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