sel

Select Bytes

SEL<c> <Rd>, <Rn>, <Rm>

Selects bytes from Rn or Rm based on GE flags.

Pseudocode Operation

for i = 0 to 3 do
  if GE[i] == 1 then
    Rd[8*i+7:8*i] ← Rn[8*i+7:8*i]
  else
    Rd[8*i+7:8*i] ← Rm[8*i+7:8*i]

Example

SEL r0, r1, r2

Encoding

Binary Layout

cond

31:28

01101000

27:20

19:16

15:12

1011

7:4

3:0

Format Data Proc

Opcode 0x06800FB0

Extension A32 (DSP)

Operands

Rd
Destination general-purpose register
Rn
First source / base general-purpose register
Rm
Second source / offset general-purpose register

Other forms of sel

sel SVE Select Elements

Reference

View in Arm A64 ISA Reference ↗ Arm AArch32 ISA

Instruction Forms

Encoding	Instruction		ISA		Bit pattern
0x06800FB0	SEL{<c>}{<q>} {<Rd>,} <Rn>, <Rm>		A32		cond \| 01101000 \| Rn \| Rd \| 1 \| 1 \| 1 \| 1 \| 1011 \| Rm
0xFAA0F080	SEL{<c>}{<q>} {<Rd>,} <Rn>, <Rm>		T32		111110101 \| 010 \| Rn \| 1111 \| Rd \| 10 \| 00 \| Rm

Description

Select Bytes selects each byte of its result from either its first operand or its second operand, according to the values of the PSTATE.GE flags.

Operation

if ConditionPassed() then
    EncodingSpecificOperations();
    R[d]<7:0>   = if PSTATE.GE<0> == '1' then R[n]<7:0>   else R[m]<7:0>;
    R[d]<15:8>  = if PSTATE.GE<1> == '1' then R[n]<15:8>  else R[m]<15:8>;
    R[d]<23:16> = if PSTATE.GE<2> == '1' then R[n]<23:16> else R[m]<23:16>;
    R[d]<31:24> = if PSTATE.GE<3> == '1' then R[n]<31:24> else R[m]<31:24>;

sel