Differential D3129 Diff 14506 ps/trunk/source/lib/bits.cpp

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ps/trunk/source/lib/bits.cpp

	/* Copyright (C) 2010 Wildfire Games.			/* Copyright (C) 2020 Wildfire Games.
	*			*
	* Permission is hereby granted, free of charge, to any person obtaining			* Permission is hereby granted, free of charge, to any person obtaining
	* a copy of this software and associated documentation files (the			* a copy of this software and associated documentation files (the
	* "Software"), to deal in the Software without restriction, including			* "Software"), to deal in the Software without restriction, including
	* without limitation the rights to use, copy, modify, merge, publish,			* without limitation the rights to use, copy, modify, merge, publish,
	* distribute, sublicense, and/or sell copies of the Software, and to			* distribute, sublicense, and/or sell copies of the Software, and to
	* permit persons to whom the Software is furnished to do so, subject to			* permit persons to whom the Software is furnished to do so, subject to
	* the following conditions:			* the following conditions:
	Show All 12 Lines

	/*			/*
	* bit-twiddling.			* bit-twiddling.
	*/			*/

	#include "precompiled.h"			#include "precompiled.h"
	#include "lib/bits.h"			#include "lib/bits.h"

				#include <cstring>

	static inline u32 get_float_bits(const float x)			static inline u32 get_float_bits(const float x)
	{			{
	u32 ret;			u32 ret;
	memcpy(&ret, &x, 4);			memcpy(&ret, &x, 4);
	return ret;			return ret;
	}			}

	int floor_log2(const float x)			int floor_log2(const float x)
	{			{
	const u32 i = get_float_bits(x);			const u32 i = get_float_bits(x);
	const u32 biased_exp = (i >> 23) & 0xFF;			const u32 biased_exp = (i >> 23) & 0xFF;
	return (int)biased_exp - 127;			return (int)biased_exp - 127;
	}			}