285 lines
6.9 KiB
C++
285 lines
6.9 KiB
C++
/// Copyright (C) 1993 by Sun Microsystems, Inc. All rights reserved.
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///
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/// Developed at SunPro, a Sun Microsystems, Inc. business.
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/// Permission to use, copy, modify, and distribute this
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/// software is freely granted, provided that this notice
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/// is preserved.
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#include "../detail/type_float.hpp"
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#include "../ext/scalar_constants.hpp"
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#include <cmath>
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#include <cfloat>
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#if(GLM_COMPILER & GLM_COMPILER_VC)
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# pragma warning(push)
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# pragma warning(disable : 4127)
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#endif
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typedef union
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{
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float value;
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/* FIXME: Assumes 32 bit int. */
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unsigned int word;
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} ieee_float_shape_type;
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typedef union
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{
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double value;
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struct
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{
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int lsw;
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int msw;
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} parts;
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} ieee_double_shape_type;
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#define GLM_EXTRACT_WORDS(ix0,ix1,d) \
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do { \
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ieee_double_shape_type ew_u; \
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ew_u.value = (d); \
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(ix0) = ew_u.parts.msw; \
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(ix1) = ew_u.parts.lsw; \
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} while (0)
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#define GLM_GET_FLOAT_WORD(i,d) \
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do { \
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ieee_float_shape_type gf_u; \
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gf_u.value = (d); \
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(i) = gf_u.word; \
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} while (0)
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#define GLM_SET_FLOAT_WORD(d,i) \
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do { \
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ieee_float_shape_type sf_u; \
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sf_u.word = (i); \
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(d) = sf_u.value; \
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} while (0)
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#define GLM_INSERT_WORDS(d,ix0,ix1) \
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do { \
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ieee_double_shape_type iw_u; \
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iw_u.parts.msw = (ix0); \
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iw_u.parts.lsw = (ix1); \
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(d) = iw_u.value; \
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} while (0)
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namespace glm{
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namespace detail
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{
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GLM_FUNC_QUALIFIER float nextafterf(float x, float y)
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{
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volatile float t;
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int hx, hy, ix, iy;
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GLM_GET_FLOAT_WORD(hx, x);
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GLM_GET_FLOAT_WORD(hy, y);
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ix = hx & 0x7fffffff; // |x|
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iy = hy & 0x7fffffff; // |y|
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if((ix > 0x7f800000) || // x is nan
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(iy > 0x7f800000)) // y is nan
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return x + y;
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if(abs(y - x) <= epsilon<float>())
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return y; // x=y, return y
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if(ix == 0)
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{ // x == 0
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GLM_SET_FLOAT_WORD(x, (hy & 0x80000000) | 1);// return +-minsubnormal
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t = x * x;
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if(abs(t - x) <= epsilon<float>())
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return t;
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else
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return x; // raise underflow flag
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}
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if(hx >= 0)
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{ // x > 0
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if(hx > hy) // x > y, x -= ulp
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hx -= 1;
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else // x < y, x += ulp
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hx += 1;
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}
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else
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{ // x < 0
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if(hy >= 0 || hx > hy) // x < y, x -= ulp
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hx -= 1;
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else // x > y, x += ulp
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hx += 1;
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}
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hy = hx & 0x7f800000;
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if(hy >= 0x7f800000)
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return x + x; // overflow
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if(hy < 0x00800000) // underflow
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{
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t = x * x;
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if(abs(t - x) > epsilon<float>())
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{ // raise underflow flag
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GLM_SET_FLOAT_WORD(y, hx);
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return y;
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}
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}
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GLM_SET_FLOAT_WORD(x, hx);
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return x;
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}
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GLM_FUNC_QUALIFIER double nextafter(double x, double y)
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{
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volatile double t;
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int hx, hy, ix, iy;
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unsigned int lx, ly;
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GLM_EXTRACT_WORDS(hx, lx, x);
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GLM_EXTRACT_WORDS(hy, ly, y);
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ix = hx & 0x7fffffff; // |x|
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iy = hy & 0x7fffffff; // |y|
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if(((ix >= 0x7ff00000) && ((ix - 0x7ff00000) | lx) != 0) || // x is nan
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((iy >= 0x7ff00000) && ((iy - 0x7ff00000) | ly) != 0)) // y is nan
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return x + y;
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if(abs(y - x) <= epsilon<double>())
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return y; // x=y, return y
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if((ix | lx) == 0)
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{ // x == 0
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GLM_INSERT_WORDS(x, hy & 0x80000000, 1); // return +-minsubnormal
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t = x * x;
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if(abs(t - x) <= epsilon<double>())
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return t;
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else
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return x; // raise underflow flag
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}
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if(hx >= 0) { // x > 0
