/* $OpenBSD: e_exp.S,v 1.5 2008/09/07 20:36:08 martynas Exp $ */ /* $NetBSD: e_exp.S,v 1.12 2002/02/27 16:32:46 christos Exp $ */ /* * Copyright (c) 1993,94 Winning Strategies, Inc. * All rights reserved. * * Redistribution and use in source and binary forms, with or without * modification, are permitted provided that the following conditions * are met: * 1. Redistributions of source code must retain the above copyright * notice, this list of conditions and the following disclaimer. * 2. Redistributions in binary form must reproduce the above copyright * notice, this list of conditions and the following disclaimer in the * documentation and/or other materials provided with the distribution. * 3. All advertising materials mentioning features or use of this software * must display the following acknowledgement: * This product includes software developed by Winning Strategies, Inc. * 4. The name of the author may not be used to endorse or promote products * derived from this software without specific prior written permission. * * THIS SOFTWARE IS PROVIDED BY THE AUTHOR ``AS IS'' AND ANY EXPRESS OR * IMPLIED WARRANTIES, INCLUDING, BUT NOT LIMITED TO, THE IMPLIED WARRANTIES * OF MERCHANTABILITY AND FITNESS FOR A PARTICULAR PURPOSE ARE DISCLAIMED. * IN NO EVENT SHALL THE AUTHOR BE LIABLE FOR ANY DIRECT, INDIRECT, * INCIDENTAL, SPECIAL, EXEMPLARY, OR CONSEQUENTIAL DAMAGES (INCLUDING, BUT * NOT LIMITED TO, PROCUREMENT OF SUBSTITUTE GOODS OR SERVICES; LOSS OF USE, * DATA, OR PROFITS; OR BUSINESS INTERRUPTION) HOWEVER CAUSED AND ON ANY * THEORY OF LIABILITY, WHETHER IN CONTRACT, STRICT LIABILITY, OR TORT * (INCLUDING NEGLIGENCE OR OTHERWISE) ARISING IN ANY WAY OUT OF THE USE OF * THIS SOFTWARE, EVEN IF ADVISED OF THE POSSIBILITY OF SUCH DAMAGE. */ /* * Written by: * J.T. Conklin (jtc@wimsey.com), Winning Strategies, Inc. */ #include <machine/asm.h> #include "abi.h" /* e^x = 2^(x * log2(e)) */ ENTRY(exp) XMM_ONE_ARG_DOUBLE_PROLOGUE /* * If x is +-Inf, then the subtraction would give Inf-Inf = NaN. * Avoid this. Also avoid it if x is NaN for convenience. */ movl -4(%rsp),%eax andl $0x7fffffff,%eax cmpl $0x7ff00000,%eax jae x_Inf_or_NaN fldl ARG_DOUBLE_ONE /* * Ensure that the rounding mode is to nearest (to give the smallest * possible fraction) and that the precision is as high as possible. * We may as well mask interrupts if we switch the mode. */ fstcw -8(%rsp) movl -8(%rsp),%eax andl $0x0300,%eax cmpl $0x0300,%eax /* RC == 0 && PC == 3? */ je 1f /* jump if mode is good */ movl $0x137f,-4(%rsp) fldcw -4(%rsp) 1: fldl2e fmulp /* x * log2(e) */ fst %st(1) frndint /* int(x * log2(e)) */ fst %st(2) fsubrp /* fract(x * log2(e)) */ f2xm1 /* 2^(fract(x * log2(e))) - 1 */ fld1 faddp /* 2^(fract(x * log2(e))) */ fscale /* e^x */ fstp %st(1) je 1f fldcw -8(%rsp) 1: XMM_DOUBLE_EPILOGUE ret x_Inf_or_NaN: /* * Return 0 if x is -Inf. Otherwise just return x, although the * C version would return (x + x) (Real Indefinite) if x is a NaN. */ cmpl $0xfff00000,-4(%rsp) jne x_not_minus_Inf cmpl $0,-8(%rsp) jne x_not_minus_Inf xorpd %xmm0,%xmm0 ret x_not_minus_Inf: movsd ARG_DOUBLE_ONE,%xmm0 ret