Two-way unsigned absolute difference sum and accumulate long
This instruction calculates the sum of the absolute difference between even-numbered unsigned elements and the absolute difference between the odd-numbered unsigned elements of each double-width container of the first and second vectors, and destructively adds the results to the overlapping double-width elements of the addend vector.
This instruction is unpredicated.
| 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 | Zm | 1 | 1 | 0 | 1 | 1 | 1 | Zn | Zda | |||||||||||||
| U | |||||||||||||||||||||||||||||||
if !IsFeatureImplemented(FEAT_SVE2p3) && !IsFeatureImplemented(FEAT_SME2p3) then EndOfDecode(Decode_UNDEF); end; if size == '00' then EndOfDecode(Decode_UNDEF); end; let esize : integer{} = 8 << UInt(size); let n : integer = UInt(Zn); let m : integer = UInt(Zm); let da : integer = UInt(Zda);
| <Zda> |
Is the name of the third source and destination scalable vector register, encoded in the "Zda" field. |
| <T> |
Is the size specifier,
encoded in
|
| <Zn> |
Is the name of the first source scalable vector register, encoded in the "Zn" field. |
| <Tb> |
Is the size specifier,
encoded in
|
| <Zm> |
Is the name of the second source scalable vector register, encoded in the "Zm" field. |
CheckSVEEnabled(); let VL : integer{} = CurrentVL(); let elements : integer = VL DIV esize; let operand1 : bits(VL) = Z{}(n); let operand2 : bits(VL) = Z{}(m); var result : bits(VL) = Z{}(da); for e = 0 to elements-1 do let elt1_a : integer = UInt(operand1[(2*e + 0)*:(esize DIV 2)]); let elt1_b : integer = UInt(operand1[(2*e + 1)*:(esize DIV 2)]); let elt2_a : integer = UInt(operand2[(2*e + 0)*:(esize DIV 2)]); let elt2_b : integer = UInt(operand2[(2*e + 1)*:(esize DIV 2)]); let sum = Abs(elt1_a - elt2_a) + Abs(elt1_b - elt2_b); result[e*:esize] = result[e*:esize] + sum[esize-1:0]; end; Z{VL}(da) = result;
This instruction is a data-independent-time instruction as described in About PSTATE.DIT.
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:
2025-09_diff_tag 2025-11-28 16:29:05
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