Load Register Signed Byte (register) calculates an address from a base register value and an offset register value, loads a byte from memory, sign-extends it, and writes it to a register. For information about addressing modes, see Load/Store addressing modes.
| 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 | 0 | 1 | 1 | 1 | 0 | 0 | 0 | 1 | x | 1 | Rm | option | S | 1 | 0 | Rn | Rt | ||||||||||||||
| size | VR | opc | |||||||||||||||||||||||||||||
if option<1> == '0' then UNDEFINED; // sub-word index ExtendType extend_type = DecodeRegExtend(option); integer shift = 0;
| <Wt> |
Is the 32-bit name of the general-purpose register to be transferred, encoded in the "Rt" field. |
| <Xn|SP> |
Is the 64-bit name of the general-purpose base register or stack pointer, encoded in the "Rn" field. |
| <Wm> |
When option<0> is set to 0, is the 32-bit name of the general-purpose index register, encoded in the "Rm" field. |
| <Xm> |
When option<0> is set to 1, is the 64-bit name of the general-purpose index register, encoded in the "Rm" field. |
| <extend> |
Is the index extend specifier,
encoded in
|
| <amount> |
Is the index shift amount, it must be #0, encoded in "S" as 0 if omitted, or as 1 if present. |
| <Xt> |
Is the 64-bit name of the general-purpose register to be transferred, encoded in the "Rt" field. |
integer t = UInt(Rt); integer n = UInt(Rn); integer m = UInt(Rm); integer regsize = 64 >> UInt(opc<0>); boolean nontemporal = FALSE; boolean tagchecked = TRUE;
bits(64) offset = ExtendReg(m, extend_type, shift, 64); bits(64) address; boolean privileged = PSTATE.EL != EL0; AccessDescriptor accdesc = CreateAccDescGPR(MemOp_LOAD, nontemporal, privileged, tagchecked); if n == 31 then CheckSPAlignment(); address = SP[]; else address = X[n, 64]; address = AddressAdd(address, offset, accdesc); bits(8) data = Mem[address, 1, accdesc]; X[t, regsize] = SignExtend(data, regsize);
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: aarchmrs v2024-03_relA, pseudocode v2024-03_rel, sve v2024-03_rel ; Build timestamp: 2024-03-26T09:45
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