UBFM gives the operational pseudocode for this instruction.

Operational information

If PSTATE.DIT is 1: