ia-32_instruction-set-ref_a-m

Computing the remainder of various classes of numbers

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Unformatted text preview: lue, modulus (divisor) is 0, dividend is , or unsupported format. Source operand is a denormal value. Result is too small for destination format. Protected Mode Exceptions #NM #MF CR0.EM[bit 2] or CR0.TS[bit 3] = 1. If there is a pending x87 FPU exception. Real-Address Mode Exceptions Same exceptions as in Protected Mode. Virtual-8086 Mode Exceptions Same exceptions as in Protected Mode. Compatibility Mode Exceptions Same exceptions as in Protected Mode. 64-Bit Mode Exceptions Same exceptions as in Protected Mode. 3-362 Vol. 2 INSTRUCTION SET REFERENCE, A-M FPTAN--Partial Tangent Opcode D9 F2 Instruction FPTAN 64-Bit Mode Valid Compat/ Leg Mode Valid Description Replace ST(0) with its tangent and push 1 onto the FPU stack. Description Computes the tangent of the source operand in register ST(0), stores the result in ST(0), and pushes a 1.0 onto the FPU register stack. The source operand must be given in radians and must be less than 263. The following table shows the unmasked results obtained when computing the partial tangent of various classes of numbers, assuming that underflow does not occur. Table 3-38. FPTAN Results ST(0) SRC - -F ST(0) DEST * -F to +F -0 -0 +0 +F + NaN NOTES: F Means finite floating-point value. * Indicates floating-point invalid-arithmetic-operand (#IA) exception. +0 -F to +F * NaN If the source operand is outside the acceptable range, the C2 flag in the FPU status word is set, and the value in register ST(0) remains unchanged. The instruction does not raise an exception when the source operand is out of range. It is up to the program to check the C2 flag for out-of-range conditions. Source values outside the range -263 to +263 can be reduced to the range of the instruction by subtracting an appropriate integer multiple of 2 or by using the FPREM instruction with a divisor of 2. See the section titled "Pi" in Chapter 8 of the Intel 64 and IA-32 Architectures Software Developer's Manual, Volume 1, for a discussion of the proper value to use for in performing such reductions. The value 1.0 is pushed onto the register stack after the tangent has been computed to maintain compatibility with the Intel 8087 and Intel287 math coprocessors. This operation also simplifies the calculation of other trigonometric functions. For Vol. 2 3-363 INSTRUCTION SET REFERENCE, A-M instance, the cotangent (which is the reciprocal of the tangent) can be computed by executing a FDIVR instruction after the FPTAN instruction. This instruction's operation is the same in non-64-bit modes and 64-bit mode. Operation IF ST(0) < 263 THEN C2 0; ST(0) tan(ST(0)); TOP TOP - 1; ST(0) 1.0; ELSE (* Source operand is out-of-range *) C2 1; FI; FPU Flags Affected C1 Set to 0 if stack underflow occurred; set to 1 if stack overflow occurred. Set if result was rounded up; cleared otherwise. C2 C0, C3 Set to 1 if outside range (-263 < source operand < +263); otherwise, set to 0. Undefined. Floating-Point Exceptions #IS #IA #D #U #P Stack underflow...
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  • Winter '11
  • Watlins
  • X86, Intel corporation, Packed Single-Precision Floating-Point, Packed Double-Precision Floating-Point, single-precision floating-point values

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