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ldexp(denormal, exp>1023) would generate the wrong result in all non-overflow 

cases.  Totally rework this code to fix this bug *and* make it faster.
This commit is contained in:
mycroft 1999-08-29 22:45:32 +00:00
parent a5903905c2
commit 5f34ffabca
6 changed files with 588 additions and 492 deletions
Show Stats Download Patch File Download Diff File Expand all files Collapse all files

192
lib/libc/arch/alpha/gen/ldexp.c
View File

@ -1,12 +1,11 @@
/* $NetBSD: ldexp.c,v 1.5 1999/08/29 19:04:02 mycroft Exp $ */
/* $NetBSD: ldexp.c,v 1.6 1999/08/29 22:45:32 mycroft Exp $ */
/*
* Copyright (c) 1992, 1993
* The Regents of the University of California. All rights reserved.
/*-
* Copyright (c) 1999 The NetBSD Foundation, Inc.
* All rights reserved.
*
* This software was developed by the Computer Systems Engineering group
* at Lawrence Berkeley Laboratory under DARPA contract BG 91-66 and
* contributed to Berkeley.
* This code is derived from software contributed to The NetBSD Foundation
* by Charles M. Hannum.
*
* Redistribution and use in source and binary forms, with or without
* modification, are permitted provided that the following conditions
@ -18,34 +17,28 @@
* 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 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 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 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
* 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.
*/
#include <sys/cdefs.h>
#if defined(LIBC_SCCS) && !defined(lint)
#if 0
static const char sccsid[] = "@(#)ldexp.c 8.1 (Berkeley) 6/4/93";
#else
__RCSID("$NetBSD: ldexp.c,v 1.5 1999/08/29 19:04:02 mycroft Exp $");
#endif
__RCSID("$NetBSD: ldexp.c,v 1.6 1999/08/29 22:45:32 mycroft Exp $");
#endif /* LIBC_SCCS and not lint */
#include <sys/types.h>
@ -54,8 +47,7 @@ __RCSID("$NetBSD: ldexp.c,v 1.5 1999/08/29 19:04:02 mycroft Exp $");
#include <math.h>
/*
* double ldexp(double val, int exp)
* returns: val * (2**exp)
* Multiply the given value by 2^exp.
*/
double
ldexp(val, exp)
@ -68,85 +60,95 @@ ldexp(val, exp)
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);
/*
* 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.
* If input is zero, Inf or NaN, just return it.
*/
if (u.v == 0.0 || oldexp == DBL_EXP_INFNAN)
return (val);
if (oldexp == 0) {
/*
* u.v is denormal. We must adjust it so that the exponent
* arithmetic below will work.
*/
if (exp <= DBL_EXP_BIAS) {
/*
* Optimization: if the scaling can be done in a single
* multiply, or underflows, just do it now.
*/
if (exp <= -DBL_FRACBITS) {
errno = ERANGE;
return (0.0);
}
mul.v = 1.0;
mul.s.dbl_exp = exp + DBL_EXP_BIAS;
u.v *= mul.v;
if (u.v == 0.0) {
errno = ERANGE;
return (0.0);
}
return (u.v);
} else {
/*
* We know that exp is very large, and therefore the
* result cannot be denormal (though it may be Inf).
* Shift u.v by just enough to make it normal.
*/
mul.v = 1.0;
mul.s.dbl_exp = DBL_FRACBITS + DBL_EXP_BIAS;
u.v *= mul.v;
exp -= DBL_FRACBITS;
oldexp = u.s.dbl_exp;
}
}
/*
* u.v is now normalized and oldexp has been adjusted if necessary.
* Calculate the new exponent and check for underflow and overflow.
*/
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).
* The result overflowed; return +/-Inf.
*/
u.s.dbl_exp = DBL_EXP_INFNAN;
u.s.dbl_frach = 0;
u.s.dbl_fracl = 0;
errno = ERANGE;
return (u.v);
} else if (newexp <= 0) {
/*
* The output number is either 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).
* Denormalize the result. We do this with a multiply. If exp
* is very large, it won't fit in a double, so we have to
* adjust the exponent first. This is safe because we know
* that u.v is normal at this point.
*/
mul.v = 1.0;
while (exp <= -DBL_EXP_BIAS) {
mul.s.dbl_exp = 1;
val *= mul.v;
exp += DBL_EXP_BIAS - 1;
if (exp <= -DBL_EXP_BIAS) {
u.s.dbl_exp = 1;
exp += oldexp - 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;
mul.s.dbl_exp = exp + DBL_EXP_BIAS;
u.v *= mul.v;
return (u.v);
} else {
/*
* The result is normal; just replace the old exponent with the
* new one.
*/
u.s.dbl_exp = newexp;
return (u.v);
}
/*
* Both oldexp and newexp are positive; just replace the
* old exponent with the new one.
*/
u.s.dbl_exp = newexp;
return (u.v);
}

192
lib/libc/arch/arm32/gen/ldexp.c
View File

@ -1,12 +1,11 @@
/* $NetBSD: ldexp.c,v 1.8 1999/08/29 19:04:03 mycroft Exp $ */
/* $NetBSD: ldexp.c,v 1.9 1999/08/29 22:45:33 mycroft Exp $ */
/*
* Copyright (c) 1992, 1993
* The Regents of the University of California. All rights reserved.
/*-
* Copyright (c) 1999 The NetBSD Foundation, Inc.
* All rights reserved.
*
* This software was developed by the Computer Systems Engineering group
* at Lawrence Berkeley Laboratory under DARPA contract BG 91-66 and
* contributed to Berkeley.
* This code is derived from software contributed to The NetBSD Foundation
* by Charles M. Hannum.
*
* Redistribution and use in source and binary forms, with or without
* modification, are permitted provided that the following conditions
@ -18,34 +17,28 @@
* 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 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 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 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
* 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.
*/
#include <sys/cdefs.h>
#if defined(LIBC_SCCS) && !defined(lint)
#if 0
static const char sccsid[] = "@(#)ldexp.c 8.1 (Berkeley) 6/4/93";
#else
__RCSID("$NetBSD: ldexp.c,v 1.8 1999/08/29 19:04:03 mycroft Exp $");
#endif
__RCSID("$NetBSD: ldexp.c,v 1.9 1999/08/29 22:45:33 mycroft Exp $");
#endif /* LIBC_SCCS and not lint */
#include <sys/types.h>
@ -54,8 +47,7 @@ __RCSID("$NetBSD: ldexp.c,v 1.8 1999/08/29 19:04:03 mycroft Exp $");
#include <math.h>
/*
* double ldexp(double val, int exp)
* returns: val * (2**exp)
* Multiply the given value by 2^exp.
*/
double
ldexp(val, exp)
@ -68,85 +60,95 @@ ldexp(val, exp)
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);
/*
* 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.
* If input is zero, Inf or NaN, just return it.
*/
if (u.v == 0.0 || oldexp == DBL_EXP_INFNAN)
return (val);
if (oldexp == 0) {
/*
* u.v is denormal. We must adjust it so that the exponent
* arithmetic below will work.
*/
if (exp <= DBL_EXP_BIAS) {
/*
* Optimization: if the scaling can be done in a single
* multiply, or underflows, just do it now.
*/
if (exp <= -DBL_FRACBITS) {
errno = ERANGE;
return (0.0);
}
mul.v = 1.0;
mul.s.dbl_exp = exp + DBL_EXP_BIAS;
u.v *= mul.v;
if (u.v == 0.0) {
errno = ERANGE;
return (0.0);
}
return (u.v);
} else {
/*
* We know that exp is very large, and therefore the
* result cannot be denormal (though it may be Inf).
* Shift u.v by just enough to make it normal.
*/
mul.v = 1.0;
mul.s.dbl_exp = DBL_FRACBITS + DBL_EXP_BIAS;
u.v *= mul.v;
exp -= DBL_FRACBITS;
oldexp = u.s.dbl_exp;
}
}
/*
* u.v is now normalized and oldexp has been adjusted if necessary.
* Calculate the new exponent and check for underflow and overflow.
*/
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).
* The result overflowed; return +/-Inf.
*/
u.s.dbl_exp = DBL_EXP_INFNAN;
u.s.dbl_frach = 0;
u.s.dbl_fracl = 0;
errno = ERANGE;
return (u.v);
} else if (newexp <= 0) {
/*
* The output number is either 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).
* Denormalize the result. We do this with a multiply. If exp
* is very large, it won't fit in a double, so we have to
* adjust the exponent first. This is safe because we know
* that u.v is normal at this point.
*/
mul.v = 1.0;
while (exp <= -DBL_EXP_BIAS) {
mul.s.dbl_exp = 1;
val *= mul.v;
exp += DBL_EXP_BIAS - 1;
if (exp <= -DBL_EXP_BIAS) {
u.s.dbl_exp = 1;
exp += oldexp - 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;
mul.s.dbl_exp = exp + DBL_EXP_BIAS;
u.v *= mul.v;
return (u.v);
} else {
/*
* The result is normal; just replace the old exponent with the
* new one.
*/
u.s.dbl_exp = newexp;
return (u.v);
}
/*
* Both oldexp and newexp are positive; just replace the
* old exponent with the new one.
*/
u.s.dbl_exp = newexp;
return (u.v);
}

