basisu_enc.h

// basisu_enc.h
// Copyright (C) 2017-2019 Binomial LLC. All Rights Reserved.
//
// Licensed under the Apache License, Version 2.0 (the "License");
// you may not use this file except in compliance with the License.
// You may obtain a copy of the License at
//
//    http://www.apache.org/licenses/LICENSE-2.0
//
// Unless required by applicable law or agreed to in writing, software
// distributed under the License is distributed on an "AS IS" BASIS,
// WITHOUT WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied.
// See the License for the specific language governing permissions and
// limitations under the License.
#pragma once
#include "transcoder/basisu.h"
#include "basisu_enc.h"
#include "transcoder/basisu_transcoder_internal.h"

#ifndef _WIN32
#include <libgen.h>
#endif

namespace basisu
{
	extern uint8_t g_hamming_dist[256];

	// Encoder library initialization
	void basisu_encoder_init();

	void error_printf(const char *pFmt, ...);

	// Helpers

	inline uint8_t clamp255(int32_t i)
	{
		return (uint8_t)((i & 0xFFFFFF00U) ? (~(i >> 31)) : i);
	}

	// Linear algebra

	template <uint32_t N, typename T>
	class vec
	{
	protected:
		T m_v[N];

	public:
		enum { num_elements = N };

		inline vec() { }
		inline vec(eZero) { set_zero();  }

		explicit inline vec(T val) { set(val); }
		inline vec(T v0, T v1) { set(v0, v1); }
		inline vec(T v0, T v1, T v2) { set(v0, v1, v2); }
		inline vec(T v0, T v1, T v2, T v3) { set(v0, v1, v2, v3); }
		inline vec(const vec &other) { for (uint32_t i = 0; i < N; i++) m_v[i] = other.m_v[i]; }
		template <uint32_t OtherN, typename OtherT> inline vec(const vec<OtherN, OtherT> &other) { set(other); }

		inline T operator[](uint32_t i) const { assert(i < N); return m_v[i]; }
		inline T &operator[](uint32_t i) { assert(i < N); return m_v[i]; }

		inline T getX() const { return m_v[0]; }
		inline T getY() const { static_assert(N >= 2, "N too small"); return m_v[1]; }
		inline T getZ() const { static_assert(N >= 3, "N too small"); return m_v[2]; }
		inline T getW() const { static_assert(N >= 4, "N too small"); return m_v[3]; }

		inline bool operator==(const vec &rhs) const { for (uint32_t i = 0; i < N; i++) if (m_v[i] != rhs.m_v[i]) return false;	return true; }
		inline bool operator<(const vec &rhs) const { for (uint32_t i = 0; i < N; i++) { if (m_v[i] < rhs.m_v[i]) return true; else if (m_v[i] != rhs.m_v[i]) return false; } return false; }

		inline void set_zero() { for (uint32_t i = 0; i < N; i++) m_v[i] = 0; }

		template <uint32_t OtherN, typename OtherT>
		inline vec &set(const vec<OtherN, OtherT> &other)
		{
			uint32_t i;
			if (static_cast<void *>(&other) == static_cast<void *>(this))
				return *this;
			const uint32_t m = minimum(OtherN, N);
			for (i = 0; i < m; i++)
				m_v[i] = static_cast<T>(other[i]);
			for (; i < N; i++)
				m_v[i] = 0;
			return *this;
		}

		inline vec &set_component(uint32_t index, T val) { assert(index < N); m_v[index] = val; return *this; }
		inline vec &set(T val) { for (uint32_t i = 0; i < N; i++) m_v[i] = val; return *this; }
		inline void clear_elements(uint32_t s, uint32_t e) { assert(e <= N); for (uint32_t i = s; i < e; i++) m_v[i] = 0; }

		inline vec &set(T v0, T v1)
		{
			m_v[0] = v0;
			if (N >= 2)
			{
				m_v[1] = v1;
				clear_elements(2, N);
			}
			return *this;
		}

		inline vec &set(T v0, T v1, T v2)
		{
			m_v[0] = v0;
			if (N >= 2)
			{
				m_v[1] = v1;
				if (N >= 3)
				{
					m_v[2] = v2;
					clear_elements(3, N);
				}
			}
			return *this;
		}

		inline vec &set(T v0, T v1, T v2, T v3)
		{
			m_v[0] = v0;
			if (N >= 2)
			{
				m_v[1] = v1;
				if (N >= 3)
				{
					m_v[2] = v2;

					if (N >= 4)
					{
						m_v[3] = v3;
						clear_elements(5, N);
					}
				}
			}
			return *this;
		}

		inline vec &operator=(const vec &rhs) { if (this != &rhs) for (uint32_t i = 0; i < N; i++) m_v[i] = rhs.m_v[i]; return *this; }
		template <uint32_t OtherN, typename OtherT> inline vec &operator=(const vec<OtherN, OtherT> &rhs) { set(rhs); return *this; }

		inline const T *get_ptr() const { return reinterpret_cast<const T *>(&m_v[0]); }
		inline T *get_ptr() { return reinterpret_cast<T *>(&m_v[0]); }
		
		inline vec operator- () const { vec res; for (uint32_t i = 0; i < N; i++) res.m_v[i] = -m_v[i]; return res; }
		inline vec operator+ () const { return *this; }
		inline vec &operator+= (const vec &other) { for (uint32_t i = 0; i < N; i++) m_v[i] += other.m_v[i]; return *this; }
		inline vec &operator-= (const vec &other) { for (uint32_t i = 0; i < N; i++) m_v[i] -= other.m_v[i]; return *this; }
		inline vec &operator/= (const vec &other) { for (uint32_t i = 0; i < N; i++) m_v[i] /= other.m_v[i]; return *this; }
		inline vec &operator*=(const vec &other) { for (uint32_t i = 0; i < N; i++) m_v[i] *= other.m_v[i]; return *this; }
		inline vec &operator/= (T s) { for (uint32_t i = 0; i < N; i++) m_v[i] /= s; return *this; }
		inline vec &operator*= (T s) { for (uint32_t i = 0; i < N; i++) m_v[i] *= s; return *this; }
		
		friend inline vec operator+(const vec &lhs, const vec &rhs) { vec res; for (uint32_t i = 0; i < N; i++) res.m_v[i] = lhs.m_v[i] + rhs.m_v[i]; return res; }
		friend inline vec operator-(const vec &lhs, const vec &rhs) { vec res; for (uint32_t i = 0; i < N; i++) res.m_v[i] = lhs.m_v[i] - rhs.m_v[i]; return res; }
		friend inline vec operator*(const vec &lhs, T val) { vec res; for (uint32_t i = 0; i < N; i++) res.m_v[i] = lhs.m_v[i] * val; return res; }
		friend inline vec operator*(T val, const vec &rhs) { vec res; for (uint32_t i = 0; i < N; i++) res.m_v[i] = val * rhs.m_v[i]; return res; }
		friend inline vec operator/(const vec &lhs, T val) { vec res; for (uint32_t i = 0; i < N; i++) res.m_v[i] = lhs.m_v[i] / val; return res; }
		friend inline vec operator/(const vec &lhs, const vec &rhs) { vec res; for (uint32_t i = 0; i < N; i++) res.m_v[i] = lhs.m_v[i] / rhs.m_v[i]; return res; }
		
		static inline T dot_product(const vec &lhs, const vec &rhs) { T res = lhs.m_v[0] * rhs.m_v[0]; for (uint32_t i = 1; i < N; i++) res += lhs.m_v[i] * rhs.m_v[i]; return res; }

		inline T dot(const vec &rhs) const { return dot_product(*this, rhs); }

		inline T norm() const { return dot_product(*this, *this); }
		inline T length() const { return sqrt(norm()); }

		inline T squared_distance(const vec &other) const { T d2 = 0; for (uint32_t i = 0; i < N; i++) { T d = m_v[i] - other.m_v[i]; d2 += d * d; } return d2; }

		inline T distance(const vec &other) const { return squared_distance(other); }

		inline vec &normalize_in_place() { T len = length(); if (len != 0.0f) *this *= (1.0f / len);	return *this; }

		inline vec &clamp(T l, T h)
		{
			for (uint32_t i = 0; i < N; i++)
				m_v[i] = basisu::clamp(m_v[i], l, h);
			return *this;
		}
	};

	typedef vec<4, double> vec4D;
	typedef vec<3, double> vec3D;
	typedef vec<2, double> vec2D;
	typedef vec<1, double> vec1D;

	typedef vec<4, float> vec4F;
	typedef vec<3, float> vec3F;
	typedef vec<2, float> vec2F;
	typedef vec<1, float> vec1F;
		
	template <uint32_t Rows, uint32_t Cols, typename T>
	class matrix
	{
	public:
		typedef vec<Rows, T> col_vec;
		typedef vec<Cols, T> row_vec;

		typedef T scalar_type;

		enum { rows = Rows, cols = Cols };

	protected:
		row_vec m_r[Rows];

	public:
		inline matrix() {}
		inline matrix(eZero) { set_zero();  }
		inline matrix(const matrix &other) { for (uint32_t i = 0; i < Rows; i++) m_r[i] = other.m_r[i];	}
		inline matrix &operator=(const matrix &rhs) { if (this != &rhs) for (uint32_t i = 0; i < Rows; i++) m_r[i] = rhs.m_r[i]; return *this; }

		inline T operator()(uint32_t r, uint32_t c) const { assert((r < Rows) && (c < Cols)); return m_r[r][c]; }
		inline T &operator()(uint32_t r, uint32_t c) { assert((r < Rows) && (c < Cols)); return m_r[r][c]; }

		inline const row_vec &operator[](uint32_t r) const { assert(r < Rows); return m_r[r]; }
		inline row_vec &operator[](uint32_t r) { assert(r < Rows); return m_r[r]; }

		inline matrix &set_zero()
		{
			for (uint32_t i = 0; i < Rows; i++)
				m_r[i].set_zero();
			return *this;
		}

		inline matrix &set_identity()
		{
			for (uint32_t i = 0; i < Rows; i++)
			{
				m_r[i].set_zero();
				if (i < Cols)
					m_r[i][i] = 1.0f;
			}
			return *this;
		}
	};

	template<uint32_t N, typename VectorType>
	inline VectorType compute_pca_from_covar(matrix<N, N, float> &cmatrix)
	{
		VectorType axis;
		if (N == 1)
			axis.set(1.0f);
		else
		{
			for (uint32_t i = 0; i < N; i++)
				axis[i] = lerp(.75f, 1.25f, i * (1.0f / maximum<int>(N - 1, 1)));
		}

