Code:
/ Net / Net / 3.5.50727.3053 / DEVDIV / depot / DevDiv / releases / whidbey / netfxsp / ndp / fx / src / Sys / System / IO / compression / InputBuffer.cs / 1 / InputBuffer.cs
namespace System.IO.Compression { using System; using System.Diagnostics; // This class can be used to read bits from an byte array quickly. // Normally we get bits from 'bitBuffer' field and bitsInBuffer stores // the number of bits available in 'BitBuffer'. // When we used up the bits in bitBuffer, we will try to get byte from // the byte array and copy the byte to appropiate position in bitBuffer. // // The byte array is not reused. We will go from 'start' to 'end'. // When we reach the end, most read operations will return -1, // which means we are running out of input. internal class InputBuffer { private byte[] buffer; // byte array to store input private int start; // start poisition of the buffer private int end; // end position of the buffer private uint bitBuffer = 0; // store the bits here, we can quickly shift in this buffer private int bitsInBuffer = 0; // number of bits available in bitBuffer // Total bits available in the input buffer public int AvailableBits { get{ return bitsInBuffer; } } // Total bytes available in the input buffer public int AvailableBytes { get{ return(end - start) + (bitsInBuffer / 8); } } // Ensure that count bits are in the bit buffer. // Returns false if input is not sufficient to make this true. // Count can be up to 16. public bool EnsureBitsAvailable(int count) { Debug.Assert( 0 < count && count <= 16, "count is invalid."); // manual inlining to improve perf if (bitsInBuffer < count) { if (NeedsInput()) { return false; } // insert a byte to bitbuffer bitBuffer |= (uint)buffer[start++] << bitsInBuffer; bitsInBuffer += 8; if (bitsInBuffer < count) { if (NeedsInput()) { return false; } // insert a byte to bitbuffer bitBuffer |= (uint)buffer[start++] << bitsInBuffer; bitsInBuffer += 8; } } return true; } // This function will try to load 16 or more bits into bitBuffer. // It returns whatever is contained in bitBuffer after loading. // The main difference between this and GetBits is that this will // never return -1. So the caller needs to check AvailableBits to // see how many bits are available. public uint TryLoad16Bits() { if(bitsInBuffer < 8) { if( start < end) { bitBuffer |= (uint)buffer[start++] << bitsInBuffer; bitsInBuffer += 8; } if( start < end) { bitBuffer |= (uint)buffer[start++] << bitsInBuffer; bitsInBuffer += 8; } } else if(bitsInBuffer < 16) { if( start < end) { bitBuffer |= (uint)buffer[start++] << bitsInBuffer; bitsInBuffer += 8; } } return bitBuffer; } private uint GetBitMask(int count) { return ((uint)1 << count) - 1; } // Gets count bits from the input buffer. Returns -1 if not enough bits available. public int GetBits(int count) { Debug.Assert( 0 < count && count <= 16, "count is invalid."); if ( !EnsureBitsAvailable(count) ) { return -1; } int result = (int)(bitBuffer & GetBitMask(count)); bitBuffer >>= count; bitsInBuffer -= count; return result; } /// Copies length bytes from input buffer to output buffer starting /// at output[offset]. You have to make sure, that the buffer is /// byte aligned. If not enough bytes are available, copies fewer /// bytes. /// Returns the number of bytes copied, 0 if no byte is available. public int CopyTo(byte[] output, int offset, int length) { Debug.Assert( output != null, ""); Debug.Assert( offset >=0 , ""); Debug.Assert( length >=0 , ""); Debug.Assert( offset <= output.Length - length, ""); Debug.Assert( (bitsInBuffer % 8) ==0, ""); // Copy the bytes in bitBuffer first. int bytesFromBitBuffer = 0; while (bitsInBuffer > 0 && length > 0) { output[offset++] = (byte) bitBuffer; bitBuffer >>= 8; bitsInBuffer -= 8; length--; bytesFromBitBuffer++; } if (length == 0) { return bytesFromBitBuffer; } int avail = end - start; if (length > avail) { length = avail; } Array.Copy(buffer, start, output, offset, length); start += length; return bytesFromBitBuffer + length; } // Return true is all input bytes are used. // This means the caller can call SetInput to add more input. public bool NeedsInput() { return start == end; } // Set the byte array to be processed. // All the bits remained in bitBuffer will be processed before the new bytes. // We don't clone the byte array here since it is expensive. // The caller should make sure after a buffer is passed in. // It will not be changed before calling this function again. public void SetInput(byte[] buffer, int offset, int length) { Debug.Assert( buffer != null, ""); Debug.Assert( offset >=0 , ""); Debug.Assert( length >=0 , ""); Debug.Assert( offset <= buffer.Length - length, ""); Debug.Assert( start == end, ""); this.buffer = buffer; start = offset; end = offset + length; } // Skip n bits in the buffer public void SkipBits(int n) { Debug.Assert(bitsInBuffer >= n, "No enough bits in the buffer, Did you call EnsureBitsAvailable?"); bitBuffer >>= n; bitsInBuffer -= n; } // Skips to the next byte boundary. public void SkipToByteBoundary() { bitBuffer >>= (bitsInBuffer % 8); bitsInBuffer = bitsInBuffer - (bitsInBuffer % 8); } } } // File provided for Reference Use Only by