freebsd-dev/lib/msun/ld128/s_cexpl.c
Steve Kargl 046e2d5db1 Implementations of cexpl()
The change implements cexpl() for both ld80 and ld128 architectures.
Testing was done on x86_64 and aarch64 systems.

Along the way sincos[fl]() use an optimization that reduces the argument
to being done one rather than twice.  This optimization actually pointed
to a bug in the ld128 version of sincosl(), which is now fixed.  In
addition, the minmax polynomial coefficients for sincosl() have been
updated.

A concise log of the file-by-file changes follows.

* include/complex.h:
  . Add a prototype for cexpl().

* lib/msun/Makefile:
  . Add s_cexpl.c to the build.
  . Setup a link for cexpl.3 to cexp.3.

* lib/msun/Symbol.map:
  . Expose cexpl symbol in libm shared library.

* lib/msun/ld128/s_cexpl.c:
  * Implementation of cexpl() for 128-bit long double architectures.
    Tested on an aarch64 system.

* lib/msun/ld80/s_cexpl.c:
  * Implementation of cexpl() for Intel 80-bit long double.

* lib/msun/man/cexp.3:
  . Document cexpl().

* lib/msun/man/complex.3:
  . Add a BUGS section about cpow[fl].

* lib/msun/src/s_cexp.c:
  . Include float.h for weak references on 53-bit long double targets.
  . Use sincos() to reduce argument reduction cost.

* lib/msun/src/s_cexpf.c:
  . Use sincosf() to reduce argument reduction cost.

* lib/msun/src/k_sincosl.h:
  . Catch up with the new minmax polynomial coefficients for the kernel for
    the 128-bit cosl() implementation.
  . BUG FIX: *cs was used where *sn should have been.  This means that sinl()
    was no computed correctly when iy != 0.

* lib/msun/src/s_cosl.c:
  . Include fpmath.h to get access to IEEEl2bits.
  . Replace M_PI_4 with pio4,  a 64-bit or 113-bit approximation for pi / 4.

PR:	216862
MFC after:	1 week
2021-11-05 13:51:42 +02:00

95 lines
2.9 KiB
C

/*-
* SPDX-License-Identifier: BSD-2-Clause-FreeBSD
*
* Copyright (c) 2019 Steven G. Kargl <kargl@FreeBSD.ORG>
* All rights reserved.
*
* Redistribution and use in source and binary forms, with or without
* modification, are permitted provided that the following conditions
* are met:
* 1. Redistributions of source code must retain the above copyright
* notice, this list of conditions and the following disclaimer.
* 2. Redistributions in binary form must reproduce the above copyright
* notice, this list of conditions and the following disclaimer in the
* documentation and/or other materials provided with the distribution.
*
* THIS SOFTWARE IS PROVIDED BY THE AUTHOR 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 AUTHOR 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>
__FBSDID("$FreeBSD$");
#include <complex.h>
#include <float.h>
#include <math.h>
#include "fpmath.h"
#include "math_private.h"
#include "k_expl.h"
/* XXX cexpl() should be converted to use bits likeo src/s_cexp.c. */
static const long double
cexp_ovfl = 2.27892930024498818830197576893019292e+04L,
exp_ovfl = 1.13565234062941439494919310779707649e+04L;
long double complex
cexpl(long double complex z)
{
long double c, exp_x, s, x, y;
x = creall(z);
y = cimagl(z);
/* cexp(x + I 0) = exp(x) + I 0 */
if (y == 0)
return (CMPLXL(expl(x), y));
/* cexp(0 + I y) = cos(y) + I sin(y) */
if (x == 0) {
sincosl(y, &s, &c);
return (CMPLXL(c, s));
}
if (!isfinite(y)) {
if (isfinite(x) || isnan(x)) {
/* cexp(finite|NaN +- I Inf|NaN) = NaN + I NaN */
return (CMPLXL(y - y, y - y));
} else if (isinf(x) && copysignl(1.L, x) < 0) {
/* cexp(-Inf +- I Inf|NaN) = 0 + I 0 */
return (CMPLXL(0.0, 0.0));
} else {
/* cexp(+Inf +- I Inf|NaN) = Inf + I NaN */
return (CMPLXL(x, y - y));
}
}
if (x > exp_ovfl && x < cexp_ovfl) {
/*
* x is between exp_ovfl and cexp_ovfl, so we must scale to
* avoid overflow in exp(x).
*/
return (__ldexp_cexpl(z, 0));
} else {
/*
* Cases covered here:
* - x < exp_ovfl and exp(x) won't overflow (common case)
* - x > cexp_ovfl, so exp(x) * s overflows for all s > 0
* - x = +-Inf (generated by exp())
* - x = NaN (spurious inexact exception from y)
*/
exp_x = expl(x);
sincosl(y, &s, &c);
return (CMPLXL(exp_x * c, exp_x * s));
}
}