1/* 2 * CDDL HEADER START 3 * 4 * The contents of this file are subject to the terms of the 5 * Common Development and Distribution License (the "License"). 6 * You may not use this file except in compliance with the License. 7 * 8 * You can obtain a copy of the license at usr/src/OPENSOLARIS.LICENSE 9 * or http://www.opensolaris.org/os/licensing. 10 * See the License for the specific language governing permissions 11 * and limitations under the License. 12 * 13 * When distributing Covered Code, include this CDDL HEADER in each 14 * file and include the License file at usr/src/OPENSOLARIS.LICENSE. 15 * If applicable, add the following below this CDDL HEADER, with the 16 * fields enclosed by brackets "[]" replaced with your own identifying 17 * information: Portions Copyright [yyyy] [name of copyright owner] 18 * 19 * CDDL HEADER END 20 */ 21/* 22 * Copyright 2011 Nexenta Systems, Inc. All rights reserved. 23 */ 24/* 25 * Copyright 2006 Sun Microsystems, Inc. All rights reserved. 26 * Use is subject to license terms. 27 */ 28 29 .file "exp2f.s" 30 31#include "libm.h" 32LIBM_ANSI_PRAGMA_WEAK(exp2f,function) 33#include "libm_synonyms.h" 34 35 ENTRY(exp2f) 36 movl 4(%esp),%ecx / ecx <-- x 37 andl $0x7fffffff,%ecx / ecx <-- |x| 38 cmpl $0x3f800000,%ecx / Is |x| <= 1? 39 jbe .shortcut / If so, take a shortcut. 40 cmpl $0x7f800000,%ecx / |x| >= INF? 41 jae .not_finite / if so, x is not finite 42 flds 4(%esp) / push arg 43 fld %st(0) / duplicate stack top 44 frndint / [x],x 45 fucom / x integral? 46 fstsw %ax 47 sahf 48 je .x_integral / branch if x integral 49 fxch / x, [x] 50 fsub %st(1),%st / x-[x], [x] 51 f2xm1 / 2**(x-[x])-1, [x] 52 fld1 / 1,2**(x-[x])-1, [x] 53 faddp %st,%st(1) / 2**(x-[x]), [x] 54 fscale / 2**x = 2**(arg), [x] 55 fstp %st(1) 56 ret 57 58.x_integral: / here, x is integral 59 fstp %st(0) / ,x 60 fld1 / 1 = 2**0, x 61 fscale / 2**(0 + x) = 2**x, x 62 fstp %st(1) / 2**x 63 ret 64 65.shortcut: 66 / Here, |x| <= 1, 67 / whence x is in f2xm1's domain. 68 flds 4(%esp) / push x 69 f2xm1 / 2**x - 1 70 fld1 / 1,2**x - 1 71 faddp %st,%st(1) / 2**x 72 ret 73 74.not_finite: 75 ja .NaN_or_pinf / branch if x is NaN 76 movl 4(%esp),%eax / eax <-- x 77 andl $0x80000000,%eax / here, x is infinite, but +/-? 78 jz .NaN_or_pinf / branch if x = +INF 79 fldz / Here, x = -inf, so return 0 80 ret 81 82.NaN_or_pinf: 83 / Here, x = NaN or +inf, so load x and return immediately. 84 flds 4(%esp) 85 fwait 86 ret 87 .align 4 88 SET_SIZE(exp2f) 89