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Half-precision floating-point multiply-subtract long from single-precision (bottom, indexed).
This half-precision floating-point multiply-subtract long instruction widens the even-numbered 16-bit half-precision elements in the first source vector and the indexed element from the corresponding 128-bit segment in the second source vector to single-precision format and then destructively multiplies and subtracts these values without intermediate rounding from the overlapping 32-bit single-precision elements of the addend and destination 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 | 1 | 0 | 0 | 1 | 0 | 0 | 1 | 0 | 1 | i3h | Zm | 0 | 1 | 1 | 0 | i3l | 0 | Zn | Zda |
if !HaveSVE2() then UNDEFINED; integer esize = 32; integer n = UInt(Zn); integer m = UInt(Zm); integer da = UInt(Zda); integer index = UInt(i3h:i3l); boolean op1_neg = TRUE;
<Zda> | Is the name of the third source and destination scalable vector register, encoded in the "Zda" field. |
<Zn> | Is the name of the first source scalable vector register, encoded in the "Zn" field. |
<Zm> | Is the name of the second source scalable vector register Z0-Z7, encoded in the "Zm" field. |
<imm> | Is the immediate index, in the range 0 to 7, encoded in the "i3h:i3l" fields. |
CheckSVEEnabled(); integer elements = VL DIV esize; integer eltspersegment = 128 DIV esize; bits(VL) operand1 = Z[n]; bits(VL) operand2 = Z[m]; bits(VL) operand3 = Z[da]; bits(VL) result; for e = 0 to elements-1 integer segmentbase = e - e MOD eltspersegment; integer s = 2 * segmentbase + index; bits(esize DIV 2) element1 = Elem[operand1, 2 * e + 0, esize DIV 2]; bits(esize DIV 2) element2 = Elem[operand2, s, esize DIV 2]; bits(esize) element3 = Elem[operand3, e, esize]; if op1_neg then element1 = FPNeg(element1); Elem[result, e, esize] = FPMulAddH(element3, element1, element2, FPCR); Z[da] = result;
This instruction might be immediately preceded in program order by a MOVPRFX instruction.instruction Thethat conforms to all of the following requirements, otherwise the behavior of either or both instructions is MOVPRFXunpredictable instruction must conform to all of the following requirements, otherwise the behavior of the:
Internal version only: isa v31.05bv31.04, AdvSIMD v29.02, pseudocode v2019-12_rc3_1v2019-09_rc2_1, sve v2019-12_rc3v2019-09_rc3
; Build timestamp: 2019-12-13T112019-09-27T17:0228
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