s_scalbn.c

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Author : Pierre-Loup A. Griffais
Date : 2014-09-11 19:24:42
Hash : 24c86b55
Message : [X11] Reconcile logical keyboard state with physical state on FocusIn since the window system doesn't do it for us like other platforms. This prevents sticky keys and missed keys when going in and out of focus, for example Alt would appear to stick if switching away from an SDL app with Alt-Tab and had to be pressed again. CR: Sam

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