s_scalbn.c

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Author : David Ludwig
Date : 2014-12-03 10:55:23
Hash : 70438be2
Message : WinRT: fixed bug whereby SDL would override an app's default orientation WinRT apps can set a default, preferred orientation via a .appxmanifest file. SDL was overriding this on app startup, and making the app use all possible orientations (landscape and portrait). Thanks to Eric Wing for the heads up on this!

src/libm/s_scalbn.c

/* @(#)s_scalbn.c 5.1 93/09/24 */
/*
 * ====================================================
 * Copyright (C) 1993 by Sun Microsystems, Inc. All rights reserved.
 *
 * Developed at SunPro, a Sun Microsystems, Inc. business.
 * Permission to use, copy, modify, and distribute this
 * software is freely granted, provided that this notice
 * is preserved.
 * ====================================================
 */

#if defined(LIBM_SCCS) && !defined(lint)
static const char rcsid[] =
    "$NetBSD: s_scalbn.c,v 1.8 1995/05/10 20:48:08 jtc Exp $";
#endif

/*
 * scalbn (double x, int n)
 * scalbn(x,n) returns x* 2**n  computed by  exponent
 * manipulation rather than by actually performing an
 * exponentiation or a multiplication.
 */

#include "math_libm.h"
#include "math_private.h"

libm_hidden_proto(copysign)
#ifdef __STDC__
     static const double
#else
     static double
#endif
       two54 = 1.80143985094819840000e+16,      /* 0x43500000, 0x00000000 */
         twom54 = 5.55111512312578270212e-17,   /* 0x3C900000, 0x00000000 */
         huge_val = 1.0e+300, tiny = 1.0e-300;

libm_hidden_proto(scalbn)
#ifdef __STDC__
     double scalbn(double x, int n)
#else
     double scalbn(x, n)
     double x;
     int n;
#endif
{
    int32_t k, hx, lx;
    EXTRACT_WORDS(hx, lx, x);
    k = (hx & 0x7ff00000) >> 20;        /* extract exponent */
    if (k == 0) {               /* 0 or subnormal x */
        if ((lx | (hx & 0x7fffffff)) == 0)
            return x;           /* +-0 */
        x *= two54;
        GET_HIGH_WORD(hx, x);
        k = ((hx & 0x7ff00000) >> 20) - 54;
        if (n < -50000)
            return tiny * x;    /* underflow */
    }
    if (k == 0x7ff)
        return x + x;           /* NaN or Inf */
    k = k + n;
    if (k > 0x7fe)
        return huge_val * copysign(huge_val, x);        /* overflow  */
    if (k > 0) {                /* normal result */
        SET_HIGH_WORD(x, (hx & 0x800fffff) | (k << 20));
        return x;
    }
    if (k <= -54) {
        if (n > 50000)          /* in case integer overflow in n+k */
            return huge_val * copysign(huge_val, x);    /* overflow */
        else
            return tiny * copysign(tiny, x);    /* underflow */
    }
    k += 54;                    /* subnormal result */
    SET_HIGH_WORD(x, (hx & 0x800fffff) | (k << 20));
    return x * twom54;
}

libm_hidden_def(scalbn)

kc3-lang/SDL/src/libm/s_scalbn.c

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kc3-lang/SDL /src/libm/s_scalbn.c