STR (register)

Store Register (register) calculates an address from a base register value and an offset register value, and stores a 32-bit word or a 64-bit doubleword to the calculated address, from a register. For information about memory accesses, see Load/Store addressing modes.

The instruction uses an offset addressing mode, that calculates the address used for the memory access from a base register value and an offset register value. The offset can be optionally shifted and extended.

313029282726252423222120191817161514131211109876543210
1x111000001RmoptionS10RnRt
sizeVRopc

32-bit (size == 10)

STR <Wt>, [<Xn|SP>, (<Wm>|<Xm>){, <extend> {<amount>}}]

64-bit (size == 11)

STR <Xt>, [<Xn|SP>, (<Wm>|<Xm>){, <extend> {<amount>}}]

integer scale = UInt(size); if option<1> == '0' then UNDEFINED; // sub-word index ExtendType extend_type = DecodeRegExtend(option); integer shift = if S == '1' then scale else 0;

Assembler Symbols

<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/shift specifier, defaulting to LSL, and which must be omitted for the LSL option when <amount> is omitted. encoded in option:

option <extend>
010 UXTW
011 LSL
110 SXTW
111 SXTX
<amount>

For the 32-bit variant: is the index shift amount, optional only when <extend> is not LSL. Where it is permitted to be optional, it defaults to #0. It is encoded in S:

S <amount>
0 #0
1 #2

For the 64-bit variant: is the index shift amount, optional only when <extend> is not LSL. Where it is permitted to be optional, it defaults to #0. It is encoded in S:

S <amount>
0 #0
1 #3
<Xt>

Is the 64-bit name of the general-purpose register to be transferred, encoded in the "Rt" field.

Shared Decode

integer n = UInt(Rn); integer t = UInt(Rt); integer m = UInt(Rm); constant integer datasize = 8 << scale;

Operation

bits(64) offset = ExtendReg(m, extend_type, shift, 64); bits(64) address; bits(datasize) data; boolean privileged = PSTATE.EL != EL0; AccessDescriptor accdesc = CreateAccDescGPR(MemOp_STORE, FALSE, privileged, TRUE); 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;

Operational information

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 v2023-12_rel, pseudocode v2023-12_rel, sve v2023-12_rel ; Build timestamp: 2023-12-15T16:46

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