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+/*
+ *  Copyright (c) 2018 Stanislav Denisov
+ *
+ *  Permission is hereby granted, free of charge, to any person obtaining a copy
+ *  of this software and associated documentation files (the "Software"), to deal
+ *  in the Software without restriction, including without limitation the rights
+ *  to use, copy, modify, merge, publish, distribute, sublicense, and/or sell
+ *  copies of the Software, and to permit persons to whom the Software is
+ *  furnished to do so, subject to the following conditions:
+ *
+ *  The above copyright notice and this permission notice shall be included in all
+ *  copies or substantial portions of the Software.
+ *
+ *  THE SOFTWARE IS PROVIDED "AS IS", WITHOUT WARRANTY OF ANY KIND, EXPRESS OR
+ *  IMPLIED, INCLUDING BUT NOT LIMITED TO THE WARRANTIES OF MERCHANTABILITY,
+ *  FITNESS FOR A PARTICULAR PURPOSE AND NONINFRINGEMENT. IN NO EVENT SHALL THE
+ *  AUTHORS OR COPYRIGHT HOLDERS BE LIABLE FOR ANY CLAIM, DAMAGES OR OTHER
+ *  LIABILITY, WHETHER IN AN ACTION OF CONTRACT, TORT OR OTHERWISE, ARISING FROM,
+ *  OUT OF OR IN CONNECTION WITH THE SOFTWARE OR THE USE OR OTHER DEALINGS IN THE
+ *  SOFTWARE.
+ */
+
+using System.Runtime.CompilerServices;
+using System.Runtime.InteropServices;
+
+namespace NetStack.Quantization {
+	public static class HalfPrecision {
+		[StructLayout(LayoutKind.Explicit)]
+		private struct Values {
+			[FieldOffset(0)]
+			public float f;
+			[FieldOffset(0)]
+			public int i;
+			[FieldOffset(0)]
+			public uint u;
+		}
+
+		[MethodImpl(256)]
+		public static ushort Quantize(float value) {
+			var values = new Values {
+				f = value
+			};
+
+			return Quantize(values.i);
+		}
+
+		public static ushort Quantize(int value) {
+			int s = (value >> 16) & 0x00008000;
+			int e = ((value >> 23) & 0X000000FF) - (127 - 15);
+			int m = value & 0X007FFFFF;
+
+			if (e <= 0) {
+				if (e < -10)
+					return (ushort)s;
+
+				m = m | 0x00800000;
+
+				int t = 14 - e;
+				int a = (1 << (t - 1)) - 1;
+				int b = (m >> t) & 1;
+
+				m = (m + a + b) >> t;
+
+				return (ushort)(s | m);
+			}
+
+			if (e == 0XFF - (127 - 15)) {
+				if (m == 0)
+					return (ushort)(s | 0X7C00);
+
+				m >>= 13;
+
+				return (ushort)(s | 0X7C00 | m | ((m == 0) ? 1 : 0));
+			}
+
+			m = m + 0X00000FFF + ((m >> 13) & 1);
+
+			if ((m & 0x00800000) != 0) {
+				m = 0;
+				e++;
+			}
+
+			if (e > 30)
+				return (ushort)(s | 0X7C00);
+
+			return (ushort)(s | (e << 10) | (m >> 13));
+		}
+
+		public static float Dequantize(ushort value) {
+			uint result;
+			uint mantissa = (uint)(value & 1023);
+			uint exponent = 0XFFFFFFF2;
+
+			if ((value & -33792) == 0) {
+				if (mantissa != 0) {
+					while ((mantissa & 1024) == 0) {
+						exponent--;
+						mantissa = mantissa << 1;
+					}
+
+					mantissa &= 0XFFFFFBFF;
+					result = ((uint)((((uint)value & 0x8000) << 16) | ((exponent + 127) << 23))) | (mantissa << 13);
+				} else {
+					result = (uint)((value & 0x8000) << 16);
+				}
+			} else {
+				result = ((((uint)value & 0x8000) << 16) | ((((((uint)value >> 10) & 0X1F) - 15) + 127) << 23)) | (mantissa << 13);
+			}
+
+			var values = new Values {
+				u = result
+			};
+
+			return values.f;
+		}
+	}
+}