/*
* 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
* 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 2004 Sun Microsystems, Inc. All rights reserved.
* Use is subject to license terms.
*/
#pragma ident "%Z%%M% %I% %E% SMI"
/*
* _X_cplx_div(z, w) returns z / w with infinities handled according
* to C99.
*
* If z and w are both finite and w is nonzero, _X_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, _X_cplx_div delivers an infinite
* result. If z is finite and w is infinite, _X_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, _X_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.
*/
#endif
static union {
int i;
float f;
} inf = {
0x7f800000
};
/*
* Return +1 if x is +Inf, -1 if x is -Inf, and 0 otherwise
*/
static int
testinfl(long double x)
{
union {
int i[3];
long double e;
} xx;
xx.e = x;
return (0);
}
long double _Complex
_X_cplx_div(long double _Complex z, long double _Complex w)
{
long double _Complex v;
union {
int i[3];
long double e;
long double a, b, c, d, r;
/*
* 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 exponents to estimate |z| and |w| */
aa.e = a;
bb.e = b;
cc.e = c;
dd.e = d;
/* check for special cases */
r = 0.0f;
i = testinfl(c);
j = testinfl(d);
if (i | j) { /* w is infinite */
/*
* "factor out" infinity, being careful to preserve
* signs of finite values
*/
if (ez >= 0x7ffe) {
/* scale to avoid overflow below */
c *= 0.5f;
d *= 0.5f;
}
}
((long double *)&v)[0] = (a * c + b * d) * r;
((long double *)&v)[1] = (b * c - a * d) * r;
return (v);
}
/* w is zero; multiply z by 1/Re(w) - I * Im(w) */
c = 1.0f / c;
i = testinfl(a);
j = testinfl(b);
if (i | j) { /* z is infinite */
a = i;
b = j;
}
((long double *)&v)[0] = a * c + b * d;
((long double *)&v)[1] = b * c - a * d;
return (v);
}
i = testinfl(a);
j = testinfl(b);
if (i | j) { /* z is infinite */
a = i;
b = j;
r = inf.f;
}
((long double *)&v)[0] = a * c + b * d;
((long double *)&v)[1] = b * c - a * d;
return (v);
}
/*
* Scale c and d to compute 1/|w|^2 and the real and imaginary
* parts of the quotient.
*/
}
ss.i[0] = 0;
c *= ss.e;
d *= ss.e;
r = 1.0f / (c * c + d * d);
c *= ss.e;
d *= ss.e;
((long double *)&v)[0] = (a * c + b * d) * r;
((long double *)&v)[1] = (b * c - a * d) * r;
return (v);
}