sdl2_frt/src/libm/s_scalbn.c
Philipp Wiesemann 0e45984fa0 Fixed crash if initialization of EGL failed but was tried again later.
The internal function SDL_EGL_LoadLibrary() did not delete and remove a mostly
uninitialized data structure if loading the library first failed. A later try to
use EGL then skipped initialization and assumed it was previously successful
because the data structure now already existed. This led to at least one crash
in the internal function SDL_EGL_ChooseConfig() because a NULL pointer was
dereferenced to make a call to eglBindAPI().
2015-06-21 17:33:46 +02:00

80 lines
2.3 KiB
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)