mesa/src/mesa/pipe/p_util.h

/*
 * Mesa 3-D graphics library
 * Version:  6.5.2
 *
 * Copyright (C) 1999-2006  Brian Paul   All Rights Reserved.
 *
 * Permission is hereby granted, free of charge, to any person obtaining a
 * copy of this software and associated documentation files (the "Software"),
 * to deal in the Software without restriction, including without limitation
 * the rights to use, copy, modify, merge, publish, distribute, sublicense,
 * and/or sell copies of the Software, and to permit persons to whom the
 * Software is furnished to do so, subject to the following conditions:
 *
 * The above copyright notice and this permission notice shall be included
 * in all copies or substantial portions of the Software.
 *
 * THE SOFTWARE IS PROVIDED "AS IS", WITHOUT WARRANTY OF ANY KIND, EXPRESS
 * OR IMPLIED, INCLUDING BUT NOT LIMITED TO THE WARRANTIES OF MERCHANTABILITY,
 * FITNESS FOR A PARTICULAR PURPOSE AND NONINFRINGEMENT.  IN NO EVENT SHALL
 * BRIAN PAUL BE LIABLE FOR ANY CLAIM, DAMAGES OR OTHER LIABILITY, WHETHER IN
 * AN ACTION OF CONTRACT, TORT OR OTHERWISE, ARISING FROM, OUT OF OR IN
 * CONNECTION WITH THE SOFTWARE OR THE USE OR OTHER DEALINGS IN THE SOFTWARE.
 */


#ifndef P_UTIL_H
#define P_UTIL_H

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

#define CALLOC_STRUCT(T)   (struct T *) calloc(1, sizeof(struct T))

#define FREE( PTR )  free( PTR )

#define CLAMP( X, MIN, MAX )  ( (X)<(MIN) ? (MIN) : ((X)>(MAX) ? (MAX) : (X)) )
#define MIN2( A, B )   ( (A)<(B) ? (A) : (B) )
#define MAX2( A, B )   ( (A)>(B) ? (A) : (B) )

#define Elements(x) sizeof(x)/sizeof(*(x))

/**
 * Return a pointer aligned to next multiple of 16 bytes.
 */
static INLINE void *
align16( void *unaligned )
{
   union {
      void *p;
      uint64 u;
   } pu;
   pu.p = unaligned;
   pu.u = (pu.u + 15) & ~15;
   return pu.p;
}


#if defined(__MSC__) && defined(__WIN32__)
static INLINE unsigned ffs( unsigned u )
{
   unsigned i;

   if( u == 0 ) {
      return 0;
   }

   __asm bsf eax, [u]
   __asm inc eax
   __asm mov [i], eax

   return i;
}
#endif

union fi {
   float f;
   int i;
   unsigned ui;
};

#define UBYTE_TO_FLOAT( ub ) ((float)(ub) / 255.0F)

#define IEEE_0996 0x3f7f0000	/* 0.996 or so */

/* This function/macro is sensitive to precision.  Test very carefully
 * if you change it!
 */
#define UNCLAMPED_FLOAT_TO_UBYTE(UB, F)					\
        do {								\
           union fi __tmp;						\
           __tmp.f = (F);						\
           if (__tmp.i < 0)						\
              UB = (ubyte) 0;						\
           else if (__tmp.i >= IEEE_0996)				\
              UB = (ubyte) 255;					\
           else {							\
              __tmp.f = __tmp.f * (255.0f/256.0f) + 32768.0f;		\
              UB = (ubyte) __tmp.i;					\
           }								\
        } while (0)



static INLINE unsigned pack_ub4( unsigned char b0,
				 unsigned char b1,
				 unsigned char b2,
				 unsigned char b3 )
{
   return ((((unsigned int)b0) << 0) |
	   (((unsigned int)b1) << 8) |
	   (((unsigned int)b2) << 16) |
	   (((unsigned int)b3) << 24));
}

static INLINE unsigned fui( float f )
{
   union fi fi;
   fi.f = f;
   return fi.ui;
}

static INLINE unsigned char float_to_ubyte( float f )
{
   unsigned char ub;
   UNCLAMPED_FLOAT_TO_UBYTE(ub, f);
   return ub;
}

static INLINE unsigned pack_ui32_float4( float a,
					 float b, 
					 float d, 
					 float c )
{
   return pack_ub4( float_to_ubyte(a),
		    float_to_ubyte(b),
		    float_to_ubyte(c),
		    float_to_ubyte(d) );
}

#define COPY_4V( DST, SRC )         \
do {                                \
   (DST)[0] = (SRC)[0];             \
   (DST)[1] = (SRC)[1];             \
   (DST)[2] = (SRC)[2];             \
   (DST)[3] = (SRC)[3];             \
} while (0)


#define COPY_4FV( DST, SRC )  COPY_4V(DST, SRC)


#define ASSIGN_4V( DST, V0, V1, V2, V3 ) \
do {                                     \
   (DST)[0] = (V0);                      \
   (DST)[1] = (V1);                      \
   (DST)[2] = (V2);                      \
   (DST)[3] = (V3);                      \
} while (0)


static INLINE int ifloor(float f)
{
   int ai, bi;
   double af, bf;
   union fi u;

   af = (3 << 22) + 0.5 + (double)f;
   bf = (3 << 22) + 0.5 - (double)f;
   u.f = (float) af;  ai = u.i;
   u.f = (float) bf;  bi = u.i;
   return (ai - bi) >> 1;
}


#if defined(__GNUC__) && defined(__i386__) 
static INLINE int iround(float f)
{
   int r;
   __asm__ ("fistpl %0" : "=m" (r) : "t" (f) : "st");
   return r;
}
#elif defined(__MSC__) && defined(__WIN32__)
static INLINE int iround(float f)
{
   int r;
   _asm {
	 fld f
	 fistp r
	}
   return r;
}
#else
#define IROUND(f)  ((int) (((f) >= 0.0F) ? ((f) + 0.5F) : ((f) - 0.5F)))
#endif


/* Could maybe have an inline version of this?
 */
#if defined(__GNUC__)
#define FABSF(x)   fabsf(x)
#else
#define FABSF(x)   ((float) fabs(x))
#endif

/* Pretty fast, and accurate.
 * Based on code from http://www.flipcode.com/totd/
 */
static INLINE float LOG2(float val)
{
   union fi num;
   int log_2;

   num.f = val;
   log_2 = ((num.i >> 23) & 255) - 128;
   num.i &= ~(255 << 23);
   num.i += 127 << 23;
   num.f = ((-1.0f/3) * num.f + 2) * num.f - 2.0f/3;
   return num.f + log_2;
}


#endif