1/* $OpenBSD: e_exp.S,v 1.7 2018/07/03 22:43:34 mortimer 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 RETGUARD_SETUP(exp, r11) 46 XMM_ONE_ARG_DOUBLE_PROLOGUE 47 /* 48 * If x is +-Inf, then the subtraction would give Inf-Inf = NaN. 49 * Avoid this. Also avoid it if x is NaN for convenience. 50 */ 51 movl -4(%rsp),%eax 52 andl $0x7fffffff,%eax 53 cmpl $0x7ff00000,%eax 54 jae x_Inf_or_NaN 55 56 fldl ARG_DOUBLE_ONE 57 58 /* 59 * Ensure that the rounding mode is to nearest (to give the smallest 60 * possible fraction) and that the precision is as high as possible. 61 * We may as well mask interrupts if we switch the mode. 62 */ 63 fstcw -8(%rsp) 64 movl -8(%rsp),%eax 65 andl $0x0300,%eax 66 cmpl $0x0300,%eax /* RC == 0 && PC == 3? */ 67 je 1f /* jump if mode is good */ 68 movl $0x137f,-4(%rsp) 69 fldcw -4(%rsp) 701: 71 fldl2e 72 fmulp /* x * log2(e) */ 73 fst %st(1) 74 frndint /* int(x * log2(e)) */ 75 fst %st(2) 76 fsubrp /* fract(x * log2(e)) */ 77 f2xm1 /* 2^(fract(x * log2(e))) - 1 */ 78 fld1 79 faddp /* 2^(fract(x * log2(e))) */ 80 fscale /* e^x */ 81 fstp %st(1) 82 je 1f 83 fldcw -8(%rsp) 841: 85 XMM_DOUBLE_EPILOGUE 86 RETGUARD_CHECK(exp, r11) 87 ret 88 89x_Inf_or_NaN: 90 /* 91 * Return 0 if x is -Inf. Otherwise just return x, although the 92 * C version would return (x + x) (Real Indefinite) if x is a NaN. 93 */ 94 cmpl $0xfff00000,-4(%rsp) 95 jne x_not_minus_Inf 96 cmpl $0,-8(%rsp) 97 jne x_not_minus_Inf 98 xorpd %xmm0,%xmm0 99 RETGUARD_CHECK(exp, r11) 100 ret 101 102x_not_minus_Inf: 103 movsd ARG_DOUBLE_ONE,%xmm0 104 RETGUARD_CHECK(exp, r11) 105 ret 106END_STD(exp) 107