BinHexDecoder.cs source code in C# .NET

                        Code:
                         / FX-1434 / FX-1434 / 1.0 / untmp / whidbey / REDBITS / ndp / fx / src / Xml / System / Xml / BinHexDecoder.cs / 1 / BinHexDecoder.cs
                        
                        
                            //------------------------------------------------------------------------------ 
// 
//     Copyright (c) Microsoft Corporation.  All rights reserved.
// 
// [....] 
//-----------------------------------------------------------------------------
 
using System; 
using System.Diagnostics;
 
namespace System.Xml
{
    internal class BinHexDecoder : IncrementalReadDecoder {
// 
// Fields
// 
        byte[]  buffer; 
        int     startIndex;
        int     curIndex; 
        int     endIndex;
        bool    hasHalfByteCached;
        byte    cachedHalfByte;
 
//
// IncrementalReadDecoder interface 
// 
        internal override int DecodedCount {
            get { 
                return curIndex - startIndex;
            }
        }
 
        internal override bool IsFull {
            get { 
                return curIndex == endIndex; 
            }
        } 

        internal override unsafe int Decode( char[] chars, int startPos, int len ) {
            Debug.Assert( chars != null );
            Debug.Assert( len >= 0 ); 
            Debug.Assert( startPos >= 0 );
            Debug.Assert( chars.Length - startPos >= len ); 
 
            if ( len == 0 ) {
                return 0; 
            }
            int bytesDecoded, charsDecoded;
            fixed ( char* pChars = &chars[startPos] ) {
                fixed ( byte* pBytes = &buffer[curIndex] ) { 
                    Decode( pChars, pChars + len, pBytes, pBytes + ( endIndex - curIndex ),
                            ref this.hasHalfByteCached, ref this.cachedHalfByte, out charsDecoded, out bytesDecoded ); 
                } 
            }
            curIndex += bytesDecoded; 
            return charsDecoded;
        }

        internal override unsafe int Decode( string str, int startPos, int len ) { 
            Debug.Assert( str != null );
            Debug.Assert( len >= 0 ); 
            Debug.Assert( startPos >= 0 ); 
            Debug.Assert( str.Length - startPos >= len );
 
            if ( len == 0 ) {
                return 0;
            }
            int bytesDecoded, charsDecoded; 
            fixed ( char* pChars = str ) {
                fixed ( byte* pBytes = &buffer[curIndex] ) { 
                    Decode( pChars + startPos, pChars + startPos + len, pBytes, pBytes + ( endIndex - curIndex ), 
                            ref this.hasHalfByteCached, ref this.cachedHalfByte, out charsDecoded, out bytesDecoded );
                } 
            }
            curIndex += bytesDecoded;
            return charsDecoded;
        } 

        internal override void Reset() { 
            this.hasHalfByteCached = false; 
            this.cachedHalfByte = 0;
        } 

        internal override void SetNextOutputBuffer( Array buffer, int index, int count ) {
            Debug.Assert( buffer != null );
            Debug.Assert( count >= 0 ); 
            Debug.Assert( index >= 0 );
            Debug.Assert( buffer.Length - index >= count ); 
            Debug.Assert( ( buffer as byte[] ) != null ); 

            this.buffer = (byte[])buffer; 
            this.startIndex = index;
            this.curIndex = index;
            this.endIndex = index + count;
        } 

// 
// Static methods 
//
        public static unsafe byte[] Decode( char[] chars, bool allowOddChars ) { 
            if ( chars == null ) {
                throw new ArgumentException( "chars" );
            }
 
            int len = chars.Length;
            if ( len == 0 ) { 
                return new byte[0]; 
            }
 
            byte[] bytes = new byte[ ( len + 1 ) / 2 ];
            int bytesDecoded, charsDecoded;
            bool hasHalfByteCached = false;
            byte cachedHalfByte = 0; 

            fixed ( char* pChars = &chars[0] ) { 
                fixed ( byte* pBytes = &bytes[0] ) { 
                    Decode( pChars, pChars + len, pBytes, pBytes + bytes.Length, ref hasHalfByteCached, ref cachedHalfByte, out charsDecoded, out bytesDecoded );
                } 
            }

            if ( hasHalfByteCached && !allowOddChars ) {
                throw new XmlException( Res.Xml_InvalidBinHexValueOddCount, new string( chars ) ); 
            }
 
            if ( bytesDecoded < bytes.Length ) { 
                byte[] tmp = new byte[ bytesDecoded ];
                Buffer.BlockCopy( bytes, 0, tmp, 0, bytesDecoded ); 
                bytes = tmp;
            }

            return bytes; 
        }
 
 
//
// Private methods 
//

        private static unsafe void Decode( char* pChars, char *pCharsEndPos,
                                    byte* pBytes, byte* pBytesEndPos, 
                                    ref bool hasHalfByteCached, ref byte cachedHalfByte,
 								    out int charsDecoded, out int bytesDecoded ) { 
#if DEBUG 
            Debug.Assert( pCharsEndPos - pChars >= 0 );
            Debug.Assert( pBytesEndPos - pBytes >= 0 ); 
#endif

            char* pChar = pChars;
            byte* pByte = pBytes; 
            XmlCharType xmlCharType = XmlCharType.Instance;
            while ( pChar < pCharsEndPos && pByte < pBytesEndPos ) { 
                byte halfByte; 
                char ch = *pChar++;
 
                if ( ch >= 'a' && ch <= 'f' ) {
                    halfByte = (byte)(ch - 'a' + 10);
                }
                else if ( ch >= 'A' && ch <= 'F' ) { 
                    halfByte = (byte)(ch - 'A' + 10);
                } 
                else if ( ch >= '0' && ch <= '9' ) { 
                    halfByte = (byte)(ch - '0');
                } 
                else if ( ( xmlCharType.charProperties[ch] & XmlCharType.fWhitespace ) != 0 ) { // else if ( xmlCharType.IsWhiteSpace( ch ) ) {
                    continue;
                }
                else { 
                    throw new XmlException(Res.Xml_InvalidBinHexValue, new string( pChars, 0, (int)( pCharsEndPos - pChars ) ) );
                } 
 
                if ( hasHalfByteCached ) {
                    *pByte++ = (byte)( ( cachedHalfByte << 4 ) + halfByte ); 
                    hasHalfByteCached = false;
                }
                else {
                    cachedHalfByte = halfByte; 
                    hasHalfByteCached = true;
                } 
            } 

            bytesDecoded = (int)(pByte - pBytes); 
            charsDecoded = (int)(pChar - pChars);
        }
    }
} 

// File provided for Reference Use Only by Microsoft Corporation (c) 2007.
// Copyright (c) Microsoft Corporation. All rights reserved.
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BinHexDecoder.cs source code in C# .NET

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