include/c99_math.h

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/**
 * Wrapper for math.h which makes sure we have definitions of all the c99
 * functions.
 */


#ifndef _C99_MATH_H_
#define _C99_MATH_H_

#include <math.h>
#include "c99_compat.h"


#if defined(_MSC_VER)

/* This is to ensure that we get M_PI, etc. definitions */
#if !defined(_USE_MATH_DEFINES)
#error _USE_MATH_DEFINES define required when building with MSVC
#endif 

#if _MSC_VER < 1800
#define isfinite(x) _finite((double)(x))
#define isnan(x) _isnan((double)(x))
#endif /* _MSC_VER < 1800 */

#if _MSC_VER < 1800
static inline double log2( double x )
{
   const double invln2 = 1.442695041;
   return log( x ) * invln2;
}

static inline double
round(double x)
{
   return x >= 0.0 ? floor(x + 0.5) : ceil(x - 0.5);
}

static inline float
roundf(float x)
{
   return x >= 0.0f ? floorf(x + 0.5f) : ceilf(x - 0.5f);
}
#endif

#ifndef INFINITY
#include <float.h> // DBL_MAX
#define INFINITY (DBL_MAX + DBL_MAX)
#endif

#ifndef NAN
#define NAN (INFINITY - INFINITY)
#endif

#endif /* _MSC_VER */


#if (defined(_MSC_VER) && _MSC_VER < 1800) || \
    (!defined(_MSC_VER) && \
     __STDC_VERSION__ < 199901L && \
     (!defined(_XOPEN_SOURCE) || _XOPEN_SOURCE < 600) && \
     !defined(__cplusplus))

static inline long int
lrint(double d)
{
   long int rounded = (long int)(d + 0.5);

   if (d - floor(d) == 0.5) {
      if (rounded % 2 != 0)
         rounded += (d > 0) ? -1 : 1;
   }

   return rounded;
}

static inline long int
lrintf(float f)
{
   long int rounded = (long int)(f + 0.5f);

   if (f - floorf(f) == 0.5f) {
      if (rounded % 2 != 0)
         rounded += (f > 0) ? -1 : 1;
   }

   return rounded;
}

static inline long long int
llrint(double d)
{
   long long int rounded = (long long int)(d + 0.5);

   if (d - floor(d) == 0.5) {
      if (rounded % 2 != 0)
         rounded += (d > 0) ? -1 : 1;
   }

   return rounded;
}

static inline long long int
llrintf(float f)
{
   long long int rounded = (long long int)(f + 0.5f);

   if (f - floorf(f) == 0.5f) {
      if (rounded % 2 != 0)
         rounded += (f > 0) ? -1 : 1;
   }

   return rounded;
}

static inline float
exp2f(float f)
{
   return powf(2.0f, f);
}

static inline double
exp2(double d)
{
   return pow(2.0, d);
}

#endif /* C99 */


/*
 * signbit() is a macro on Linux.  Not available on Windows.
 */
#ifndef signbit
#define signbit(x) ((x) < 0.0f)
#endif


#ifndef M_PI
#define M_PI (3.14159265358979323846)
#endif

#ifndef M_E
#define M_E (2.7182818284590452354)
#endif

#ifndef M_LOG2E
#define M_LOG2E (1.4426950408889634074)
#endif

#ifndef FLT_MAX_EXP
#define FLT_MAX_EXP 128
#endif


#if defined(fpclassify)
/* ISO C99 says that fpclassify is a macro.  Assume that any implementation
 * of fpclassify, whether it's in a C99 compiler or not, will be a macro.
 */
#elif defined(__cplusplus)
/* For C++, fpclassify() should be defined in <cmath> */
#elif defined(_MSC_VER)
/* Not required on VS2013 and above.  Oddly, the fpclassify() function
 * doesn't exist in such a form on MSVC.  This is an implementation using
 * slightly different lower-level Windows functions.
 */
#include <float.h>

static inline enum {FP_NAN, FP_INFINITE, FP_ZERO, FP_SUBNORMAL, FP_NORMAL}
fpclassify(double x)
{
   switch(_fpclass(x)) {
   case _FPCLASS_SNAN: /* signaling NaN */
   case _FPCLASS_QNAN: /* quiet NaN */
      return FP_NAN;
   case _FPCLASS_NINF: /* negative infinity */
   case _FPCLASS_PINF: /* positive infinity */
      return FP_INFINITE;
   case _FPCLASS_NN:   /* negative normal */
   case _FPCLASS_PN:   /* positive normal */
      return FP_NORMAL;
   case _FPCLASS_ND:   /* negative denormalized */
   case _FPCLASS_PD:   /* positive denormalized */
      return FP_SUBNORMAL;
   case _FPCLASS_NZ:   /* negative zero */
   case _FPCLASS_PZ:   /* positive zero */
      return FP_ZERO;
   default:
      /* Should never get here; but if we do, this will guarantee
       * that the pattern is not treated like a number.
       */
      return FP_NAN;
   }
}
#else
#error "Need to include or define an fpclassify function"
#endif


#endif /* #define _C99_MATH_H_ */