From f95a4a932476be2ba99e2fd081e8d2bc6ea12813 Mon Sep 17 00:00:00 2001 From: PikalaxALT Date: Fri, 15 Dec 2017 09:38:53 -0500 Subject: Import newlib and create makefile --- newlib/libc/machine/i386/f_powf.c | 44 +++++++++++++++++++++++++++++++++++++++ 1 file changed, 44 insertions(+) create mode 100644 newlib/libc/machine/i386/f_powf.c (limited to 'newlib/libc/machine/i386/f_powf.c') diff --git a/newlib/libc/machine/i386/f_powf.c b/newlib/libc/machine/i386/f_powf.c new file mode 100644 index 0000000..501b6b1 --- /dev/null +++ b/newlib/libc/machine/i386/f_powf.c @@ -0,0 +1,44 @@ +/* + * ==================================================== + * Copyright (C) 1998 by Cygnus Solutions. All rights reserved. + * + * Permission to use, copy, modify, and distribute this + * software is freely granted, provided that this notice + * is preserved. + * ==================================================== + */ + +/* +Fast version of pow using Intel float instructions. + + float _f_powf (float x, float y); + +Function calculates x to power of y. +The function optimizes the case where x is >0.0 and y is finite. +In such a case, there is no error checking or setting of errno. +All other cases defer to normal powf() function which will +set errno as normal. +*/ + +#include +#include +#include "f_math.h" + +float _f_powf (float x, float y) +{ + /* following sequence handles the majority of cases for pow() */ + if (x > 0.0 && check_finitef(y)) + { + float result; + /* calculate x ** y as 2 ** (y log2(x)). On Intel, can only + raise 2 to an integer or a small fraction, thus, we have + to perform two steps 2**integer portion * 2**fraction. */ + asm ("flds 8(%%ebp); fyl2x; fld %%st; frndint; fsub %%st,%%st(1);" \ + "fxch; fchs; f2xm1; fld1; faddp; fxch; fld1; fscale; fstp %%st(1);"\ + "fmulp" : "=t" (result) : "0" (y)); + return result; + } + else /* all other strange cases, defer to normal pow() */ + return powf (x,y); +} + -- cgit v1.2.3