		VectorType prev_axis(axis);

		// Power iterations
		for (uint32_t power_iter = 0; power_iter < 8; power_iter++)
		{
			VectorType trial_axis;
			double max_sum = 0;

			for (uint32_t i = 0; i < N; i++)
			{
				double sum = 0;
				for (uint32_t j = 0; j < N; j++)
					sum += cmatrix[i][j] * axis[j];

				trial_axis[i] = static_cast<float>(sum);

				max_sum = maximum(fabs(sum), max_sum);
			}

			if (max_sum != 0.0f)
				trial_axis *= static_cast<float>(1.0f / max_sum);

			VectorType delta_axis(prev_axis - trial_axis);

			prev_axis = axis;
			axis = trial_axis;

			if (delta_axis.norm() < .0024f)
				break;
		}

		return axis.normalize_in_place();
	}

	template<typename T> inline void indirect_sort(uint32_t num_indices, uint32_t* pIndices, const T* pKeys)
	{
		for (uint32_t i = 0; i < num_indices; i++)
			pIndices[i] = i;

		std::sort(
			pIndices,
			pIndices + num_indices,
			[pKeys](uint32_t a, uint32_t b) { return pKeys[a] < pKeys[b]; }
		);
	}

	// Simple 32-bit color class

	class color_rgba_i16
	{
	public:
		union
		{
			int16_t m_comps[4];

			struct
			{
				int16_t r;
				int16_t g;
				int16_t b;
				int16_t a;
			};
		};

		inline color_rgba_i16()
		{
			static_assert(sizeof(*this) == sizeof(int16_t)*4, "sizeof(*this) == sizeof(int16_t)*4");
		}

		inline color_rgba_i16(int sr, int sg, int sb, int sa)
		{
			set(sr, sg, sb, sa);
		}

		inline color_rgba_i16 &set(int sr, int sg, int sb, int sa)
		{
			m_comps[0] = (int16_t)clamp<int>(sr, INT16_MIN, INT16_MAX);
			m_comps[1] = (int16_t)clamp<int>(sg, INT16_MIN, INT16_MAX);
			m_comps[2] = (int16_t)clamp<int>(sb, INT16_MIN, INT16_MAX);
			m_comps[3] = (int16_t)clamp<int>(sa, INT16_MIN, INT16_MAX);
			return *this;
		}
	};
		
	class color_rgba
	{
	public:
		union
		{
			uint8_t m_comps[4];

			struct
			{
				uint8_t r;
				uint8_t g;
				uint8_t b;
				uint8_t a;
			};
		};

		inline color_rgba()
		{
			static_assert(sizeof(*this) == 4, "sizeof(*this) != 4");
		}

		inline color_rgba(int y)
		{
			set(y);
		}

		inline color_rgba(int y, int na)
		{
			set(y, na);
		}

		inline color_rgba(int sr, int sg, int sb, int sa)
		{
			set(sr, sg, sb, sa);
		}

		inline color_rgba(eNoClamp, int sr, int sg, int sb, int sa)
		{
			set_noclamp_rgba((uint8_t)sr, (uint8_t)sg, (uint8_t)sb, (uint8_t)sa);
		}

		inline color_rgba& set_noclamp_y(int y)
		{
			m_comps[0] = (uint8_t)y;
			m_comps[1] = (uint8_t)y;
			m_comps[2] = (uint8_t)y;
			m_comps[3] = (uint8_t)255;
			return *this;
		}

		inline color_rgba &set_noclamp_rgba(int sr, int sg, int sb, int sa)
		{
			m_comps[0] = (uint8_t)sr;
			m_comps[1] = (uint8_t)sg;
			m_comps[2] = (uint8_t)sb;
			m_comps[3] = (uint8_t)sa;
			return *this;
		}

		inline color_rgba &set(int y)
		{
			m_comps[0] = static_cast<uint8_t>(clamp<int>(y, 0, 255));
			m_comps[1] = m_comps[0];
			m_comps[2] = m_comps[0];
			m_comps[3] = 255;
			return *this;
		}

		inline color_rgba &set(int y, int na)
		{
			m_comps[0] = static_cast<uint8_t>(clamp<int>(y, 0, 255));
			m_comps[1] = m_comps[0];
			m_comps[2] = m_comps[0];
			m_comps[3] = static_cast<uint8_t>(clamp<int>(na, 0, 255));
			return *this;
		}

		inline color_rgba &set(int sr, int sg, int sb, int sa)
		{
			m_comps[0] = static_cast<uint8_t>(clamp<int>(sr, 0, 255));
			m_comps[1] = static_cast<uint8_t>(clamp<int>(sg, 0, 255));
			m_comps[2] = static_cast<uint8_t>(clamp<int>(sb, 0, 255));
			m_comps[3] = static_cast<uint8_t>(clamp<int>(sa, 0, 255));
			return *this;
		}

		inline color_rgba &set_rgb(int sr, int sg, int sb)
		{
			m_comps[0] = static_cast<uint8_t>(clamp<int>(sr, 0, 255));
			m_comps[1] = static_cast<uint8_t>(clamp<int>(sg, 0, 255));
			m_comps[2] = static_cast<uint8_t>(clamp<int>(sb, 0, 255));
			return *this;
		}

		inline color_rgba &set_rgb(const color_rgba &other)
		{
			r = other.r;
			g = other.g;
			b = other.b;
			return *this;
		}

		inline const uint8_t &operator[] (uint32_t index) const { assert(index < 4); return m_comps[index]; }
		inline uint8_t &operator[] (uint32_t index) { assert(index < 4); return m_comps[index]; }
		
		inline void clear()
		{
			m_comps[0] = 0;
			m_comps[1] = 0;
			m_comps[2] = 0;
			m_comps[3] = 0;
		}

		inline bool operator== (const color_rgba &rhs) const
		{
			if (m_comps[0] != rhs.m_comps[0]) return false;
			if (m_comps[1] != rhs.m_comps[1]) return false;
			if (m_comps[2] != rhs.m_comps[2]) return false;
			if (m_comps[3] != rhs.m_comps[3]) return false;
			return true;
		}

		inline bool operator!= (const color_rgba &rhs) const
		{
			return !(*this == rhs);
		}

		inline bool operator<(const color_rgba &rhs) const
		{
			for (int i = 0; i < 4; i++)
			{
				if (m_comps[i] < rhs.m_comps[i])
					return true;
				else if (m_comps[i] != rhs.m_comps[i])
					return false;
			}
			return false;
		}

		inline int get_601_luma() const { return (19595U * m_comps[0] + 38470U * m_comps[1] + 7471U * m_comps[2] + 32768U) >> 16U; }
		inline int get_709_luma() const { return (13938U * m_comps[0] + 46869U * m_comps[1] + 4729U * m_comps[2] + 32768U) >> 16U; } 
		inline int get_luma(bool luma_601) const { return luma_601 ? get_601_luma() : get_709_luma(); }
	};

	typedef std::vector<color_rgba> color_rgba_vec;

	const color_rgba g_black_color(0, 0, 0, 255);
	const color_rgba g_white_color(255, 255, 255, 255);

	inline int color_distance(int r0, int g0, int b0, int r1, int g1, int b1)
	{
		int dr = r0 - r1, dg = g0 - g1, db = b0 - b1;
		return dr * dr + dg * dg + db * db;
	}

	inline int color_distance(int r0, int g0, int b0, int a0, int r1, int g1, int b1, int a1)
	{
		int dr = r0 - r1, dg = g0 - g1, db = b0 - b1, da = a0 - a1;
		return dr * dr + dg * dg + db * db + da * da;
	}

	inline int color_distance(const color_rgba &c0, const color_rgba &c1, bool alpha)
	{
		if (alpha)
			return color_distance(c0.r, c0.g, c0.b, c0.a, c1.r, c1.g, c1.b, c1.a);
		else
			return color_distance(c0.r, c0.g, c0.b, c1.r, c1.g, c1.b);
	}
		
