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路径: \\game3dprogramming\materials\DarkPuzzle\libs\bullet_src\LinearMath\btScalar.h
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/*
Copyright (c) 2003-2006 Gino van den Bergen / Erwin Coumans  http://continuousphysics.com/Bullet/

This software is provided 'as-is', without any express or implied warranty.
In no event will the authors be held liable for any damages arising from the use of this software.
Permission is granted to anyone to use this software for any purpose, 
including commercial applications, and to alter it and redistribute it freely, 
subject to the following restrictions:

1. The origin of this software must not be misrepresented; you must not claim that you wrote the original software. If you use this software in a product, an acknowledgment in the product documentation would be appreciated but is not required.
2. Altered source versions must be plainly marked as such, and must not be misrepresented as being the original software.
3. This notice may not be removed or altered from any source distribution.
*/



#ifndef SIMD___SCALAR_H
#define SIMD___SCALAR_H

#include <math.h>

#include <cstdlib>
#include <cfloat>
#include <float.h>

#define BT_BULLET_VERSION 267

inline int	btGetVersion()
{
	return BT_BULLET_VERSION;
}

#if defined(DEBUG) || defined (_DEBUG)
#define BT_DEBUG
#endif


#ifdef WIN32

		#if defined(__MINGW32__) || defined(__CYGWIN__) || (defined (_MSC_VER) && _MSC_VER < 1300)

			#define SIMD_FORCE_INLINE inline
			#define ATTRIBUTE_ALIGNED16(a) a
			#define ATTRIBUTE_ALIGNED128(a) a
		#else
			#define BT_HAS_ALIGNED_ALLOCATOR
			#pragma warning(disable:4530)
			#pragma warning(disable:4996)
			#pragma warning(disable:4786)
			#define SIMD_FORCE_INLINE __forceinline
			#define ATTRIBUTE_ALIGNED16(a) __declspec(align(16)) a
			#define ATTRIBUTE_ALIGNED128(a) __declspec (align(128)) a
		#ifdef _XBOX
			#define BT_USE_VMX128

			#include <ppcintrinsics.h>
 			#define BT_HAVE_NATIVE_FSEL
 			#define btFsel(a,b,c) __fsel((a),(b),(c))
		#else
			#define BT_USE_SSE
		#endif
		#endif //__MINGW32__

		#include <assert.h>
		#define btAssert assert
		//btFullAssert is optional, slows down a lot
		#define btFullAssert(x)

		#define btLikely(_c)  _c
		#define btUnlikely(_c) _c

#else
	
#if defined	(__CELLOS_LV2__)
		#define SIMD_FORCE_INLINE inline
		#define ATTRIBUTE_ALIGNED16(a) a __attribute__ ((aligned (16)))
		#define ATTRIBUTE_ALIGNED128(a) a __attribute__ ((aligned (128)))
		#ifndef assert
		#include <assert.h>
		#endif
		#define btAssert assert
		//btFullAssert is optional, slows down a lot
		#define btFullAssert(x)

		#define btLikely(_c)  _c
		#define btUnlikely(_c) _c

#else

#ifdef USE_LIBSPE2

		#define SIMD_FORCE_INLINE __inline
		#define ATTRIBUTE_ALIGNED16(a) a __attribute__ ((aligned (16)))
		#define ATTRIBUTE_ALIGNED128(a) a __attribute__ ((aligned (128)))
		#ifndef assert
		#include <assert.h>
		#endif
		#define btAssert assert
		//btFullAssert is optional, slows down a lot
		#define btFullAssert(x)


		#define btLikely(_c)   __builtin_expect((_c), 1)
		#define btUnlikely(_c) __builtin_expect((_c), 0)
		

#else
	//non-windows systems

		#define SIMD_FORCE_INLINE inline
		#define ATTRIBUTE_ALIGNED16(a) a
		#define ATTRIBUTE_ALIGNED128(a) a
		#ifndef assert
		#include <assert.h>
		#endif
		#define btAssert assert
		//btFullAssert is optional, slows down a lot
		#define btFullAssert(x)
		#define btLikely(_c)  _c
		#define btUnlikely(_c) _c