120
lib/libc/arch/ns32k/gen/ldexp.c
View File

@ -1,7 +1,7 @@
/* $NetBSD: ldexp.c,v 1.1 1999/08/29 19:08:44 mycroft Exp $ */
/* $NetBSD: ldexp.c,v 1.2 1999/08/29 22:45:34 mycroft Exp $ */
/*-
* Copyright (c) 1998 The NetBSD Foundation, Inc.
* Copyright (c) 1999 The NetBSD Foundation, Inc.
* All rights reserved.
*
* This code is derived from software contributed to The NetBSD Foundation
@ -38,31 +38,117 @@
#include <sys/cdefs.h>
#if defined(LIBC_SCCS) && !defined(lint)
__RCSID("$NetBSD: ldexp.c,v 1.1 1999/08/29 19:08:44 mycroft Exp $");
__RCSID("$NetBSD: ldexp.c,v 1.2 1999/08/29 22:45:34 mycroft Exp $");
#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).
* Multiply the given value by 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 __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);
u.v = val;
oldexp = u.s.dbl_exp;
/*
* If input is zero, Inf or NaN, just return it.
*/
if (u.v == 0.0 || oldexp == DBL_EXP_INFNAN)
return (val);
if (oldexp == 0) {
/*
* u.v is denormal. We must adjust it so that the exponent
* arithmetic below will work.
*/
if (exp <= DBL_EXP_BIAS) {
/*
* Optimization: if the scaling can be done in a single
* multiply, or underflows, just do it now.
*/
if (exp <= -DBL_FRACBITS) {
errno = ERANGE;
return (0.0);
}
mul.v = 1.0;
mul.s.dbl_exp = exp + DBL_EXP_BIAS;
u.v *= mul.v;
if (u.v == 0.0) {
errno = ERANGE;
return (0.0);
}
return (u.v);
} else {
/*
* We know that exp is very large, and therefore the
* result cannot be denormal (though it may be Inf).
* Shift u.v by just enough to make it normal.
*/
mul.v = 1.0;
mul.s.dbl_exp = DBL_FRACBITS + DBL_EXP_BIAS;
u.v *= mul.v;
exp -= DBL_FRACBITS;
oldexp = u.s.dbl_exp;
}
}
/*
* u.v is now normalized and oldexp has been adjusted if necessary.
* Calculate the new exponent and check for underflow and overflow.
*/
newexp = oldexp + exp;
if (newexp >= DBL_EXP_INFNAN) {
/*
* The result overflowed; return +/-Inf.
*/
u.s.dbl_exp = DBL_EXP_INFNAN;
u.s.dbl_frach = 0;
u.s.dbl_fracl = 0;
errno = ERANGE;
return (u.v);
} else if (newexp <= 0) {
/*
* The output number is either denormal or underflows (see
* comments in machine/ieee.h).
*/
if (newexp <= -DBL_FRACBITS) {
errno = ERANGE;
return (0.0);
}
/*
* Denormalize the result. We do this with a multiply. If exp
* is very large, it won't fit in a double, so we have to
* adjust the exponent first. This is safe because we know
* that u.v is normal at this point.
*/
if (exp <= -DBL_EXP_BIAS) {
u.s.dbl_exp = 1;
exp += oldexp - 1;
}
mul.v = 1.0;
mul.s.dbl_exp = exp + DBL_EXP_BIAS;
u.v *= mul.v;
return (u.v);
} else {
/*
* The result is normal; just replace the old exponent with the
* new one.
*/
u.s.dbl_exp = newexp;
return (u.v);
}
}

