dependencies/glm/GLM/ext/scalar_ulp.inl

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2022-02-28 19:03:15 +00:00
/// 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.
#include "../detail/type_float.hpp"
#include "../ext/scalar_constants.hpp"
#include <cmath>
#include <cfloat>
#if(GLM_COMPILER & GLM_COMPILER_VC)
# pragma warning(push)
# pragma warning(disable : 4127)
#endif
typedef union
{
float value;
/* FIXME: Assumes 32 bit int. */
unsigned int word;
} ieee_float_shape_type;
typedef union
{
double value;
struct
{
int lsw;
int msw;
} parts;
} ieee_double_shape_type;
#define GLM_EXTRACT_WORDS(ix0,ix1,d) \
do { \
ieee_double_shape_type ew_u; \
ew_u.value = (d); \
(ix0) = ew_u.parts.msw; \
(ix1) = ew_u.parts.lsw; \
} while (0)
#define GLM_GET_FLOAT_WORD(i,d) \
do { \
ieee_float_shape_type gf_u; \
gf_u.value = (d); \
(i) = gf_u.word; \
} while (0)
#define GLM_SET_FLOAT_WORD(d,i) \
do { \
ieee_float_shape_type sf_u; \
sf_u.word = (i); \
(d) = sf_u.value; \
} while (0)
#define GLM_INSERT_WORDS(d,ix0,ix1) \
do { \
ieee_double_shape_type iw_u; \
iw_u.parts.msw = (ix0); \
iw_u.parts.lsw = (ix1); \
(d) = iw_u.value; \
} while (0)
namespace glm{
namespace detail
{
GLM_FUNC_QUALIFIER float nextafterf(float x, float y)
{
volatile float t;
int hx, hy, ix, iy;
GLM_GET_FLOAT_WORD(hx, x);
GLM_GET_FLOAT_WORD(hy, y);
ix = hx & 0x7fffffff; // |x|
iy = hy & 0x7fffffff; // |y|
if((ix > 0x7f800000) || // x is nan
(iy > 0x7f800000)) // y is nan
return x + y;
if(abs(y - x) <= epsilon<float>())
return y; // x=y, return y
if(ix == 0)
{ // x == 0
GLM_SET_FLOAT_WORD(x, (hy & 0x80000000) | 1);// return +-minsubnormal
t = x * x;
if(abs(t - x) <= epsilon<float>())
return t;
else
return x; // raise underflow flag
}
if(hx >= 0)
{ // x > 0
if(hx > hy) // x > y, x -= ulp
hx -= 1;
else // x < y, x += ulp
hx += 1;
}
else
{ // x < 0
if(hy >= 0 || hx > hy) // x < y, x -= ulp
hx -= 1;
else // x > y, x += ulp
hx += 1;
}
hy = hx & 0x7f800000;
if(hy >= 0x7f800000)
return x + x; // overflow
if(hy < 0x00800000) // underflow
{
t = x * x;
if(abs(t - x) > epsilon<float>())
{ // raise underflow flag
GLM_SET_FLOAT_WORD(y, hx);
return y;
}
}
GLM_SET_FLOAT_WORD(x, hx);
return x;
}
GLM_FUNC_QUALIFIER double nextafter(double x, double y)
{
volatile double t;
int hx, hy, ix, iy;
unsigned int lx, ly;
GLM_EXTRACT_WORDS(hx, lx, x);
GLM_EXTRACT_WORDS(hy, ly, y);
ix = hx & 0x7fffffff; // |x|
iy = hy & 0x7fffffff; // |y|
if(((ix >= 0x7ff00000) && ((ix - 0x7ff00000) | lx) != 0) || // x is nan
((iy >= 0x7ff00000) && ((iy - 0x7ff00000) | ly) != 0)) // y is nan
return x + y;
if(abs(y - x) <= epsilon<double>())
return y; // x=y, return y
if((ix | lx) == 0)
{ // x == 0
GLM_INSERT_WORDS(x, hy & 0x80000000, 1); // return +-minsubnormal
t = x * x;
if(abs(t - x) <= epsilon<double>())
return t;
else
return x; // raise underflow flag
}
if(hx >= 0) { // x > 0
if(hx > hy || ((hx == hy) && (lx > ly))) { // x > y, x -= ulp
if(lx == 0) hx -= 1;
lx -= 1;
}
else { // x < y, x += ulp
lx += 1;
if(lx == 0) hx += 1;
}
}
else { // x < 0
if(hy >= 0 || hx > hy || ((hx == hy) && (lx > ly))){// x < y, x -= ulp
