freebsd-dev/lib/msun/ld80/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

108 lines
3.2 KiB
C

/*-
* SPDX-License-Identifier: BSD-2-Clause-FreeBSD
*
* Copyright (c) 2011 David Schultz <das@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.
*
* src/s_cexp.c converted to long double complex by Steven G. Kargl
*/
#include <sys/cdefs.h>
__FBSDID("$FreeBSD$");
#include <complex.h>
#include <float.h>
#ifdef __i386__
#include <ieeefp.h>
#endif
#include "fpmath.h"
#include "math.h"
#include "math_private.h"
#include "k_expl.h"
long double complex
cexpl (long double complex z)
{
long double c, exp_x, s, x, y;
uint64_t lx, ly;
uint16_t hx, hy;
ENTERI();
x = creall(z);
y = cimagl(z);
EXTRACT_LDBL80_WORDS(hy, ly, y);
hy &= 0x7fff;
/* cexp(x + I 0) = exp(x) + I 0 */
if ((hy | ly) == 0)
RETURNI(CMPLXL(expl(x), y));
EXTRACT_LDBL80_WORDS(hx, lx, x);
/* cexp(0 + I y) = cos(y) + I sin(y) */
if (((hx & 0x7fff) | lx) == 0) {
sincosl(y, &s, &c);
RETURNI(CMPLXL(c, s));
}
if (hy >= 0x7fff) {
if ((hx & 0x7fff) < 0x7fff || ((hx & 0x7fff) == 0x7fff &&
(lx & 0x7fffffffffffffffULL) != 0)) {
/* cexp(finite|NaN +- I Inf|NaN) = NaN + I NaN */
RETURNI(CMPLXL(y - y, y - y));
} else if (hx & 0x8000) {
/* cexp(-Inf +- I Inf|NaN) = 0 + I 0 */
RETURNI(CMPLXL(0.0, 0.0));
} else {
/* cexp(+Inf +- I Inf|NaN) = Inf + I NaN */
RETURNI(CMPLXL(x, y - y));
}
}
/*
* exp_ovfl = 11356.5234062941439497
* cexp_ovfl = 22755.3287906024445633
*/
if ((hx == 0x400c && lx > 0xb17217f7d1cf79acULL) ||
(hx == 0x400d && lx < 0xb1c6a8573de9768cULL)) {
/*
* x is between exp_ovfl and cexp_ovfl, so we must scale to
* avoid overflow in exp(x).
*/
RETURNI(__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);
RETURNI(CMPLXL(exp_x * c, exp_x * s));
}
}