1/* 2 * Copyright (c) 1993,94 Winning Strategies, Inc. 3 * All rights reserved. 4 * 5 * Redistribution and use in source and binary forms, with or without 6 * modification, are permitted provided that the following conditions 7 * are met: 8 * 1. Redistributions of source code must retain the above copyright 9 * notice, this list of conditions and the following disclaimer. 10 * 2. Redistributions in binary form must reproduce the above copyright 11 * notice, this list of conditions and the following disclaimer in the 12 * documentation and/or other materials provided with the distribution. 13 * 3. All advertising materials mentioning features or use of this software 14 * must display the following acknowledgement: 15 * This product includes software developed by Winning Strategies, Inc. 16 * 4. The name of the author may not be used to endorse or promote products 17 * derived from this software without specific prior written permission. 18 * 19 * THIS SOFTWARE IS PROVIDED BY THE AUTHOR ``AS IS'' AND ANY EXPRESS OR 20 * IMPLIED WARRANTIES, INCLUDING, BUT NOT LIMITED TO, THE IMPLIED WARRANTIES 21 * OF MERCHANTABILITY AND FITNESS FOR A PARTICULAR PURPOSE ARE DISCLAIMED. 22 * IN NO EVENT SHALL THE AUTHOR BE LIABLE FOR ANY DIRECT, INDIRECT, 23 * INCIDENTAL, SPECIAL, EXEMPLARY, OR CONSEQUENTIAL DAMAGES (INCLUDING, BUT 24 * NOT LIMITED TO, PROCUREMENT OF SUBSTITUTE GOODS OR SERVICES; LOSS OF USE, 25 * DATA, OR PROFITS; OR BUSINESS INTERRUPTION) HOWEVER CAUSED AND ON ANY 26 * THEORY OF LIABILITY, WHETHER IN CONTRACT, STRICT LIABILITY, OR TORT 27 * (INCLUDING NEGLIGENCE OR OTHERWISE) ARISING IN ANY WAY OUT OF THE USE OF 28 * THIS SOFTWARE, EVEN IF ADVISED OF THE POSSIBILITY OF SUCH DAMAGE. 29 */ 30 31/* 32 * Written by: 33 * J.T. Conklin (jtc@wimsey.com), Winning Strategies, Inc. 34 */ 35 36#include <machine/asm.h> 37__FBSDID("$FreeBSD$") 38 39/* e^x = 2^(x * log2(e)) */ 40ENTRY(exp) 41 /* 42 * If x is +-Inf, then the subtraction would give Inf-Inf = NaN. 43 * Avoid this. Also avoid it if x is NaN for convenience. 44 */ 45 movl 8(%esp),%eax 46 andl $0x7fffffff,%eax 47 cmpl $0x7ff00000,%eax 48 jae x_Inf_or_NaN 49 50 fldl 4(%esp) 51 52 /* 53 * Extended precision is needed to reduce the maximum error from 54 * hundreds of ulps to less than 1 ulp. Switch to it if necessary. 55 * We may as well set the rounding mode to to-nearest and mask traps 56 * if we switch. 57 */ 58 fstcw 4(%esp) 59 movl 4(%esp),%eax 60 andl $0x0300,%eax 61 cmpl $0x0300,%eax /* RC == 0 && PC == 3? */ 62 je 1f /* jump if mode is good */ 63 movl $0x137f,8(%esp) 64 fldcw 8(%esp) 651: 66 fldl2e 67 fmulp /* x * log2(e) */ 68 fst %st(1) 69 frndint /* int(x * log2(e)) */ 70 fst %st(2) 71 fsubrp /* fract(x * log2(e)) */ 72 f2xm1 /* 2^(fract(x * log2(e))) - 1 */ 73 fld1 74 faddp /* 2^(fract(x * log2(e))) */ 75 fscale /* e^x */ 76 fstp %st(1) 77 je 1f 78 fldcw 4(%esp) 791: 80 ret 81 82x_Inf_or_NaN: 83 /* 84 * Return 0 if x is -Inf. Otherwise just return x; when x is Inf 85 * this gives Inf, and when x is a NaN this gives the same result 86 * as (x + x) (x quieted). 87 */ 88 cmpl $0xfff00000,8(%esp) 89 jne x_not_minus_Inf 90 cmpl $0,4(%esp) 91 jne x_not_minus_Inf 92 fldz 93 ret 94 95x_not_minus_Inf: 96 fldl 4(%esp) 97 ret 98END(exp) 99 100 .section .note.GNU-stack,"",%progbits 101