Floatingpoint exponential accelerator
The FEXPA instruction accelerates the polynomial series calculation of the exp(x) function.
The doubleprecision variant copies the low 52 bits of an entry from a hardwired table of 64bit coefficients, indexed by the low 6 bits of each element of the source vector, and prepends to that the next 11 bits of the source element (src<16:6>), setting the sign bit to zero.
The singleprecision variant copies the low 23 bits of an entry from hardwired table of 32bit coefficients, indexed by the low 6 bits of each element of the source vector, and prepends to that the next 8 bits of the source element (src<13:6>), setting the sign bit to zero.
The halfprecision variant copies the low 10 bits of an entry from hardwired table of 16bit coefficients, indexed by the low 5 bits of each element of the source vector, and prepends to that the next 5 bits of the source element (src<9:5>), setting the sign bit to zero.
A coefficient table entry with index m holds the floatingpoint value 2^{(m/64)}, or for the halfprecision variant 2^{(m/32)}. This instruction is unpredicated.
This instruction is illegal when executed in Streaming SVE mode, unless FEAT_SME_FA64 is implemented and enabled.
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  0  0  0  0  1  0  0  size  1  0  0  0  0  0  1  0  1  1  1  0  Zn  Zd 
if !IsFeatureImplemented(FEAT_SVE) then UNDEFINED; if size == '00' then UNDEFINED; constant integer esize = 8 << UInt(size); constant integer n = UInt(Zn); constant integer d = UInt(Zd);
<Zd> 
Is the name of the destination scalable vector register, encoded in the "Zd" field. 
<T> 
Is the size specifier,
encoded in

<Zn> 
Is the name of the source scalable vector register, encoded in the "Zn" field. 
CheckNonStreamingSVEEnabled(); constant integer VL = CurrentVL; constant integer PL = VL DIV 8; constant integer elements = VL DIV esize; constant bits(VL) operand = Z[n, VL]; bits(VL) result; for e = 0 to elements1 constant bits(esize) element = Elem[operand, e, esize]; Elem[result, e, esize] = FPExpA(element); Z[d, VL] = result;
Internal version only: aarchmrs v202403_relA, pseudocode v202403_rel, sve v202403_rel ; Build timestamp: 20240326T09:45
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