OutputBuffer.cs source code in C# .NET

Source code for the .NET framework in C#

                        
Code:

                         / 4.0 / 4.0 / untmp / DEVDIV_TFS / Dev10 / Releases / RTMRel / ndp / fx / src / Sys / System / IO / compression / OutputBuffer.cs / 1305376 / OutputBuffer.cs
                        

                        
                            namespace System.IO.Compression { 
    using System.Diagnostics;

    internal class OutputBuffer {
 
        private byte[] byteBuffer;  // buffer for storing bytes
        private int pos;            // position 
        private uint bitBuf;        // store uncomplete bits 
        private int bitCount;       // number of bits in bitBuffer
 
        // set the output buffer we will be using
        internal void UpdateBuffer(byte[] output) {
            byteBuffer = output;
            pos = 0; 
        }
 
        internal int BytesWritten { 
            get {
                return pos; 
            }
        }

        internal int FreeBytes { 
            get {
                return byteBuffer.Length - pos; 
            } 
        }
 
        internal void WriteUInt16(ushort value) {
            Debug.Assert(FreeBytes >= 2, "No enough space in output buffer!");

            byteBuffer[pos++] = (byte)value; 
            byteBuffer[pos++] = (byte)(value >> 8);
        } 
 
        internal void WriteBits(int n, uint bits) {
            Debug.Assert(n <= 16, "length must be larger than 16!"); 
            bitBuf |= bits << bitCount;
            bitCount += n;
            if (bitCount >= 16) {
                Debug.Assert(byteBuffer.Length - pos >= 2, "No enough space in output buffer!"); 
                byteBuffer[pos++] = unchecked((byte)bitBuf);
                byteBuffer[pos++] = unchecked((byte)(bitBuf >> 8)); 
                bitCount -= 16; 
                bitBuf >>= 16;
            } 
        }

        // write the bits left in the output as bytes.
        internal void FlushBits() { 
            // flush bits from bit buffer to output buffer
            while (bitCount >= 8) { 
                byteBuffer[pos++] = unchecked((byte)bitBuf); 
                bitCount -= 8;
                bitBuf >>= 8; 
            }

            if (bitCount > 0) {
                byteBuffer[pos++] = unchecked((byte)bitBuf); 
                bitBuf = 0;
                bitCount = 0; 
            } 
        }
 
        internal void WriteBytes(byte[] byteArray, int offset, int count) {
            Debug.Assert(FreeBytes >= count, "Not enough space in output buffer!");
            // faster
            if (bitCount == 0) { 
                Array.Copy(byteArray, offset, byteBuffer, pos, count);
                pos += count; 
            } 
            else {
                WriteBytesUnaligned(byteArray, offset, count); 
            }
        }

        private void WriteBytesUnaligned(byte[] byteArray, int offset, int count) { 
            for (int i = 0; i < count; i++) {
                byte b = byteArray[offset + i]; 
                WriteByteUnaligned(b); 
            }
        } 

        private void WriteByteUnaligned(byte b) {
            WriteBits(8, b);
        } 

        internal int BitsInBuffer { 
            get { 
                return (bitCount / 8) + 1;
            } 
        }

        internal OutputBuffer.BufferState DumpState() {
            OutputBuffer.BufferState savedState; 
            savedState.pos = pos;
            savedState.bitBuf = bitBuf; 
            savedState.bitCount = bitCount; 
            return savedState;
        } 

        internal void RestoreState(OutputBuffer.BufferState state) {
            pos = state.pos;
            bitBuf = state.bitBuf; 
            bitCount = state.bitCount;
        } 
 
        internal struct BufferState {
            internal int pos;            // position 
            internal uint bitBuf;        // store uncomplete bits
            internal int bitCount;       // number of bits in bitBuffer
        }
    } 

} 
 

// File provided for Reference Use Only by Microsoft Corporation (c) 2007.
// Copyright (c) Microsoft Corporation. All rights reserved.

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