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Optimizations of log2 for ivec4
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@ -35,20 +35,22 @@
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namespace glm{
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namespace detail
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{
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template <bool isFloat>
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struct compute_log2{};
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template <>
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struct compute_log2<true>
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{
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template <typename T>
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GLM_FUNC_QUALIFIER T operator() (T Value) const
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{
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# if GLM_LANG & GLM_LANG_CXX11_FLAG
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return std::log2(Value);
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using std::log2;
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# else
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return std::log(Value) * static_cast<T>(1.4426950408889634073599246810019);
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template <typename genType>
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genType log2(genType Value)
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{
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return std::log(Value) * static_cast<genType>(1.4426950408889634073599246810019);
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}
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# endif
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template <typename T, precision P, template <class, precision> class vecType, bool isFloat = true>
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struct compute_log2
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{
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GLM_FUNC_QUALIFIER static vecType<T, P> call(vecType<T, P> const & vec)
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{
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return detail::functor1<T, T, P, vecType>::call(log2, vec);
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}
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};
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@ -121,17 +123,13 @@ namespace detail
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template <typename genType>
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GLM_FUNC_QUALIFIER genType log2(genType x)
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{
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GLM_STATIC_ASSERT(std::numeric_limits<genType>::is_iec559 || std::numeric_limits<genType>::is_integer,
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"GLM core 'log2' only accept floating-point inputs. Include <glm/gtx/integer.hpp> for additional integer support.");
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assert(x > genType(0)); // log2 is only defined on the range (0, inf]
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return detail::compute_log2<std::numeric_limits<genType>::is_iec559>()(x);
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return log2(tvec1<genType>(x)).x;
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}
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template <typename T, precision P, template <typename, precision> class vecType>
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GLM_FUNC_QUALIFIER vecType<T, P> log2(vecType<T, P> const & x)
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{
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return detail::functor1<T, T, P, vecType>::call(log2, x);
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return detail::compute_log2<T, P, vecType, std::numeric_limits<T>::is_iec559>::call(x);
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}
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// sqrt
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@ -564,11 +564,12 @@
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// User defines: GLM_FORCE_PURE GLM_FORCE_SSE2 GLM_FORCE_SSE3 GLM_FORCE_AVX GLM_FORCE_AVX2
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#define GLM_ARCH_PURE 0x0000
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#define GLM_ARCH_SSE2 0x0001
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#define GLM_ARCH_SSE3 0x0002
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#define GLM_ARCH_SSE4 0x0004
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#define GLM_ARCH_AVX 0x0008
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#define GLM_ARCH_AVX2 0x0010
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#define GLM_ARCH_X86 0x0001
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#define GLM_ARCH_SSE2 0x0002
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#define GLM_ARCH_SSE3 0x0004
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#define GLM_ARCH_SSE4 0x0008
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#define GLM_ARCH_AVX 0x0010
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#define GLM_ARCH_AVX2 0x0020
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#if defined(GLM_FORCE_PURE)
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# define GLM_ARCH GLM_ARCH_PURE
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@ -29,19 +29,35 @@
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namespace glm{
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namespace detail
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{
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GLM_FUNC_QUALIFIER unsigned int nlz(unsigned int x)
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template <typename T, precision P, template <class, precision> class vecType>
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struct compute_log2<T, P, vecType, false>
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{
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return 31u - findMSB(x);
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}
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template <>
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struct compute_log2<false>
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GLM_FUNC_QUALIFIER static vecType<T, P> call(vecType<T, P> const & vec)
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{
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template <typename T>
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GLM_FUNC_QUALIFIER T operator() (T const & Value) const
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{
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return Value <= static_cast<T>(1) ? T(0) : T(32) - nlz(Value - T(1));
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//Equivalent to return findMSB(vec); but save one function call in ASM with VC
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//return findMSB(vec);
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return detail::compute_findMSB_vec<T, P, vecType, sizeof(T) * 8>::call(vec);
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}
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};
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# if(GLM_ARCH != GLM_ARCH_PURE) && (GLM_COMPILER & (GLM_COMPILER_VC | GLM_COMPILER_APPLE_CLANG | GLM_COMPILER_LLVM))
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template <precision P>
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struct compute_log2<int, P, tvec4, false>
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{
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GLM_FUNC_QUALIFIER static tvec4<int, P> call(tvec4<int, P> const & vec)
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{
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tvec4<int, P> Result(glm::uninitialize);
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_BitScanReverse(reinterpret_cast<unsigned long*>(&Result.x), vec.x);
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_BitScanReverse(reinterpret_cast<unsigned long*>(&Result.y), vec.y);
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_BitScanReverse(reinterpret_cast<unsigned long*>(&Result.z), vec.z);
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_BitScanReverse(reinterpret_cast<unsigned long*>(&Result.w), vec.w);
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return Result;
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}
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};
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# endif//GLM_ARCH != GLM_ARCH_PURE
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}//namespace detail
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}//namespace glm
