UMULLB (indexed)

Unsigned multiply long (bottom, indexed)

Multiply the even-numbered unsigned elements within each 128-bit segment of the first source vector by the specified unsigned element in the corresponding second source vector segment, and place the results in the overlapping double-width elements of the destination vector register.

The elements within the second source vector are specified using an immediate index which selects the same element position within each 128-bit vector segment. The index range is from 0 to one less than the number of elements per 128-bit segment, encoded in 2 or 3 bits depending on the size of the element.

It has encodings from 2 classes: 32-bit and 64-bit

32-bit

313029282726252423222120191817161514131211109876543210
01000100101i3hZm1101i3l0ZnZd
size<1>size<0>UT

UMULLB <Zd>.S, <Zn>.H, <Zm>.H[<imm>]

if !HaveSVE2() && !HaveSME() then UNDEFINED; integer esize = 16; integer index = UInt(i3h:i3l); integer n = UInt(Zn); integer m = UInt(Zm); integer d = UInt(Zd); integer sel = 0;

64-bit

313029282726252423222120191817161514131211109876543210
01000100111i2hZm1101i2l0ZnZd
size<1>size<0>UT

UMULLB <Zd>.D, <Zn>.S, <Zm>.S[<imm>]

if !HaveSVE2() && !HaveSME() then UNDEFINED; integer esize = 32; integer index = UInt(i2h:i2l); integer n = UInt(Zn); integer m = UInt(Zm); integer d = UInt(Zd); integer sel = 0;

Assembler Symbols

<Zd>

Is the name of the destination scalable vector register, encoded in the "Zd" field.

<Zn>

Is the name of the first source scalable vector register, encoded in the "Zn" field.

<Zm>

For the 32-bit variant: is the name of the second source scalable vector register Z0-Z7, encoded in the "Zm" field.

For the 64-bit variant: is the name of the second source scalable vector register Z0-Z15, encoded in the "Zm" field.

<imm>

For the 32-bit variant: is the element index, in the range 0 to 7, encoded in the "i3h:i3l" fields.

For the 64-bit variant: is the element index, in the range 0 to 3, encoded in the "i2h:i2l" fields.

Operation

CheckSVEEnabled(); integer elements = VL DIV (2 * esize); integer eltspersegment = 128 DIV (2 * esize); bits(VL) operand1 = Z[n]; bits(VL) operand2 = Z[m]; bits(VL) result; for e = 0 to elements-1 integer s = e - (e MOD eltspersegment); integer element1 = UInt(Elem[operand1, 2 * e + sel, esize]); integer element2 = UInt(Elem[operand2, 2 * s + index, esize]); integer res = element1 * element2; Elem[result, e, 2*esize] = res<2*esize-1:0>; Z[d] = result;

Operational information

If FEAT_SVE2 is enabled or FEAT_SME is enabled, then when PSTATE.DIT is 1:


Internal version only: isa v33.11seprel, AdvSIMD v29.05, pseudocode v2021-09_rel, sve v2021-09_rc3d ; Build timestamp: 2021-10-06T11:41

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