janwas
0720025073
reduce dependency on PCH. move KiB constants to alignment, ARRAY_SIZE to code_annotation.h. move glext_funcs.h to external_libraries/glext_funcs.h, move part of ogl.h to external_libraries/opengl.h remove unused saturating arithmetic functions This was SVN commit r9363.
168 lines
5.1 KiB
C++
168 lines
5.1 KiB
C++
/* Copyright (c) 2010 Wildfire Games
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*
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* Permission is hereby granted, free of charge, to any person obtaining
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* a copy of this software and associated documentation files (the
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* "Software"), to deal in the Software without restriction, including
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* without limitation the rights to use, copy, modify, merge, publish,
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* distribute, sublicense, and/or sell copies of the Software, and to
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* permit persons to whom the Software is furnished to do so, subject to
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* the following conditions:
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*
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* The above copyright notice and this permission notice shall be included
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* in all copies or substantial portions of the Software.
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*
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* THE SOFTWARE IS PROVIDED "AS IS", WITHOUT WARRANTY OF ANY KIND,
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* EXPRESS OR IMPLIED, INCLUDING BUT NOT LIMITED TO THE WARRANTIES OF
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* MERCHANTABILITY, FITNESS FOR A PARTICULAR PURPOSE AND NONINFRINGEMENT.
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* IN NO EVENT SHALL THE AUTHORS OR COPYRIGHT HOLDERS BE LIABLE FOR ANY
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* CLAIM, DAMAGES OR OTHER LIABILITY, WHETHER IN AN ACTION OF CONTRACT,
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* TORT OR OTHERWISE, ARISING FROM, OUT OF OR IN CONNECTION WITH THE
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* SOFTWARE OR THE USE OR OTHER DEALINGS IN THE SOFTWARE.
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*/
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/*
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* various utility functions.
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*/
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/**
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low-level aka "lib"
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-------------------
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this codebase was grown from modules shared between several projects,
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i.e. my personal library; hence the name "lib". it has been expanded to
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fit the needs of 0ad - in particular, resource loading.
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owing to the dual-use situation, the 0ad coding conventions are not met;
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also, major changes are ill-advised because they may break other projects.
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design goals
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------------
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- fast and low-overhead, including startup time
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- portable: must run on Win32, Mac OS X and Linux
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- reusable across projects, i.e. no dependency on a
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central 'manager' that ties modules together.
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scope
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-----
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- POSIX definitions
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- resource management
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- debugging tools (including memory tracker)
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- low-level helper functions, e.g. ADTs, endian conversion and timing
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- platform-dependent system/feature detection
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**/
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#ifndef INCLUDED_LIB
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#define INCLUDED_LIB
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#include <cmath> // fabsf
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#include <limits> // numeric_limits
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#include <stdexcept> // out_of_range
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template<typename T>
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T Clamp(T val, T min, T max)
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{
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ASSERT(min <= max);
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return std::max(min, std::min(val, max));
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}
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template<typename T>
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T DivideRoundUp(T dividend, T divisor)
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{
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ASSERT(divisor != 0);
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return (dividend + divisor-1) / divisor;
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}
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/**
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* are the given floats nearly "equal"?
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*
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* @return whether the numbers are within "epsilon" of each other.
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*
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* notes:
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* - the epsilon magic number varies with the magnitude of the inputs.
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* we use a sane default, but don't use this routine for very
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* large/small comparands.
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* - floating-point numbers don't magically lose precision. addition,
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* subtraction and multiplication results are precise up to the mantissa's
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* least-significant bit. only division, sqrt, sin/cos and other
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* transcendental operations introduce error.
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**/
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inline bool feq(double d1, double d2, double epsilon = 0.00001)
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{
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return fabs(d1 - d2) < epsilon;
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}
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inline bool feqf(float f1, float f2, float epsilon = 0.001f)
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{
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return fabsf(f1 - f2) < epsilon;
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}
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inline bool IsSimilarMagnitude(double d1, double d2, const double relativeErrorTolerance = 0.05)
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{
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const double relativeError = fabs(d1/d2 - 1.0);
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if(relativeError > relativeErrorTolerance)
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return false;
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return true;
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}
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//-----------------------------------------------------------------------------
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// type conversion
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// note: these avoid a common mistake in using >> (ANSI requires
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// shift count be less than the bit width of the type).
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extern u32 u64_hi(u64 x); /// return upper 32-bits
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extern u32 u64_lo(u64 x); /// return lower 32-bits
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extern u16 u32_hi(u32 x); /// return upper 16-bits
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extern u16 u32_lo(u32 x); /// return lower 16-bits
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extern u64 u64_from_u32(u32 hi, u32 lo); /// assemble u64 from u32
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extern u32 u32_from_u16(u16 hi, u16 lo); /// assemble u32 from u16
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// safe downcasters: cast from any integral type to u32 or u16;
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// issues warning if larger than would fit in the target type.
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//
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// these are generally useful but included here (instead of e.g. lib.h) for
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// several reasons:
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// - including implementation in lib.h doesn't work because the definition
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// of ENSURE in turn requires lib.h's STMT.
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// - separate compilation of templates via export isn't supported by
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// most compilers.
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template<typename T> u8 u8_from_larger(T x)
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{
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const u8 max = std::numeric_limits<u8>::max();
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if((u64)x > (u64)max)
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throw std::out_of_range("u8_from_larger");
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return (u8)(x & max);
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}
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template<typename T> u16 u16_from_larger(T x)
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{
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const u16 max = std::numeric_limits<u16>::max();
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if((u64)x > (u64)max)
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throw std::out_of_range("u16_from_larger");
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return (u16)(x & max);
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}
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template<typename T> u32 u32_from_larger(T x)
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{
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const u32 max = std::numeric_limits<u32>::max();
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if((u64)x > (u64)max)
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throw std::out_of_range("u32_from_larger");
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return (u32)(x & max);
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}
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/// convert double to u8; verifies number is in range.
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extern u8 u8_from_double(double in);
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/// convert double to u16; verifies number is in range.
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extern u16 u16_from_double(double in);
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#endif // #ifndef INCLUDED_LIB
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