1/* $OpenBSD: e_exp.S,v 1.5 2008/09/07 20:36:08 martynas Exp $ */ 2/* $NetBSD: e_exp.S,v 1.12 2002/02/27 16:32:46 christos Exp $ */ 3 4/* 5 * Copyright (c) 1993,94 Winning Strategies, Inc. 6 * All rights reserved. 7 * 8 * Redistribution and use in source and binary forms, with or without 9 * modification, are permitted provided that the following conditions 10 * are met: 11 * 1. Redistributions of source code must retain the above copyright 12 * notice, this list of conditions and the following disclaimer. 13 * 2. Redistributions in binary form must reproduce the above copyright 14 * notice, this list of conditions and the following disclaimer in the 15 * documentation and/or other materials provided with the distribution. 16 * 3. All advertising materials mentioning features or use of this software 17 * must display the following acknowledgement: 18 * This product includes software developed by Winning Strategies, Inc. 19 * 4. The name of the author may not be used to endorse or promote products 20 * derived from this software without specific prior written permission. 21 * 22 * THIS SOFTWARE IS PROVIDED BY THE AUTHOR ``AS IS'' AND ANY EXPRESS OR 23 * IMPLIED WARRANTIES, INCLUDING, BUT NOT LIMITED TO, THE IMPLIED WARRANTIES 24 * OF MERCHANTABILITY AND FITNESS FOR A PARTICULAR PURPOSE ARE DISCLAIMED. 25 * IN NO EVENT SHALL THE AUTHOR BE LIABLE FOR ANY DIRECT, INDIRECT, 26 * INCIDENTAL, SPECIAL, EXEMPLARY, OR CONSEQUENTIAL DAMAGES (INCLUDING, BUT 27 * NOT LIMITED TO, PROCUREMENT OF SUBSTITUTE GOODS OR SERVICES; LOSS OF USE, 28 * DATA, OR PROFITS; OR BUSINESS INTERRUPTION) HOWEVER CAUSED AND ON ANY 29 * THEORY OF LIABILITY, WHETHER IN CONTRACT, STRICT LIABILITY, OR TORT 30 * (INCLUDING NEGLIGENCE OR OTHERWISE) ARISING IN ANY WAY OUT OF THE USE OF 31 * THIS SOFTWARE, EVEN IF ADVISED OF THE POSSIBILITY OF SUCH DAMAGE. 32 */ 33 34/* 35 * Written by: 36 * J.T. Conklin (jtc@wimsey.com), Winning Strategies, Inc. 37 */ 38 39#include <machine/asm.h> 40 41#include "abi.h" 42 43/* e^x = 2^(x * log2(e)) */ 44ENTRY(exp) 45 XMM_ONE_ARG_DOUBLE_PROLOGUE 46 /* 47 * If x is +-Inf, then the subtraction would give Inf-Inf = NaN. 48 * Avoid this. Also avoid it if x is NaN for convenience. 49 */ 50 movl -4(%rsp),%eax 51 andl $0x7fffffff,%eax 52 cmpl $0x7ff00000,%eax 53 jae x_Inf_or_NaN 54 55 fldl ARG_DOUBLE_ONE 56 57 /* 58 * Ensure that the rounding mode is to nearest (to give the smallest 59 * possible fraction) and that the precision is as high as possible. 60 * We may as well mask interrupts if we switch the mode. 61 */ 62 fstcw -8(%rsp) 63 movl -8(%rsp),%eax 64 andl $0x0300,%eax 65 cmpl $0x0300,%eax /* RC == 0 && PC == 3? */ 66 je 1f /* jump if mode is good */ 67 movl $0x137f,-4(%rsp) 68 fldcw -4(%rsp) 691: 70 fldl2e 71 fmulp /* x * log2(e) */ 72 fst %st(1) 73 frndint /* int(x * log2(e)) */ 74 fst %st(2) 75 fsubrp /* fract(x * log2(e)) */ 76 f2xm1 /* 2^(fract(x * log2(e))) - 1 */ 77 fld1 78 faddp /* 2^(fract(x * log2(e))) */ 79 fscale /* e^x */ 80 fstp %st(1) 81 je 1f 82 fldcw -8(%rsp) 831: 84 XMM_DOUBLE_EPILOGUE 85 ret 86 87x_Inf_or_NaN: 88 /* 89 * Return 0 if x is -Inf. Otherwise just return x, although the 90 * C version would return (x + x) (Real Indefinite) if x is a NaN. 91 */ 92 cmpl $0xfff00000,-4(%rsp) 93 jne x_not_minus_Inf 94 cmpl $0,-8(%rsp) 95 jne x_not_minus_Inf 96 xorpd %xmm0,%xmm0 97 ret 98 99x_not_minus_Inf: 100 movsd ARG_DOUBLE_ONE,%xmm0 101 ret 102END(exp) 103 104 .section .note.GNU-stack,"",%progbits 105