	// TODO: Allow user to control channel weightings.
	inline uint32_t color_distance(bool perceptual, const color_rgba &e1, const color_rgba &e2, bool alpha)
	{
		if (perceptual)
		{
			const float l1 = e1.r * .2126f + e1.g * .715f + e1.b * .0722f;
			const float l2 = e2.r * .2126f + e2.g * .715f + e2.b * .0722f;

			const float cr1 = e1.r - l1;
			const float cr2 = e2.r - l2;

			const float cb1 = e1.b - l1;
			const float cb2 = e2.b - l2;

			const float dl = l1 - l2;
			const float dcr = cr1 - cr2;
			const float dcb = cb1 - cb2;

			uint32_t d = static_cast<uint32_t>(32.0f*4.0f*dl*dl + 32.0f*2.0f*(.5f / (1.0f - .2126f))*(.5f / (1.0f - .2126f))*dcr*dcr + 32.0f*.25f*(.5f / (1.0f - .0722f))*(.5f / (1.0f - .0722f))*dcb*dcb);
			
			if (alpha)
			{
				int da = static_cast<int>(e1.a) - static_cast<int>(e2.a);
				d += static_cast<uint32_t>(128.0f*da*da);
			}

			return d;
		}
		else
			return color_distance(e1, e2, alpha);
	}

	// String helpers

	inline int string_find_right(const std::string& filename, char c)
	{
		size_t result = filename.find_last_of(c);
		return (result == std::string::npos) ? -1 : (int)result;
	}

	inline std::string string_get_extension(const std::string &filename)
	{
		int sep = -1;
#ifdef _WIN32
		sep = string_find_right(filename, '\\');
#endif
		if (sep < 0)
			sep = string_find_right(filename, '/');

		int dot = string_find_right(filename, '.');
		if (dot <= sep)
			return "";

		std::string result(filename);
		result.erase(0, dot + 1);

		return result;
	}

	inline bool string_remove_extension(std::string &filename)
	{
		int sep = -1;
#ifdef _WIN32
		sep = string_find_right(filename, '\\');
#endif
		if (sep < 0)
			sep = string_find_right(filename, '/');

		int dot = string_find_right(filename, '.');
		if ((dot < sep) || (dot < 0))
			return false;

		filename.resize(dot);

		return true;
	}

	inline std::string string_format(const char* pFmt, ...)
	{
		char buf[2048];

		va_list args;
		va_start(args, pFmt);
#ifdef _WIN32		
		vsprintf_s(buf, sizeof(buf), pFmt, args);
#else
		vsnprintf(buf, sizeof(buf), pFmt, args);
#endif		
		va_end(args);

		return std::string(buf);
	}

	inline std::string string_tolower(const std::string& s)
	{
		std::string result(s);
		for (size_t i = 0; i < result.size(); i++)
			result[i] = (char)tolower((int)result[i]);
		return result;
	}

	inline char *strcpy_safe(char *pDst, size_t dst_len, const char *pSrc)
	{
		assert(pDst && pSrc && dst_len);
		if (!dst_len)
			return pDst;

		const size_t src_len = strlen(pSrc);
		const size_t src_len_plus_terminator = src_len + 1;

		if (src_len_plus_terminator <= dst_len)
			memcpy(pDst, pSrc, src_len_plus_terminator);
		else
		{
			if (dst_len > 1)
				memcpy(pDst, pSrc, dst_len - 1);
			pDst[dst_len - 1] = '\0';
		}

		return pDst;
	}

	inline bool string_ends_with(const std::string& s, char c)
	{
		return (s.size() != 0) && (s.back() == c);
	}

	inline bool string_split_path(const char *p, std::string *pDrive, std::string *pDir, std::string *pFilename, std::string *pExt)
	{
#ifdef _MSC_VER
		char drive_buf[_MAX_DRIVE] = { 0 };
		char dir_buf[_MAX_DIR] = { 0 };
		char fname_buf[_MAX_FNAME] = { 0 };
		char ext_buf[_MAX_EXT] = { 0 };

		errno_t error = _splitpath_s(p, 
			pDrive ? drive_buf : NULL, pDrive ? _MAX_DRIVE : 0,
			pDir ? dir_buf : NULL, pDir ? _MAX_DIR : 0,
			pFilename ? fname_buf : NULL, pFilename ? _MAX_FNAME : 0,
			pExt ? ext_buf : NULL, pExt ? _MAX_EXT : 0);
		if (error != 0)
			return false;

		if (pDrive) *pDrive = drive_buf;
		if (pDir) *pDir = dir_buf;
		if (pFilename) *pFilename = fname_buf;
		if (pExt) *pExt = ext_buf;
		return true;
#else
		char dirtmp[1024], nametmp[1024];
		strcpy_safe(dirtmp, sizeof(dirtmp), p);
		strcpy_safe(nametmp, sizeof(nametmp), p);

		if (pDrive)
			pDrive->resize(0);

		const char *pDirName = dirname(dirtmp);
		const char* pBaseName = basename(nametmp);
		if ((!pDirName) || (!pBaseName))
			return false;

		if (pDir)
		{
			*pDir = pDirName;
			if ((pDir->size()) && (pDir->back() != '/'))
				*pDir += "/";
		}
				
		if (pFilename)
		{
			*pFilename = pBaseName;
			string_remove_extension(*pFilename);
		}

		if (pExt)
		{
			*pExt = pBaseName;
			*pExt = string_get_extension(*pExt);
			if (pExt->size())
				*pExt = "." + *pExt;
		}

		return true;
#endif
	}

	inline bool is_path_separator(char c)
	{
#ifdef _WIN32
		return (c == '/') || (c == '\\');
#else
		return (c == '/');
#endif
	}
		
	inline bool is_drive_separator(char c)
	{
#ifdef _WIN32
		return (c == ':');
#else
		(void)c;
		return false;
#endif
	}

	inline void string_combine_path(std::string &dst, const char *p, const char *q)
	{
		std::string temp(p);
		if (temp.size() && !is_path_separator(q[0]))
		{
			if (!is_path_separator(temp.back()))
				temp.append(1, BASISU_PATH_SEPERATOR_CHAR);
		}
		temp += q;
		dst.swap(temp);
	}

	inline void string_combine_path(std::string &dst, const char *p, const char *q, const char *r)
	{
		string_combine_path(dst, p, q);
		string_combine_path(dst, dst.c_str(), r);
	}
		
	inline void string_combine_path_and_extension(std::string &dst, const char *p, const char *q, const char *r, const char *pExt)
	{
		string_combine_path(dst, p, q, r);
		if ((!string_ends_with(dst, '.')) && (pExt[0]) && (pExt[0] != '.'))
			dst.append(1, '.');
		dst.append(pExt);
	}

	inline bool string_get_pathname(const char *p, std::string &path)
	{
		std::string temp_drive, temp_path;
		if (!string_split_path(p, &temp_drive, &temp_path, NULL, NULL))
			return false;
		string_combine_path(path, temp_drive.c_str(), temp_path.c_str());
		return true;
	}

	inline bool string_get_filename(const char *p, std::string &filename)
	{
		std::string temp_ext;
		if (!string_split_path(p, nullptr, nullptr, &filename, &temp_ext))
			return false;
		filename += temp_ext;
		return true;
	}

	class rand
	{
		std::mt19937 m_mt;

	public:
		rand() {	}

		rand(uint32_t s) { seed(s); }
		void seed(uint32_t s) { m_mt.seed(s); }

		// between [l,h]
		int irand(int l, int h) { std::uniform_int_distribution<int> d(l, h); return d(m_mt); }

		uint32_t urand32() { return static_cast<uint32_t>(irand(INT32_MIN, INT32_MAX)); }

		bool bit() { return irand(0, 1) == 1; }

		uint8_t byte() { return static_cast<uint8_t>(urand32()); }

		// between [l,h)
		float frand(float l, float h) { std::uniform_real_distribution<float> d(l, h); return d(m_mt); }

		float gaussian(float mean, float stddev) { std::normal_distribution<float> d(mean, stddev); return d(m_mt); }
	};

	class priority_queue
	{
	public:
		priority_queue() :
			m_size(0)
		{
		}

		void clear()
		{
			m_heap.clear();
			m_size = 0;
		}

		void init(uint32_t max_entries, uint32_t first_index, float first_priority)
		{
			m_heap.resize(max_entries + 1);
			m_heap[1].m_index = first_index;
			m_heap[1].m_priority = first_priority;
			m_size = 1;
		}

		inline uint32_t size() const { return m_size; }

		inline uint32_t get_top_index() const { return m_heap[1].m_index; }
		inline float get_top_priority() const { return m_heap[1].m_priority; }

		inline void delete_top()
		{
			assert(m_size > 0);
			m_heap[1] = m_heap[m_size];
			m_size--;
			if (m_size)
				down_heap(1);
		}

		inline void add_heap(uint32_t index, float priority)
		{
			m_size++;

			uint32_t k = m_size;

			if (m_size >= m_heap.size())
				m_heap.resize(m_size + 1);

			for (;;)
			{
				uint32_t parent_index = k >> 1;
				if ((!parent_index) || (m_heap[parent_index].m_priority > priority))
					break;
				m_heap[k] = m_heap[parent_index];
				k = parent_index;
			}

			m_heap[k].m_index = index;
			m_heap[k].m_priority = priority;
		}

	private:
		struct entry
		{
			uint32_t m_index;
			float m_priority;
		};

		std::vector<entry> m_heap;
		uint32_t m_size;