192
lib/libc/arch/powerpc/gen/ldexp.c
View File

@ -1,12 +1,11 @@
/* $NetBSD: ldexp.c,v 1.5 1999/08/29 19:04:03 mycroft Exp $ */
/* $NetBSD: ldexp.c,v 1.6 1999/08/29 22:45:34 mycroft Exp $ */
/*
* Copyright (c) 1992, 1993
* The Regents of the University of California. All rights reserved.
/*-
* Copyright (c) 1999 The NetBSD Foundation, Inc.
* All rights reserved.
*
* This software was developed by the Computer Systems Engineering group
* at Lawrence Berkeley Laboratory under DARPA contract BG 91-66 and
* contributed to Berkeley.
* This code is derived from software contributed to The NetBSD Foundation
* by Charles M. Hannum.
*
* Redistribution and use in source and binary forms, with or without
* modification, are permitted provided that the following conditions
@ -18,34 +17,28 @@
* 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 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 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 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
* 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.
*/
#include <sys/cdefs.h>
#if defined(LIBC_SCCS) && !defined(lint)
#if 0
static const char sccsid[] = "@(#)ldexp.c 8.1 (Berkeley) 6/4/93";
#else
__RCSID("$NetBSD: ldexp.c,v 1.5 1999/08/29 19:04:03 mycroft Exp $");
#endif
__RCSID("$NetBSD: ldexp.c,v 1.6 1999/08/29 22:45:34 mycroft Exp $");
#endif /* LIBC_SCCS and not lint */
#include <sys/types.h>
@ -54,8 +47,7 @@ __RCSID("$NetBSD: ldexp.c,v 1.5 1999/08/29 19:04:03 mycroft Exp $");
#include <math.h>
/*
* double ldexp(double val, int exp)
* returns: val * (2**exp)
* Multiply the given value by 2^exp.
*/
double
ldexp(val, exp)
@ -68,85 +60,95 @@ ldexp(val, exp)
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);
/*
* 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.
* If input is zero, Inf or NaN, just return it.
*/
if (u.v == 0.0 || oldexp == DBL_EXP_INFNAN)
return (val);
if (oldexp == 0) {
/*
* u.v is denormal. We must adjust it so that the exponent
* arithmetic below will work.
*/
if (exp <= DBL_EXP_BIAS) {
/*
* Optimization: if the scaling can be done in a single
* multiply, or underflows, just do it now.
*/
if (exp <= -DBL_FRACBITS) {
errno = ERANGE;
return (0.0);
}
mul.v = 1.0;
mul.s.dbl_exp = exp + DBL_EXP_BIAS;
u.v *= mul.v;
if (u.v == 0.0) {
errno = ERANGE;
return (0.0);
}
return (u.v);
} else {
/*
* We know that exp is very large, and therefore the
* result cannot be denormal (though it may be Inf).
* Shift u.v by just enough to make it normal.
*/
mul.v = 1.0;
mul.s.dbl_exp = DBL_FRACBITS + DBL_EXP_BIAS;
u.v *= mul.v;
exp -= DBL_FRACBITS;
oldexp = u.s.dbl_exp;
}
}
/*
* u.v is now normalized and oldexp has been adjusted if necessary.
* Calculate the new exponent and check for underflow and overflow.
*/
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).
* The result overflowed; return +/-Inf.
*/
u.s.dbl_exp = DBL_EXP_INFNAN;
u.s.dbl_frach = 0;
u.s.dbl_fracl = 0;
errno = ERANGE;
return (u.v);
} else if (newexp <= 0) {
/*
* The output number is either 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).
* Denormalize the result. We do this with a multiply. If exp
* is very large, it won't fit in a double, so we have to
* adjust the exponent first. This is safe because we know
* that u.v is normal at this point.
*/
mul.v = 1.0;
while (exp <= -DBL_EXP_BIAS) {
mul.s.dbl_exp = 1;
val *= mul.v;
exp += DBL_EXP_BIAS - 1;
if (exp <= -DBL_EXP_BIAS) {
u.s.dbl_exp = 1;
exp += oldexp - 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;
mul.s.dbl_exp = exp + DBL_EXP_BIAS;
u.v *= mul.v;
return (u.v);
} else {
/*
* The result is normal; just replace the old exponent with the
* new one.
*/
u.s.dbl_exp = newexp;
return (u.v);
}
/*
* Both oldexp and newexp are positive; just replace the
* old exponent with the new one.
*/
u.s.dbl_exp = newexp;
return (u.v);
}

