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VSQRT

Square Root calculates the square root of the value in a floating-point register and writes the result to another floating-point register.

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

313029282726252423222120191817161514131211109876543210
!= 111111101D110001Vd10size11M0Vm
cond

Half-precision scalar (size == 01)
(Armv8.2)

VSQRT{<c>}{<q>}.F16 <Sd>, <Sm>

Single-precision scalar (size == 10)

VSQRT{<c>}{<q>}.F32 <Sd>, <Sm>

Double-precision scalar (size == 11)

VSQRT{<c>}{<q>}.F64 <Dd>, <Dm>

if size == '00' || (size == '01' && !HaveFP16Ext()) then UNDEFINED;
if size == '01' && cond != '1110' then UNPREDICTABLE;
if FPSCR.Len != '000' || FPSCR.Stride != '00' then UNDEFINED;
case size of
    when '01' esize = 16; d = UInt(Vd:D); m = UInt(Vm:M);
    when '10' esize = 32; d = UInt(Vd:D); m = UInt(Vm:M);
    when '11' esize = 64; d = UInt(D:Vd); m = UInt(M:Vm);

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

15141312111098765432101514131211109876543210
111011101D110001Vd10size11M0Vm

Half-precision scalar (size == 01)
(Armv8.2)

VSQRT{<c>}{<q>}.F16 <Sd>, <Sm>

Single-precision scalar (size == 10)

VSQRT{<c>}{<q>}.F32 <Sd>, <Sm>

Double-precision scalar (size == 11)

VSQRT{<c>}{<q>}.F64 <Dd>, <Dm>

if size == '00' || (size == '01' && !HaveFP16Ext()) then UNDEFINED;
if size == '01' && InITBlock()  then UNPREDICTABLE;
if FPSCR.Len != '000' || FPSCR.Stride != '00' then UNDEFINED;
case size of
    when '01' esize = 16; d = UInt(Vd:D); m = UInt(Vm:M);
    when '10' esize = 32; d = UInt(Vd:D); m = UInt(Vm:M);
    when '11' esize = 64; d = UInt(D:Vd); m = UInt(M:Vm);

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.

Assembler Symbols

<c>

See Standard assembler syntax fields.

<q>

See Standard assembler syntax fields.

<Sd>

Is the 32-bit name of the SIMD&FP destination register, encoded in the "Vd:D" field.

<Sm>

Is the 32-bit name of the SIMD&FP source register, encoded in the "Vm:M" field.

<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();  CheckVFPEnabled(TRUE);
    case esize of
        when 16 S[d] = Zeros(16) : FPSqrt(S[m]<15:0>, FPSCR);
        when 32 S[d] = FPSqrt(S[m], FPSCR);
        when 64 D[d] = FPSqrt(D[m], FPSCR);
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