divdc3.c revision 2d1fdb26e458c4ddc04155c1d421bced3ba90cd0 
1/* ===-- divdc3.c - Implement __divdc3 -------------------------------------===
2 *
3 *                     The LLVM Compiler Infrastructure
4 *
5 * This file is dual licensed under the MIT and the University of Illinois Open
6 * Source Licenses. See LICENSE.TXT for details.
7 *
8 * ===----------------------------------------------------------------------===
9 *
10 * This file implements __divdc3 for the compiler_rt library.
11 *
12 * ===----------------------------------------------------------------------===
13 */
14
15#include "int_lib.h"
16#include "int_math.h"
17
18/* Returns: the quotient of (a + ib) / (c + id) */
19
20COMPILER_RT_ABI double _Complex
21__divdc3(double __a, double __b, double __c, double __d)
22{
23    int __ilogbw = 0;
24    double __logbw = crt_logb(crt_fmax(crt_fabs(__c), crt_fabs(__d)));
25    if (crt_isfinite(__logbw))
26    {
27        __ilogbw = (int)__logbw;
28        __c = crt_scalbn(__c, -__ilogbw);
29        __d = crt_scalbn(__d, -__ilogbw);
30    }
31    double __denom = __c * __c + __d * __d;
32    double _Complex z;
33    __real__ z = crt_scalbn((__a * __c + __b * __d) / __denom, -__ilogbw);
34    __imag__ z = crt_scalbn((__b * __c - __a * __d) / __denom, -__ilogbw);
35    if (crt_isnan(__real__ z) && crt_isnan(__imag__ z))
36    {
37        if ((__denom == 0.0) && (!crt_isnan(__a) || !crt_isnan(__b)))
38        {
39            __real__ z = crt_copysign(CRT_INFINITY, __c) * __a;
40            __imag__ z = crt_copysign(CRT_INFINITY, __c) * __b;
41        }
42        else if ((crt_isinf(__a) || crt_isinf(__b)) &&
43                 crt_isfinite(__c) && crt_isfinite(__d))
44        {
45            __a = crt_copysign(crt_isinf(__a) ? 1.0 : 0.0, __a);
46            __b = crt_copysign(crt_isinf(__b) ? 1.0 : 0.0, __b);
47            __real__ z = CRT_INFINITY * (__a * __c + __b * __d);
48            __imag__ z = CRT_INFINITY * (__b * __c - __a * __d);
49        }
50        else if (crt_isinf(__logbw) && __logbw > 0.0 &&
51                 crt_isfinite(__a) && crt_isfinite(__b))
52        {
53            __c = crt_copysign(crt_isinf(__c) ? 1.0 : 0.0, __c);
54            __d = crt_copysign(crt_isinf(__d) ? 1.0 : 0.0, __d);
55            __real__ z = 0.0 * (__a * __c + __b * __d);
56            __imag__ z = 0.0 * (__b * __c - __a * __d);
57        }
58    }
59    return z;
60}
61