Home | History | Annotate | Line # | Download | only in gen
ldexp.S revision 1.3 
      1 /*
      2  * Copyright (c) 1983, 1993
      3  *	The Regents of the University of California.  All rights reserved.
      4  *
      5  * Redistribution and use in source and binary forms, with or without
      6  * modification, are permitted provided that the following conditions
      7  * are met:
      8  * 1. Redistributions of source code must retain the above copyright
      9  *    notice, this list of conditions and the following disclaimer.
     10  * 2. Redistributions in binary form must reproduce the above copyright
     11  *    notice, this list of conditions and the following disclaimer in the
     12  *    documentation and/or other materials provided with the distribution.
     13  * 3. All advertising materials mentioning features or use of this software
     14  *    must display the following acknowledgement:
     15  *	This product includes software developed by the University of
     16  *	California, Berkeley and its contributors.
     17  * 4. Neither the name of the University nor the names of its contributors
     18  *    may be used to endorse or promote products derived from this software
     19  *    without specific prior written permission.
     20  *
     21  * THIS SOFTWARE IS PROVIDED BY THE REGENTS AND CONTRIBUTORS ``AS IS'' AND
     22  * ANY EXPRESS OR IMPLIED WARRANTIES, INCLUDING, BUT NOT LIMITED TO, THE
     23  * IMPLIED WARRANTIES OF MERCHANTABILITY AND FITNESS FOR A PARTICULAR PURPOSE
     24  * ARE DISCLAIMED.  IN NO EVENT SHALL THE REGENTS OR CONTRIBUTORS BE LIABLE
     25  * FOR ANY DIRECT, INDIRECT, INCIDENTAL, SPECIAL, EXEMPLARY, OR CONSEQUENTIAL
     26  * DAMAGES (INCLUDING, BUT NOT LIMITED TO, PROCUREMENT OF SUBSTITUTE GOODS
     27  * OR SERVICES; LOSS OF USE, DATA, OR PROFITS; OR BUSINESS INTERRUPTION)
     28  * HOWEVER CAUSED AND ON ANY THEORY OF LIABILITY, WHETHER IN CONTRACT, STRICT
     29  * LIABILITY, OR TORT (INCLUDING NEGLIGENCE OR OTHERWISE) ARISING IN ANY WAY
     30  * OUT OF THE USE OF THIS SOFTWARE, EVEN IF ADVISED OF THE POSSIBILITY OF
     31  * SUCH DAMAGE.
     32  */
     33 
     34 #if defined(LIBC_SCCS) && !defined(lint)
     35 	/*.asciz "@(#)ldexp.s	8.1 (Berkeley) 6/4/93" */
     36 	.asciz "$NetBSD: ldexp.S,v 1.3 2000/02/05 19:53:54 kleink Exp $"
     37 #endif /* LIBC_SCCS and not lint */
     38 
     39 /*
     40  * double ldexp (value, exp)
     41  * double value;
     42  * int exp;
     43  *
     44  * Ldexp returns value*2**exp, if that result is in range.
     45  * If underflow occurs, it returns zero.  If overflow occurs,
     46  * it returns a value of appropriate sign and largest
     47  * possible magnitude.  In case of either overflow or underflow,
     48  * errno is set to ERANGE.  Note that errno is not modified if
     49  * no error occurs.
     50  */
     51 
     52 #include "DEFS.h"
     53 
     54 /*
     55  * don't include errno.h, ANSI C says it defines errno.
     56  *
     57  * #include <errno.h>
     58  */
     59 #define	ERANGE	34
     60 
     61 	.globl	_errno
     62 
     63 ENTRY(ldexp, 0)
     64 	movd	4(ap),r0	/* fetch "value" */
     65 	extzv	$7,$8,r0,r2	/* r2 := biased exponent */
     66 	jeql	1f		/* if zero, done */
     67 
     68 	addl2	12(ap),r2	/* r2 := new biased exponent */
     69 	jleq	2f		/* if <= 0, underflow */
     70 	cmpl	r2,$256		/* otherwise check if too big */
     71 	jgeq	3f		/* jump if overflow */
     72 	insv	r2,$7,$8,r0	/* put exponent back in result */
     73 1:
     74 	ret
     75 2:
     76 	clrd	r0
     77 	jbr	1f
     78 3:
     79 	movd	huge,r0		/* largest possible floating magnitude */
     80 	jbc	$15,4(ap),1f	/* jump if argument was positive */
     81 	mnegd	r0,r0		/* if arg < 0, make result negative */
     82 1:
     83 #ifdef _REENTRANT
     84 	pushl	r0
     85 	calls	$0,___errno
     86 	movl	$ ERANGE,(r0)
     87 	movl	(sp)+,r0
     88 #else
     89 	movl	$ ERANGE,_errno
     90 #endif
     91 	ret
     92 
     93 	.data
     94 huge:	.word	0x7fff		/* the largest number that can */
     95 	.word	0xffff		/*   be represented in a long floating */
     96 	.word	0xffff		/*   number.  This is given in hex in order */
     97 	.word	0xffff		/*   to avoid floating conversions */
     98