usr/src/lib/libc/tahoe/fpe/cvtdl.s

/*
 * Copyright (c) 1986, 1993
 *      The Regents of the University of California.  All rights reserved.
 *
 * This code is derived from software contributed to Berkeley by
 * Computer Consoles Inc.
 *
 * Redistribution and use in source and binary forms, with or without
 * modification, are permitted provided that the following conditions
 * are met:
 * 1. Redistributions of source code must retain the above copyright
 *    notice, this list of conditions and the following disclaimer.
 * 2. Redistributions in binary form must reproduce the above copyright
 *    notice, this list of conditions and the following disclaimer in the
 *    documentation and/or other materials provided with the distribution.
 * 3. All advertising materials mentioning features or use of this software
 *    must display the following acknowledgement:
 *      This product includes software developed by the University of
 *      California, Berkeley and its contributors.
 * 4. Neither the name of the University nor the names of its contributors
 *    may be used to endorse or promote products derived from this software
 *    without specific prior written permission.
 *
 * THIS SOFTWARE IS PROVIDED BY THE REGENTS AND CONTRIBUTORS ``AS IS'' AND
 * ANY EXPRESS OR IMPLIED WARRANTIES, INCLUDING, BUT NOT LIMITED TO, THE
 * IMPLIED WARRANTIES OF MERCHANTABILITY AND FITNESS FOR A PARTICULAR PURPOSE
 * ARE DISCLAIMED.  IN NO EVENT SHALL THE REGENTS OR CONTRIBUTORS BE LIABLE
 * FOR ANY DIRECT, INDIRECT, INCIDENTAL, SPECIAL, EXEMPLARY, OR CONSEQUENTIAL
 * DAMAGES (INCLUDING, BUT NOT LIMITED TO, PROCUREMENT OF SUBSTITUTE GOODS
 * OR SERVICES; LOSS OF USE, DATA, OR PROFITS; OR BUSINESS INTERRUPTION)
 * HOWEVER CAUSED AND ON ANY THEORY OF LIABILITY, WHETHER IN CONTRACT, STRICT
 * LIABILITY, OR TORT (INCLUDING NEGLIGENCE OR OTHERWISE) ARISING IN ANY WAY
 * OUT OF THE USE OF THIS SOFTWARE, EVEN IF ADVISED OF THE POSSIBILITY OF
 * SUCH DAMAGE.
 */

#if defined(SYSLIBC_SCCS) && !defined(lint)
        .asciz "@(#)cvtdl.s     8.1 (Berkeley) 6/4/93"
#endif /* SYSLIBC_SCCS and not lint */

#include <tahoemath/fp.h>
#include "DEFS.h"

XENTRY(cvtdu, R2|R3|R4|R5)
        jbr     1f

XENTRY(cvtdl, R2|R3|R4|R5)
 #
 #Some initializations:
 #
1:
        movl    4(fp),r0        # fetch operand.
        movl    8(fp),r1
        clrl    r3              # r3 - negative flag.
 #
 #get exponent
 #
        andl3   $EXPMASK,r0,r2  # r2 will hold the exponent.
        jeql    is_reserved     # check for reserved operand.
        cmpl    $ONE_EXP,r2     # if exponent is less then 1,return zero.
        jgtr    retzero
        andl2   $0!EXPSIGN,r2   # turn off biased exponent sign
        shrl    $EXPSHIFT,r2,r2
 #
 #get fraction
 #
        bbc     $31,r0,positive # if negative remember it.
        incl    r3
positive:
                                # clear the non fraction parts.
        andl2   $(0!(EXPMASK | SIGNBIT)),r0
                                # add the hidden bit.
        orl2    $(0!CLEARHID),r0
        subl2   $24,r2          # compute the shift.
        jgtr    shift_left
        mnegl   r2,r2
        shrl    r2,r0,r0        # shift right.
        jmp     shifted
shift_left:
        cmpl    r2,$7
        jgtr    overflow
go_on:  shlq    r2,r0,r0        # shift right.
shifted:
        bbc     $0,r3,done      # check for negative
        mnegl   r0,r0
done:
        ret

retzero:
        clrl    r0
        ret
overflow:
        callf   $4,fpover
        jmp     go_on

is_reserved:
        bbc     $31,r0,retzero

        callf   $4,fpresop
        ret