Arm® A64 Instruction Set Architecture: Future Architecture Technologies in the A architecture profile

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 read 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

if !HaveSVE() then UNDEFINED;
if Rm == '11111' then UNDEFINED;
integer t = UInt(Zt);
integer n = UInt(Rn);
integer m = UInt(Rm);
integer g = UInt(Pg);
integer esize = 32;
integer msize = 16;
boolean unsigned = FALSE;

64-bit element

if !HaveSVE() then UNDEFINED;
if Rm == '11111' then UNDEFINED;
integer t = UInt(Zt);
integer n = UInt(Rn);
integer m = UInt(Rm);
integer g = UInt(Pg);
integer esize = 64;
integer msize = 16;
boolean unsigned = FALSE;

Assembler Symbols

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

if HaveMTEExt() then SetNotTagCheckedInstruction(FALSE);

if n == 31 then
    CheckSPAlignment();
    base = SP[];
else
    base = X[n];

for e = 0 to elements-1
    addr = base + UInt(offset) * mbytes;
    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();
    offset = offset + 1;

Z[t] = result;