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@ -887,12 +887,6 @@ namespace sign
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Error += Data[i].Return == Result ? 0 : 1;
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}
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for(std::size_t i = 0; i < sizeof(Data) / sizeof(type<glm::int32>); ++i)
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{
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glm::int32 Result = sign_sub(Data[i].Value);
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Error += Data[i].Return == Result ? 0 : 1;
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}
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return Error;
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}
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@ -7,9 +7,11 @@
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// File : test/gtc/integer.cpp
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///////////////////////////////////////////////////////////////////////////////////////////////////
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#define GLM_FORCE_INLINE
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#include <glm/gtc/integer.hpp>
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#include <glm/gtc/type_precision.hpp>
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#include <glm/gtc/vec1.hpp>
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#include <glm/gtx/type_aligned.hpp>
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#include <glm/vector_relational.hpp>
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#include <glm/vec2.hpp>
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#include <glm/vec3.hpp>
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@ -48,6 +50,126 @@ namespace log2_
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int perf()
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{
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int Error = 0;
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std::size_t const Count(100000000);
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{
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std::vector<int> Result;
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Result.resize(Count);
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std::clock_t Begin = clock();
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for(std::size_t i = 0; i < Count; ++i)
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Result[i] = glm::log2(static_cast<int>(i));
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std::clock_t End = clock();
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printf("glm::log2<int>: %d clocks\n", End - Begin);
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}
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{
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std::vector<glm::ivec4> Result;
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Result.resize(Count);
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std::clock_t Begin = clock();
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for(std::size_t i = 0; i < Count; ++i)
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Result[i] = glm::log2(glm::ivec4(i));
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std::clock_t End = clock();
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printf("glm::log2<ivec4>: %d clocks\n", End - Begin);
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}
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# if(GLM_ARCH != GLM_ARCH_PURE) && (GLM_COMPILER & (GLM_COMPILER_VC | GLM_COMPILER_APPLE_CLANG | GLM_COMPILER_LLVM))
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{
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std::vector<glm::ivec4> Result;
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Result.resize(Count);
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std::clock_t Begin = clock();
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for(std::size_t i = 0; i < Count; ++i)
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{
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glm::tvec4<unsigned long, glm::defaultp> Tmp(glm::uninitialize);
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_BitScanReverse(&Tmp.x, i);
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_BitScanReverse(&Tmp.y, i);
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_BitScanReverse(&Tmp.z, i);
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_BitScanReverse(&Tmp.w, i);
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Result[i] = glm::ivec4(Tmp);
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}
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std::clock_t End = clock();
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printf("glm::log2<ivec4> inlined: %d clocks\n", End - Begin);
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}
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{
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std::vector<glm::tvec4<unsigned long, glm::defaultp> > Result;
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Result.resize(Count);
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std::clock_t Begin = clock();
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for(std::size_t i = 0; i < Count; ++i)
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{
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_BitScanReverse(&Result[i].x, i);
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_BitScanReverse(&Result[i].y, i);
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_BitScanReverse(&Result[i].z, i);
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_BitScanReverse(&Result[i].w, i);
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}
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std::clock_t End = clock();
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printf("glm::log2<ivec4> inlined no cast: %d clocks\n", End - Begin);
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}
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{
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std::vector<glm::ivec4> Result;
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Result.resize(Count);
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std::clock_t Begin = clock();
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for(std::size_t i = 0; i < Count; ++i)
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{
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_BitScanReverse(reinterpret_cast<unsigned long*>(&Result[i].x), i);
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_BitScanReverse(reinterpret_cast<unsigned long*>(&Result[i].y), i);
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_BitScanReverse(reinterpret_cast<unsigned long*>(&Result[i].z), i);
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_BitScanReverse(reinterpret_cast<unsigned long*>(&Result[i].w), i);
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}
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std::clock_t End = clock();
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printf("glm::log2<ivec4> reinterpret: %d clocks\n", End - Begin);
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}
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# endif//GLM_ARCH != GLM_ARCH_PURE
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{
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std::vector<float> Result;
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Result.resize(Count);
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std::clock_t Begin = clock();
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for(std::size_t i = 0; i < Count; ++i)
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Result[i] = glm::log2(static_cast<float>(i));
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std::clock_t End = clock();
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printf("glm::log2<float>: %d clocks\n", End - Begin);
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}
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{
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std::vector<glm::vec4> Result;
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Result.resize(Count);
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std::clock_t Begin = clock();
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for(std::size_t i = 0; i < Count; ++i)
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Result[i] = glm::log2(glm::vec4(i));
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std::clock_t End = clock();
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printf("glm::log2<vec4>: %d clocks\n", End - Begin);
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}
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return Error;
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}
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