www.pudn.com > neuroocr_src.zip > Tools.cs

// AForge Math Library 
// 
// Copyright © Andrew Kirillov, 2005 
// andrew.kirillov@gmail.com 
// 
 
namespace AForge.Math 
{ 
	using System; 
 
	/// 
 
	/// Tools 
	/// 
 
	public class Tools 
	{ 
		// Calculate the power of 2, exp: [0, 30] 
		public static int Pow2(int exp) 
		{ 
			return ((exp >= 0) && (exp <= 30)) ? (1 << exp) : 0; 
		} 
 
		// Check if the integer is a power of 2 
		public static bool IsPowerOf2(int x)  
		{ 
			return (x & (x - 1)) == 0; 
		} 
 
		// Get base of 2 logarithm 
		public static int Log2(int x) 
		{ 
			if (x <= 65536) 
			{ 
				if (x <= 256) 
				{ 
					if (x <= 16) 
					{ 
						if (x <= 4) 
						{ 
							if (x <= 2) 
							{ 
								if (x <= 1) 
									return 0; 
								return 1; 
							} 
							return 2; 
						} 
						if (x <= 8) 
							return 3; 
						return 4; 
					} 
					if (x <= 64) 
					{ 
						if (x <= 32) 
							return 5; 
						return 6; 
					} 
					if (x <= 128) 
						return 7; 
					return 8; 
				} 
				if (x <= 4096) 
				{ 
					if (x <= 1024) 
					{ 
						if (x <= 512) 
							return 9; 
						return 10; 
					} 
					if (x <= 2048) 
						return 11; 
					return 12; 
				} 
				if (x <= 16384) 
				{ 
					if (x <= 8192) 
						return 13; 
					return 14; 
				} 
				if (x <= 32768) 
					return 15; 
				return 16; 
			} 
 
			if (x <= 16777216) 
			{ 
				if (x <= 1048576) 
				{ 
					if (x <= 262144) 
					{ 
						if (x <= 131072) 
							return 17; 
						return 18; 
					} 
					if (x <= 524288) 
						return 19; 
					return 20; 
				} 
				if (x <= 4194304)  
				{ 
					if (x <= 2097152) 
						return 21; 
					return 22; 
				} 
				if (x <= 8388608) 
					return 23; 
				return 24; 
			} 
			if (x <= 268435456) 
			{ 
				if (x <= 67108864) 
				{ 
					if (x <= 33554432) 
						return 25; 
					return 26; 
				} 
				if (x <= 134217728) 
					return 27; 
				return 28; 
			} 
			if (x <= 1073741824) 
			{ 
				if (x <= 536870912) 
					return 29; 
				return 30; 
			} 
			return 31; 
		} 
	} 
}