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LD1SH (scalar plus scalar)

Contiguous load signed halfwords to vector (scalar index)

Contiguous load of signed halfwords to elements of a vector register from the memory address generated by a 64-bit scalar base and scalar index which is multiplied by 2 and added to the base address. After each element access the index value is incremented, but the index register is not updated. Inactive elements will not cause a read from Device memory or signal a fault, and are set to zero in the destination vector.

It has encodings from 2 classes: 32-bit element and 64-bit element

32-bit element

(FEAT_SVE || FEAT_SME)

313029282726252423222120191817161514131211109876543210
10100101001!= 11111010PgRnZt
dtypeRm

Encoding

LD1SH { <Zt>.S }, <Pg>/Z, [<Xn|SP>, <Xm>, LSL #1]

Decode for this encoding

if !IsFeatureImplemented(FEAT_SVE) && !IsFeatureImplemented(FEAT_SME) then EndOfDecode(Decode_UNDEF); if Rm == '11111' then EndOfDecode(Decode_UNDEF); constant integer t = UInt(Zt); constant integer n = UInt(Rn); constant integer m = UInt(Rm); constant integer g = UInt(Pg); constant integer esize = 32; constant integer msize = 16; constant boolean unsigned = FALSE;

64-bit element

(FEAT_SVE || FEAT_SME)

313029282726252423222120191817161514131211109876543210
10100101000!= 11111010PgRnZt
dtypeRm

Encoding

LD1SH { <Zt>.D }, <Pg>/Z, [<Xn|SP>, <Xm>, LSL #1]

Decode for this encoding

if !IsFeatureImplemented(FEAT_SVE) && !IsFeatureImplemented(FEAT_SME) then EndOfDecode(Decode_UNDEF); if Rm == '11111' then EndOfDecode(Decode_UNDEF); constant integer t = UInt(Zt); constant integer n = UInt(Rn); constant integer m = UInt(Rm); constant integer g = UInt(Pg); constant integer esize = 64; constant integer msize = 16; constant boolean unsigned = FALSE;

Assembler Symbols

<Zt>

Is the name of the scalable vector register to be transferred, encoded in the "Zt" field.

<Pg>

Is the name of the governing scalable predicate register P0-P7, encoded in the "Pg" field.

<Xn|SP>

Is the 64-bit name of the general-purpose base register or stack pointer, encoded in the "Rn" field.

<Xm>

Is the 64-bit name of the general-purpose offset register, encoded in the "Rm" field.

Operation

CheckSVEEnabled(); constant integer VL = CurrentVL; constant integer PL = VL DIV 8; constant integer elements = VL DIV esize; bits(64) base; constant bits(PL) mask = P[g, PL]; bits(VL) result; bits(msize) data; bits(64) offset; bits(64) addr; constant integer mbytes = msize DIV 8; constant boolean contiguous = TRUE; constant boolean nontemporal = FALSE; constant boolean tagchecked = TRUE; constant AccessDescriptor accdesc = CreateAccDescSVE(MemOp_LOAD, nontemporal, contiguous, tagchecked); if !AnyActiveElement(mask, esize) then if n == 31 && ConstrainUnpredictableBool(Unpredictable_CHECKSPNONEACTIVE) then CheckSPAlignment(); else if n == 31 then CheckSPAlignment(); base = if n == 31 then SP[64] else X[n, 64]; offset = X[m, 64]; addr = AddressAdd(base, UInt(offset) * mbytes, accdesc); for e = 0 to elements-1 if ActivePredicateElement(mask, e, esize) then data = Mem[addr, mbytes, accdesc]; Elem[result, e, esize] = Extend(data, esize, unsigned); else Elem[result, e, esize] = Zeros(esize); addr = AddressIncrement(addr, mbytes, accdesc); Z[t, VL] = result;