LD1RSH

Load a single signed halfword from a memory address generated by a 64-bit scalar base address plus an immediate offset which is a multiple of 2 in the range 0 to 126.

Broadcast the loaded data into all active elements of the destination vector, setting the inactive elements to zero. If all elements are inactive then the instruction will not perform a read from Device memory or cause a data abort.

32-bit element

if !IsFeatureImplemented(FEAT_SVE) && !IsFeatureImplemented(FEAT_SME) 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 = FALSE; constant integer offset = UInt(imm6);

64-bit element

if !IsFeatureImplemented(FEAT_SVE) && !IsFeatureImplemented(FEAT_SME) 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 = FALSE; constant integer offset = UInt(imm6);

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 unsigned immediate byte offset, a multiple of 2 in the range 0 to 126, defaulting to 0, encoded in the "imm6" 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; constant integer mbytes = msize DIV 8; constant boolean contiguous = TRUE; constant boolean nontemporal = FALSE; constant boolean tagchecked = n != 31; 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[] else X[n, 64]; constant bits(64) addr = AddressAdd(base, offset * mbytes, accdesc); data = Mem[addr, mbytes, accdesc]; for e = 0 to elements-1 if ActivePredicateElement(mask, e, esize) then Elem[result, e, esize] = Extend(data, esize, unsigned); else Elem[result, e, esize] = Zeros(esize); Z[t, VL] = result;

Operational information

If FEAT_SVE2 is implemented or FEAT_SME is implemented, then if PSTATE.DIT is 1, the timing of this instruction is insensitive to the value of the data being loaded or stored when its governing predicate register contains the same value for each execution.

Internal version only: aarchmrs v2024-03_relA, pseudocode v2024-03_rel, sve v2024-03_rel ; Build timestamp: 2024-03-26T09:45

31	30	29	28	27	26	25	24	23	22	21	20	19	18	17	16	15	14	13	12	11	10	9	8	7	6	5	4	3	2	1	0
1	0	0	0	0	1	0	1	0	1	imm6						1	0	1	Pg			Rn					Zt
							dtypeh<1>	dtypeh<0>									dtypel<1>	dtypel<0>

31	30	29	28	27	26	25	24	23	22	21	20	19	18	17	16	15	14	13	12	11	10	9	8	7	6	5	4	3	2	1	0
1	0	0	0	0	1	0	1	0	1	imm6						1	0	0	Pg			Rn					Zt
							dtypeh<1>	dtypeh<0>									dtypel<1>	dtypel<0>