compiler-rt/lib/builtins/divtc3.c

/*===-- divtc3.c - Implement __divtc3 -------------------------------------===
 *
 *                     The LLVM Compiler Infrastructure
 *
 * This file is dual licensed under the MIT and the University of Illinois Open
 * Source Licenses. See LICENSE.TXT for details.
 *
 * ===----------------------------------------------------------------------===
 *
 * This file implements __divtc3 for the compiler_rt library.
 *
 *===----------------------------------------------------------------------===
 */

#define QUAD_PRECISION
#include "fp_lib.h"
#include "int_lib.h"
#include "int_math.h"

/* Returns: the quotient of (a + ib) / (c + id) */

COMPILER_RT_ABI Lcomplex
__divtc3(long double __a, long double __b, long double __c, long double __d)
{
    int __ilogbw = 0;
    long double __logbw =
        __compiler_rt_logbl(crt_fmaxl(crt_fabsl(__c), crt_fabsl(__d)));
    if (crt_isfinite(__logbw))
    {
        __ilogbw = (int)__logbw;
        __c = crt_scalbnl(__c, -__ilogbw);
        __d = crt_scalbnl(__d, -__ilogbw);
    }
    long double __denom = __c * __c + __d * __d;
    Lcomplex z;
    COMPLEX_REAL(z) = crt_scalbnl((__a * __c + __b * __d) / __denom, -__ilogbw);
    COMPLEX_IMAGINARY(z) = crt_scalbnl((__b * __c - __a * __d) / __denom, -__ilogbw);
    if (crt_isnan(COMPLEX_REAL(z)) && crt_isnan(COMPLEX_IMAGINARY(z)))
    {
        if ((__denom == 0.0) && (!crt_isnan(__a) || !crt_isnan(__b)))
        {
            COMPLEX_REAL(z) = crt_copysignl(CRT_INFINITY, __c) * __a;
            COMPLEX_IMAGINARY(z) = crt_copysignl(CRT_INFINITY, __c) * __b;
        }
        else if ((crt_isinf(__a) || crt_isinf(__b)) &&
                 crt_isfinite(__c) && crt_isfinite(__d))
        {
            __a = crt_copysignl(crt_isinf(__a) ? 1.0 : 0.0, __a);
            __b = crt_copysignl(crt_isinf(__b) ? 1.0 : 0.0, __b);
            COMPLEX_REAL(z) = CRT_INFINITY * (__a * __c + __b * __d);
            COMPLEX_IMAGINARY(z) = CRT_INFINITY * (__b * __c - __a * __d);
        }
        else if (crt_isinf(__logbw) && __logbw > 0.0 &&
                 crt_isfinite(__a) && crt_isfinite(__b))
        {
            __c = crt_copysignl(crt_isinf(__c) ? 1.0 : 0.0, __c);
            __d = crt_copysignl(crt_isinf(__d) ? 1.0 : 0.0, __d);
            COMPLEX_REAL(z) = 0.0 * (__a * __c + __b * __d);
            COMPLEX_IMAGINARY(z) = 0.0 * (__b * __c - __a * __d);
        }
    }
    return z;
}