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modf.S revision 1.9 
      1 /*	$NetBSD: modf.S,v 1.9 2002/11/10 18:10:25 thorpej Exp $	*/
      2 
      3 /*-
      4  * Copyright (c) 1991, 1993, 1995
      5  *	The Regents of the University of California.  All rights reserved.
      6  *
      7  * This code is derived from software contributed to Berkeley by
      8  * Ralph Campbell.
      9  *
     10  * Redistribution and use in source and binary forms, with or without
     11  * modification, are permitted provided that the following conditions
     12  * are met:
     13  * 1. Redistributions of source code must retain the above copyright
     14  *    notice, this list of conditions and the following disclaimer.
     15  * 2. Redistributions in binary form must reproduce the above copyright
     16  *    notice, this list of conditions and the following disclaimer in the
     17  *    documentation and/or other materials provided with the distribution.
     18  * 3. All advertising materials mentioning features or use of this software
     19  *    must display the following acknowledgement:
     20  *	This product includes software developed by the University of
     21  *	California, Berkeley and its contributors.
     22  * 4. Neither the name of the University nor the names of its contributors
     23  *    may be used to endorse or promote products derived from this software
     24  *    without specific prior written permission.
     25  *
     26  * THIS SOFTWARE IS PROVIDED BY THE REGENTS AND CONTRIBUTORS ``AS IS'' AND
     27  * ANY EXPRESS OR IMPLIED WARRANTIES, INCLUDING, BUT NOT LIMITED TO, THE
     28  * IMPLIED WARRANTIES OF MERCHANTABILITY AND FITNESS FOR A PARTICULAR PURPOSE
     29  * ARE DISCLAIMED.  IN NO EVENT SHALL THE REGENTS OR CONTRIBUTORS BE LIABLE
     30  * FOR ANY DIRECT, INDIRECT, INCIDENTAL, SPECIAL, EXEMPLARY, OR CONSEQUENTIAL
     31  * DAMAGES (INCLUDING, BUT NOT LIMITED TO, PROCUREMENT OF SUBSTITUTE GOODS
     32  * OR SERVICES; LOSS OF USE, DATA, OR PROFITS; OR BUSINESS INTERRUPTION)
     33  * HOWEVER CAUSED AND ON ANY THEORY OF LIABILITY, WHETHER IN CONTRACT, STRICT
     34  * LIABILITY, OR TORT (INCLUDING NEGLIGENCE OR OTHERWISE) ARISING IN ANY WAY
     35  * OUT OF THE USE OF THIS SOFTWARE, EVEN IF ADVISED OF THE POSSIBILITY OF
     36  * SUCH DAMAGE.
     37  */
     38 
     39 #include <mips/asm.h>
     40 
     41 #if defined(LIBC_SCCS) && !defined(lint)
     42 	ASMSTR("from: @(#)modf.s	8.1 (Berkeley) 6/4/93")
     43 	ASMSTR("$NetBSD: modf.S,v 1.9 2002/11/10 18:10:25 thorpej Exp $")
     44 #endif /* LIBC_SCCS and not lint */
     45 
     46 #ifdef __ABICALLS__
     47 	.abicalls
     48 #endif
     49 
     50 /*
     51  * double modf(val, iptr)
     52  *	double val, *iptr;
     53  * returns: xxx and n (in *iptr) where val == n.xxx
     54  */
     55 LEAF(modf)
     56 #ifdef __ABICALLS__
     57 	.set	noreorder
     58 	.cpload	t9
     59 	.set	reorder
     60 #endif
     61 	cfc1	t0, $31			# get the control register
     62 	li.d	$f2, 4503599627370496e0 # f2 <- 2^52
     63 
     64 	or	t1, t0, 0x3		# set rounding mode to round to zero
     65 	xor	t1, t1, 0x2		#  (i.e., 01)
     66 	ctc1	t1, $31
     67 
     68 	mov.d	$f0, $f12		# f0 <- f12
     69 	abs.d	$f4, $f12		# f4 <- |f12|
     70 	c.olt.d $f4, $f2		# f4 ? < f2
     71 	bc1f	1f			# leave f0 alone if Nan, infinity
     72 					# or >=2^52
     73 	c.eq.d	$f12,$f4		# was f12 positive ?
     74 	add.d	$f4,$f2,$f4		# round off to integer
     75 	bc1f	2f			# No -> will have to negate result
     76 	sub.d	$f0,$f4,$f2		# Remove fudge factor
     77 	j	1f			# integer fraction got
     78 2:
     79 	sub.d	$f0,$f2,$f4		# Remove fudge factor and negate
     80 1:
     81 	ctc1	t0, $31			# restore old rounding mode
     82 	s.d	$f0, 0(a2)		# save the integer part
     83 	sub.d	$f0, $f12, $f0		# subtract val - integer part
     84 	j	ra
     85 END(modf)
     86