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