| /* |
| * 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> |
| |
| RCSID("$FreeBSD: src/lib/msun/i387/e_exp.S,v 1.11 2005/10/30 12:21:02 bde Exp $") |
| |
| /* e^x = 2^(x * log2(e)) */ |
| ENTRY(exp) |
| /* |
| * If x is +-Inf, then the subtraction would give Inf-Inf = NaN. |
| * Avoid this. Also avoid it if x is NaN for convenience. |
| */ |
| movl 8(%esp),%eax |
| andl $0x7fffffff,%eax |
| cmpl $0x7ff00000,%eax |
| jae x_Inf_or_NaN |
| |
| fldl 4(%esp) |
| |
| /* |
| * Extended precision is needed to reduce the maximum error from |
| * hundreds of ulps to less than 1 ulp. Switch to it if necessary. |
| * We may as well set the rounding mode to to-nearest and mask traps |
| * if we switch. |
| */ |
| fstcw 4(%esp) |
| movl 4(%esp),%eax |
| andl $0x0300,%eax |
| cmpl $0x0300,%eax /* RC == 0 && PC == 3? */ |
| je 1f /* jump if mode is good */ |
| movl $0x137f,8(%esp) |
| fldcw 8(%esp) |
| 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 4(%esp) |
| 1: |
| ret |
| |
| x_Inf_or_NaN: |
| /* |
| * Return 0 if x is -Inf. Otherwise just return x; when x is Inf |
| * this gives Inf, and when x is a NaN this gives the same result |
| * as (x + x) (x quieted). |
| */ |
| cmpl $0xfff00000,8(%esp) |
| jne x_not_minus_Inf |
| cmpl $0,4(%esp) |
| jne x_not_minus_Inf |
| fldz |
| ret |
| |
| x_not_minus_Inf: |
| fldl 4(%esp) |
| ret |