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if(hx > hy || ((hx == hy) && (lx > ly))) { // x > y, x -= ulp
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if(lx == 0) hx -= 1;
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lx -= 1;
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}
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else { // x < y, x += ulp
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lx += 1;
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if(lx == 0) hx += 1;
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}
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}
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else { // x < 0
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if(hy >= 0 || hx > hy || ((hx == hy) && (lx > ly))){// x < y, x -= ulp
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if(lx == 0) hx -= 1;
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lx -= 1;
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}
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else { // x > y, x += ulp
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lx += 1;
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if(lx == 0) hx += 1;
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}
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}
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hy = hx & 0x7ff00000;
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if(hy >= 0x7ff00000)
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return x + x; // overflow
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if(hy < 0x00100000)
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{ // underflow
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t = x * x;
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if(abs(t - x) > epsilon<double>())
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{ // raise underflow flag
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GLM_INSERT_WORDS(y, hx, lx);
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return y;
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}
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}
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GLM_INSERT_WORDS(x, hx, lx);
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return x;
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}
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}//namespace detail
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}//namespace glm
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#if(GLM_COMPILER & GLM_COMPILER_VC)
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# pragma warning(pop)
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#endif
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namespace glm
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{
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template<>
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GLM_FUNC_QUALIFIER float nextFloat(float x)
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{
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# if GLM_HAS_CXX11_STL
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return std::nextafter(x, std::numeric_limits<float>::max());
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# elif((GLM_COMPILER & GLM_COMPILER_VC) || ((GLM_COMPILER & GLM_COMPILER_INTEL) && (GLM_PLATFORM & GLM_PLATFORM_WINDOWS)))
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return detail::nextafterf(x, FLT_MAX);
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# elif(GLM_PLATFORM & GLM_PLATFORM_ANDROID)
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return __builtin_nextafterf(x, FLT_MAX);
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# else
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return nextafterf(x, FLT_MAX);
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# endif
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}
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template<>
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GLM_FUNC_QUALIFIER double nextFloat(double x)
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{
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# if GLM_HAS_CXX11_STL
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return std::nextafter(x, std::numeric_limits<double>::max());
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# elif((GLM_COMPILER & GLM_COMPILER_VC) || ((GLM_COMPILER & GLM_COMPILER_INTEL) && (GLM_PLATFORM & GLM_PLATFORM_WINDOWS)))
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return detail::nextafter(x, std::numeric_limits<double>::max());
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# elif(GLM_PLATFORM & GLM_PLATFORM_ANDROID)
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return __builtin_nextafter(x, DBL_MAX);
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# else
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return nextafter(x, DBL_MAX);
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# endif
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}
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template<typename T>
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GLM_FUNC_QUALIFIER T nextFloat(T x, int ULPs)
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{
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GLM_STATIC_ASSERT(std::numeric_limits<T>::is_iec559, "'next_float' only accept floating-point input");
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assert(ULPs >= 0);
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T temp = x;
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for(int i = 0; i < ULPs; ++i)
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temp = nextFloat(temp);
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return temp;
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}
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GLM_FUNC_QUALIFIER float prevFloat(float x)
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{
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# if GLM_HAS_CXX11_STL
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return std::nextafter(x, std::numeric_limits<float>::min());
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# elif((GLM_COMPILER & GLM_COMPILER_VC) || ((GLM_COMPILER & GLM_COMPILER_INTEL) && (GLM_PLATFORM & GLM_PLATFORM_WINDOWS)))
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return detail::nextafterf(x, FLT_MIN);
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# elif(GLM_PLATFORM & GLM_PLATFORM_ANDROID)
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return __builtin_nextafterf(x, FLT_MIN);
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# else
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return nextafterf(x, FLT_MIN);
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# endif
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}
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GLM_FUNC_QUALIFIER double prevFloat(double x)
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{
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# if GLM_HAS_CXX11_STL
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return std::nextafter(x, std::numeric_limits<double>::min());
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# elif((GLM_COMPILER & GLM_COMPILER_VC) || ((GLM_COMPILER & GLM_COMPILER_INTEL) && (GLM_PLATFORM & GLM_PLATFORM_WINDOWS)))
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return _nextafter(x, DBL_MIN);
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# elif(GLM_PLATFORM & GLM_PLATFORM_ANDROID)
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return __builtin_nextafter(x, DBL_MIN);
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# else
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return nextafter(x, DBL_MIN);
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# endif
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}
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template<typename T>
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GLM_FUNC_QUALIFIER T prevFloat(T x, int ULPs)
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{
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GLM_STATIC_ASSERT(std::numeric_limits<T>::is_iec559, "'prev_float' only accept floating-point input");
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assert(ULPs >= 0);
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T temp = x;
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for(int i = 0; i < ULPs; ++i)
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temp = prevFloat(temp);
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return temp;
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}
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GLM_FUNC_QUALIFIER int floatDistance(float x, float y)
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{
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detail::float_t<float> const a(x);
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detail::float_t<float> const b(y);
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return abs(a.i - b.i);
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}
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GLM_FUNC_QUALIFIER int64 floatDistance(double x, double y)
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{
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detail::float_t<double> const a(x);
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detail::float_t<double> const b(y);
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return abs(a.i - b.i);
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}
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}//namespace glm
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