image/svg+xmlF2XM1—Compute 2x–1DescriptionComputes the exponential value of 2 to the power of the source operand minus 1. The source operand is located in register ST(0) and the result is also stored in ST(0). The value of the source operand must lie in the range –1.0 to +1.0. If the source value is outside this range, the result is undefined.The following table shows the results obtained when computing the exponential value of various classes of numbers, assuming that neither overflow nor underflow occurs.Values other than 2 can be exponentiated using the following formula:xy := 2(y ∗ log2x)This instruction’s operation is the same in non-64-bit modes and 64-bit mode.OperationST(0) := (2ST(0) − 1);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.#DSource is a denormal value.#UResult is too small for destination format.#PValue cannot be represented exactly in destination format.Protected Mode Exceptions#NMCR0.EM[bit 2] or CR0.TS[bit 3] = 1.#UD If the LOCK prefix is used.Real-Address Mode ExceptionsSame exceptions as in protected mode.Virtual-8086 Mode ExceptionsSame exceptions as in protected mode.OpcodeInstruction64-Bit ModeCompat/Leg ModeDescriptionD9 F0F2XM1ValidValidReplace ST(0) with (2ST(0) – 1).Table 3-16. Results Obtained from F2XM1ST(0) SRCST(0) DEST− 1.0 to −0− 0.5 to − 0− 0− 0+ 0+ 0+ 0 to +1.0+ 0 to 1.0

image/svg+xmlCompatibility Mode ExceptionsSame exceptions as in protected mode.64-Bit Mode ExceptionsSame exceptions as in protected mode.

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