		// Push down entry at index
		inline void down_heap(uint32_t heap_index)
		{
			uint32_t orig_index = m_heap[heap_index].m_index;
			const float orig_priority = m_heap[heap_index].m_priority;

			uint32_t child_index;
			while ((child_index = (heap_index << 1)) <= m_size)
			{
				if ((child_index < m_size) && (m_heap[child_index].m_priority < m_heap[child_index + 1].m_priority)) ++child_index;
				if (orig_priority > m_heap[child_index].m_priority)
					break;
				m_heap[heap_index] = m_heap[child_index];
				heap_index = child_index;
			}

			m_heap[heap_index].m_index = orig_index;
			m_heap[heap_index].m_priority = orig_priority;
		}
	};

	// Tree structured vector quantization (TSVQ)

	template <typename TrainingVectorType>
	class tree_vector_quant
	{
	public:
		typedef std::pair<TrainingVectorType, uint32_t> training_vec_with_weight;
		typedef std::vector< training_vec_with_weight > array_of_weighted_training_vecs;

		tree_vector_quant()
		{
		}

		void clear()
		{
			clear_vector(m_training_vecs);
			clear_vector(m_nodes);
		}

		void add_training_vec(const TrainingVectorType &v, uint32_t weight) { m_training_vecs.push_back(std::make_pair(v, weight)); }

		void retrieve(std::vector< std::vector<uint32_t> > &codebook) const
		{
			for (uint32_t i = 0; i < m_nodes.size(); i++)
			{
				const tsvq_node &n = m_nodes[i];
				if (!n.is_leaf())
					continue;

				codebook.resize(codebook.size() + 1);
				codebook.back() = n.m_training_vecs;
			}
		}

		void retrieve(std::vector<TrainingVectorType> &codebook) const
		{
			for (uint32_t i = 0; i < m_nodes.size(); i++)
			{
				const tsvq_node &n = m_nodes[i];
				if (!n.is_leaf())
					continue;

				codebook.resize(codebook.size() + 1);
				codebook.back() = n.m_origin;
			}
		}

		bool generate(uint32_t max_size)
		{
			if (!m_training_vecs.size())
				return false;

			clear_vector(m_nodes);
			m_nodes.reserve(max_size * 2 + 1);

			m_nodes.push_back(prepare_root());

			priority_queue var_heap;
			var_heap.init(max_size, 0, m_nodes[0].m_var);

			std::vector<uint32_t> l_children, r_children;

			// Now split the worst nodes
			l_children.reserve(m_training_vecs.size() + 1);
			r_children.reserve(m_training_vecs.size() + 1);

			uint32_t total_leaf_nodes = 1;

			while ((var_heap.size()) && (total_leaf_nodes < max_size))
			{
				const uint32_t node_index = var_heap.get_top_index();
				const tsvq_node &node = m_nodes[node_index];

				assert(node.m_var == var_heap.get_top_priority());
				assert(node.is_leaf());

				var_heap.delete_top();

				if (node.m_training_vecs.size() > 1)
				{
					if (split_node(node_index, var_heap, l_children, r_children))
					{
						// This removes one leaf node (making an internal node) and replaces it with two new leaves, so +1 total.
						total_leaf_nodes += 1;
					}
				}
			}

			return true;
		}

	private:
		class tsvq_node
		{
		public:
			inline tsvq_node() : m_weight(0), m_origin(cZero), m_left_index(-1), m_right_index(-1) { }

			// vecs is erased
			inline void set(const TrainingVectorType &org, uint64_t weight, float var, std::vector<uint32_t> &vecs) { m_origin = org; m_weight = weight; m_var = var; m_training_vecs.swap(vecs); }

			inline bool is_leaf() const { return m_left_index < 0; }

			float m_var;
			uint64_t m_weight;
			TrainingVectorType m_origin;
			int32_t m_left_index, m_right_index;
			std::vector<uint32_t> m_training_vecs;
		};

		typedef std::vector<tsvq_node> tsvq_node_vec;
		tsvq_node_vec m_nodes;

		array_of_weighted_training_vecs m_training_vecs;

		tsvq_node prepare_root() const
		{
			double ttsum = 0.0f;

			// Prepare root node containing all training vectors
			tsvq_node root;
			root.m_training_vecs.reserve(m_training_vecs.size());

			for (uint32_t i = 0; i < m_training_vecs.size(); i++)
			{
				const TrainingVectorType &v = m_training_vecs[i].first;
				const uint32_t weight = m_training_vecs[i].second;

				root.m_training_vecs.push_back(i);

				root.m_origin += (v * static_cast<float>(weight));
				root.m_weight += weight;

				ttsum += v.dot(v) * weight;
			}

			root.m_var = static_cast<float>(ttsum - (root.m_origin.dot(root.m_origin) / root.m_weight));

			root.m_origin *= (1.0f / root.m_weight);

			return root;
		}

		bool split_node(uint32_t node_index, priority_queue &var_heap, std::vector<uint32_t> &l_children, std::vector<uint32_t> &r_children)
		{
			TrainingVectorType l_child_org, r_child_org;
			uint64_t l_weight = 0, r_weight = 0;
			float l_var = 0.0f, r_var = 0.0f;

			// Compute initial left/right child origins
			prep_split(m_nodes[node_index], l_child_org, r_child_org);

			// Use k-means iterations to refine these children vectors
			if (!refine_split(m_nodes[node_index], l_child_org, l_weight, l_var, l_children, r_child_org, r_weight, r_var, r_children))
				return false;

			// Create children
			const uint32_t l_child_index = (uint32_t)m_nodes.size(), r_child_index = (uint32_t)m_nodes.size() + 1;

			m_nodes[node_index].m_left_index = l_child_index;
			m_nodes[node_index].m_right_index = r_child_index;

			m_nodes.resize(m_nodes.size() + 2);

			tsvq_node &l_child = m_nodes[l_child_index], &r_child = m_nodes[r_child_index];

			l_child.set(l_child_org, l_weight, l_var, l_children);
			r_child.set(r_child_org, r_weight, r_var, r_children);

			if ((l_child.m_var > 0.0f) && (l_child.m_training_vecs.size() > 1))
				var_heap.add_heap(l_child_index, l_var);

			if ((r_child.m_var > 0.0f) && (r_child.m_training_vecs.size() > 1))
				var_heap.add_heap(r_child_index, r_var);

			return true;
		}

		TrainingVectorType compute_split_axis(const tsvq_node &node) const
		{
			const uint32_t N = TrainingVectorType::num_elements;

			matrix<N, N, float> cmatrix(cZero);

			// Compute covariance matrix from weighted input vectors
			for (uint32_t i = 0; i < node.m_training_vecs.size(); i++)
			{
				const TrainingVectorType v(m_training_vecs[node.m_training_vecs[i]].first - node.m_origin);
				const TrainingVectorType w(static_cast<float>(m_training_vecs[node.m_training_vecs[i]].second) * v);

				for (uint32_t x = 0; x < N; x++)
					for (uint32_t y = x; y < N; y++)
						cmatrix[x][y] = cmatrix[x][y] + v[x] * w[y];
			}

			const float renorm_scale = 1.0f / node.m_weight;

			for (uint32_t x = 0; x < N; x++)
				for (uint32_t y = x; y < N; y++)
					cmatrix[x][y] *= renorm_scale;

			// Diagonal flip
			for (uint32_t x = 0; x < (N - 1); x++)
				for (uint32_t y = x + 1; y < N; y++)
					cmatrix[y][x] = cmatrix[x][y];

			return compute_pca_from_covar<N, TrainingVectorType>(cmatrix);
		}

		void prep_split(const tsvq_node &node, TrainingVectorType &l_child_result, TrainingVectorType &r_child_result) const
		{
			const uint32_t N = TrainingVectorType::num_elements;

			if (2 == node.m_training_vecs.size())
			{
				l_child_result = m_training_vecs[node.m_training_vecs[0]].first;
				r_child_result = m_training_vecs[node.m_training_vecs[1]].first;
				return;
			}

			TrainingVectorType axis(compute_split_axis(node)), l_child(0.0f), r_child(0.0f);
			double l_weight = 0.0f, r_weight = 0.0f;

			// Compute initial left/right children
			for (uint32_t i = 0; i < node.m_training_vecs.size(); i++)
			{
				const float weight = (float)m_training_vecs[node.m_training_vecs[i]].second;

				const TrainingVectorType &v = m_training_vecs[node.m_training_vecs[i]].first;

				double t = (v - node.m_origin).dot(axis);
				if (t >= 0.0f)
				{
					r_child += v * weight;
					r_weight += weight;
				}
				else
				{
					l_child += v * weight;
					l_weight += weight;
				}
			}

			if ((l_weight > 0.0f) && (r_weight > 0.0f))
			{
				l_child_result = l_child * static_cast<float>(1.0f / l_weight);
				r_child_result = r_child * static_cast<float>(1.0f / r_weight);
			}
			else
			{
				// Empty cell problem
				l_child_result = node.m_origin;
				r_child_result = node.m_origin;

