BFloat16 floating-point multiply-subtract long from single-precision (bottom, indexed)
This BFloat16 floating-point multiply-subtract long instruction widens the even-numbered BFloat16 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 single-precision elements of the destination vector that overlap with the corresponding BFloat16 elements in the first source 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 | 1 | 1 | i3h | Zm | 0 | 1 | 1 | 0 | i3l | 0 | Zn | Zda | |||||||||||
| o2 | op | T | |||||||||||||||||||||||||||||
if !IsFeatureImplemented(FEAT_SME2) && !IsFeatureImplemented(FEAT_SVE2p1) then UNDEFINED; constant integer n = UInt(Zn); constant integer m = UInt(Zm); constant integer da = UInt(Zda); constant integer index = UInt(i3h:i3l); constant 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(); constant integer VL = CurrentVL; constant integer PL = VL DIV 8; constant integer elements = VL DIV 32; constant integer eltspersegment = 128 DIV 32; constant bits(VL) op1 = Z[n, VL]; constant bits(VL) op2 = Z[m, VL]; constant bits(VL) op3 = Z[da, VL]; bits(VL) result; for e = 0 to elements-1 constant integer segmentbase = e - (e MOD eltspersegment); constant integer s = 2 * segmentbase + index; constant bits(16) elem1 = (if op1_neg then BFNeg(Elem[op1, 2*e + 0, 16]) else Elem[op1, 2*e + 0, 16]); constant bits(16) elem2 = Elem[op2, s, 16]; constant bits(32) elem3 = Elem[op3, e, 32]; Elem[result, e, 32] = BFMulAddH(elem3, elem1, elem2, FPCR); Z[da, VL] = 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:
Internal version only: aarchmrs v2024-03_relA, pseudocode v2024-03_rel, sve v2024-03_rel ; Build timestamp: 2024-03-26T09:45
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