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VSWP

Vector Swap exchanges the contents of two vectors. The vectors can be either doubleword or quadword. There is no distinction between data types.

Depending on settings in the CPACR, NSACR, and HCPTR 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

313029282726252423222120191817161514131211109876543210
111100111D110010Vd00000QM0Vm
size

64-bit SIMD vector (Q == 0)

VSWP{<c>}{<q>}{.<dt>} <Dd>, <Dm>

128-bit SIMD vector (Q == 1)

VSWP{<c>}{<q>}{.<dt>} <Qd>, <Qm>

if size != '00' then UNDEFINED;
if Q == '1' && (Vd<0> == '1' || Vm<0> == '1') then UNDEFINED;
d = UInt(D:Vd);  m = UInt(M:Vm);  regs = if Q == '0' then 1 else 2;

T1

15141312111098765432101514131211109876543210
111111111D110010Vd00000QM0Vm
size

64-bit SIMD vector (Q == 0)

VSWP{<c>}{<q>}{.<dt>} <Dd>, <Dm>

128-bit SIMD vector (Q == 1)

VSWP{<c>}{<q>}{.<dt>} <Qd>, <Qm>

if size != '00' then UNDEFINED;
if Q == '1' && (Vd<0> == '1' || Vm<0> == '1') then UNDEFINED;
d = UInt(D:Vd);  m = UInt(M:Vm);  regs = if Q == '0' then 1 else 2;

Assembler Symbols

<c>

For encoding A1: see Standard assembler syntax fields. This encoding must be unconditional.

For encoding T1: see Standard assembler syntax fields.

<q>

See Standard assembler syntax fields.

<dt>

An optional data type. It is ignored by assemblers, and does not affect the encoding.

<Qd>

Is the 128-bit name of the SIMD&FP destination register, encoded in the "D:Vd" field as <Qd>*2.

<Qm>

Is the 128-bit name of the SIMD&FP source register, encoded in the "M:Vm" field as <Qm>*2.

<Dd>

Is the 64-bit name of the SIMD&FP destination register, encoded in the "D:Vd" field.

<Dm>

Is the 64-bit name of the SIMD&FP source register, encoded in the "M:Vm" field.

Operation

if ConditionPassed() then
    EncodingSpecificOperations();  CheckAdvSIMDEnabled();
    for r = 0 to regs-1
        if d == m then
            D[d+r] = bits(64) UNKNOWN;
        else
            D[d+r] = Din[m+r];
            D[m+r] = Din[d+r];

Operational information

If CPSR.DIT is 1 and this instruction passes its condition execution check:

  • The execution time of this instruction is independent of:
    • The values of the data supplied in any of its registers.
    • The values of the NZCV flags.
  • The response of this instruction to asynchronous exceptions does not vary based on:
    • The values of the data supplied in any of its registers.
    • The values of the NZCV flags.
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