VSTR
Store SIMD&FP register stores a single register from the Advanced SIMD and floating-point register file to memory, using an address from a general-purpose register, with an optional offset.
Depending on settings in the CPACR, NSACR, HCPTR, and FPEXC registers, and the Security state and PE mode in which the instruction is executed, an attempt to execute the instruction might be undefined, or trapped to Hyp mode. For more information see Enabling Advanced SIMD and floating-point support.
It has encodings from the following instruction sets: A32 ( A1 ) and T32 ( T1 ) .
A1
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 |
!= 1111 | 1 | 1 | 0 | 1 | U | D | 0 | 0 | Rn | Vd | 1 | 0 | size | imm8 | |||||||||||||||||
cond |
if size == '00' || (size == '01' && !HaveFP16Ext()) then UNDEFINED; if size == '01' && cond != '1110' then UNPREDICTABLE; esize = 8 << UInt(size); add = (U == '1'); imm32 = if esize == 16 then ZeroExtend(imm8:'0', 32) else ZeroExtend(imm8:'00', 32); case size of when '01' d = UInt(Vd:D); when '10' d = UInt(Vd:D); when '11' d = UInt(D:Vd); n = UInt(Rn); if n == 15 && CurrentInstrSet() != InstrSet_A32 then UNPREDICTABLE;
CONSTRAINED UNPREDICTABLE behavior
If size == '01' && cond != '1110', then one of the following behaviors must occur:
- The instruction is undefined.
- The instruction executes as if it passes the Condition code check.
- The instruction executes as NOP. This means it behaves as if it fails the Condition code check.
T1
15 | 14 | 13 | 12 | 11 | 10 | 9 | 8 | 7 | 6 | 5 | 4 | 3 | 2 | 1 | 0 | 15 | 14 | 13 | 12 | 11 | 10 | 9 | 8 | 7 | 6 | 5 | 4 | 3 | 2 | 1 | 0 |
1 | 1 | 1 | 0 | 1 | 1 | 0 | 1 | U | D | 0 | 0 | Rn | Vd | 1 | 0 | size | imm8 |
if size == '00' || (size == '01' && !HaveFP16Ext()) then UNDEFINED; if size == '01' && InITBlock() then UNPREDICTABLE; esize = 8 << UInt(size); add = (U == '1'); imm32 = if esize == 16 then ZeroExtend(imm8:'0', 32) else ZeroExtend(imm8:'00', 32); case size of when '01' d = UInt(Vd:D); when '10' d = UInt(Vd:D); when '11' d = UInt(D:Vd); n = UInt(Rn); if n == 15 && CurrentInstrSet() != InstrSet_A32 then UNPREDICTABLE;
CONSTRAINED UNPREDICTABLE behavior
If size == '01' && InITBlock(), then one of the following behaviors must occur:
- The instruction is undefined.
- The instruction executes as if it passes the Condition code check.
- The instruction executes as NOP. This means it behaves as if it fails the Condition code check.
For more information about the constrained unpredictable behavior of this instruction, see Architectural Constraints on UNPREDICTABLE behaviors.
Assembler Symbols
<c> |
<q> |
.64 |
Is an optional data size specifier for 64-bit memory accesses that can be used in the assembler source code, but is otherwise ignored. |
<Dd> |
Is the 64-bit name of the SIMD&FP source register, encoded in the "D:Vd" field. |
.32 |
Is an optional data size specifier for 32-bit memory accesses that can be used in the assembler source code, but is otherwise ignored. |
<Sd> |
Is the 32-bit name of the SIMD&FP source register, encoded in the "Vd:D" field. |
<Rn> |
Is the general-purpose base register, encoded in the "Rn" field. The PC can be used, but this is deprecated. |
+/- |
Specifies the offset is added to or subtracted from the base register, defaulting to + if omitted and
encoded in
U:
|
Operation
if ConditionPassed() then EncodingSpecificOperations(); CheckVFPEnabled(TRUE); address = if add then (R[n] + imm32) else (R[n] - imm32); case esize of when 16 MemA[address,2] = S[d]<15:0>; when 32 MemA[address,4] = S[d]; when 64 // Store as two word-aligned words in the correct order for current endianness. MemA[address,4] = if BigEndian() then D[d]<63:32> else D[d]<31:0>; MemA[address+4,4] = if BigEndian() then D[d]<31:0> else D[d]<63:32>;