				// Nudge the two cells apart and hope k-means can separate them.
				for (uint32_t i = 0; i < N; i++)
				{
					l_child_result[i] -= .000125f;
					r_child_result[i] += .000125f;
				}
			}
		}

		bool refine_split(const tsvq_node &node,
			TrainingVectorType &l_child, uint64_t &l_weight, float &l_var, std::vector<uint32_t> &l_children,
			TrainingVectorType &r_child, uint64_t &r_weight, float &r_var, std::vector<uint32_t> &r_children) const
		{
			l_children.reserve(node.m_training_vecs.size());
			r_children.reserve(node.m_training_vecs.size());

			float prev_total_variance = 1e+10f;

			// Refine left/right children locations using k-means iterations
			const uint32_t cMaxIters = 6;
			for (uint32_t iter = 0; iter < cMaxIters; iter++)
			{
				l_children.resize(0); 
				r_children.resize(0); 

				TrainingVectorType new_l_child(cZero), new_r_child(cZero);

				double l_ttsum = 0.0f, r_ttsum = 0.0f;

				l_weight = 0;
				r_weight = 0;

				for (uint32_t i = 0; i < node.m_training_vecs.size(); i++)
				{
					const TrainingVectorType &v = m_training_vecs[node.m_training_vecs[i]].first;
					const uint32_t weight = m_training_vecs[node.m_training_vecs[i]].second;

					double left_dist2 = l_child.squared_distance(v), right_dist2 = r_child.squared_distance(v);

					if (left_dist2 >= right_dist2)
					{
						new_r_child += (v * static_cast<float>(weight));
						r_weight += weight;

						r_ttsum += weight * v.dot(v);
						r_children.push_back(node.m_training_vecs[i]);
					}
					else
					{
						new_l_child += (v * static_cast<float>(weight));
						l_weight += weight;

						l_ttsum += weight * v.dot(v);
						l_children.push_back(node.m_training_vecs[i]);
					}
				}

				if ((!l_weight) || (!r_weight))
					return false;

				l_var = static_cast<float>(l_ttsum - (new_l_child.dot(new_l_child) / l_weight));
				r_var = static_cast<float>(r_ttsum - (new_r_child.dot(new_r_child) / r_weight));

				new_l_child *= (1.0f / l_weight);
				new_r_child *= (1.0f / r_weight);

				l_child = new_l_child;
				r_child = new_r_child;

				float total_var = l_var + r_var;
				const float cGiveupVariance = .00001f;
				if (total_var < cGiveupVariance)
					break;

				// Check to see if the variance has settled
				const float cVarianceDeltaThresh = .00125f;
				if (((prev_total_variance - total_var) / total_var) < cVarianceDeltaThresh)
					break;

				prev_total_variance = total_var;
			}

			return true;
		}
	};

	// Canonical Huffman coding

	class histogram
	{
		std::vector<uint32_t> m_hist;

	public:
		histogram(uint32_t size = 0) { init(size); }

		void clear()
		{
			clear_vector(m_hist);
		}

		void init(uint32_t size)
		{
			m_hist.resize(0);
			m_hist.resize(size);
		}

		inline uint32_t size() const { return static_cast<uint32_t>(m_hist.size()); }

		inline const uint32_t &operator[] (uint32_t index) const
		{
			return m_hist[index];
		}

		inline uint32_t &operator[] (uint32_t index)
		{
			return m_hist[index];
		}

		inline void inc(uint32_t index)
		{
			m_hist[index]++;
		}

		uint64_t get_total() const
		{
			uint64_t total = 0;
			for (uint32_t i = 0; i < m_hist.size(); ++i)
				total += m_hist[i];
			return total;
		}

		double get_entropy() const
		{
			double total = static_cast<double>(get_total());
			if (total == 0.0f)
				return 0.0f;

			const double inv_total = 1.0f / total;
			const double neg_inv_log2 = -1.0f / log(2.0f);
			
			double e = 0.0f;
			for (uint32_t i = 0; i < m_hist.size(); i++)
				if (m_hist[i])
					e += log(m_hist[i] * inv_total) * neg_inv_log2 * static_cast<double>(m_hist[i]);

			return e;
		}
	};
		
	struct sym_freq
	{
		uint16_t m_key, m_sym_index;
	};

	sym_freq *canonical_huffman_radix_sort_syms(uint32_t num_syms, sym_freq *pSyms0, sym_freq *pSyms1);
	void canonical_huffman_calculate_minimum_redundancy(sym_freq *A, int num_syms);
	void canonical_huffman_enforce_max_code_size(int *pNum_codes, int code_list_len, int max_code_size);
	
	class huffman_encoding_table
	{
	public:
		huffman_encoding_table()
		{
		}

		void clear()
		{
			clear_vector(m_codes);
			clear_vector(m_code_sizes);
		}

		bool init(const histogram &h, uint32_t max_code_size = cHuffmanMaxSupportedCodeSize)
		{
			return init(h.size(), &h[0], max_code_size);
		}

		bool init(uint32_t num_syms, const uint16_t *pFreq, uint32_t max_code_size);
		bool init(uint32_t num_syms, const uint32_t *pSym_freq, uint32_t max_code_size);
		
		inline const uint16_vec &get_codes() const { return m_codes; }
		inline const uint8_vec &get_code_sizes() const { return m_code_sizes; }

		uint32_t get_total_used_codes() const
		{
			for (int i = static_cast<int>(m_code_sizes.size()) - 1; i >= 0; i--)
				if (m_code_sizes[i])
					return i + 1;
			return 0;
		}

	private:
		uint16_vec m_codes;
		uint8_vec m_code_sizes;
	};

	class bitwise_coder
	{
	public:
		bitwise_coder() :
			m_bit_buffer(0),
			m_bit_buffer_size(0),
			m_total_bits(0)
		{
		}

		inline void clear()
		{
			clear_vector(m_bytes);
			m_bit_buffer = 0;
			m_bit_buffer_size = 0;
			m_total_bits = 0;
		}

		inline const uint8_vec &get_bytes() const { return m_bytes; }

		inline uint64_t get_total_bits() const { return m_total_bits; }
		inline void clear_total_bits() { m_total_bits = 0; }

		inline void init(uint32_t reserve_size = 1024)
		{
			m_bytes.reserve(reserve_size);
			m_bytes.resize(0);

			m_bit_buffer = 0;
			m_bit_buffer_size = 0;
			m_total_bits = 0;
		}

		inline uint32_t flush()
		{
			if (m_bit_buffer_size)
			{
				m_total_bits += 8;
				append_byte(static_cast<uint8_t>(m_bit_buffer));

				m_bit_buffer = 0;
				m_bit_buffer_size = 0;
				
				return 8;
			}

			return 0;
		}

		inline uint32_t put_bits(uint32_t bits, uint32_t num_bits)
		{
			assert(num_bits <= 32);
			assert(bits < (1ULL << num_bits));

			if (!num_bits)
				return 0;

			m_total_bits += num_bits;

			uint64_t v = (static_cast<uint64_t>(bits) << m_bit_buffer_size) | m_bit_buffer;
			m_bit_buffer_size += num_bits;

			while (m_bit_buffer_size >= 8)
			{
				append_byte(static_cast<uint8_t>(v));
				v >>= 8;
				m_bit_buffer_size -= 8;
			}

			m_bit_buffer = static_cast<uint8_t>(v);
			return num_bits;
		}

		inline uint32_t put_code(uint32_t sym, const huffman_encoding_table &tab)
		{
			uint32_t code = tab.get_codes()[sym];
			uint32_t code_size = tab.get_code_sizes()[sym];
			assert(code_size >= 1);
			put_bits(code, code_size);
			return code_size;
		}

		inline uint32_t put_truncated_binary(uint32_t v, uint32_t n)
		{
			assert((n >= 2) && (v < n));

			uint32_t k = floor_log2i(n);
			uint32_t u = (1 << (k + 1)) - n;

			if (v < u)
				return put_bits(v, k);
			
			uint32_t x = v + u;
			assert((x >> 1) >= u);

			put_bits(x >> 1, k);
			put_bits(x & 1, 1);
			return k + 1;
		}

		inline uint32_t put_rice(uint32_t v, uint32_t m)
		{
			assert(m);
			
			const uint64_t start_bits = m_total_bits;

			uint32_t q = v >> m, r = v & ((1 << m) - 1);

