Load multiple 2-element structures to two registers. This instruction loads multiple 2-element structures from memory and writes the result to the two SIMD&FP registers, with de-interleaving.
For an example of de-interleaving, see LD3 (multiple structures).
Depending on the settings in the CPACR_EL1, CPTR_EL2, and CPTR_EL3 registers, and the current Security state and Exception level, an attempt to execute the instruction might be trapped.
It has encodings from 2 classes: No offset and Post-index
| 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 |
| 0 | Q | 0 | 0 | 1 | 1 | 0 | 0 | 0 | 1 | 0 | 0 | 0 | 0 | 0 | 0 | 1 | 0 | 0 | 0 | size | Rn | Rt | |||||||||
| L | opcode | ||||||||||||||||||||||||||||||
integer t = UInt(Rt); integer n = UInt(Rn); integer m = integer UNKNOWN; boolean wback = FALSE; boolean tag_checked = wback || n != 31;
| 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 |
| 0 | Q | 0 | 0 | 1 | 1 | 0 | 0 | 1 | 1 | 0 | Rm | 1 | 0 | 0 | 0 | size | Rn | Rt | |||||||||||||
| L | opcode | ||||||||||||||||||||||||||||||
integer t = UInt(Rt); integer n = UInt(Rn); integer m = UInt(Rm); boolean wback = TRUE; boolean tag_checked = wback || n != 31;
| <Vt> |
Is the name of the first or only SIMD&FP register to be transferred, encoded in the "Rt" field. |
| <T> |
Is an arrangement specifier,
encoded in
|
| <Vt2> |
Is the name of the second SIMD&FP register to be transferred, encoded as "Rt" plus 1 modulo 32. |
| <Xn|SP> |
Is the 64-bit name of the general-purpose base register or stack pointer, encoded in the "Rn" field. |
| <imm> |
Is the post-index immediate offset,
encoded in
|
| <Xm> |
Is the 64-bit name of the general-purpose post-index register, excluding XZR, encoded in the "Rm" field. |
MemOp memop = if L == '1' then MemOp_LOAD else MemOp_STORE; integer datasize = if Q == '1' then 128 else 64; integer esize = 8 << UInt(size); integer elements = datasize DIV esize; integer rpt; // number of iterations integer selem; // structure elements case opcode of when '0000' rpt = 1; selem = 4; // LD/ST4 (4 registers) when '0010' rpt = 4; selem = 1; // LD/ST1 (4 registers) when '0100' rpt = 1; selem = 3; // LD/ST3 (3 registers) when '0110' rpt = 3; selem = 1; // LD/ST1 (3 registers) when '0111' rpt = 1; selem = 1; // LD/ST1 (1 register) when '1000' rpt = 1; selem = 2; // LD/ST2 (2 registers) when '1010' rpt = 2; selem = 1; // LD/ST1 (2 registers) otherwise UNDEFINED; // .1D format only permitted with LD1 & ST1 if size:Q == '110' && selem != 1 then UNDEFINED;
CheckFPAdvSIMDEnabled64(); bits(64) address; bits(64) offs; bits(datasize) rval; integer tt; constant integer ebytes = esize DIV 8; if HaveMTE2Ext() then SetTagCheckedInstruction(tag_checked); if n == 31 then CheckSPAlignment(); address = SP[]; else address = X[n]; offs = Zeros(); for r = 0 to rpt-1 for e = 0 to elements-1 tt = (t + r) MOD 32; for s = 0 to selem-1 rval = V[tt]; if memop == MemOp_LOAD then Elem[rval, e, esize] = Mem[address + offs, ebytes, AccType_VEC]; V[tt] = rval; else // memop == MemOp_STORE Mem[address + offs, ebytes, AccType_VEC] = Elem[rval, e, esize]; offs = offs + ebytes; tt = (tt + 1) MOD 32; if wback then if m != 31 then offs = X[m]; if n == 31 then SP[] = address + offs; else X[n] = address + offs;
If PSTATE.DIT is 1, the timing of this instruction is insensitive to the value of the data being loaded or stored.
Internal version only: isa v33.11seprel, AdvSIMD v29.05, pseudocode v2021-09_rel, sve v2021-09_rc3d ; Build timestamp: 2021-10-06T11:41
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