192
lib/libc/arch/sparc/gen/ldexp.c
View File

@ -1,12 +1,11 @@
/* $NetBSD: ldexp.c,v 1.5 1999/08/29 19:04:03 mycroft Exp $ */
/* $NetBSD: ldexp.c,v 1.6 1999/08/29 22:45:34 mycroft Exp $ */
/*
* Copyright (c) 1992, 1993
* The Regents of the University of California. All rights reserved.
/*-
* Copyright (c) 1999 The NetBSD Foundation, Inc.
* All rights reserved.
*
* This software was developed by the Computer Systems Engineering group
* at Lawrence Berkeley Laboratory under DARPA contract BG 91-66 and
* contributed to Berkeley.
* This code is derived from software contributed to The NetBSD Foundation
* by Charles M. Hannum.
*
* Redistribution and use in source and binary forms, with or without
* modification, are permitted provided that the following conditions
@ -18,34 +17,28 @@
* 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 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 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 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
* 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.
*/
#include <sys/cdefs.h>
#if defined(LIBC_SCCS) && !defined(lint)
#if 0
static const char sccsid[] = "@(#)ldexp.c 8.1 (Berkeley) 6/4/93";
#else
__RCSID("$NetBSD: ldexp.c,v 1.5 1999/08/29 19:04:03 mycroft Exp $");
#endif
__RCSID("$NetBSD: ldexp.c,v 1.6 1999/08/29 22:45:34 mycroft Exp $");
#endif /* LIBC_SCCS and not lint */
#include <sys/types.h>
@ -54,8 +47,7 @@ __RCSID("$NetBSD: ldexp.c,v 1.5 1999/08/29 19:04:03 mycroft Exp $");
#include <math.h>
/*
* double ldexp(double val, int exp)
* returns: val * (2**exp)
* Multiply the given value by 2^exp.
*/
double
ldexp(val, exp)
@ -68,85 +60,95 @@ ldexp(val, exp)
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);
/*
* 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.
* If input is zero, Inf or NaN, just return it.
*/
if (u.v == 0.0 || oldexp == DBL_EXP_INFNAN)
return (val);
if (oldexp == 0) {
/*
* u.v is denormal. We must adjust it so that the exponent
* arithmetic below will work.
*/
if (exp <= DBL_EXP_BIAS) {
/*
* Optimization: if the scaling can be done in a single
* multiply, or underflows, just do it now.
*/
if (exp <= -DBL_FRACBITS) {
errno = ERANGE;
return (0.0);
}
mul.v = 1.0;
mul.s.dbl_exp = exp + DBL_EXP_BIAS;
u.v *= mul.v;
if (u.v == 0.0) {
errno = ERANGE;
return (0.0);
}
return (u.v);
} else {
/*
* We know that exp is very large, and therefore the
* result cannot be denormal (though it may be Inf).
* Shift u.v by just enough to make it normal.
*/
mul.v = 1.0;
mul.s.dbl_exp = DBL_FRACBITS + DBL_EXP_BIAS;
u.v *= mul.v;
exp -= DBL_FRACBITS;
oldexp = u.s.dbl_exp;
}
}
/*
* u.v is now normalized and oldexp has been adjusted if necessary.
* Calculate the new exponent and check for underflow and overflow.
*/
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).
* The result overflowed; return +/-Inf.
*/
u.s.dbl_exp = DBL_EXP_INFNAN;
u.s.dbl_frach = 0;
u.s.dbl_fracl = 0;
errno = ERANGE;
return (u.v);
} else if (newexp <= 0) {
/*
* The output number is either 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).
* Denormalize the result. We do this with a multiply. If exp
* is very large, it won't fit in a double, so we have to
* adjust the exponent first. This is safe because we know
* that u.v is normal at this point.
*/
mul.v = 1.0;
while (exp <= -DBL_EXP_BIAS) {
mul.s.dbl_exp = 1;
val *= mul.v;
exp += DBL_EXP_BIAS - 1;
if (exp <= -DBL_EXP_BIAS) {
u.s.dbl_exp = 1;
exp += oldexp - 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;
mul.s.dbl_exp = exp + DBL_EXP_BIAS;
u.v *= mul.v;
return (u.v);
} else {
/*
* The result is normal; just replace the old exponent with the
* new one.
*/
u.s.dbl_exp = newexp;
return (u.v);
}
/*
* Both oldexp and newexp are positive; just replace the
* old exponent with the new one.
*/
u.s.dbl_exp = newexp;
return (u.v);
}