#endif // LIBSPE2

#endif	//__CELLOS_LV2__
#endif

/// older compilers (gcc 3.x) and Sun needs double version of sqrt etc.
/// exclude Apple Intel (i's assumed to be a Macbook or new Intel Dual Core Processor)
#if defined (__sun) || defined (__sun__) || defined (__sparc) || (defined (__APPLE__) && ! defined (__i386__))
//use slow double float precision operation on those platforms
#ifndef BT_USE_DOUBLE_PRECISION
#define BT_FORCE_DOUBLE_FUNCTIONS
#endif
#endif

#if defined(BT_USE_DOUBLE_PRECISION)
typedef double btScalar;
#else
typedef float btScalar;
#endif


#define BT_DECLARE_ALIGNED_ALLOCATOR() \
	SIMD_FORCE_INLINE void* operator new(size_t sizeInBytes)	{ return btAlignedAlloc(sizeInBytes,16); }	\
	SIMD_FORCE_INLINE void  operator delete(void* ptr)			{ btAlignedFree(ptr); }	\
	SIMD_FORCE_INLINE void* operator new(size_t, void* ptr)	{ return ptr; }	\
	SIMD_FORCE_INLINE void  operator delete(void*, void*)		{ }	\



#if defined(BT_USE_DOUBLE_PRECISION) || defined(BT_FORCE_DOUBLE_FUNCTIONS)
		
SIMD_FORCE_INLINE btScalar btSqrt(btScalar x) { return sqrt(x); }
SIMD_FORCE_INLINE btScalar btFabs(btScalar x) { return fabs(x); }
SIMD_FORCE_INLINE btScalar btCos(btScalar x) { return cos(x); }
SIMD_FORCE_INLINE btScalar btSin(btScalar x) { return sin(x); }
SIMD_FORCE_INLINE btScalar btTan(btScalar x) { return tan(x); }
SIMD_FORCE_INLINE btScalar btAcos(btScalar x) { return acos(x); }
SIMD_FORCE_INLINE btScalar btAsin(btScalar x) { return asin(x); }
SIMD_FORCE_INLINE btScalar btAtan(btScalar x) { return atan(x); }
SIMD_FORCE_INLINE btScalar btAtan2(btScalar x, btScalar y) { return atan2(x, y); }
SIMD_FORCE_INLINE btScalar btExp(btScalar x) { return exp(x); }
SIMD_FORCE_INLINE btScalar btLog(btScalar x) { return log(x); }
SIMD_FORCE_INLINE btScalar btPow(btScalar x,btScalar y) { return pow(x,y); }

#else
		
SIMD_FORCE_INLINE btScalar btSqrt(btScalar y) 
{ 
#ifdef USE_APPROXIMATION
    double x, z, tempf;
    unsigned long *tfptr = ((unsigned long *)&tempf) + 1;

	tempf = y;
	*tfptr = (0xbfcdd90a - *tfptr)>>1; /* estimate of 1/sqrt(y) */
	x =  tempf;
	z =  y*btScalar(0.5);                        /* hoist out the �/2�    */
	x = (btScalar(1.5)*x)-(x*x)*(x*z);         /* iteration formula     */
	x = (btScalar(1.5)*x)-(x*x)*(x*z);
	x = (btScalar(1.5)*x)-(x*x)*(x*z);
	x = (btScalar(1.5)*x)-(x*x)*(x*z);
	x = (btScalar(1.5)*x)-(x*x)*(x*z);
	return x*y;
#else
	return sqrtf(y); 
#endif
}
SIMD_FORCE_INLINE btScalar btFabs(btScalar x) { return fabsf(x); }
SIMD_FORCE_INLINE btScalar btCos(btScalar x) { return cosf(x); }
SIMD_FORCE_INLINE btScalar btSin(btScalar x) { return sinf(x); }
SIMD_FORCE_INLINE btScalar btTan(btScalar x) { return tanf(x); }
SIMD_FORCE_INLINE btScalar btAcos(btScalar x) { 
	btAssert(x <= btScalar(1.));
	return acosf(x); 
}
SIMD_FORCE_INLINE btScalar btAsin(btScalar x) { return asinf(x); }
SIMD_FORCE_INLINE btScalar btAtan(btScalar x) { return atanf(x); }
SIMD_FORCE_INLINE btScalar btAtan2(btScalar x, btScalar y) { return atan2f(x, y); }
SIMD_FORCE_INLINE btScalar btExp(btScalar x) { return expf(x); }
SIMD_FORCE_INLINE btScalar btLog(btScalar x) { return logf(x); }
SIMD_FORCE_INLINE btScalar btPow(btScalar x,btScalar y) { return powf(x,y); }
	
