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/*
* CDDL HEADER START
*
* The contents of this file are subject to the terms of the
* Common Development and Distribution License, Version 1.0 only
* (the "License"). You may not use this file except in compliance
* with the License.
*
* You can obtain a copy of the license at usr/src/OPENSOLARIS.LICENSE
* or http://www.opensolaris.org/os/licensing.
* See the License for the specific language governing permissions
* and limitations under the License.
*
* When distributing Covered Code, include this CDDL HEADER in each
* file and include the License file at usr/src/OPENSOLARIS.LICENSE.
* If applicable, add the following below this CDDL HEADER, with the
* fields enclosed by brackets "[]" replaced with your own identifying
* information: Portions Copyright [yyyy] [name of copyright owner]
*
* CDDL HEADER END
*/
/*
* Copyright 2003 Sun Microsystems, Inc. All rights reserved.
* Use is subject to license terms.
*/
/*
* On SPARC V8, _Q_cplx_div(v, z, w) sets *v = *z / *w with infin-
* ities handling according to C99.
*
* On SPARC V9, _Q_cplx_div(z, w) returns *z / *w with infinities
* handled according to C99.
*
* If z and w are both finite and w is nonzero, _Q_cplx_div delivers
* the complex quotient q according to the usual formula: let a =
* Re(z), b = Im(z), c = Re(w), and d = Im(w); then q = x + I * y
* where x = (a * c + b * d) / r and y = (b * c - a * d) / r with
* r = c * c + d * d. This implementation scales to avoid premature
* underflow or overflow.
*
* If z is neither NaN nor zero and w is zero, or if z is infinite
* and w is finite and nonzero, _Q_cplx_div delivers an infinite
* result. If z is finite and w is infinite, _Q_cplx_div delivers
* a zero result.
*
* If z and w are both zero or both infinite, or if either z or w is
* a complex NaN, _Q_cplx_div delivers NaN + I * NaN. C99 doesn't
* specify these cases.
*
* This implementation can raise spurious underflow, overflow, in-
* valid operation, inexact, and division-by-zero exceptions. C99
* allows this.
*/
#if !defined(sparc) && !defined(__sparc)
#error This code is for SPARC only
#endif
static union {
int i[4];
long double q;
} inf = {
0x7fff0000, 0, 0, 0
};
/*
* Return +1 if x is +Inf, -1 if x is -Inf, and 0 otherwise
*/
static int
testinfl(long double x)
{
union {
int i[4];
long double q;
} xx;
xx.q = x;
return (((((xx.i[0] << 1) - 0xfffe0000) | xx.i[1] | xx.i[2] | xx.i[3])
== 0)? (1 | (xx.i[0] >> 31)) : 0);
}
#ifdef __sparcv9
long double _Complex
_Q_cplx_div(const long double _Complex *z, const long double _Complex *w)
{
long double _Complex v = 0;
#else
void
_Q_cplx_div(long double _Complex *v, const long double _Complex *z,
const long double _Complex *w)
{
#endif
union {
int i[4];
long double q;
} aa, bb, cc, dd, ss;
long double a, b, c, d, r;
int ha, hb, hc, hd, hz, hw, hs, i, j;
/*
* The following is equivalent to
*
* a = creall(*z); b = cimagl(*z);
* c = creall(*w); d = cimagl(*w);
*/
a = ((long double *)z)[0];
b = ((long double *)z)[1];
c = ((long double *)w)[0];
d = ((long double *)w)[1];
/* extract high-order words to estimate |z| and |w| */
aa.q = a;
bb.q = b;
ha = aa.i[0] & ~0x80000000;
hb = bb.i[0] & ~0x80000000;
hz = (ha > hb)? ha : hb;
cc.q = c;
dd.q = d;
hc = cc.i[0] & ~0x80000000;
hd = dd.i[0] & ~0x80000000;
hw = (hc > hd)? hc : hd;
/* check for special cases */
if (hw >= 0x7fff0000) { /* w is inf or nan */
r = 0.0l;
i = testinfl(c);
j = testinfl(d);
if (i | j) { /* w is infinite */
/*
* "factor out" infinity, being careful to preserve
* signs of finite values
*/
c = i? i : ((cc.i[0] < 0)? -0.0l : 0.0l);
d = j? j : ((dd.i[0] < 0)? -0.0l : 0.0l);
if (hz >= 0x7ffe0000) {
/* scale to avoid overflow below */
c *= 0.5l;
d *= 0.5l;
}
}
goto done;
}
if (hw == 0 && (cc.i[1] | cc.i[2] | cc.i[3] |
dd.i[1] | dd.i[2] | dd.i[3]) == 0) {
/* w is zero; multiply z by 1/Re(w) - I * Im(w) */
r = 1.0l;
c = 1.0l / c;
i = testinfl(a);
j = testinfl(b);
if (i | j) { /* z is infinite */
a = i;
b = j;
}
goto done;
}
if (hz >= 0x7fff0000) { /* z is inf or nan */
r = 1.0l;
i = testinfl(a);
j = testinfl(b);
if (i | j) { /* z is infinite */
a = i;
b = j;
r = inf.q;
}
goto done;
}
/*
* Scale c and d to compute 1/|w|^2 and the real and imaginary
* parts of the quotient.
*/
hs = (((hw >> 2) - hw) + 0x6ffd7fff) & 0xffff0000;
if (hz < 0x00ea0000) { /* |z| < 2^-16149 */
if (((hw - 0x3e380000) | (0x40e90000 - hw)) >= 0)
hs = (((0x40e90000 - hw) >> 1) & 0xffff0000)
+ 0x3fff0000;
}
ss.i[0] = hs;
ss.i[1] = ss.i[2] = ss.i[3] = 0;
c *= ss.q;
d *= ss.q;
r = 1.0l / (c * c + d * d);
c *= ss.q;
d *= ss.q;
done:
#ifdef __sparcv9
((long double *)&v)[0] = (a * c + b * d) * r;
((long double *)&v)[1] = (b * c - a * d) * r;
return (v);
#else
((long double *)v)[0] = (a * c + b * d) * r;
((long double *)v)[1] = (b * c - a * d) * r;
#endif
}
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