Mercurial > mxe-octave
comparison src/build-msvctools/math/log2.S @ 3061:f8299bb6c872
Initial support for native MSVC compilation.
* add MSVC support files: compiler wrappers and support libraries
* adapt libiconv to work with MSVC
* adapt gettext to work with MSVC
| author | Michael Goffioul <michael.goffioul@gmail.com> |
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| date | Mon, 17 Jun 2013 22:43:11 -0400 |
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| children |
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| 3060:cbdf4575016d | 3061:f8299bb6c872 |
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| 1 /* | |
| 2 * Written by J.T. Conklin <jtc@netbsd.org>. | |
| 3 * Adapted for use as log2 by Ulrich Drepper <drepper@cygnus.com>. | |
| 4 * Public domain. | |
| 5 * | |
| 6 * Changed to use fyl2xp1 for values near 1, <drepper@cygnus.com>. | |
| 7 * | |
| 8 * Removed header file dependency for use in libmingwex.a by | |
| 9 * Danny Smith <dannysmith@users.sourceforge.net> | |
| 10 */ | |
| 11 | |
| 12 .file "log2.S" | |
| 13 .text | |
| 14 .align 4 | |
| 15 one: .double 1.0 | |
| 16 /* It is not important that this constant is precise. It is only | |
| 17 a value which is known to be on the safe side for using the | |
| 18 fyl2xp1 instruction. */ | |
| 19 limit: .double 0.29 | |
| 20 | |
| 21 .text | |
| 22 .align 4 | |
| 23 .globl _log2 | |
| 24 .def _log2; .scl 2; .type 32; .endef | |
| 25 _log2: | |
| 26 fldl one | |
| 27 fldl 4(%esp) /* x : 1 */ | |
| 28 fxam | |
| 29 fnstsw | |
| 30 fld %st /* x : x : 1 */ | |
| 31 sahf | |
| 32 jc 3f /* in case x is NaN or ħInf */ | |
| 33 4: fsub %st(2), %st /* x-1 : x : 1 */ | |
| 34 fld %st /* x-1 : x-1 : x : 1 */ | |
| 35 fabs /* |x-1| : x-1 : x : 1 */ | |
| 36 fcompl limit /* x-1 : x : 1 */ | |
| 37 fnstsw /* x-1 : x : 1 */ | |
| 38 andb $0x45, %ah | |
| 39 jz 2f | |
| 40 fstp %st(1) /* x-1 : 1 */ | |
| 41 fyl2xp1 /* log(x) */ | |
| 42 ret | |
| 43 | |
| 44 2: fstp %st(0) /* x : 1 */ | |
| 45 fyl2x /* log(x) */ | |
| 46 ret | |
| 47 | |
| 48 3: jp 4b /* in case x is ħInf */ | |
| 49 fstp %st(1) | |
| 50 fstp %st(1) | |
| 51 ret |