			// rice coding sanity check
			assert(q <= 64);
			
			for (; q > 16; q -= 16)
				put_bits(0xFFFF, 16);

			put_bits((1 << q) - 1, q);
			put_bits(r << 1, m + 1);
			
			return (uint32_t)(m_total_bits - start_bits);
		}

		inline uint32_t put_vlc(uint32_t v, uint32_t chunk_bits)
		{
			assert(chunk_bits);

			const uint32_t chunk_size = 1 << chunk_bits;
			const uint32_t chunk_mask = chunk_size - 1;
					
			uint32_t total_bits = 0;

			for ( ; ; )
			{
				uint32_t next_v = v >> chunk_bits;
								
				total_bits += put_bits((v & chunk_mask) | (next_v ? chunk_size : 0), chunk_bits + 1);
				if (!next_v)
					break;

				v = next_v;
			}

			return total_bits;
		}

		uint32_t emit_huffman_table(const huffman_encoding_table &tab);
		
	private:
		uint8_vec m_bytes;
		uint32_t m_bit_buffer, m_bit_buffer_size;
		uint64_t m_total_bits;

		void append_byte(uint8_t c)
		{
			m_bytes.resize(m_bytes.size() + 1);
			m_bytes.back() = c;
		}

		static void end_nonzero_run(uint16_vec &syms, uint32_t &run_size, uint32_t len);
		static void end_zero_run(uint16_vec &syms, uint32_t &run_size);
	};

	class huff2D
	{
	public:
		huff2D() { }
		huff2D(uint32_t bits_per_sym, uint32_t total_syms_per_group) { init(bits_per_sym, total_syms_per_group); }

		inline const histogram &get_histogram() const { return m_histogram; }
		inline const huffman_encoding_table &get_encoding_table() const { return m_encoding_table; }

		inline void init(uint32_t bits_per_sym, uint32_t total_syms_per_group)
		{
			assert((bits_per_sym * total_syms_per_group) <= 16 && total_syms_per_group >= 1 && bits_per_sym >= 1);
						
			m_bits_per_sym = bits_per_sym;
			m_total_syms_per_group = total_syms_per_group;
			m_cur_sym_bits = 0;
			m_cur_num_syms = 0;
			m_decode_syms_remaining = 0;
			m_next_decoder_group_index = 0;

			m_histogram.init(1 << (bits_per_sym * total_syms_per_group));
		}

		inline void clear()
		{
			m_group_bits.clear();

			m_cur_sym_bits = 0;
			m_cur_num_syms = 0;
			m_decode_syms_remaining = 0;
			m_next_decoder_group_index = 0;
		}

		inline void emit(uint32_t sym)
		{
			m_cur_sym_bits |= (sym << (m_cur_num_syms * m_bits_per_sym));
			m_cur_num_syms++;

			if (m_cur_num_syms == m_total_syms_per_group)
				flush();
		}

		inline void flush()
		{
			if (m_cur_num_syms)
			{
				m_group_bits.push_back(m_cur_sym_bits);
				m_histogram.inc(m_cur_sym_bits);

				m_cur_sym_bits = 0;
				m_cur_num_syms = 0;
			}
		}

		inline bool start_encoding(uint32_t code_size_limit = 16)
		{
			flush();

			if (!m_encoding_table.init(m_histogram, code_size_limit))
				return false;

			m_decode_syms_remaining = 0;
			m_next_decoder_group_index = 0;

			return true;
		}
				
		inline uint32_t emit_next_sym(bitwise_coder &c)
		{
			uint32_t bits = 0;

			if (!m_decode_syms_remaining)
			{
				bits = c.put_code(m_group_bits[m_next_decoder_group_index++], m_encoding_table);
				m_decode_syms_remaining = m_total_syms_per_group;
			}

			m_decode_syms_remaining--;
			return bits;
		}

		inline void emit_flush()
		{
			m_decode_syms_remaining = 0;
		}

	private:
		uint_vec m_group_bits;
		huffman_encoding_table m_encoding_table;
		histogram m_histogram;
		uint32_t m_bits_per_sym, m_total_syms_per_group, m_cur_sym_bits, m_cur_num_syms, m_next_decoder_group_index, m_decode_syms_remaining;
	};

	bool huffman_test(int rand_seed);

	// VQ index reordering
	
	class palette_index_reorderer
	{
	public:
		palette_index_reorderer()
		{
		}

		void clear()
		{
			clear_vector(m_hist);
			clear_vector(m_total_count_to_picked);
			clear_vector(m_entries_picked);
			clear_vector(m_entries_to_do);
			clear_vector(m_remap_table);
		}

		// returns [0,1] distance of entry i to entry j
		typedef float(*pEntry_dist_func)(uint32_t i, uint32_t j, void *pCtx);

		void init(uint32_t num_indices, const uint32_t *pIndices, uint32_t num_syms, pEntry_dist_func pDist_func, void *pCtx, float dist_func_weight);
		
		// Table remaps old to new symbol indices
		inline const uint_vec &get_remap_table() const { return m_remap_table; }

	private:
		uint_vec m_hist, m_total_count_to_picked, m_entries_picked, m_entries_to_do, m_remap_table;

		inline uint32_t get_hist(int i, int j, int n) const { return (i > j) ? m_hist[j * n + i] : m_hist[i * n + j]; }
		inline void inc_hist(int i, int j, int n) { if ((i != j) && (i < j) && (i != -1) && (j != -1)) { assert(((uint32_t)i < (uint32_t)n) && ((uint32_t)j < (uint32_t)n)); m_hist[i * n + j]++; } }

		void prepare_hist(uint32_t num_syms, uint32_t num_indices, const uint32_t *pIndices);
		void find_initial(uint32_t num_syms);
		void find_next_entry(uint32_t &best_entry, double &best_count, pEntry_dist_func pDist_func, void *pCtx, float dist_func_weight);
		float pick_side(uint32_t num_syms, uint32_t entry_to_move, pEntry_dist_func pDist_func, void *pCtx, float dist_func_weight);
	};

	// Simple 32-bit 2D image class

	class image
	{
	public:
		image() : 
			m_width(0), m_height(0), m_pitch(0)
		{
		}

		image(uint32_t w, uint32_t h, uint32_t p = UINT32_MAX) : 
			m_width(0), m_height(0), m_pitch(0)
		{
			resize(w, h, p);
		}

		image(const image &other) :
			m_width(0), m_height(0), m_pitch(0)
		{
			*this = other;
		}

		image &swap(image &other)
		{
			std::swap(m_width, other.m_width);
			std::swap(m_height, other.m_height);
			std::swap(m_pitch, other.m_pitch);
			m_pixels.swap(other.m_pixels);
			return *this;
		}

		image &operator= (const image &rhs)
		{
			if (this != &rhs)
			{
				m_width = rhs.m_width;
				m_height = rhs.m_height;
				m_pitch = rhs.m_pitch;
				m_pixels = rhs.m_pixels;
			}
			return *this;
		}

		image &clear()
		{
			m_width = 0; 
			m_height = 0;
			m_pitch = 0;
			clear_vector(m_pixels);
			return *this;
		}

		image &resize(uint32_t w, uint32_t h, uint32_t p = UINT32_MAX, const color_rgba& background = g_black_color)
		{
			return crop(w, h, p, background);
		}

		image &set_all(const color_rgba &c)
		{
			for (uint32_t i = 0; i < m_pixels.size(); i++)
				m_pixels[i] = c;
			return *this;
		}

		image &fill_box(uint32_t x, uint32_t y, uint32_t w, uint32_t h, const color_rgba &c)
		{
			for (uint32_t iy = 0; iy < h; iy++)
				for (uint32_t ix = 0; ix < w; ix++)
					set_clipped(x + ix, y + iy, c);
			return *this;
		}

		image &crop_dup_borders(uint32_t w, uint32_t h)
		{
			const uint32_t orig_w = m_width, orig_h = m_height;

			crop(w, h);

			if (orig_w && orig_h)
			{
				if (m_width > orig_w)
				{
					for (uint32_t x = orig_w; x < m_width; x++)
						for (uint32_t y = 0; y < m_height; y++)
							set_clipped(x, y, get_clamped(minimum(x, orig_w - 1U), minimum(y, orig_h - 1U)));
				}

				if (m_height > orig_h)
				{
					for (uint32_t y = orig_h; y < m_height; y++)
						for (uint32_t x = 0; x < m_width; x++)
							set_clipped(x, y, get_clamped(minimum(x, orig_w - 1U), minimum(y, orig_h - 1U)));
				}
			}
			return *this;
		}

		image &crop(uint32_t w, uint32_t h, uint32_t p = UINT32_MAX, const color_rgba &background = g_black_color)
		{
			if (p == UINT32_MAX)
				p = w;

			if ((w == m_width) && (m_height == h) && (m_pitch == p))
				return *this;

			if ((!w) || (!h) || (!p))
			{
				clear();
				return *this;
			}

			color_rgba_vec cur_state;
			cur_state.swap(m_pixels);

			m_pixels.resize(p * h);
			
			for (uint32_t y = 0; y < h; y++)
			{
				for (uint32_t x = 0; x < w; x++)
				{
					if ((x < m_width) && (y < m_height))
						m_pixels[x + y * p] = cur_state[x + y * m_pitch];
					else
						m_pixels[x + y * p] = background;
				}
			}

			m_width = w;
			m_height = h;
			m_pitch = p;

			return *this;
		}

		inline const color_rgba &operator() (uint32_t x, uint32_t y) const { assert(x < m_width && y < m_height); return m_pixels[x + y * m_pitch]; }
		inline color_rgba &operator() (uint32_t x, uint32_t y) { assert(x < m_width && y < m_height); return m_pixels[x + y * m_pitch]; }

		inline const color_rgba &get_clamped(int x, int y) const { return (*this)(clamp<int>(x, 0, m_width - 1), clamp<int>(y, 0, m_height - 1)); }
		inline color_rgba &get_clamped(int x, int y) { return (*this)(clamp<int>(x, 0, m_width - 1), clamp<int>(y, 0, m_height - 1)); }

		inline const color_rgba &get_clamped_or_wrapped(int x, int y, bool wrap_u, bool wrap_v) const
		{
			x = wrap_u ? posmod(x, m_width) : clamp<int>(x, 0, m_width - 1);
			y = wrap_v ? posmod(y, m_height) : clamp<int>(y, 0, m_height - 1);
			return m_pixels[x + y * m_pitch];
		}

		inline color_rgba &get_clamped_or_wrapped(int x, int y, bool wrap_u, bool wrap_v)
		{
			x = wrap_u ? posmod(x, m_width) : clamp<int>(x, 0, m_width - 1);
			y = wrap_v ? posmod(y, m_height) : clamp<int>(y, 0, m_height - 1);
			return m_pixels[x + y * m_pitch];
		}
		
		inline image &set_clipped(int x, int y, const color_rgba &c) 
		{
			if ((static_cast<uint32_t>(x) < m_width) && (static_cast<uint32_t>(y) < m_height))
				(*this)(x, y) = c;
			return *this;
		}

