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modf.S revision 1.4 
      1 /*-
      2  * Copyright (c) 1991, 1993, 1995
      3  *	The Regents of the University of California.  All rights reserved.
      4  *
      5  * This code is derived from software contributed to Berkeley by
      6  * Ralph Campbell.
      7  *
      8  * Redistribution and use in source and binary forms, with or without
      9  * modification, are permitted provided that the following conditions
     10  * are met:
     11  * 1. Redistributions of source code must retain the above copyright
     12  *    notice, this list of conditions and the following disclaimer.
     13  * 2. Redistributions in binary form must reproduce the above copyright
     14  *    notice, this list of conditions and the following disclaimer in the
     15  *    documentation and/or other materials provided with the distribution.
     16  * 3. All advertising materials mentioning features or use of this software
     17  *    must display the following acknowledgement:
     18  *	This product includes software developed by the University of
     19  *	California, Berkeley and its contributors.
     20  * 4. Neither the name of the University nor the names of its contributors
     21  *    may be used to endorse or promote products derived from this software
     22  *    without specific prior written permission.
     23  *
     24  * THIS SOFTWARE IS PROVIDED BY THE REGENTS AND CONTRIBUTORS ``AS IS'' AND
     25  * ANY EXPRESS OR IMPLIED WARRANTIES, INCLUDING, BUT NOT LIMITED TO, THE
     26  * IMPLIED WARRANTIES OF MERCHANTABILITY AND FITNESS FOR A PARTICULAR PURPOSE
     27  * ARE DISCLAIMED.  IN NO EVENT SHALL THE REGENTS OR CONTRIBUTORS BE LIABLE
     28  * FOR ANY DIRECT, INDIRECT, INCIDENTAL, SPECIAL, EXEMPLARY, OR CONSEQUENTIAL
     29  * DAMAGES (INCLUDING, BUT NOT LIMITED TO, PROCUREMENT OF SUBSTITUTE GOODS
     30  * OR SERVICES; LOSS OF USE, DATA, OR PROFITS; OR BUSINESS INTERRUPTION)
     31  * HOWEVER CAUSED AND ON ANY THEORY OF LIABILITY, WHETHER IN CONTRACT, STRICT
     32  * LIABILITY, OR TORT (INCLUDING NEGLIGENCE OR OTHERWISE) ARISING IN ANY WAY
     33  * OUT OF THE USE OF THIS SOFTWARE, EVEN IF ADVISED OF THE POSSIBILITY OF
     34  * SUCH DAMAGE.
     35  */
     36 
     37 #include <machine/machAsmDefs.h>
     38 
     39 #if defined(LIBC_SCCS) && !defined(lint)
     40 	ASMSTR("from: @(#)modf.s	8.1 (Berkeley) 6/4/93")
     41 	ASMSTR("$Id: modf.S,v 1.4 1995/09/25 19:28:27 jonathan Exp $")
     42 #endif /* LIBC_SCCS and not lint */
     43 
     44 /*
     45  * double modf(val, iptr)
     46  *	double val, *iptr;
     47  * returns: xxx and n (in *iptr) where val == n.xxx
     48  */
     49 LEAF(modf)
     50 	cfc1	t0, $31			# get the control register
     51 	li.d	$f2, 4503599627370496e0 # f2 <- 2^52
     52 
     53 	or	t1, t0, 0x3		# set rounding mode to round to zero
     54 	xor	t1, t1, 0x2		#  (i.e., 01)
     55 	ctc1	t1, $31
     56 
     57 	abs.d	$f4, $f12		# f4 <- |f12|
     58 	c.olt.d $f4, $f2		# f4 ? < f2
     59 	bc1f	1f			# leave alone if Nan, infinity
     60 					# or >=2^52
     61 	c.eq.d	$f12,$f4		# was f12 positive ?
     62 	add.d	$f4,$f2,$f4		# round off to integer
     63 	bc1f	2f			# No -> will have to negate result
     64 	sub.d	$f0,$f4,$f2		# Remove fudge factor
     65 	j	1f			# integer fraction got
     66 2:
     67 	sub.d	$f0,$f2,$f4		# Remove fudge factor and negate
     68 1:
     69 	ctc1	t0, $31			# restore old rounding mode
     70 	s.d	$f0, 0(a2)		# save the integer part
     71 	sub.d	$f0, $f12, $f0		# subtract val - integer part
     72 	j	ra
     73 END(modf)
     74