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[src/trunk]: src/lib/libc/arch/m68k/gen Oops; committed wrong version here.
details: https://anonhg.NetBSD.org/src/rev/6a732584cb2f
branches: trunk
changeset: 475917:6a732584cb2f
user: mycroft <mycroft%NetBSD.org@localhost>
date: Sun Aug 29 19:42:54 1999 +0000
description:
Oops; committed wrong version here.
diffstat:
lib/libc/arch/m68k/gen/ldexp_040.c | 158 ++++++++++++++++++++++++++++--------
1 files changed, 121 insertions(+), 37 deletions(-)
diffs (189 lines):
diff -r afae062413c7 -r 6a732584cb2f lib/libc/arch/m68k/gen/ldexp_040.c
--- a/lib/libc/arch/m68k/gen/ldexp_040.c Sun Aug 29 19:41:53 1999 +0000
+++ b/lib/libc/arch/m68k/gen/ldexp_040.c Sun Aug 29 19:42:54 1999 +0000
@@ -1,11 +1,12 @@
-/* $NetBSD: ldexp_040.c,v 1.1 1999/08/29 19:41:53 mycroft Exp $ */
+/* $NetBSD: ldexp_040.c,v 1.2 1999/08/29 19:42:54 mycroft Exp $ */
-/*-
- * Copyright (c) 1998 The NetBSD Foundation, Inc.
- * All rights reserved.
+/*
+ * Copyright (c) 1992, 1993
+ * The Regents of the University of California. All rights reserved.
*
- * This code is derived from software contributed to The NetBSD Foundation
- * by Charles M. Hannum.
+ * This software was developed by the Computer Systems Engineering group
+ * at Lawrence Berkeley Laboratory under DARPA contract BG 91-66 and
+ * contributed to Berkeley.
*
* Redistribution and use in source and binary forms, with or without
* modification, are permitted provided that the following conditions
@@ -17,52 +18,135 @@
* 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 NetBSD
- * Foundation, Inc. and its contributors.
- * 4. Neither the name of The NetBSD Foundation nor the names of its
- * contributors may be used to endorse or promote products derived
- * from this software without specific prior written permission.
+ * 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 NETBSD FOUNDATION, INC. 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 FOUNDATION 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.
+ * 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.
+ *
+ * from: Header: ldexp.c,v 1.1 91/07/07 04:28:19 torek Exp
*/
#include <sys/cdefs.h>
#if defined(LIBC_SCCS) && !defined(lint)
-__RCSID("$NetBSD: ldexp_040.c,v 1.1 1999/08/29 19:41:53 mycroft Exp $");
+#if 0
+static const char sccsid[] = "@(#)ldexp.c 8.1 (Berkeley) 6/4/93";
+#else
+__RCSID("$NetBSD: ldexp_040.c,v 1.2 1999/08/29 19:42:54 mycroft Exp $");
+#endif
#endif /* LIBC_SCCS and not lint */
#include <sys/types.h>
#include <machine/ieee.h>
+#include <errno.h>
#include <math.h>
/*
- * ldexp(value, exp): return value * (2 ** exp).
+ * double ldexp(double val, int exp)
+ * returns: val * (2**exp)
*/
double
-ldexp(value, exp)
- double value;
+ldexp(val, exp)
+ double val;
int exp;
{
- double temp;
+ register int oldexp, newexp, mulexp;
+ union {
+ double v;
+ struct ieee_double s;
+ } u, mul;
+
+ /*
+ * If input is zero, or no change, just return input.
+ * Likewise, if input is Inf or NaN, just return it.
+ */
+ u.v = val;
+ oldexp = u.s.dbl_exp;
+ if (val == 0.0 || exp == 0 || oldexp == DBL_EXP_INFNAN)
+ return (val);
-#if __GNUC__ >= 2
- __asm ("fscale"
- : "=t" (temp)
- : "0" (value), "u" ((double)exp));
-#else
- __asm ("fscale; fstp %%st(1)"
- : "=f" (temp)
- : "f" (value), "0" ((double)exp));
-#endif
- return (temp);
+ /*
+ * Compute new exponent and check for over/under flow.
+ * Underflow, unfortunately, could mean switching to denormal.
+ * If result out of range, set ERANGE and return 0 if too small
+ * or Inf if too big, with the same sign as the input value.
+ */
+ newexp = oldexp + exp;
+ if (newexp >= DBL_EXP_INFNAN) {
+ /* u.s.dbl_sign = val < 0.0; -- already set */
+ u.s.dbl_exp = DBL_EXP_INFNAN;
+ u.s.dbl_frach = u.s.dbl_fracl = 0;
+ errno = ERANGE;
+ return (u.v); /* Inf */
+ }
+ if (newexp <= 0) {
+ /*
+ * The output number is either a denormal or underflows
+ * (see comments in machine/ieee.h).
+ */
+ if (newexp <= -DBL_FRACBITS) {
+ errno = ERANGE;
+ return (0.0);
+ }
+ /*
+ * We are going to produce a denorm. Our `exp' argument
+ * might be as small as -2097, and we cannot compute
+ * 2^-2097, so we may have to do this as many as three
+ * steps (not just two, as for positive `exp's below).
+ */
+ mul.v = 1.0;
+ while (exp <= -DBL_EXP_BIAS) {
+ mul.s.dbl_exp = 1;
+ val *= mul.v;
+ exp += DBL_EXP_BIAS - 1;
+ }
+ mul.s.dbl_exp = exp + DBL_EXP_BIAS;
+ val *= mul.v;
+ return (val);
+ }
+
+ /*
+ * Newexp is positive.
+ *
+ * If oldexp is zero, we are starting with a denorm, and simply
+ * adjusting the exponent will produce bogus answers. We need
+ * to fix that first.
+ */
+ if (oldexp == 0) {
+ /*
+ * Multiply by 2^mulexp to make the number normalizable.
+ * We cannot multiply by more than 2^1023, but `exp'
+ * argument might be as large as 2046. A single
+ * adjustment, however, will normalize the number even
+ * for huge `exp's, and then we can use exponent
+ * arithmetic just as for normal `double's.
+ */
+ mulexp = exp <= DBL_EXP_BIAS ? exp : DBL_EXP_BIAS;
+ mul.v = 1.0;
+ mul.s.dbl_exp = mulexp + DBL_EXP_BIAS;
+ val *= mul.v;
+ if (mulexp == exp)
+ return (val);
+ u.v = val;
+ newexp -= mulexp;
+ }
+
+ /*
+ * Both oldexp and newexp are positive; just replace the
+ * old exponent with the new one.
+ */
+ u.s.dbl_exp = newexp;
+ return (u.v);
}
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