github.com/mdempsky/go@v0.0.0-20151201204031-5dd372bd1e70/src/math/log1p_386.s (about)

     1  // Copyright 2010 The Go Authors.  All rights reserved.
     2  // Use of this source code is governed by a BSD-style
     3  // license that can be found in the LICENSE file.
     4  
     5  #include "textflag.h"
     6  
     7  // func Log1p(x float64) float64
     8  TEXT ·Log1p(SB),NOSPLIT,$0
     9  	FMOVD   $(2.928932188134524e-01), F0
    10  	FMOVD   x+0(FP), F0  // F0=x, F1=1-sqrt(2)/2 = 0.29289321881345247559915564
    11  	FABS                 // F0=|x|, F1=1-sqrt(2)/2
    12  	FUCOMPP F0, F1       // compare F0 to F1
    13  	FSTSW   AX
    14  	FLDLN2               // F0=log(2)
    15  	ANDW    $0x0100, AX
    16  	JEQ     use_fyl2x    // jump if F0 >= F1
    17  	FMOVD   x+0(FP), F0  // F0=x, F1=log(2)
    18  	FYL2XP1              // F0=log(1+x)=log2(1+x)*log(2)
    19  	FMOVDP  F0, ret+8(FP)
    20  	RET
    21  use_fyl2x:
    22  	FLD1                 // F0=1, F2=log(2)
    23  	FADDD   x+0(FP), F0  // F0=1+x, F1=log(2)
    24  	FYL2X                // F0=log(1+x)=log2(1+x)*log(2)
    25  	FMOVDP  F0, ret+8(FP)
    26  	RET
    27