/*
 * CDDL HEADER START
 *
 * The contents of this file are subject to the terms of the
 * Common Development and Distribution License (the "License").
 * You may not use this file except in compliance with the License.
 *
 * You can obtain a copy of the license at usr/src/OPENSOLARIS.LICENSE
 * or http://www.opensolaris.org/os/licensing.
 * See the License for the specific language governing permissions
 * and limitations under the License.
 *
 * When distributing Covered Code, include this CDDL HEADER in each
 * file and include the License file at usr/src/OPENSOLARIS.LICENSE.
 * If applicable, add the following below this CDDL HEADER, with the
 * fields enclosed by brackets "[]" replaced with your own identifying
 * information: Portions Copyright [yyyy] [name of copyright owner]
 *
 * CDDL HEADER END
 */
/*
 * Copyright 2011 Nexenta Systems, Inc.  All rights reserved.
 */
/*
 * Copyright 2005 Sun Microsystems, Inc.  All rights reserved.
 * Use is subject to license terms.
 */

        .file "ilogbl.s"

#include "libm.h"
LIBM_ANSI_PRAGMA_WEAK(ilogbl,function)
#include "xpg6.h"

        .data
        .align  16
two63:  .4byte  0x0,0x43d00000          / 2**63

        ENTRY(ilogbl)
        movq    16(%rsp),%rax           / eax <-- sign and bexp of x
        andq    $0x7fff,%rax            / eax <-- bexp(x)
        jz      .bexp_0                 / jump iff x is 0 or subnormal
                                        / here, biased exponent is non-zero
        testl   $0x80000000,12(%rsp)    / test msb of hi_32(sgnfcnd(x))
        jz      .ilogbl_not_finite      / jump if unsupported format
        cmpq    $0x7fff,%rax
        je      .ilogbl_not_finite
        subq    $16383,%rax             / unbias exponent by 16383 = 0x3fff
        ret

.ilogbl_not_finite:
        movq    $0x7fffffff,%rax        / x is NaN/inf/unsup
        jmp     0f

.bexp_0:
        movq    8(%rsp),%rax            / rax <-- sgnfcnd(x)
        orq     %rax,%rax
        jnz     .ilogbl_subnorm         / jump iff x is subnormal
        movq    $-2147483647,%rax       / x is +/-0, so return 1-2^31
0:
        PIC_SETUP(0)
        PIC_G_LOAD(movzwq,__xpg6,rcx)
        PIC_WRAPUP
        andl    $_C99SUSv3_ilogb_0InfNaN_raises_invalid,%ecx
        cmpl    $0,%ecx
        je      1f
        fldz
        fdivp   %st,%st(0)              / raise invalid as per SUSv3
1:
        ret


.ilogbl_subnorm:                        / subnormal or pseudo-denormal input
        fldt    8(%rsp)                 / push x, setting D-flag
        PIC_SETUP(1)
        fmull   PIC_L(two63)            / x*2**63
        PIC_WRAPUP
        subq    $16,%rsp
        fstpt   (%rsp)
        movq    $0x7fff,%rax
        andq    8(%rsp),%rax            / eax <-- sign and bexp of x*2**63
        subq    $16445,%rax             / unbias it by (16,383 + 63)
        addq    $16,%rsp
        ret
        .align  16
        SET_SIZE(ilogbl)