fixedmath.h

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/*
 * $Id: fixedmath.h,v 1.35 2006/06/11 04:16:14 weiym Exp $
 *
 *             MiniGUI for Linux/uClinux, eCos, uC/OS-II, VxWorks, 
 *                     pSOS, ThreadX, NuCleus, OSE, and Win32.
 *
 *             Copyright (C) 2002-2006 Feynman Software.  
 *             Copyright (C) 1998-2002 Wei Yongming.
 *
 *             Fixed-point math routins come from Allegro (a gift software)
 *             by Shawn Hargreaves and others.
 */

#ifndef _MGUI_FIXED_MATH_H
#define _MGUI_FIXED_MATH_H

#include <errno.h>
#include <math.h>

/* Set up for C function definitions, even when using C++ */
#ifdef __cplusplus
extern "C" {
#endif

#ifdef _FIXED_MATH

MG_EXPORT fixed fixsqrt (fixed x);

MG_EXPORT fixed fixhypot (fixed x, fixed y);

MG_EXPORT fixed fixatan (fixed x);

MG_EXPORT fixed fixatan2 (fixed y, fixed x);

extern MG_EXPORT fixed _cos_tbl[];
extern MG_EXPORT fixed _tan_tbl[];
extern MG_EXPORT fixed _acos_tbl[];

/************************** inline fixed point math functions *****************/
/* ftofix and fixtof are used in generic C versions of fixmul and fixdiv */

static inline fixed ftofix (double x)
{ 
   if (x > 32767.0) {
      errno = ERANGE;
      return 0x7FFFFFFF;
   }

   if (x < -32767.0) {
      errno = ERANGE;
      return -0x7FFFFFFF;
   }

   return (long)(x * 65536.0 + (x < 0 ? -0.5 : 0.5)); 
}

static inline double fixtof (fixed x)
{ 
   return (double)x / 65536.0; 
}


static inline fixed fixadd (fixed x, fixed y)
{
   fixed result = x + y;

   if (result >= 0) {
      if ((x < 0) && (y < 0)) {
         errno = ERANGE;
         return -0x7FFFFFFF;
      }
      else
         return result;
   }
   else {
      if ((x > 0) && (y > 0)) {
         errno = ERANGE;
         return 0x7FFFFFFF;
      }
      else
         return result;
   }
}

static inline fixed fixsub (fixed x, fixed y)
{
   fixed result = x - y;

   if (result >= 0) {
      if ((x < 0) && (y > 0)) {
         errno = ERANGE;
         return -0x7FFFFFFF;
      }
      else
         return result;
   }
   else {
      if ((x > 0) && (y < 0)) {
         errno = ERANGE;
         return 0x7FFFFFFF;
      }
      else
         return result;
   }
}

static inline fixed fixmul (fixed x, fixed y)
{
   return ftofix(fixtof(x) * fixtof(y));
}

static inline fixed fixdiv (fixed x, fixed y)
{
   if (y == 0) {
      errno = ERANGE;
      return (x < 0) ? -0x7FFFFFFF : 0x7FFFFFFF;
   }
   else
      return ftofix(fixtof(x) / fixtof(y));
}

static inline int fixceil (fixed x)
{
   if (x > 0x7FFF0000) {
      errno = ERANGE;
      return 0x7FFF;
   }

   x += 0xFFFF;
   if (x > 0)
       return (x >> 16);
   else
       return ~((~x) >> 16);
}

static inline fixed itofix (int x)
{ 
   return x << 16;
}

static inline int fixtoi (fixed x)
{ 
   return (x >> 16) + ((x & 0x8000) >> 15);
}

static inline fixed fixcos (fixed x)
{
   return _cos_tbl[((x + 0x4000) >> 15) & 0x1FF];
}

static inline fixed fixsin (fixed x)
{ 
   return _cos_tbl[((x - 0x400000 + 0x4000) >> 15) & 0x1FF];
}

static inline fixed fixtan (fixed x)
{ 
   return _tan_tbl[((x + 0x4000) >> 15) & 0xFF];
}

static inline fixed fixacos (fixed x)
{
   if ((x < -65536) || (x > 65536)) {
      errno = EDOM;
      return 0;
   }

   return _acos_tbl[(x+65536+127)>>8];
}

static inline fixed fixasin (fixed x)
{ 
   if ((x < -65536) || (x > 65536)) {
      errno = EDOM;
      return 0;
   }

   return 0x00400000 - _acos_tbl[(x+65536+127)>>8];
}

#endif /* _FIXED_MATH */

/* Ends C function definitions when using C++ */
#ifdef __cplusplus
}
#endif

#endif /* _MGUI_FIXED_MATH_H */

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