192
lib/libc/arch/sparc64/gen/ldexp.c
View File

@ -1,12 +1,11 @@
/* $NetBSD: ldexp.c,v 1.4 1999/08/29 19:04:03 mycroft Exp $ */
/* $NetBSD: ldexp.c,v 1.5 1999/08/29 22:45:34 mycroft Exp $ */
/*
* Copyright (c) 1992, 1993
* The Regents of the University of California. All rights reserved.
/*-
* Copyright (c) 1999 The NetBSD Foundation, Inc.
* All rights reserved.
*
* This software was developed by the Computer Systems Engineering group
* at Lawrence Berkeley Laboratory under DARPA contract BG 91-66 and
* contributed to Berkeley.
* This code is derived from software contributed to The NetBSD Foundation
* by Charles M. Hannum.
*
* Redistribution and use in source and binary forms, with or without
* modification, are permitted provided that the following conditions
@ -18,34 +17,28 @@
* 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 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 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 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
* 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.
*/
#include <sys/cdefs.h>
#if defined(LIBC_SCCS) && !defined(lint)
#if 0
static const char sccsid[] = "@(#)ldexp.c 8.1 (Berkeley) 6/4/93";
#else
__RCSID("$NetBSD: ldexp.c,v 1.4 1999/08/29 19:04:03 mycroft Exp $");
#endif
__RCSID("$NetBSD: ldexp.c,v 1.5 1999/08/29 22:45:34 mycroft Exp $");
#endif /* LIBC_SCCS and not lint */
#include <sys/types.h>
@ -54,8 +47,7 @@ __RCSID("$NetBSD: ldexp.c,v 1.4 1999/08/29 19:04:03 mycroft Exp $");
#include <math.h>
/*
* double ldexp(double val, int exp)
* returns: val * (2**exp)
* Multiply the given value by 2^exp.
*/
double
ldexp(val, exp)
@ -68,85 +60,95 @@ ldexp(val, exp)
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);
/*
* 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.
* If input is zero, Inf or NaN, just return it.
*/
if (u.v == 0.0 || oldexp == DBL_EXP_INFNAN)
return (val);
if (oldexp == 0) {
/*
* u.v is denormal. We must adjust it so that the exponent
* arithmetic below will work.
*/
if (exp <= DBL_EXP_BIAS) {
/*
* Optimization: if the scaling can be done in a single
* multiply, or underflows, just do it now.
*/
if (exp <= -DBL_FRACBITS) {
errno = ERANGE;
return (0.0);
}
mul.v = 1.0;
mul.s.dbl_exp = exp + DBL_EXP_BIAS;
u.v *= mul.v;
if (u.v == 0.0) {
errno = ERANGE;
return (0.0);
}
return (u.v);
} else {
/*
* We know that exp is very large, and therefore the
* result cannot be denormal (though it may be Inf).
* Shift u.v by just enough to make it normal.
*/
mul.v = 1.0;
mul.s.dbl_exp = DBL_FRACBITS + DBL_EXP_BIAS;
u.v *= mul.v;
exp -= DBL_FRACBITS;
oldexp = u.s.dbl_exp;
}
}
/*
* u.v is now normalized and oldexp has been adjusted if necessary.
* Calculate the new exponent and check for underflow and overflow.
*/
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).
* The result overflowed; return +/-Inf.
*/
u.s.dbl_exp = DBL_EXP_INFNAN;
u.s.dbl_frach = 0;
u.s.dbl_fracl = 0;
errno = ERANGE;
return (u.v);
} else if (newexp <= 0) {
/*
* The output number is either 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).
* Denormalize the result. We do this with a multiply. If exp
* is very large, it won't fit in a double, so we have to
* adjust the exponent first. This is safe because we know
* that u.v is normal at this point.
*/
mul.v = 1.0;
while (exp <= -DBL_EXP_BIAS) {
mul.s.dbl_exp = 1;
val *= mul.v;
exp += DBL_EXP_BIAS - 1;
if (exp <= -DBL_EXP_BIAS) {
u.s.dbl_exp = 1;
exp += oldexp - 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;
mul.s.dbl_exp = exp + DBL_EXP_BIAS;
u.v *= mul.v;
return (u.v);
} else {
/*
* The result is normal; just replace the old exponent with the
* new one.
*/
u.s.dbl_exp = newexp;
return (u.v);
}
/*
* Both oldexp and newexp are positive; just replace the
* old exponent with the new one.
*/
u.s.dbl_exp = newexp;
return (u.v);
}