//----------------------------------------------------------------------------- // Copyright (c) Microsoft Corporation. All rights reserved. //----------------------------------------------------------------------------- namespace System.Text { using System.Globalization; using System.Runtime; using System.Runtime.Serialization; //For SR using System.Security; class Base64Encoding : Encoding { [System.Diagnostics.CodeAnalysis.SuppressMessage("Microsoft.StyleCop.CSharp.SpacingRules", "SA1025:CodeMustNotContainMultipleWhitespaceInARow", Justification = "This alignment is optimal.")] static byte[] char2val = new byte[128] { /* 0-15 */ 0xFF, 0xFF, 0xFF, 0xFF, 0xFF, 0xFF, 0xFF, 0xFF, 0xFF, 0xFF, 0xFF, 0xFF, 0xFF, 0xFF, 0xFF, 0xFF, /* 16-31 */ 0xFF, 0xFF, 0xFF, 0xFF, 0xFF, 0xFF, 0xFF, 0xFF, 0xFF, 0xFF, 0xFF, 0xFF, 0xFF, 0xFF, 0xFF, 0xFF, /* 32-47 */ 0xFF, 0xFF, 0xFF, 0xFF, 0xFF, 0xFF, 0xFF, 0xFF, 0xFF, 0xFF, 0xFF, 62, 0xFF, 0xFF, 0xFF, 63, /* 48-63 */ 52, 53, 54, 55, 56, 57, 58, 59, 60, 61, 0xFF, 0xFF, 0xFF, 64, 0xFF, 0xFF, /* 64-79 */ 0xFF, 0, 1, 2, 3, 4, 5, 6, 7, 8, 9, 10, 11, 12, 13, 14, /* 80-95 */ 15, 16, 17, 18, 19, 20, 21, 22, 23, 24, 25, 0xFF, 0xFF, 0xFF, 0xFF, 0xFF, /* 96-111 */ 0xFF, 26, 27, 28, 29, 30, 31, 32, 33, 34, 35, 36, 37, 38, 39, 40, /* 112-127 */ 41, 42, 43, 44, 45, 46, 47, 48, 49, 50, 51, 0xFF, 0xFF, 0xFF, 0xFF, 0xFF, }; static string val2char = "ABCDEFGHIJKLMNOPQRSTUVWXYZabcdefghijklmnopqrstuvwxyz0123456789+/"; static byte[] val2byte = new byte[] { (byte)'A', (byte)'B', (byte)'C', (byte)'D', (byte)'E', (byte)'F', (byte)'G', (byte)'H', (byte)'I', (byte)'J', (byte)'K', (byte)'L', (byte)'M', (byte)'N', (byte)'O', (byte)'P', (byte)'Q', (byte)'R', (byte)'S', (byte)'T', (byte)'U', (byte)'V', (byte)'W', (byte)'X', (byte)'Y', (byte)'Z', (byte)'a', (byte)'b', (byte)'c', (byte)'d', (byte)'e', (byte)'f', (byte)'g', (byte)'h', (byte)'i', (byte)'j', (byte)'k', (byte)'l', (byte)'m', (byte)'n', (byte)'o', (byte)'p', (byte)'q', (byte)'r', (byte)'s', (byte)'t', (byte)'u', (byte)'v', (byte)'w', (byte)'x', (byte)'y', (byte)'z', (byte)'0', (byte)'1', (byte)'2', (byte)'3', (byte)'4', (byte)'5', (byte)'6', (byte)'7', (byte)'8', (byte)'9', (byte)'+', (byte)'/' }; public override int GetMaxByteCount(int charCount) { if (charCount < 0) throw System.Runtime.Serialization.DiagnosticUtility.ExceptionUtility.ThrowHelperError(new ArgumentOutOfRangeException("charCount", SR.GetString(SR.ValueMustBeNonNegative))); if ((charCount % 4) != 0) throw System.Runtime.Serialization.DiagnosticUtility.ExceptionUtility.ThrowHelperError(new FormatException(SR.GetString(SR.XmlInvalidBase64Length, charCount.ToString(NumberFormatInfo.CurrentInfo)))); return charCount / 4 * 3; } bool IsValidLeadBytes(int v1, int v2, int v3, int v4) { // First two chars of a four char base64 sequence can't be ==, and must be valid return ((v1 | v2) < 64) && ((v3 | v4) != 0xFF); } bool IsValidTailBytes(int v3, int v4) { // If the third char is = then the fourth char must be = return !(v3 == 64 && v4 != 64); } [Fx.Tag.SecurityNote(Critical = "Contains unsafe code.", Safe = "Unsafe code is effectively encapsulated, all inputs are validated.")] [SecuritySafeCritical] unsafe public override int GetByteCount(char[] chars, int index, int count) { if (chars == null) throw System.Runtime.Serialization.DiagnosticUtility.ExceptionUtility.ThrowHelperError(new ArgumentNullException("chars")); if (index < 0) throw System.Runtime.Serialization.DiagnosticUtility.ExceptionUtility.ThrowHelperError(new ArgumentOutOfRangeException("index", SR.GetString(SR.ValueMustBeNonNegative))); if (index > chars.Length) throw System.Runtime.Serialization.DiagnosticUtility.ExceptionUtility.ThrowHelperError(new ArgumentOutOfRangeException("index", SR.GetString(SR.OffsetExceedsBufferSize, chars.Length))); if (count < 0) throw System.Runtime.Serialization.DiagnosticUtility.ExceptionUtility.ThrowHelperError(new ArgumentOutOfRangeException("count", SR.GetString(SR.ValueMustBeNonNegative))); if (count > chars.Length - index) throw System.Runtime.Serialization.DiagnosticUtility.ExceptionUtility.ThrowHelperError(new ArgumentOutOfRangeException("count", SR.GetString(SR.SizeExceedsRemainingBufferSpace, chars.Length - index))); if (count == 0) return 0; if ((count % 4) != 0) throw System.Runtime.Serialization.DiagnosticUtility.ExceptionUtility.ThrowHelperError(new FormatException(SR.GetString(SR.XmlInvalidBase64Length, count.ToString(NumberFormatInfo.CurrentInfo)))); fixed (byte* _char2val = char2val) { fixed (char* _chars = &chars[index]) { int totalCount = 0; char* pch = _chars; char* pchMax = _chars + count; while (pch < pchMax) { Fx.Assert(pch + 4 <= pchMax, ""); char pch0 = pch[0]; char pch1 = pch[1]; char pch2 = pch[2]; char pch3 = pch[3]; if ((pch0 | pch1 | pch2 | pch3) >= 128) throw System.Runtime.Serialization.DiagnosticUtility.ExceptionUtility.ThrowHelperError(new FormatException(SR.GetString(SR.XmlInvalidBase64Sequence, new string(pch, 0, 4), index + (int)(pch - _chars)))); // xx765432 xx107654 xx321076 xx543210 // 76543210 76543210 76543210 int v1 = _char2val[pch0]; int v2 = _char2val[pch1]; int v3 = _char2val[pch2]; int v4 = _char2val[pch3]; if (!IsValidLeadBytes(v1, v2, v3, v4) || !IsValidTailBytes(v3, v4)) throw System.Runtime.Serialization.DiagnosticUtility.ExceptionUtility.ThrowHelperError(new FormatException(SR.GetString(SR.XmlInvalidBase64Sequence, new string(pch, 0, 4), index + (int)(pch - _chars)))); int byteCount = (v4 != 64 ? 3 : (v3 != 64 ? 2 : 1)); totalCount += byteCount; pch += 4; } return totalCount; } } } [Fx.Tag.SecurityNote(Critical = "Contains unsafe code.", Safe = "Unsafe code is effectively encapsulated, all inputs are validated.")] [SecuritySafeCritical] unsafe public override int GetBytes(char[] chars, int charIndex, int charCount, byte[] bytes, int byteIndex) { if (chars == null) throw System.Runtime.Serialization.DiagnosticUtility.ExceptionUtility.ThrowHelperError(new ArgumentNullException("chars")); if (charIndex < 0) throw System.Runtime.Serialization.DiagnosticUtility.ExceptionUtility.ThrowHelperError(new ArgumentOutOfRangeException("charIndex", SR.GetString(SR.ValueMustBeNonNegative))); if (charIndex > chars.Length) throw System.Runtime.Serialization.DiagnosticUtility.ExceptionUtility.ThrowHelperError(new ArgumentOutOfRangeException("charIndex", SR.GetString(SR.OffsetExceedsBufferSize, chars.Length))); if (charCount < 0) throw System.Runtime.Serialization.DiagnosticUtility.ExceptionUtility.ThrowHelperError(new ArgumentOutOfRangeException("charCount", SR.GetString(SR.ValueMustBeNonNegative))); if (charCount > chars.Length - charIndex) throw System.Runtime.Serialization.DiagnosticUtility.ExceptionUtility.ThrowHelperError(new ArgumentOutOfRangeException("charCount", SR.GetString(SR.SizeExceedsRemainingBufferSpace, chars.Length - charIndex))); if (bytes == null) throw System.Runtime.Serialization.DiagnosticUtility.ExceptionUtility.ThrowHelperError(new ArgumentNullException("bytes")); if (byteIndex < 0) throw System.Runtime.Serialization.DiagnosticUtility.ExceptionUtility.ThrowHelperError(new ArgumentOutOfRangeException("byteIndex", SR.GetString(SR.ValueMustBeNonNegative))); if (byteIndex > bytes.Length) throw System.Runtime.Serialization.DiagnosticUtility.ExceptionUtility.ThrowHelperError(new ArgumentOutOfRangeException("byteIndex", SR.GetString(SR.OffsetExceedsBufferSize, bytes.Length))); if (charCount == 0) return 0; if ((charCount % 4) != 0) throw System.Runtime.Serialization.DiagnosticUtility.ExceptionUtility.ThrowHelperError(new FormatException(SR.GetString(SR.XmlInvalidBase64Length, charCount.ToString(NumberFormatInfo.CurrentInfo)))); fixed (byte* _char2val = char2val) { fixed (char* _chars = &chars[charIndex]) { fixed (byte* _bytes = &bytes[byteIndex]) { char* pch = _chars; char* pchMax = _chars + charCount; byte* pb = _bytes; byte* pbMax = _bytes + bytes.Length - byteIndex; while (pch < pchMax) { Fx.Assert(pch + 4 <= pchMax, ""); char pch0 = pch[0]; char pch1 = pch[1]; char pch2 = pch[2]; char pch3 = pch[3]; if ((pch0 | pch1 | pch2 | pch3) >= 128) throw System.Runtime.Serialization.DiagnosticUtility.ExceptionUtility.ThrowHelperError(new FormatException(SR.GetString(SR.XmlInvalidBase64Sequence, new string(pch, 0, 4), charIndex + (int)(pch - _chars)))); // xx765432 xx107654 xx321076 xx543210 // 76543210 76543210 76543210 int v1 = _char2val[pch0]; int v2 = _char2val[pch1]; int v3 = _char2val[pch2]; int v4 = _char2val[pch3]; if (!IsValidLeadBytes(v1, v2, v3, v4) || !IsValidTailBytes(v3, v4)) throw System.Runtime.Serialization.DiagnosticUtility.ExceptionUtility.ThrowHelperError(new FormatException(SR.GetString(SR.XmlInvalidBase64Sequence, new string(pch, 0, 4), charIndex + (int)(pch - _chars)))); int byteCount = (v4 != 64 ? 3 : (v3 != 64 ? 2 : 1)); if (pb + byteCount > pbMax) throw System.Runtime.Serialization.DiagnosticUtility.ExceptionUtility.ThrowHelperError(new ArgumentException(SR.GetString(SR.XmlArrayTooSmall), "bytes")); pb[0] = (byte)((v1 << 2) | ((v2 >> 4) & 0x03)); if (byteCount > 1) { pb[1] = (byte)((v2 << 4) | ((v3 >> 2) & 0x0F)); if (byteCount > 2) { pb[2] = (byte)((v3 << 6) | ((v4 >> 0) & 0x3F)); } } pb += byteCount; pch += 4; } return (int)(pb - _bytes); } } } } [Fx.Tag.SecurityNote(Critical = "Contains unsafe code.", Safe = "Unsafe code is effectively encapsulated, all inputs are validated.")] [SecuritySafeCritical] unsafe public virtual int GetBytes(byte[] chars, int charIndex, int charCount, byte[] bytes, int byteIndex) { if (chars == null) throw System.Runtime.Serialization.DiagnosticUtility.ExceptionUtility.ThrowHelperError(new ArgumentNullException("chars")); if (charIndex < 0) throw System.Runtime.Serialization.DiagnosticUtility.ExceptionUtility.ThrowHelperError(new ArgumentOutOfRangeException("charIndex", SR.GetString(SR.ValueMustBeNonNegative))); if (charIndex > chars.Length) throw System.Runtime.Serialization.DiagnosticUtility.ExceptionUtility.ThrowHelperError(new ArgumentOutOfRangeException("charIndex", SR.GetString(SR.OffsetExceedsBufferSize, chars.Length))); if (charCount < 0) throw System.Runtime.Serialization.DiagnosticUtility.ExceptionUtility.ThrowHelperError(new ArgumentOutOfRangeException("charCount", SR.GetString(SR.ValueMustBeNonNegative))); if (charCount > chars.Length - charIndex) throw System.Runtime.Serialization.DiagnosticUtility.ExceptionUtility.ThrowHelperError(new ArgumentOutOfRangeException("charCount", SR.GetString(SR.SizeExceedsRemainingBufferSpace, chars.Length - charIndex))); if (bytes == null) throw System.Runtime.Serialization.DiagnosticUtility.ExceptionUtility.ThrowHelperError(new ArgumentNullException("bytes")); if (byteIndex < 0) throw System.Runtime.Serialization.DiagnosticUtility.ExceptionUtility.ThrowHelperError(new