MSB

Multiply-subtract vectors (predicated), writing multiplicand [Zdn = Za - Zdn * Zm].

Multiply the corresponding active elements of the first and second source vectors and subtract from elements of the third (addend) vector. Destructively place the results in the destination and first source (multiplicand) vector. Inactive elements in the destination vector register remain unmodified.

313029282726252423222120191817161514131211109876543210
00000100size0Zm111PgZaZdn

SVE

MSB <Zdn>.<T>, <Pg>/M, <Zm>.<T>, <Za>.<T>

if !HaveSVE() then UNDEFINED; integer esize = 8 << UInt(size); integer g = UInt(Pg); integer dn = UInt(Zdn); integer m = UInt(Zm); integer a = UInt(Za); boolean sub_op = TRUE;

Assembler Symbols

<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 size:
size <T>
00 B
01 H
10 S
11 D
<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.

<Za>

Is the name of the third source scalable vector register, encoded in the "Za" field.

Operation

CheckSVEEnabled(); integer elements = VL DIV esize; bits(PL) mask = P[g]; bits(VL) operand1 = Z[dn]; bits(VL) operand2 = Z[m]; bits(VL) operand3 = Z[a]; bits(VL) result; for e = 0 to elements-1 integer element1 = UInt(Elem[operand1, e, esize]); integer element2 = UInt(Elem[operand2, e, esize]); if ElemP[mask, e, esize] == '1' then integer product = element1 * element2; if sub_op then Elem[result, e, esize] = Elem[operand3, e, esize] - product; else Elem[result, e, esize] = Elem[operand3, e, esize] + product; else Elem[result, e, esize] = Elem[operand1, e, esize]; Z[dn] = result;

Operational information

If PSTATE.DIT is 1:

This instruction might be immediately preceded in program order by a MOVPRFX instruction that conforms to all of the following requirements, otherwise the behavior of either or both instructions is unpredictable:

The MOVPRFX instructions that can be used with this instruction are as follows:


Internal version only: isa v30.44, AdvSIMD v27.08, pseudocode v8.5-2019-06_rc2-5-g22901f2, sve v2019-06_rc4 ; Build timestamp: 2019-06-26T22:30

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