Base Instructions | SIMD&FP Instructions | SVE Instructions | SME Instructions | Index by Encoding | Shared Pseudocode | Proprietary Notice

## PEXT (predicate)

Set predicate from predicate-as-counter

Expands the source predicate-as-counter into a four-predicate wide mask and copies one quarter of it into the destination predicate register.

### SVE2
(FEAT_SVE2p1)

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
0 | 0 | 1 | 0 | 0 | 1 | 0 | 1 | size | 1 | 0 | 0 | 0 | 0 | 0 | 0 | 1 | 1 | 1 | 0 | 0 | imm2 | PNn | 1 | Pd

####

PEXT <Pd>.<T>, <PNn>[<imm>]

if !HaveSME2() && !HaveSVE2p1() then UNDEFINED; constant integer esize = 8 << UInt(size); integer n = UInt('1':PNn); integer d = UInt(Pd); integer part = UInt(imm2);

### Assembler Symbols

<Pd> | Is the name of the destination scalable predicate register, encoded in the "Pd" field.

<T> | Is the size specifier, encoded in size:
size | <T>
--- | ---
00 | B
01 | H
10 | S
11 | D

<PNn> | Is the name of the first source scalable predicate register PN8-PN15, with predicate-as-counter encoding, encoded in the "PNn" field.

<imm> | Is the element index, in the range 0 to 3, encoded in the "imm2" field.

### Operation

if HaveSVE2p1() then CheckSVEEnabled(); else CheckStreamingSVEEnabled(); constant integer VL = CurrentVL; constant integer PL = VL DIV 8; constant integer elements = VL DIV esize; bits(PL) pred = P[n, PL]; bits(PL*4) mask = CounterToPredicate(pred<15:0>, PL*4); bits(PL) result; constant integer psize = esize DIV 8; for e = 0 to elements-1 bit pbit = PredicateElement(mask, part * elements + e, esize); Elem[result, e, psize] = ZeroExtend(pbit, psize); P[d, PL] = result;

### Operational information

If PSTATE.DIT is 1:

- The execution time of this instruction is independent of:
  - The values of the data supplied in any of its registers.
  - The values of the NZCV flags.
- The response of this instruction to asynchronous exceptions does not vary based on:
  - The values of the data supplied in any of its registers.
  - The values of the NZCV flags.

Base Instructions | SIMD&FP Instructions | SVE Instructions | SME Instructions | Index by Encoding | Shared Pseudocode | Proprietary Notice

Internal version only: isa v33.64, AdvSIMD v29.12, pseudocode v2023-06_rel, sve v2023-06_rel ; Build timestamp: 2023-07-04T19:42

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