#endif

#define SIMD_2_PI         btScalar(6.283185307179586232)
#define SIMD_PI           (SIMD_2_PI * btScalar(0.5))
#define SIMD_HALF_PI      (SIMD_2_PI * btScalar(0.25))
#define SIMD_RADS_PER_DEG (SIMD_2_PI / btScalar(360.0))
#define SIMD_DEGS_PER_RAD  (btScalar(360.0) / SIMD_2_PI)

#ifdef BT_USE_DOUBLE_PRECISION
#define SIMD_EPSILON      DBL_EPSILON
#define SIMD_INFINITY     DBL_MAX
#else
#define SIMD_EPSILON      FLT_EPSILON
#define SIMD_INFINITY     FLT_MAX
#endif

SIMD_FORCE_INLINE btScalar btAtan2Fast(btScalar y, btScalar x) 
{
	btScalar coeff_1 = SIMD_PI / 4.0f;
	btScalar coeff_2 = 3.0f * coeff_1;
	btScalar abs_y = btFabs(y);
	btScalar angle;
	if (x >= 0.0f) {
		btScalar r = (x - abs_y) / (x + abs_y);
		angle = coeff_1 - coeff_1 * r;
	} else {
		btScalar r = (x + abs_y) / (abs_y - x);
		angle = coeff_2 - coeff_1 * r;
	}
	return (y < 0.0f) ? -angle : angle;
}

SIMD_FORCE_INLINE bool      btFuzzyZero(btScalar x) { return btFabs(x) < SIMD_EPSILON; }

SIMD_FORCE_INLINE bool	btEqual(btScalar a, btScalar eps) {
	return (((a) <= eps) && !((a) < -eps));
}
SIMD_FORCE_INLINE bool	btGreaterEqual (btScalar a, btScalar eps) {
	return (!((a) <= eps));
}


SIMD_FORCE_INLINE int       btIsNegative(btScalar x) {
    return x < btScalar(0.0) ? 1 : 0;
}

SIMD_FORCE_INLINE btScalar btRadians(btScalar x) { return x * SIMD_RADS_PER_DEG; }
SIMD_FORCE_INLINE btScalar btDegrees(btScalar x) { return x * SIMD_DEGS_PER_RAD; }

#define BT_DECLARE_HANDLE(name) typedef struct name##__ { int unused; } *name

#ifndef btFsel
SIMD_FORCE_INLINE btScalar btFsel(btScalar a, btScalar b, btScalar c)
{
	return a >= 0 ? b : c;
}
#endif
#define btFsels(a,b,c) (btScalar)btFsel(a,b,c)


SIMD_FORCE_INLINE bool btMachineIsLittleEndian()
{
   long int i = 1;
   const char *p = (const char *) &i;
   if (p[0] == 1)  // Lowest address contains the least significant byte
	   return true;
   else
	   return false;
}



