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LD1H (scalar plus immediate)

Contiguous load unsigned halfwords to vector (immediate index).

Contiguous load of unsigned halfwords to elements of a vector register from the memory address generated by a 64-bit scalar base and immediate index in the range -8 to 7 which is multiplied by the vector's in-memory size, irrespective of predication, and added to the base address. Inactive elements will not read Device memory or signal a fault, and are set to zero in the destination vector.

It has encodings from 3 classes: 16-bit element , 32-bit element and 64-bit element

16-bit element

313029282726252423222120191817161514131211109876543210
101001001010imm4101PgRnZt

16-bit element

LD1H { <Zt>.H }, <Pg>/Z, [<Xn|SP>{, #<imm>, MUL VL}]

if !HaveSVE() then UNDEFINED;
integer t = UInt(Zt);
integer n = UInt(Rn);
integer g = UInt(Pg);
integer esize = 16;
integer msize = 16;
boolean unsigned = TRUE;
integer offset = SInt(imm4);

32-bit element

313029282726252423222120191817161514131211109876543210
101001001100imm4101PgRnZt

32-bit element

LD1H { <Zt>.S }, <Pg>/Z, [<Xn|SP>{, #<imm>, MUL VL}]

if !HaveSVE() then UNDEFINED;
integer t = UInt(Zt);
integer n = UInt(Rn);
integer g = UInt(Pg);
integer esize = 32;
integer msize = 16;
boolean unsigned = TRUE;
integer offset = SInt(imm4);

64-bit element

313029282726252423222120191817161514131211109876543210
101001001110imm4101PgRnZt

64-bit element

LD1H { <Zt>.D }, <Pg>/Z, [<Xn|SP>{, #<imm>, MUL VL}]

if !HaveSVE() then UNDEFINED;
integer t = UInt(Zt);
integer n = UInt(Rn);
integer g = UInt(Pg);
integer esize = 64;
integer msize = 16;
boolean unsigned = TRUE;
integer offset = SInt(imm4);

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.

<imm>

Is the optional signed immediate vector offset, in the range -8 to 7, defaulting to 0, encoded in the "imm4" field.

Operation

CheckSVEEnabled();
integer elements = VL DIV esize;
bits(64) base;
bits(64) addr;
bits(PL) mask = P[g];
bits(VL) result;
bits(msize) data;
constant integer mbytes = msize DIV 8;

if n == 31 then
    CheckSPAlignment();
    if HaveMTEExt() then SetNotTagCheckedInstruction(TRUE);
    base = SP[];
else
    if HaveMTEExt() then SetNotTagCheckedInstruction(FALSE);
    base = X[n];

addr = base + offset * elements * mbytes;
for e = 0 to elements-1
    if ElemP[mask, e, esize] == '1' then
        data = Mem[addr, mbytes, AccType_NORMAL];
        Elem[result, e, esize] = Extend(data, esize, unsigned);
    else
        Elem[result, e, esize] = Zeros();
    addr = addr + mbytes;

Z[t] = result;