/*
 * 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 "exp10.s"

#include "libm.h"

        ENTRY(exp10)
        movl    8(%esp),%ecx            / ecx <-- hi_32(x)
        andl    $0x7fffffff,%ecx        / ecx <-- hi_32(|x|)
        cmpl    $0x3fd34413,%ecx        / Is |x| < log10(2)?
        jb      .shortcut               / If so, take a shortcut.
        je      .check_tail             / maybe |x| only slightly < log10(2)
        cmpl    $0x7ff00000,%ecx        / hi_32(|x|) >= hi_32(INF)?
        jae     .not_finite             / if so, x is not finite
.finite_non_special:                    / Here, log10(2) < |x| < INF
        fldl    4(%esp)                 / push x (=arg)

        subl    $8,%esp                 / save RP and set round-to-64-bits
        fstcw   (%esp)
        movw    (%esp),%ax
        movw    %ax,4(%esp)
        orw     $0x0300,%ax
        movw    %ax,(%esp)
        fldcw   (%esp)

        fldl2t                          / push log2(10)  }NOT for xtndd_dbl
        fmulp   %st,%st(1)              / z = x*log2(10) }NOT for xtndd_dbl
        fld     %st(0)                  / duplicate stack top
        frndint                         / [z],z
        fucom                           / z integral?
        fstsw  %ax
        sahf
        je      .z_integral             / branch if z integral
        fxch                            / z, [z]
        fsub    %st(1),%st              / z-[z], [z]
        f2xm1                           / 2**(z-[z])-1, [z]
        fld1                            / 1,2**(z-[z])-1, [z]
        faddp   %st,%st(1)              / 2**(z-[z]), [z]
        fscale                          / 2**z = 10**(arg), [z]
        fstp    %st(1)

        fstcw   (%esp)                  / restore old RP
        movw    (%esp),%dx
        andw    $0xfcff,%dx
        movw    4(%esp),%cx
        andw    $0x0300,%cx
        orw     %dx,%cx
        movw    %cx,(%esp)
        fldcw   (%esp)
        add     $8,%esp

        ret

.z_integral:                            / here, z is integral
        fstp    %st(0)                  / ,z
        fld1                            / 1 = 2**0, z
        fscale                          / 2**(0 + z) = 2**z = 10**(arg), z
        fstp    %st(1)                  / 10**(arg)

        fstcw   (%esp)                  / restore old RP
        movw    (%esp),%dx
        andw    $0xfcff,%dx
        movw    4(%esp),%cx
        andw    $0x0300,%cx
        orw     %dx,%cx
        movw    %cx,(%esp)
        fldcw   (%esp)
        add     $8,%esp

        ret

.check_tail:
        movl    4(%esp),%edx            / edx <-- lo_32(x)
        cmpl    $0x509f79fe,%edx        / Is |x| slightly > log10(2)?
        ja      .finite_non_special     / branch if |x| slightly > log10(2)
.shortcut:
        / Here, |x| < log10(2), so |z| = |x*log2(10)| < 1
        / whence z is in f2xm1's domain.
        fldl    4(%esp)                 / push x (=arg)
        fldl2t                          / push log2(10)  }NOT for xtndd_dbl
        fmulp   %st,%st(1)              / z = x*log2(10) }NOT for xtndd_dbl
        f2xm1                           / 2**z - 1
        fld1                            / 1,2**z - 1
        faddp   %st,%st(1)              / 2**z = 10**x
        ret

.not_finite:
        cmpl    $0x7ff00000,%ecx        / hi_32(|x|) > hi_32(INF)?
        ja      .NaN_or_pinf            / if so, x is NaN
        movl    4(%esp),%edx            / edx <-- lo_32(x)
        cmpl    $0,%edx                 / lo_32(x) = 0?
        jne     .NaN_or_pinf            / if not, x is NaN
        movl    8(%esp),%eax            / eax <-- hi_32(x)
        andl    $0x80000000,%eax        / here, x is infinite, but +/-?
        jz      .NaN_or_pinf            / branch if x = +INF
        fldz                            / Here, x = -inf, so return 0
        ret

.NaN_or_pinf:
        / Here, x = NaN or +inf, so load x and return immediately.
        fldl    4(%esp)
        fwait
        ret
        .align  4
        SET_SIZE(exp10)