FSQRT—Square RootDescriptionComputes the square root of the source value in the ST(0) register and stores the result in ST(0).The following table shows the results obtained when taking the square root of various classes of numbers, assuming that neither overflow nor underflow occurs.This instruction’s operation is the same in non-64-bit modes and 64-bit mode.OperationST(0) := SquareRoot(ST(0));FPU Flags AffectedC1Set to 0 if stack underflow occurred.Set if result was rounded up; cleared otherwise.C0, C2, C3 Undefined.Floating-Point Exceptions#ISStack underflow occurred.#IASource operand is an SNaN value or unsupported format.Source operand is a negative value (except for −0).#DSource operand is a denormal value.#PValue cannot be represented exactly in destination format.Protected Mode Exceptions#NMCR0.EM[bit 2] or CR0.TS[bit 3] = 1.#MF If there is a pending x87 FPU exception.#UD If the LOCK prefix is used.Real-Address Mode ExceptionsSame exceptions as in protected mode.OpcodeInstruction64-Bit ModeCompat/Leg ModeDescriptionD9 FAFSQRTValidValidComputes square root of ST(0) and stores the result in ST(0).Table 3-37. FSQRT ResultsSRC (ST(0))DEST (ST(0))− ∞*− F*− 0− 0+ 0+ 0+ F+ F+ ∞+ ∞NaNNaN NOTES:FMeans finite floating-point value.*Indicates floating-point invalid-arithmetic-operand (#IA) exception.
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