LDNF1H
Contiguous load non-fault unsigned halfwords to vector (immediate index)
Contiguous load with non-faulting behavior 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 cause a read from Device memory or signal a fault, and are set to zero in the destination vector.
This instruction is illegal when executed in Streaming SVE mode, unless FEAT_SME_FA64 is implemented and enabled.
Green
True
True
SM_0_only
It has encodings from 3 classes:
16-bit element
,
32-bit element
and
64-bit element
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LDNF1H { <Zt>.H }, <Pg>/Z, [<Xn|SP>{, #<imm>, MUL VL}]
if !IsFeatureImplemented(FEAT_SVE) then UNDEFINED;
constant integer t = UInt(Zt);
constant integer n = UInt(Rn);
constant integer g = UInt(Pg);
constant integer esize = 16;
constant integer msize = 16;
constant boolean unsigned = TRUE;
constant integer offset = SInt(imm4);
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LDNF1H { <Zt>.S }, <Pg>/Z, [<Xn|SP>{, #<imm>, MUL VL}]
if !IsFeatureImplemented(FEAT_SVE) then UNDEFINED;
constant integer t = UInt(Zt);
constant integer n = UInt(Rn);
constant integer g = UInt(Pg);
constant integer esize = 32;
constant integer msize = 16;
constant boolean unsigned = TRUE;
constant integer offset = SInt(imm4);
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LDNF1H { <Zt>.D }, <Pg>/Z, [<Xn|SP>{, #<imm>, MUL VL}]
if !IsFeatureImplemented(FEAT_SVE) then UNDEFINED;
constant integer t = UInt(Zt);
constant integer n = UInt(Rn);
constant integer g = UInt(Pg);
constant integer esize = 64;
constant integer msize = 16;
constant boolean unsigned = TRUE;
constant integer offset = SInt(imm4);
<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.
CheckNonStreamingSVEEnabled();
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(64) addr;
bits(VL) result;
constant bits(VL) orig = Z[t, VL];
bits(msize) data;
constant integer mbytes = msize DIV 8;
boolean fault = FALSE;
boolean faulted = FALSE;
boolean unknown = FALSE;
constant boolean contiguous = TRUE;
constant boolean tagchecked = n != 31;
constant AccessDescriptor accdesc = CreateAccDescSVENF(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[] else X[n, 64];
addr = AddressAdd(base, offset * elements * mbytes, accdesc);
for e = 0 to elements-1
if ActivePredicateElement(mask, e, esize) then
// MemNF[] will return fault=TRUE if access is not performed for any reason
(data, fault) = MemNF[addr, mbytes, accdesc];
else
(data, fault) = (Zeros(msize), FALSE);
addr = AddressIncrement(addr, mbytes, accdesc);
// FFR elements set to FALSE following a suppressed access/fault
faulted = faulted || fault;
if faulted then
ElemFFR[e, esize] = '0';
// Value becomes CONSTRAINED UNPREDICTABLE after an FFR element is FALSE
unknown = unknown || ElemFFR[e, esize] == '0';
if unknown then
if !fault && ConstrainUnpredictableBool(Unpredictable_SVELDNFDATA) then
Elem[result, e, esize] = Extend(data, esize, unsigned);
elsif ConstrainUnpredictableBool(Unpredictable_SVELDNFZERO) then
Elem[result, e, esize] = Zeros(esize);
else // merge
Elem[result, e, esize] = Elem[orig, e, esize];
else
Elem[result, e, esize] = Extend(data, esize, unsigned);
Z[t, VL] = result;