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

/*
 * Copyright (c) 1986 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 are permitted
 * provided that the above copyright notice and this paragraph are
 * duplicated in all such forms and that any documentation,
 * advertising materials, and other materials related to such
 * distribution and use acknowledge that the software was developed
 * by the University of California, Berkeley.  The name of the
 * University may not be used to endorse or promote products derived
 * from this software without specific prior written permission.
 * THIS SOFTWARE IS PROVIDED ``AS IS'' AND WITHOUT ANY EXPRESS OR
 * IMPLIED WARRANTIES, INCLUDING, WITHOUT LIMITATION, THE IMPLIED
 * WARRANTIES OF MERCHANTIBILITY AND FITNESS FOR A PARTICULAR PURPOSE.
 */

#if defined(SYSLIBC_SCCS) && !defined(lint)
        .asciz "@(#)cvtfl.s     1.2 (Berkeley) %G%"
#endif /* SYSLIBC_SCCS and not lint */

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

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

XENTRY(cvtfl, R2|R3|R4|R5)
 #
 #Some initializations:
 #
1:
        movl    4(fp),r0        # fetch operand.
        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:  shll    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,sfpover
        jmp     go_on

is_reserved:
        bbc     $31,r0,retzero

        callf   $4,sfpresop
        ret