ADDHNB Add narrow high part (bottom) Add each vector element of the first source vector to the corresponding vector element of the second source vector, and place the most significant half of the result in the even-numbered half-width destination elements, while setting the odd-numbered elements to zero. This instruction is unpredicated. Green False True 0 1 0 0 0 1 0 1 1 0 1 1 0 0 0 ADDHNB <Zd>.<T>, <Zn>.<Tb>, <Zm>.<Tb> if !IsFeatureImplemented(FEAT_SVE2) && !IsFeatureImplemented(FEAT_SME) then UNDEFINED; if size == '00' then UNDEFINED; constant integer esize = 8 << UInt(size); constant integer n = UInt(Zn); constant integer m = UInt(Zm); 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, size <T> 00 RESERVED 01 B 10 H 11 S <Zn> Is the name of the first source scalable vector register, encoded in the "Zn" field. <Tb> Is the size specifier, size <Tb> 00 RESERVED 01 H 10 S 11 D <Zm> Is the name of the second source scalable vector register, encoded in the "Zm" field. CheckSVEEnabled(); constant integer VL = CurrentVL; constant integer elements = VL DIV esize; constant bits(VL) operand1 = Z[n, VL]; constant bits(VL) operand2 = Z[m, VL]; bits(VL) result; constant integer halfesize = esize DIV 2; for e = 0 to elements-1 constant integer element1 = UInt(Elem[operand1, e, esize]); constant integer element2 = UInt(Elem[operand2, e, esize]); constant integer res = (element1 + element2) >> halfesize; Elem[result, 2*e + 0, halfesize] = res<halfesize-1:0>; Elem[result, 2*e + 1, halfesize] = Zeros(halfesize); Z[d, VL] = result;