		// Very straightforward blit with full clipping. Not fast, but it works.
		image &blit(const image &src, int src_x, int src_y, int src_w, int src_h, int dst_x, int dst_y)
		{
			for (int y = 0; y < src_h; y++)
			{
				const int sy = src_y + y;
				if (sy < 0)
					continue;
				else if (sy >= (int)src.get_height())
					break;

				for (int x = 0; x < src_w; x++)
				{
					const int sx = src_x + x;
					if (sx < 0)
						continue;
					else if (sx >= (int)src.get_height())
						break;

					set_clipped(dst_x + x, dst_y + y, src(sx, sy));
				}
			}

			return *this;
		}

		const image &extract_block_clamped(color_rgba *pDst, uint32_t src_x, uint32_t src_y, uint32_t w, uint32_t h) const
		{
			for (uint32_t y = 0; y < h; y++)
				for (uint32_t x = 0; x < w; x++)
					*pDst++ = get_clamped(src_x + x, src_y + y);
			return *this;
		}

		image &set_block_clipped(const color_rgba *pSrc, uint32_t dst_x, uint32_t dst_y, uint32_t w, uint32_t h)
		{
			for (uint32_t y = 0; y < h; y++)
				for (uint32_t x = 0; x < w; x++)
					set_clipped(dst_x + x, dst_y + y, *pSrc++);
			return *this;
		}

		inline uint32_t get_width() const { return m_width; }
		inline uint32_t get_height() const { return m_height; }
		inline uint32_t get_pitch() const { return m_pitch; }
		inline uint32_t get_total_pixels() const { return m_width * m_height; }

		inline uint32_t get_block_width(uint32_t w) const { return (m_width + (w - 1)) / w; }
		inline uint32_t get_block_height(uint32_t h) const { return (m_height + (h - 1)) / h; }
		inline uint32_t get_total_blocks(uint32_t w, uint32_t h) const { return get_block_width(w) * get_block_height(h); }

		inline const color_rgba_vec &get_pixels() const { return m_pixels; }
		inline color_rgba_vec &get_pixels() { return m_pixels; }

		inline const color_rgba *get_ptr() const { return &m_pixels[0]; }
		inline color_rgba *get_ptr() { return &m_pixels[0]; }

		bool has_alpha() const
		{
			for (uint32_t y = 0; y < m_height; ++y)
				for (uint32_t x = 0; x < m_width; ++x)
					if ((*this)(x, y).a < 255)
						return true;

			return false;
		}

		image &set_alpha(uint8_t a)
		{
			for (uint32_t y = 0; y < m_height; ++y)
				for (uint32_t x = 0; x < m_width; ++x)
					(*this)(x, y).a = a;
			return *this;
		}

		image &flip_y()
		{
			for (uint32_t y = 0; y < m_height / 2; ++y)
				for (uint32_t x = 0; x < m_width; ++x)
					std::swap((*this)(x, y), (*this)(x, m_height - 1 - y));
			return *this;
		}

		// TODO: There are many ways to do this, not sure this is the best way.
		image &renormalize_normal_map()
		{
			for (uint32_t y = 0; y < m_height; y++)
			{
				for (uint32_t x = 0; x < m_width; x++)
				{
					color_rgba &c = (*this)(x, y);
					if ((c.r == 128) && (c.g == 128) && (c.b == 128))
						continue;

					vec3F v(c.r, c.g, c.b);
					v = (v * (2.0f / 255.0f)) - vec3F(1.0f);
					v.clamp(-1.0f, 1.0f);

					float length = v.length();
					const float cValidThresh = .077f;
					if (length < cValidThresh)
					{
						c.set(128, 128, 128, c.a);
					}
					else if (fabs(length - 1.0f) > cValidThresh)
					{
						if (length)
							v /= length;

						for (uint32_t i = 0; i < 3; i++)
							c[i] = static_cast<uint8_t>(clamp<float>(floor((v[i] + 1.0f) * 255.0f * .5f + .5f), 0.0f, 255.0f));

						if ((c.g == 128) && (c.r == 128))
						{
							if (c.b < 128)
								c.b = 0;
							else
								c.b = 255;
						}
					}
				}
			}
			return *this;
		}
				
	private:
		uint32_t m_width, m_height, m_pitch;  // all in pixels
		color_rgba_vec m_pixels;
	};

	// Float images

	typedef std::vector<vec4F> vec4F_vec;

	class imagef
	{
	public:
		imagef() : 
			m_width(0), m_height(0), m_pitch(0)
		{
		}

		imagef(uint32_t w, uint32_t h, uint32_t p = UINT32_MAX) : 
			m_width(0), m_height(0), m_pitch(0)
		{
			resize(w, h, p);
		}

		imagef(const imagef &other) :
			m_width(0), m_height(0), m_pitch(0)
		{
			*this = other;
		}

		imagef &swap(imagef &other)
		{
			std::swap(m_width, other.m_width);
			std::swap(m_height, other.m_height);
			std::swap(m_pitch, other.m_pitch);
			m_pixels.swap(other.m_pixels);
			return *this;
		}

		imagef &operator= (const imagef &rhs)
		{
			if (this != &rhs)
			{
				m_width = rhs.m_width;
				m_height = rhs.m_height;
				m_pitch = rhs.m_pitch;
				m_pixels = rhs.m_pixels;
			}
			return *this;
		}

		imagef &clear()
		{
			m_width = 0; 
			m_height = 0;
			m_pitch = 0;
			clear_vector(m_pixels);
			return *this;
		}

		imagef &set(const image &src, const vec4F &scale = vec4F(1), const vec4F &bias = vec4F(0))
		{
			const uint32_t width = src.get_width();
			const uint32_t height = src.get_height();

			resize(width, height);

			for (int y = 0; y < (int)height; y++)
			{
				for (uint32_t x = 0; x < width; x++)
				{
					const color_rgba &src_pixel = src(x, y);
					(*this)(x, y).set((float)src_pixel.r * scale[0] + bias[0], (float)src_pixel.g * scale[1] + bias[1], (float)src_pixel.b * scale[2] + bias[2], (float)src_pixel.a * scale[3] + bias[3]);
				}
			}

			return *this;
		}

		imagef &resize(const imagef &other, uint32_t p = UINT32_MAX, const vec4F& background = vec4F(0,0,0,1))
		{
			return resize(other.get_width(), other.get_height(), p, background);
		}

		imagef &resize(uint32_t w, uint32_t h, uint32_t p = UINT32_MAX, const vec4F& background = vec4F(0,0,0,1))
		{
			return crop(w, h, p, background);
		}

		imagef &set_all(const vec4F &c)
		{
			for (uint32_t i = 0; i < m_pixels.size(); i++)
				m_pixels[i] = c;
			return *this;
		}

		imagef &fill_box(uint32_t x, uint32_t y, uint32_t w, uint32_t h, const vec4F &c)
		{
			for (uint32_t iy = 0; iy < h; iy++)
				for (uint32_t ix = 0; ix < w; ix++)
					set_clipped(x + ix, y + iy, c);
			return *this;
		}
				
		imagef &crop(uint32_t w, uint32_t h, uint32_t p = UINT32_MAX, const vec4F &background = vec4F(0,0,0,1))
		{
			if (p == UINT32_MAX)
				p = w;

			if ((w == m_width) && (m_height == h) && (m_pitch == p))
				return *this;

			if ((!w) || (!h) || (!p))
			{
				clear();
				return *this;
			}

			vec4F_vec cur_state;
			cur_state.swap(m_pixels);

			m_pixels.resize(p * h);
			
			for (uint32_t y = 0; y < h; y++)
			{
				for (uint32_t x = 0; x < w; x++)
				{
					if ((x < m_width) && (y < m_height))
						m_pixels[x + y * p] = cur_state[x + y * m_pitch];
					else
						m_pixels[x + y * p] = background;
				}
			}

			m_width = w;
			m_height = h;
			m_pitch = p;

			return *this;
		}

		inline const vec4F &operator() (uint32_t x, uint32_t y) const { assert(x < m_width && y < m_height); return m_pixels[x + y * m_pitch]; }
		inline vec4F &operator() (uint32_t x, uint32_t y) { assert(x < m_width && y < m_height); return m_pixels[x + y * m_pitch]; }

		inline const vec4F &get_clamped(int x, int y) const { return (*this)(clamp<int>(x, 0, m_width - 1), clamp<int>(y, 0, m_height - 1)); }
		inline vec4F &get_clamped(int x, int y) { return (*this)(clamp<int>(x, 0, m_width - 1), clamp<int>(y, 0, m_height - 1)); }

		inline const vec4F &get_clamped_or_wrapped(int x, int y, bool wrap_u, bool wrap_v) const
		{
			x = wrap_u ? posmod(x, m_width) : clamp<int>(x, 0, m_width - 1);
			y = wrap_v ? posmod(y, m_height) : clamp<int>(y, 0, m_height - 1);
			return m_pixels[x + y * m_pitch];
		}

		inline vec4F &get_clamped_or_wrapped(int x, int y, bool wrap_u, bool wrap_v)
		{
			x = wrap_u ? posmod(x, m_width) : clamp<int>(x, 0, m_width - 1);
			y = wrap_v ? posmod(y, m_height) : clamp<int>(y, 0, m_height - 1);
			return m_pixels[x + y * m_pitch];
		}
		
		inline imagef &set_clipped(int x, int y, const vec4F &c) 
		{
			if ((static_cast<uint32_t>(x) < m_width) && (static_cast<uint32_t>(y) < m_height))
				(*this)(x, y) = c;
			return *this;
		}

