Unsigned saturating rounding shift left reversed (predicated)
This instruction shifts active unsigned elements of the second source vector by corresponding elements of the first source vector and destructively places the rounded results in the corresponding elements of the first source vector. A positive shift amount performs a left shift, otherwise a right shift by the negated shift amount is performed. Each result element is saturated to the N-bit element's unsigned integer range 0 to (2N)-1. Inactive elements in the destination vector register remain unmodified.
| 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 | 1 | 0 | 0 | 0 | 1 | 0 | 0 | size | 0 | 0 | 1 | 1 | 1 | 1 | 1 | 0 | 0 | Pg | Zm | Zdn | |||||||||||
| Q | R | N | U | ||||||||||||||||||||||||||||
if !IsFeatureImplemented(FEAT_SVE2) && !IsFeatureImplemented(FEAT_SME) then EndOfDecode(Decode_UNDEF); end; let esize : integer{} = 8 << UInt(size); let g : integer = UInt(Pg); let m : integer = UInt(Zm); let dn : integer = UInt(Zdn);
| <Zdn> |
Is the name of the first source and destination scalable vector register, encoded in the "Zdn" field. |
| <T> |
Is the size specifier,
encoded in
|
| <Pg> |
Is the name of the governing scalable predicate register P0-P7, encoded in the "Pg" field. |
| <Zm> |
Is the name of the second source scalable vector register, encoded in the "Zm" field. |
CheckSVEEnabled(); let VL : integer{} = CurrentVL(); let PL : integer{} = VL DIV 8; let elements : integer = VL DIV esize; let mask : bits(PL) = P{}(g); let operand1 : bits(VL) = if AnyActiveElement{PL}(mask, esize) then Z{VL}(m) else Zeros{VL}; let operand2 : bits(VL) = Z{}(dn); var result : bits(VL); for e = 0 to elements-1 do if ActivePredicateElement{PL}(mask, e, esize) then let element : integer = UInt(operand1[e*:esize]); var shift : integer = ShiftSat(SInt(operand2[e*:esize]), esize); var res : integer; if shift >= 0 then res = element << shift; else shift = -shift; res = (element + (1 << (shift - 1))) >> shift; end; result[e*:esize] = UnsignedSat{esize}(res); else result[e*:esize] = operand2[e*:esize]; end; end; Z{VL}(dn) = result;
This instruction might be immediately preceded in program order by a MOVPRFX instruction. The MOVPRFX must conform to all of the following requirements, otherwise the behavior of the MOVPRFX and this instruction is CONSTRAINED UNPREDICTABLE:
2026-03_rel 2026-03-26 20:48:11
Copyright © 2010-2026 Arm Limited or its affiliates. All rights reserved. This document is Non-Confidential.