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 "exp2.s" 30 31#include "libm.h" 32LIBM_ANSI_PRAGMA_WEAK(exp2,function) 33 34 ENTRY(exp2) 35 movl 8(%esp),%ecx / ecx <-- hi_32(x) 36 andl $0x7fffffff,%ecx / ecx <-- hi_32(|x|) 37 cmpl $0x3ff00000,%ecx / Is |x| < 1? 38 jb .shortcut / If so, take a shortcut. 39 je .check_tail / |x| may be only slightly < ln(2) 40 cmpl $0x7ff00000,%ecx / hi_32(|x|) >= hi_32(INF)? 41 jae .not_finite / if so, x is not finite 42.finite_non_special: / Here, 1 < |x| < INF 43 fldl 4(%esp) / push arg 44 fld %st(0) / duplicate stack top 45 frndint / [x],x 46 fucom / x integral? 47 fstsw %ax 48 sahf 49 je .x_integral / branch if x integral 50 fxch / x, [x] 51 fsub %st(1),%st / x-[x], [x] 52 f2xm1 / 2**(x-[x])-1, [x] 53 fld1 / 1,2**(x-[x])-1, [x] 54 faddp %st,%st(1) / 2**(x-[x]), [x] 55 fscale / 2**x = 2**(arg), [x] 56 fstp %st(1) 57 ret 58 59.x_integral: 60 fstp %st(0) / ,x 61 fld1 / 1 = 2**0, x 62 fscale / 2**(0 + x) = 2**x, x 63 fstp %st(1) / 2**x 64 ret 65 66.check_tail: 67 movl 4(%esp),%edx / edx <-- lo_32(x) 68 cmpl $0x00000000,%edx / Is |x| slightly > 1? 69 ja .finite_non_special / branch if |x| slightly > 1 70.shortcut: 71 / Here, |x| <= 1, 72 / whence x is in f2xm1's domain. 73 fldl 4(%esp) / push x 74 f2xm1 / 2**x - 1 75 fld1 / 1,2**x - 1 76 faddp %st,%st(1) / 2**x 77 ret 78 79.not_finite: 80 cmpl $0x7ff00000,%ecx / hi_32(|x|) > hi_32(INF)? 81 ja .NaN_or_pinf / if so, x is NaN 82 movl 4(%esp),%edx / edx <-- lo_32(x) 83 cmpl $0,%edx / lo_32(x) = 0? 84 jne .NaN_or_pinf / if not, x is NaN 85 movl 8(%esp),%eax / eax <-- hi_32(x) 86 andl $0x80000000,%eax / here, x is infinite, but +/-? 87 jz .NaN_or_pinf / branch if x = +INF 88 fldz / Here, x = -inf, so return 0 89 ret 90 91.NaN_or_pinf: 92 / Here, x = NaN or +inf, so load x and return immediately. 93 fldl 4(%esp) 94 fwait 95 ret 96 .align 4 97 SET_SIZE(exp2) 98