Microsoft Corporation (c) 2007. // Copyright (c) Microsoft Corporation. All rights reserved. namespace System.IO.Compression { using System; using System.Diagnostics; // This class can be used to read bits from an byte array quickly. // Normally we get bits from 'bitBuffer' field and bitsInBuffer stores // the number of bits available in 'BitBuffer'. // When we used up the bits in bitBuffer, we will try to get byte from // the byte array and copy the byte to appropiate position in bitBuffer. // // The byte array is not reused. We will go from 'start' to 'end'. // When we reach the end, most read operations will return -1, // which means we are running out of input. internal class InputBuffer { private byte[] buffer; // byte array to store input private int start; // start poisition of the buffer private int end; // end position of the buffer private uint bitBuffer = 0; // store the bits here, we can quickly shift in this buffer private int bitsInBuffer = 0; // number of bits available in bitBuffer // Total bits available in the input buffer public int AvailableBits { get{ return bitsInBuffer; } } // Total bytes available in the input buffer public int AvailableBytes { get{ return(end - start) + (bitsInBuffer / 8); } } // Ensure that count bits are in the bit buffer. // Returns false if input is not sufficient to make this true. // Count can be up to 16. public bool EnsureBitsAvailable(int count) { Debug.Assert( 0 < count && count <= 16, "count is invalid."); // manual inlining to improve perf if (bitsInBuffer < count) { if (NeedsInput()) { return false; } // insert a byte to bitbuffer bitBuffer |= (uint)buffer[start++] << bitsInBuffer; bitsInBuffer += 8; if (bitsInBuffer < count) { if (NeedsInput()) { return false; } // insert a byte to bitbuffer bitBuffer |= (uint)buffer[start++] << bitsInBuffer; bitsInBuffer += 8; } } return true; } // This function will try to load 16 or more bits into bitBuffer. // It returns whatever is contained in bitBuffer after loading. // The main difference between this and GetBits is that this will // never return -1. So the caller needs to check AvailableBits to // see how many bits are available. public uint TryLoad16Bits() { if(bitsInBuffer < 8) { if( start < end) { bitBuffer |= (uint)buffer[start++] << bitsInBuffer; bitsInBuffer += 8; } if( start < end) { bitBuffer |= (uint)buffer[start++] << bitsInBuffer; bitsInBuffer += 8; } } else if(bitsInBuffer < 16) { if( start < end) { bitBuffer |= (uint)buffer[start++] << bitsInBuffer; bitsInBuffer += 8; } } return bitBuffer; } private uint GetBitMask(int count) { return ((uint)1 << count) - 1; } // Gets count bits from the input buffer. Returns -1 if not enough bits available. public int GetBits(int count) { Debug.Assert( 0 < count && count <= 16, "count is invalid."); if ( !EnsureBitsAvailable(count) ) { return -1; } int result = (int)(bitBuffer & GetBitMask(count)); bitBuffer >>= count; bitsInBuffer -= count; return result; } /// Copies length bytes from input buffer to output buffer starting /// at output[offset]. You have to make sure, that the buffer is /// byte aligned. If not enough bytes are available, copies fewer /// bytes. /// Returns the number of bytes copied, 0 if no byte is available. public int CopyTo(byte[] output, int offset, int length) { Debug.Assert( output != null, ""); Debug.Assert( offset >=0 , ""); Debug.Assert( length >=0 , ""); Debug.Assert( offset <= output.Length - length, ""); Debug.Assert( (bitsInBuffer % 8) ==0, ""); // Copy the bytes in bitBuffer first. int bytesFromBitBuffer = 0; while (bitsInBuffer > 0 && length > 0) { output[offset++] = (byte) bitBuffer; bitBuffer >>= 8; bitsInBuffer -= 8; length--; bytesFromBitBuffer++; } if (length == 0) { return bytesFromBitBuffer; } int avail = end - start; if (length > avail) { length = avail; } Array.Copy(buffer, start, output, offset, length); start += length; return bytesFromBitBuffer + length; } // Return true is all input bytes are used. // This means the caller can call SetInput to add more input. public bool NeedsInput() { return start == end; } // Set the byte array to be processed. // All the bits remained in bitBuffer will be processed before the new bytes. // We don't clone the byte array here since it is expensive. // The caller should make sure after a buffer is passed in. // It will not be changed before calling this function again. public void SetInput(byte[] buffer, int offset, int length) { Debug.Assert( buffer != null, ""); Debug.Assert( offset >=0 , ""); Debug.Assert( length >=0 , ""); Debug.Assert( offset <= buffer.Length - length, ""); Debug.Assert( start == end, ""); this.buffer = buffer; start = offset; end = offset + length; } // Skip n bits in the buffer public void SkipBits(int n) { Debug.Assert(bitsInBuffer >= n, "No enough bits in the buffer, Did you call EnsureBitsAvailable?"); bitBuffer >>= n; bitsInBuffer -= n; } // Skips to the next byte boundary. public void SkipToByteBoundary() { bitBuffer >>= (bitsInBuffer % 8); bitsInBuffer = bitsInBuffer - (bitsInBuffer % 8); } } } // File provided for Reference Use Only by Microsoft Corporation (c) 2007. // Copyright (c) Microsoft Corporation. All rights reserved.