///btSelect avoids branches, which makes performance much better for consoles like Playstation 3 and XBox 360
///Thanks Phil Knight. See also http://www.cellperformance.com/articles/2006/04/more_techniques_for_eliminatin_1.html
SIMD_FORCE_INLINE unsigned btSelect(unsigned condition, unsigned valueIfConditionNonZero, unsigned valueIfConditionZero) 
{
    // Set testNz to 0xFFFFFFFF if condition is nonzero, 0x00000000 if condition is zero
    // Rely on positive value or'ed with its negative having sign bit on
    // and zero value or'ed with its negative (which is still zero) having sign bit off 
    // Use arithmetic shift right, shifting the sign bit through all 32 bits
    unsigned testNz = (unsigned)(((int)condition | -(int)condition) >> 31);
    unsigned testEqz = ~testNz;
    return ((valueIfConditionNonZero & testNz) | (valueIfConditionZero & testEqz)); 
}
SIMD_FORCE_INLINE int btSelect(unsigned condition, int valueIfConditionNonZero, int valueIfConditionZero)
{
    unsigned testNz = (unsigned)(((int)condition | -(int)condition) >> 31);
    unsigned testEqz = ~testNz; 
    return ((valueIfConditionNonZero & testNz) | (valueIfConditionZero & testEqz));
}
SIMD_FORCE_INLINE float btSelect(unsigned condition, float valueIfConditionNonZero, float valueIfConditionZero)
{
#ifdef BT_HAVE_NATIVE_FSEL
    return (float)btFsel((btScalar)condition - btScalar(1.0f), valueIfConditionNonZero, valueIfConditionZero);
#else
    return (condition != 0) ? valueIfConditionNonZero : valueIfConditionZero; 
#endif
}

template<typename T> SIMD_FORCE_INLINE void btSwap(T& a, T& b)
{
	T tmp = a;
	a = b;
	b = tmp;
}


//PCK: endian swapping functions
SIMD_FORCE_INLINE unsigned btSwapEndian(unsigned val)
{
	return (((val & 0xff000000) >> 24) | ((val & 0x00ff0000) >> 8) | ((val & 0x0000ff00) << 8)  | ((val & 0x000000ff) << 24));
}

SIMD_FORCE_INLINE unsigned short btSwapEndian(unsigned short val)
{
	return (((val & 0xff00) >> 8) | ((val & 0x00ff) << 8));
}

SIMD_FORCE_INLINE unsigned btSwapEndian(int val)
{
	return btSwapEndian((unsigned)val);
}

SIMD_FORCE_INLINE unsigned short btSwapEndian(short val)
{
	return btSwapEndian((unsigned short) val);
}

///btSwapFloat uses using char pointers to swap the endianness
////btSwapFloat/btSwapDouble will NOT return a float, because the machine might 'correct' invalid floating point values
///Not all values of sign/exponent/mantissa are valid floating point numbers according to IEEE 754. 
///When a floating point unit is faced with an invalid value, it may actually change the value, or worse, throw an exception. 
///In most systems, running user mode code, you wouldn't get an exception, but instead the hardware/os/runtime will 'fix' the number for you. 
///so instead of returning a float/double, we return integer/long long integer
SIMD_FORCE_INLINE unsigned int  btSwapEndianFloat(float d)
{
    unsigned int a;
    unsigned char *dst = (unsigned char *)&a;
    unsigned char *src = (unsigned char *)&d;

    dst[0] = src[3];
    dst[1] = src[2];
    dst[2] = src[1];
    dst[3] = src[0];
    return a;
}

// unswap using char pointers
SIMD_FORCE_INLINE float btUnswapEndianFloat(unsigned int a) 
{
    float d;
    unsigned char *src = (unsigned char *)&a;
    unsigned char *dst = (unsigned char *)&d;

    dst[0] = src[3];
    dst[1] = src[2];
    dst[2] = src[1];
    dst[3] = src[0];

    return d;
}


// swap using char pointers
SIMD_FORCE_INLINE void  btSwapEndianDouble(double d, unsigned char* dst)
{
    unsigned char *src = (unsigned char *)&d;

    dst[0] = src[7];
    dst[1] = src[6];
    dst[2] = src[5];
    dst[3] = src[4];
    dst[4] = src[3];
    dst[5] = src[2];
    dst[6] = src[1];
    dst[7] = src[0];

}

// unswap using char pointers
SIMD_FORCE_INLINE double btUnswapEndianDouble(const unsigned char *src) 
{
    double d;
    unsigned char *dst = (unsigned char *)&d;

    dst[0] = src[7];
    dst[1] = src[6];
    dst[2] = src[5];
    dst[3] = src[4];
    dst[4] = src[3];
    dst[5] = src[2];
    dst[6] = src[1];
    dst[7] = src[0];

	return d;
}


#endif //SIMD___SCALAR_H
btScalar.h
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