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Diffstat (limited to 'winsup/mingw/mingwex/math/expl.c')
| -rw-r--r-- | winsup/mingw/mingwex/math/expl.c | 77 |
1 files changed, 0 insertions, 77 deletions
diff --git a/winsup/mingw/mingwex/math/expl.c b/winsup/mingw/mingwex/math/expl.c deleted file mode 100644 index 5f8face2c..000000000 --- a/winsup/mingw/mingwex/math/expl.c +++ /dev/null @@ -1,77 +0,0 @@ -/* - * Written by J.T. Conklin <jtc@netbsd.org>. - * Public domain. - * - * Adapted for `long double' by Ulrich Drepper <drepper@cygnus.com>. - */ - -/* - * The 8087 method for the exponential function is to calculate - * exp(x) = 2^(x log2(e)) - * after separating integer and fractional parts - * x log2(e) = i + f, |f| <= .5 - * 2^i is immediate but f needs to be precise for long double accuracy. - * Suppress range reduction error in computing f by the following. - * Separate x into integer and fractional parts - * x = xi + xf, |xf| <= .5 - * Separate log2(e) into the sum of an exact number c0 and small part c1. - * c0 + c1 = log2(e) to extra precision - * Then - * f = (c0 xi - i) + c0 xf + c1 x - * where c0 xi is exact and so also is (c0 xi - i). - * -- moshier@na-net.ornl.gov - */ - -#include <math.h> - -static long double c0 = 1.44268798828125L; -static long double c1 = 7.05260771340735992468e-6L; - -long double -expl (long double x) -{ - long double res; - -/* I added the following ugly construct because expl(+-Inf) resulted - in NaN. The ugliness results from the bright minds at Intel. - For the i686 the code can be written better. - -- drepper@cygnus.com. */ - asm ("fxam\n\t" /* Is NaN or +-Inf? */ - "fstsw %%ax\n\t" - "movb $0x45, %%dh\n\t" - "andb %%ah, %%dh\n\t" - "cmpb $0x05, %%dh\n\t" - "je 1f\n\t" /* Is +-Inf, jump. */ - "fldl2e\n\t" /* 1 log2(e) */ - "fmul %%st(1),%%st\n\t" /* 1 x log2(e) */ - "frndint\n\t" /* 1 i */ - "fld %%st(1)\n\t" /* 2 x */ - "frndint\n\t" /* 2 xi */ - "fld %%st(1)\n\t" /* 3 i */ - "fldt %2\n\t" /* 4 c0 */ - "fld %%st(2)\n\t" /* 5 xi */ - "fmul %%st(1),%%st\n\t" /* 5 c0 xi */ - "fsubp %%st,%%st(2)\n\t" /* 4 f = c0 xi - i */ - "fld %%st(4)\n\t" /* 5 x */ - "fsub %%st(3),%%st\n\t" /* 5 xf = x - xi */ - "fmulp %%st,%%st(1)\n\t" /* 4 c0 xf */ - "faddp %%st,%%st(1)\n\t" /* 3 f = f + c0 xf */ - "fldt %3\n\t" /* 4 */ - "fmul %%st(4),%%st\n\t" /* 4 c1 * x */ - "faddp %%st,%%st(1)\n\t" /* 3 f = f + c1 * x */ - "f2xm1\n\t" /* 3 2^(fract(x * log2(e))) - 1 */ - "fld1\n\t" /* 4 1.0 */ - "faddp\n\t" /* 3 2^(fract(x * log2(e))) */ - "fstp %%st(1)\n\t" /* 2 */ - "fscale\n\t" /* 2 scale factor is st(1); e^x */ - "fstp %%st(1)\n\t" /* 1 */ - "fstp %%st(1)\n\t" /* 0 */ - "jmp 2f\n\t" - "1:\ttestl $0x200, %%eax\n\t" /* Test sign. */ - "jz 2f\n\t" /* If positive, jump. */ - "fstp %%st\n\t" - "fldz\n\t" /* Set result to 0. */ - "2:\t\n" - : "=t" (res) : "0" (x), "m" (c0), "m" (c1) : "ax", "dx"); - return res; -} |