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 "expl.s" 30 31#include "libm.h" 32LIBM_ANSI_PRAGMA_WEAK(expl,function) 33 34 .data 35 .align 4 36ln2_hi: .long 0xd1d00000, 0xb17217f7, 0x00003ffe 37ln2_lo: .long 0x4c67fc0d, 0x8654361c, 0x0000bfce 38 39 ENTRY(expl) 40 movl 12(%esp),%ecx / cx <--sign&bexp(x) 41 andl $0x7fff,%ecx / ecx <-- zero_xtnd(bexp(x)) 42 cmpl $0x3ffe,%ecx / Is |x| < 0.5? 43 jb 2f / If so, see which shortcut to take 44 je .check_tail / More checking if 0.5 <= |x| < 1 45 cmpl $0x00007fff,%ecx / bexp(|x|) = bexp(INF)? 46 je .not_finite / if so, x is not finite 47 cmpl $0x0000400e,%ecx / |x| < 32768 = 2^15? 48 jb .finite_non_special / if so, proceed with argument reduction 49 fldt 4(%esp) / x 50 fld1 / 1, x 51 jmp 1f 52.finite_non_special: / Here, ln(2) < |x| < 2^15 53 fldt 4(%esp) / x 54 fld %st(0) / x, x 55 fldl2e / log2(e), x, x 56 fmulp / z := x*log2(e), x 57 frndint / [z], x 58 fst %st(2) / [z], x, [z] 59 PIC_SETUP(1) 60 fldt PIC_L(ln2_hi) / ln2_hi, [z], x, [z] 61 fmulp / [z]*ln2_hi, x, [z] 62 fsubrp %st,%st(1) / x-[z]*ln2_hi, [z] 63 fldt PIC_L(ln2_lo) / ln2_lo, x-[z]*ln2_hi, [z] 64 PIC_WRAPUP 65 fmul %st(2),%st / [z]*ln2_lo, x-[z]*ln2_hi, [z] 66 fsubrp %st,%st(1) / r := x-[z]*ln(2), [z] 67 fldl2e / log2(e), r, [z] 68 fmulp / f := r*log2(e), [z] 69 f2xm1 / 2^f-1,[z] 70 fld1 / 1, 2^f-1, [z] 71 faddp %st,%st(1) / 2^f, [z] 721: 73 fscale / e^x, [z] 74 fstp %st(1) 75 ret 76 772: / Here, |x| < 0.5 78 cmpl $0x3fbe,%ecx / Is |x| >= 2^-65? 79 jae .shortcut / If so, take a shortcut 80 fldt 4(%esp) / x 81 fld1 / 1, x 82 faddp %st,%st(1) / 1+x (for inexact & directed rounding) 83 ret 84 85.check_tail: 86 movl 8(%esp),%ecx / ecx <-- hi_32(sgnfcnd(x)) 87 cmpl $0xb17217f7,%ecx / Is |x| < ln(2)? 88 ja .finite_non_special 89 jb .shortcut 90 movl 4(%esp),%edx / edx <-- lo_32(x) 91 cmpl $0xd1cf79ab,%edx / Is |x| slightly < ln(2)? 92 ja .finite_non_special / branch if |x| slightly > ln(2) 93.shortcut: 94 / Here, |x| < ln(2), so |z| = |x/ln(2)| < 1, 95 / whence z is in f2xm1's domain. 96 fldt 4(%esp) / x 97 fldl2e / log2(e), x 98 fmulp / x*log2(e) 99 f2xm1 / 2^(x*log2(e))-1 = e^x-1 100 fld1 / 1, e^x-1 101 faddp %st,%st(1) / e^x 102 ret 103 104.not_finite: 105 movl 8(%esp),%ecx / ecx <-- hi_32(sgnfcnd(x)) 106 cmpl $0x80000000,%ecx / hi_32(|x|) = hi_32(INF)? 107 jne .NaN_or_pinf / if not, x is NaN 108 movl 4(%esp),%edx / edx <-- lo_32(x) 109 cmpl $0,%edx / lo_32(x) = 0? 110 jne .NaN_or_pinf / if not, x is NaN 111 movl 12(%esp),%eax / ax <-- sign&bexp((x)) 112 andl $0x00008000,%eax / here, x is infinite, but +/-? 113 jz .NaN_or_pinf / branch if x = +INF 114 fldz / Here, x = -inf, so return 0 115 ret 116 117.NaN_or_pinf: 118 / Here, x = NaN or +inf, so load x and return immediately. 119 fldt 4(%esp) 120 fadd %st(0),%st / quiet SNaN 121 ret 122 .align 4 123 SET_SIZE(expl) 124