FXAM—Examine Floating-PointDescriptionExamines the contents of the ST(0) register and sets the condition code flags C0, C2, and C3 in the FPU status word to indicate the class of value or number in the register (see the table below)..The C1 flag is set to the sign of the value in ST(0), regardless of whether the register is empty or full.This instruction’s operation is the same in non-64-bit modes and 64-bit mode.OperationC1 := sign bit of ST; (* 0 for positive, 1 for negative *)CASE (class of value or number in ST(0)) OFUnsupported:C3, C2, C0 := 000;NaN:C3, C2, C0 := 001;Normal:C3, C2, C0 := 010;Infinity:C3, C2, C0 := 011;Zero:C3, C2, C0 := 100;Empty:C3, C2, C0 := 101;Denormal:C3, C2, C0 := 110;ESAC;FPU Flags AffectedC1Sign of value in ST(0).C0, C2, C3See Table 3-42.Floating-Point ExceptionsNoneProtected 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 E5FXAMValidValidClassify value or number in ST(0).Table 3-42. FXAM ResultsClassC3C2C0Unsupported000NaN001Normal finite number010Infinity011Zero100Empty101Denormal number110
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