Link Menu

This book is available now!
Buy at Amazon US or
Buy at Amazon UK
- ChangeNode.cs
- OleDbWrapper.cs
- ProtectedConfigurationSection.cs
- OletxVolatileEnlistment.cs
- BamlBinaryWriter.cs
- CopyCodeAction.cs
- ContentOperations.cs
- Intellisense.cs
- HttpRawResponse.cs
- StringPropertyBuilder.cs
- ArrayList.cs
- TableLayoutSettings.cs
- ConfigXmlComment.cs
- OutputCacheProfile.cs
- BitmapEffectDrawingContextState.cs
- WebPartVerb.cs
- DbDataSourceEnumerator.cs
- InfoCardTraceRecord.cs
- ControllableStoryboardAction.cs
- LogicalExpressionTypeConverter.cs
- CodeIndexerExpression.cs
- LogFlushAsyncResult.cs
- TaskForm.cs
- DocumentOrderComparer.cs
- HttpProfileBase.cs
- InputMethod.cs
- TypeDelegator.cs
- ToolStripSeparatorRenderEventArgs.cs
- UInt64.cs
- ProcessModule.cs
- ReferenceService.cs
- AssemblyBuilderData.cs
- PageWrapper.cs
- DockingAttribute.cs
- ExtensionWindowHeader.cs
- ErrorHandler.cs
- InlineUIContainer.cs
- Keyboard.cs
- ScrollProviderWrapper.cs
- MimeWriter.cs
- PointAnimation.cs
- PerformanceCounterPermission.cs
- Renderer.cs
- HMACSHA1.cs
- CorruptingExceptionCommon.cs
- ImageFormat.cs
- FrameAutomationPeer.cs
- Pair.cs
- StrokeDescriptor.cs
- SoapCodeExporter.cs
- EntityDataReader.cs
- DBNull.cs
- XmlValidatingReaderImpl.cs
- TablePattern.cs
- XmlAnyElementAttributes.cs
- PropertyDescriptors.cs
- Keyboard.cs
- EntitySet.cs
- SystemResourceKey.cs
- RichTextBoxConstants.cs
- DesignBindingEditor.cs
- ValidationHelper.cs
- DesignerSerializationOptionsAttribute.cs
- PolicyManager.cs
- DPTypeDescriptorContext.cs
- SoapHttpTransportImporter.cs
- versioninfo.cs
- Constants.cs
- ConnectionManagementSection.cs
- AuthorizationRule.cs
- Button.cs
- MemoryStream.cs
- Single.cs
- TypedElement.cs
- recordstatefactory.cs
- IdleTimeoutMonitor.cs
- Converter.cs
- ObjectAnimationUsingKeyFrames.cs
- Attributes.cs
- TreeView.cs
- Event.cs
- LogWriteRestartAreaState.cs
- ObjectItemCollectionAssemblyCacheEntry.cs
- BookmarkResumptionRecord.cs
- EFAssociationProvider.cs
- XPathMessageFilterTable.cs
- HtmlTernaryTree.cs
- Component.cs
- ProcessStartInfo.cs
- HandlerMappingMemo.cs
- PublishLicense.cs
- TransformationRules.cs
- Solver.cs
- DetailsViewRowCollection.cs
- CryptoHandle.cs
- CheckBoxBaseAdapter.cs
- NameValueConfigurationCollection.cs
- TraceSwitch.cs
- DataControlHelper.cs
- DataGridTable.cs