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 "ilogbf.s" 30 31#include "libm.h" 32LIBM_ANSI_PRAGMA_WEAK(ilogbf,function) 33#include "xpg6.h" 34 35 .data 36 .align 8 37two23: .long 0x4b000000 / 2**23 38 39 ENTRY(ilogbf) 40 movl 4(%esp),%eax / eax <-- x 41 testl $0x7f800000,%eax / is bexp(x) 0? 42 jz .bexp_0 / jump if x is 0 or subnormal 43 / here, biased exponent is non-zero 44 andl $0x7fffffff,%eax / eax <-- abs(x) 45 cmpl $0x7f800000,%eax / is bexp(x) 0xff? 46 jae .bexp_all_1 / jump if x is NaN or Inf 47 shrl $23,%eax / eax <-- zero_xtnd(bexp(x)) 48 subl $127,%eax / unbias exponent by 127 49 ret 50 51.bexp_all_1: 52 movl $0x7fffffff,%eax / x is NaN or inf, so return 0x7fffffff 53 jmp 0f 54 55.bexp_0: 56 andl $0x7fffffff,%eax / eax <-- abs(x), and 57 / ZF = 1 iff x = 0.0 58 jnz .ilogb_subnorm 59 movl $0x80000001,%eax / x is +/-0, so return 0x80000001 600: 61 PIC_SETUP(0) 62 PIC_G_LOAD(movzwl,__xpg6,ecx) 63 PIC_WRAPUP 64 andl $_C99SUSv3_ilogb_0InfNaN_raises_invalid,%ecx 65 cmpl $0,%ecx 66 je 1f 67 fldz 68 fdivp %st,%st(0) / raise invalid as per SUSv3 691: 70 ret 71 72.ilogb_subnorm: / subnormal input 73 flds 4(%esp) / push x 74 PIC_SETUP(1) 75 fmuls PIC_L(two23) / x*2**23; rebias x by 127+23, 76 / instead of 127 77 PIC_WRAPUP 78 subl $4,%esp / set up storage area 79 fstps (%esp) / store x*2**23 in storage area 80 fwait / (shouldn't raise exception, but 81 / just in case) 82 movl $0x7f800000,%eax / eax <-- single_bexp_mask 83 andl (%esp),%eax / eax[23..30] <-- bexp(x*2**23), 84 / rest_of(eax) <-- 0 85 shrl $23,%eax / eax <-- zero_xtnd(bexp(x*2**23)) 86 subl $150,%eax / unbias rebiased x by 150 (= 127 + 23) 87 addl $4,%esp / restore stack for caller 88 ret 89 .align 4 90 SET_SIZE(ilogbf) 91