		// Very straightforward blit with full clipping. Not fast, but it works.
		imagef &blit(const imagef &src, int src_x, int src_y, int src_w, int src_h, int dst_x, int dst_y)
		{
			for (int y = 0; y < src_h; y++)
			{
				const int sy = src_y + y;
				if (sy < 0)
					continue;
				else if (sy >= (int)src.get_height())
					break;

				for (int x = 0; x < src_w; x++)
				{
					const int sx = src_x + x;
					if (sx < 0)
						continue;
					else if (sx >= (int)src.get_height())
						break;

					set_clipped(dst_x + x, dst_y + y, src(sx, sy));
				}
			}

			return *this;
		}

		const imagef &extract_block_clamped(vec4F *pDst, uint32_t src_x, uint32_t src_y, uint32_t w, uint32_t h) const
		{
			for (uint32_t y = 0; y < h; y++)
				for (uint32_t x = 0; x < w; x++)
					*pDst++ = get_clamped(src_x + x, src_y + y);
			return *this;
		}

		imagef &set_block_clipped(const vec4F *pSrc, uint32_t dst_x, uint32_t dst_y, uint32_t w, uint32_t h)
		{
			for (uint32_t y = 0; y < h; y++)
				for (uint32_t x = 0; x < w; x++)
					set_clipped(dst_x + x, dst_y + y, *pSrc++);
			return *this;
		}

		inline uint32_t get_width() const { return m_width; }
		inline uint32_t get_height() const { return m_height; }
		inline uint32_t get_pitch() const { return m_pitch; }
		inline uint32_t get_total_pixels() const { return m_width * m_height; }

		inline uint32_t get_block_width(uint32_t w) const { return (m_width + (w - 1)) / w; }
		inline uint32_t get_block_height(uint32_t h) const { return (m_height + (h - 1)) / h; }
		inline uint32_t get_total_blocks(uint32_t w, uint32_t h) const { return get_block_width(w) * get_block_height(h); }

		inline const vec4F_vec &get_pixels() const { return m_pixels; }
		inline vec4F_vec &get_pixels() { return m_pixels; }

		inline const vec4F *get_ptr() const { return &m_pixels[0]; }
		inline vec4F *get_ptr() { return &m_pixels[0]; }
						
	private:
		uint32_t m_width, m_height, m_pitch;  // all in pixels
		vec4F_vec m_pixels;
	};

	// Image metrics
		
	class image_metrics
	{
	public:
		// TODO: Add ssim
		float m_max, m_mean, m_mean_squared, m_rms, m_psnr, m_ssim;

		image_metrics()
		{
			clear();
		}

		void clear()
		{
			m_max = 0;
			m_mean = 0;
			m_mean_squared = 0;
			m_rms = 0;
			m_psnr = 0;
			m_ssim = 0;
		}

		void print(const char *pPrefix = nullptr)	{ printf("%sMax: %3.0f Mean: %3.3f RMS: %3.3f PSNR: %2.3f dB\n", pPrefix ? pPrefix : "", m_max, m_mean, m_rms, m_psnr);	}

		void calc(const image &a, const image &b, uint32_t first_chan = 0, uint32_t total_chans = 0, bool avg_comp_error = true, bool use_601_luma = false);
	};

	// Image saving/loading/resampling

	bool load_png(const char* pFilename, image& img);
	inline bool load_png(const std::string &filename, image &img) { return load_png(filename.c_str(), img); }

	enum
	{
		cImageSaveGrayscale = 1,
		cImageSaveIgnoreAlpha = 2
	};

	bool save_png(const char* pFilename, const image& img, uint32_t image_save_flags = 0, uint32_t grayscale_comp = 0);
	inline bool save_png(const std::string &filename, const image &img, uint32_t image_save_flags = 0, uint32_t grayscale_comp = 0) { return save_png(filename.c_str(), img, image_save_flags, grayscale_comp); }
	
	bool read_file_to_vec(const char* pFilename, uint8_vec& data);
	
	bool write_data_to_file(const char* pFilename, const void* pData, size_t len);
	
	inline bool write_vec_to_file(const char* pFilename, const uint8_vec& v) {	return v.size() ? write_data_to_file(pFilename, &v[0], v.size()) : write_data_to_file(pFilename, "", 0); }

	float linear_to_srgb(float l);
	float srgb_to_linear(float s);

	bool image_resample(const image &src, image &dst, bool srgb = false,
		const char *pFilter = "lanczos4", float filter_scale = 1.0f, 
		bool wrapping = false,
		uint32_t first_comp = 0, uint32_t num_comps = 4);

	// Timing
			
	typedef uint64_t timer_ticks;

	class interval_timer
	{
	public:
		interval_timer();

		void start();
		void stop();

		double get_elapsed_secs() const;
		inline double get_elapsed_ms() const { return 1000.0f* get_elapsed_secs(); }
		
		static void init();
		static inline timer_ticks get_ticks_per_sec() { return g_freq; }
		static timer_ticks get_ticks();
		static double ticks_to_secs(timer_ticks ticks);
		static inline double ticks_to_ms(timer_ticks ticks) {	return ticks_to_secs(ticks) * 1000.0f; }

	private:
		static timer_ticks g_init_ticks, g_freq;
		static double g_timer_freq;

		timer_ticks m_start_time, m_stop_time;

		bool m_started, m_stopped;
	};

	// 2D array

	template<typename T>
	class vector2D
	{
		typedef std::vector<T> TVec;

		uint32_t m_width, m_height;
		TVec m_values;

	public:
		vector2D() :
			m_width(0),
			m_height(0)
		{
		}

		vector2D(uint32_t w, uint32_t h) :
			m_width(0),
			m_height(0)
		{
			resize(w, h);
		}

		vector2D(const vector2D &other)
		{
			*this = other;
		}

		vector2D &operator= (const vector2D &other)
		{
			if (this != &other)
			{
				m_width = other.m_width;
				m_height = other.m_height;
				m_values = other.m_values;
			}
			return *this;
		}

		inline bool operator== (const vector2D &rhs) const
		{
			return (m_width == rhs.m_width) && (m_height == rhs.m_height) && (m_values == rhs.m_values);
		}

		inline uint32_t size_in_bytes() const { return (uint32_t)m_values.size() * sizeof(m_values[0]); }

		inline const T &operator() (uint32_t x, uint32_t y) const { assert(x < m_width && y < m_height); return m_values[x + y * m_width]; }
		inline T &operator() (uint32_t x, uint32_t y) { assert(x < m_width && y < m_height); return m_values[x + y * m_width]; }

		inline const T &operator[] (uint32_t i) const { return m_values[i]; }
		inline T &operator[] (uint32_t i) { return m_values[i]; }
				
		inline const T &at_clamped(int x, int y) const { return (*this)(clamp<int>(x, 0, m_width), clamp<int>(y, 0, m_height)); }		
		inline T &at_clamped(int x, int y) { return (*this)(clamp<int>(x, 0, m_width), clamp<int>(y, 0, m_height)); }

		void clear()
		{
			m_width = 0;
			m_height = 0;
			m_values.clear();
		}

		void set_all(const T&val)
		{
			vector_set_all(m_values, val);
		}

		inline const T* get_ptr() const { return &m_values[0]; }
		inline T* get_ptr() { return &m_values[0]; }

		vector2D &resize(uint32_t new_width, uint32_t new_height)
		{
			if ((m_width == new_width) && (m_height == new_height))
				return *this;

			TVec oldVals(new_width * new_height);
			oldVals.swap(m_values);

			const uint32_t w = minimum(m_width, new_width);
			const uint32_t h = minimum(m_height, new_height);

			if ((w) && (h))
			{
				for (uint32_t y = 0; y < h; y++)
					for (uint32_t x = 0; x < w; x++)
						m_values[x + y * new_width] = oldVals[x + y * m_width];
			}

			m_width = new_width;
			m_height = new_height;

			return *this;
		}
	};

	inline FILE *fopen_safe(const char *pFilename, const char *pMode)
	{
#ifdef _WIN32
		FILE *pFile = nullptr;
		fopen_s(&pFile, pFilename, pMode);
		return pFile;
#else
		return fopen(pFilename, pMode);
#endif
	}
		
} // namespace basisu