if(lx == 0) hx -= 1;
lx -= 1;
}
else { // x > y, x += ulp
lx += 1;
if(lx == 0) hx += 1;
}
}
hy = hx & 0x7ff00000;
if(hy >= 0x7ff00000)
return x + x; // overflow
if(hy < 0x00100000)
{ // underflow
t = x * x;
if(abs(t - x) > epsilon<double>())
{ // raise underflow flag
GLM_INSERT_WORDS(y, hx, lx);
return y;
}
}
GLM_INSERT_WORDS(x, hx, lx);
return x;
}
}//namespace detail
}//namespace glm
#if(GLM_COMPILER & GLM_COMPILER_VC)
# pragma warning(pop)
#endif
namespace glm
{
template<>
GLM_FUNC_QUALIFIER float nextFloat(float x)
{
# if GLM_HAS_CXX11_STL
return std::nextafter(x, std::numeric_limits<float>::max());
# elif((GLM_COMPILER & GLM_COMPILER_VC) || ((GLM_COMPILER & GLM_COMPILER_INTEL) && (GLM_PLATFORM & GLM_PLATFORM_WINDOWS)))
return detail::nextafterf(x, FLT_MAX);
# elif(GLM_PLATFORM & GLM_PLATFORM_ANDROID)
return __builtin_nextafterf(x, FLT_MAX);
# else
return nextafterf(x, FLT_MAX);
# endif
}
template<>
GLM_FUNC_QUALIFIER double nextFloat(double x)
{
# if GLM_HAS_CXX11_STL
return std::nextafter(x, std::numeric_limits<double>::max());
# elif((GLM_COMPILER & GLM_COMPILER_VC) || ((GLM_COMPILER & GLM_COMPILER_INTEL) && (GLM_PLATFORM & GLM_PLATFORM_WINDOWS)))
return detail::nextafter(x, std::numeric_limits<double>::max());
# elif(GLM_PLATFORM & GLM_PLATFORM_ANDROID)
return __builtin_nextafter(x, DBL_MAX);
# else
return nextafter(x, DBL_MAX);
# endif
}
template<typename T>
GLM_FUNC_QUALIFIER T nextFloat(T x, int ULPs)
{
GLM_STATIC_ASSERT(std::numeric_limits<T>::is_iec559, "'next_float' only accept floating-point input");
assert(ULPs >= 0);
T temp = x;
for(int i = 0; i < ULPs; ++i)
temp = nextFloat(temp);
return temp;
}
GLM_FUNC_QUALIFIER float prevFloat(float x)
{
# if GLM_HAS_CXX11_STL
return std::nextafter(x, std::numeric_limits<float>::min());
# elif((GLM_COMPILER & GLM_COMPILER_VC) || ((GLM_COMPILER & GLM_COMPILER_INTEL) && (GLM_PLATFORM & GLM_PLATFORM_WINDOWS)))
return detail::nextafterf(x, FLT_MIN);
# elif(GLM_PLATFORM & GLM_PLATFORM_ANDROID)
return __builtin_nextafterf(x, FLT_MIN);
# else
return nextafterf(x, FLT_MIN);
# endif
}
GLM_FUNC_QUALIFIER double prevFloat(double x)
{
# if GLM_HAS_CXX11_STL
return std::nextafter(x, std::numeric_limits<double>::min());
# elif((GLM_COMPILER & GLM_COMPILER_VC) || ((GLM_COMPILER & GLM_COMPILER_INTEL) && (GLM_PLATFORM & GLM_PLATFORM_WINDOWS)))
return _nextafter(x, DBL_MIN);
# elif(GLM_PLATFORM & GLM_PLATFORM_ANDROID)
return __builtin_nextafter(x, DBL_MIN);
# else
return nextafter(x, DBL_MIN);
# endif
}
template<typename T>
GLM_FUNC_QUALIFIER T prevFloat(T x, int ULPs)
{
GLM_STATIC_ASSERT(std::numeric_limits<T>::is_iec559, "'prev_float' only accept floating-point input");
assert(ULPs >= 0);
T temp = x;
for(int i = 0; i < ULPs; ++i)
temp = prevFloat(temp);
return temp;
}
GLM_FUNC_QUALIFIER int floatDistance(float x, float y)
{
detail::float_t<float> const a(x);
detail::float_t<float> const b(y);
return abs(a.i - b.i);
}
GLM_FUNC_QUALIFIER int64 floatDistance(double x, double y)
{
detail::float_t<double> const a(x);
detail::float_t<double> const b(y);
return abs(a.i - b.i);
}
}//namespace glm