143 lines
3.2 KiB
C
143 lines
3.2 KiB
C
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// File: lzham_math.h
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// See Copyright Notice and license at the end of include/lzham.h
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#pragma once
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#if defined(LZHAM_USE_MSVC_INTRINSICS) && !defined(__MINGW32__)
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#include <intrin.h>
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#if defined(_MSC_VER)
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#pragma intrinsic(_BitScanReverse)
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#endif
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#endif
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namespace lzham
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{
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namespace math
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{
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// Yes I know these should probably be pass by ref, not val:
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// http://www.stepanovpapers.com/notes.pdf
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// Just don't use them on non-simple (non built-in) types!
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template<typename T> inline T minimum(T a, T b) { return (a < b) ? a : b; }
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template<typename T> inline T minimum(T a, T b, T c) { return minimum(minimum(a, b), c); }
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template<typename T> inline T maximum(T a, T b) { return (a > b) ? a : b; }
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template<typename T> inline T maximum(T a, T b, T c) { return maximum(maximum(a, b), c); }
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template<typename T> inline T clamp(T value, T low, T high) { return (value < low) ? low : ((value > high) ? high : value); }
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inline bool is_power_of_2(uint32 x) { return x && ((x & (x - 1U)) == 0U); }
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inline bool is_power_of_2(uint64 x) { return x && ((x & (x - 1U)) == 0U); }
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template<typename T> inline T align_up_pointer(T p, uint alignment)
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{
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LZHAM_ASSERT(is_power_of_2(alignment));
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ptr_bits_t q = reinterpret_cast<ptr_bits_t>(p);
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q = (q + alignment - 1) & (~((uint_ptr)alignment - 1));
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return reinterpret_cast<T>(q);
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}
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// From "Hackers Delight"
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// val remains unchanged if it is already a power of 2.
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inline uint32 next_pow2(uint32 val)
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{
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val--;
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val |= val >> 16;
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val |= val >> 8;
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val |= val >> 4;
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val |= val >> 2;
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val |= val >> 1;
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return val + 1;
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}
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// val remains unchanged if it is already a power of 2.
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inline uint64 next_pow2(uint64 val)
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{
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val--;
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val |= val >> 32;
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val |= val >> 16;
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val |= val >> 8;
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val |= val >> 4;
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val |= val >> 2;
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val |= val >> 1;
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return val + 1;
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}
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inline uint floor_log2i(uint v)
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{
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uint l = 0;
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while (v > 1U)
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{
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v >>= 1;
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l++;
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}
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return l;
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}
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inline uint ceil_log2i(uint v)
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{
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uint l = floor_log2i(v);
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if ((l != cIntBits) && (v > (1U << l)))
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l++;
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return l;
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}
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// Returns the total number of bits needed to encode v.
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inline uint total_bits(uint v)
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{
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unsigned long l = 0;
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#if defined(__MINGW32__)
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if (v)
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{
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l = 32 -__builtin_clz(v);
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}
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#elif defined(LZHAM_USE_MSVC_INTRINSICS)
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if (_BitScanReverse(&l, v))
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{
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l++;
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}
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else
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{
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l = 0;
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}
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#else
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while (v > 0U)
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{
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v >>= 1;
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l++;
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}
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#endif
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return static_cast<uint>(l);
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}
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inline uint compute_mask_size(uint x)
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{
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uint l = 0;
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while (x)
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{
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x &= (x - 1);
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l++;
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}
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return l;
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}
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inline uint compute_mask_shift(uint x)
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{
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if (!x)
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return 0;
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uint l = 0;
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while ((x & 1) == 0)
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{
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x >>= 1;
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l++;
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}
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return l;
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}
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}
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} // namespace lzham
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