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 2005 Sun Microsystems, Inc.  All rights reserved.
  26  * Use is subject to license terms.
  27  */
  28 
  29         .file "ilogbl.s"
  30 
  31 #include "libm.h"
  32 LIBM_ANSI_PRAGMA_WEAK(ilogbl,function)
  33 #include "libm_synonyms.h"
  34 #include "xpg6.h"
  35 
  36         .data
  37         .align  16
  38 two63:  .4byte  0x0,0x43d00000          / 2**63
  39 
  40         ENTRY(ilogbl)
  41         movq    16(%rsp),%rax           / eax <-- sign and bexp of x
  42         andq    $0x7fff,%rax            / eax <-- bexp(x)
  43         jz      .bexp_0                 / jump iff x is 0 or subnormal
  44                                         / here, biased exponent is non-zero
  45         testl   $0x80000000,12(%rsp)    / test msb of hi_32(sgnfcnd(x))
  46         jz      .ilogbl_not_finite      / jump if unsupported format
  47         cmpq    $0x7fff,%rax
  48         je      .ilogbl_not_finite
  49         subq    $16383,%rax             / unbias exponent by 16383 = 0x3fff
  50         ret
  51 
  52 .ilogbl_not_finite:
  53         movq    $0x7fffffff,%rax        / x is NaN/inf/unsup
  54         jmp     0f
  55 
  56 .bexp_0:
  57         movq    8(%rsp),%rax            / rax <-- sgnfcnd(x)
  58         orq     %rax,%rax
  59         jnz     .ilogbl_subnorm         / jump iff x is subnormal
  60         movq    $-2147483647,%rax       / x is +/-0, so return 1-2^31
  61 0:
  62         PIC_SETUP(0)
  63         PIC_G_LOAD(movzwq,__xpg6,rcx)
  64         PIC_WRAPUP
  65         andl    $_C99SUSv3_ilogb_0InfNaN_raises_invalid,%ecx
  66         cmpl    $0,%ecx
  67         je      1f
  68         fldz
  69         fdivp   %st,%st(0)              / raise invalid as per SUSv3
  70 1:
  71         ret
  72 
  73 
  74 .ilogbl_subnorm:                        / subnormal or pseudo-denormal input
  75         fldt    8(%rsp)                 / push x, setting D-flag
  76         PIC_SETUP(1)
  77         fmull   PIC_L(two63)            / x*2**63
  78         PIC_WRAPUP
  79         subq    $16,%rsp
  80         fstpt   (%rsp)
  81         movq    $0x7fff,%rax
  82         andq    8(%rsp),%rax            / eax <-- sign and bexp of x*2**63
  83         subq    $16445,%rax             / unbias it by (16,383 + 63)
  84         addq    $16,%rsp
  85         ret
  86         .align  16
  87         SET_SIZE(ilogbl)