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	x	1	1	1	0	0	0	0	0	0	imm9									0	0	Rn					Rt
size								opc

32-bit (size == 10)

STUR <Wt>, [<Xn|SP>{, #<simm>}]

64-bit (size == 11)

STUR <Xt>, [<Xn|SP>{, #<simm>}]

integer scale = UInt(size);
bits(64) offset = SignExtend(imm9, 64);

<Wt>	Is the 32-bit name of the general-purpose register to be transferred, encoded in the "Rt" field.

<Xt>	Is the 64-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.

<simm>

Is the optional signed immediate byte offset, in the range -256 to 255, defaulting to 0 and encoded in the "imm9" field.

Shared Decode

integer n = UInt(Rn);
integer t = UInt(Rt);

constant integer datasize = 8 << scale;
boolean tagchecked = n != 31;

Operation

bits(64) address;
bits(datasize) data;

boolean privileged = PSTATE.EL != EL0;
AccessDescriptor accdesc = CreateAccDescGPR(MemOp_STORE, FALSE, privileged, tagchecked);

if n == 31 then
    CheckSPAlignment();
    address = SP[];
else
    address = X[n, 64];

address = GenerateAddress(address, offset, accdesc);

data = X[t, datasize];
Mem[address, datasize DIV 8, accdesc] = data;