ArgumentOutOfRangeException("byteIndex", SR.GetString(SR.ValueMustBeNonNegative))); if (byteIndex > bytes.Length) throw System.Runtime.Serialization.DiagnosticUtility.ExceptionUtility.ThrowHelperError(new ArgumentOutOfRangeException("byteIndex", SR.GetString(SR.OffsetExceedsBufferSize, bytes.Length))); if (charCount == 0) return 0; if ((charCount % 4) != 0) throw System.Runtime.Serialization.DiagnosticUtility.ExceptionUtility.ThrowHelperError(new FormatException(SR.GetString(SR.XmlInvalidBase64Length, charCount.ToString(NumberFormatInfo.CurrentInfo)))); fixed (byte* _char2val = char2val) { fixed (byte* _chars = &chars[charIndex]) { fixed (byte* _bytes = &bytes[byteIndex]) { byte* pch = _chars; byte* pchMax = _chars + charCount; byte* pb = _bytes; byte* pbMax = _bytes + bytes.Length - byteIndex; while (pch < pchMax) { Fx.Assert(pch + 4 <= pchMax, ""); byte pch0 = pch[0]; byte pch1 = pch[1]; byte pch2 = pch[2]; byte pch3 = pch[3]; if ((pch0 | pch1 | pch2 | pch3) >= 128) throw System.Runtime.Serialization.DiagnosticUtility.ExceptionUtility.ThrowHelperError(new FormatException(SR.GetString(SR.XmlInvalidBase64Sequence, new string((sbyte*)pch, 0, 4), charIndex + (int)(pch - _chars)))); // xx765432 xx107654 xx321076 xx543210 // 76543210 76543210 76543210 int v1 = _char2val[pch0]; int v2 = _char2val[pch1]; int v3 = _char2val[pch2]; int v4 = _char2val[pch3]; if (!IsValidLeadBytes(v1, v2, v3, v4) || !IsValidTailBytes(v3, v4)) throw System.Runtime.Serialization.DiagnosticUtility.ExceptionUtility.ThrowHelperError(new FormatException(SR.GetString(SR.XmlInvalidBase64Sequence, new string((sbyte*)pch, 0, 4), charIndex + (int)(pch - _chars)))); int byteCount = (v4 != 64 ? 3 : (v3 != 64 ? 2 : 1)); if (pb + byteCount > pbMax) throw System.Runtime.Serialization.DiagnosticUtility.ExceptionUtility.ThrowHelperError(new ArgumentException(SR.GetString(SR.XmlArrayTooSmall), "bytes")); pb[0] = (byte)((v1 << 2) | ((v2 >> 4) & 0x03)); if (byteCount > 1) { pb[1] = (byte)((v2 << 4) | ((v3 >> 2) & 0x0F)); if (byteCount > 2) { pb[2] = (byte)((v3 << 6) | ((v4 >> 0) & 0x3F)); } } pb += byteCount; pch += 4; } return (int)(pb - _bytes); } } } } #if NO public override Encoder GetEncoder() { return new BufferedEncoder(this, 4); } public override Decoder GetDecoder() { return new BufferedDecoder(this, 3); } #endif public override int GetMaxCharCount(int byteCount) { if (byteCount < 0 || byteCount > int.MaxValue / 4 * 3 - 2) throw System.Runtime.Serialization.DiagnosticUtility.ExceptionUtility.ThrowHelperError(new ArgumentOutOfRangeException("byteCount", SR.GetString(SR.ValueMustBeInRange, 0, int.MaxValue / 4 * 3 - 2))); return ((byteCount + 2) / 3) * 4; } public override int GetCharCount(byte[] bytes, int index, int count) { return GetMaxCharCount(count); } [Fx.Tag.SecurityNote(Critical = "Contains unsafe code.", Safe = "Unsafe code is effectively encapsulated, all inputs are validated.")] [SecuritySafeCritical] unsafe public override int GetChars(byte[] bytes, int byteIndex, int byteCount, char[] chars, int charIndex) { if (bytes == null) throw System.Runtime.Serialization.DiagnosticUtility.ExceptionUtility.ThrowHelperError(new ArgumentNullException("bytes")); if (byteIndex < 0) throw System.Runtime.Serialization.DiagnosticUtility.ExceptionUtility.ThrowHelperError(new ArgumentOutOfRangeException("byteIndex", SR.GetString(SR.ValueMustBeNonNegative))); if (byteIndex > bytes.Length) throw System.Runtime.Serialization.DiagnosticUtility.ExceptionUtility.ThrowHelperError(new ArgumentOutOfRangeException("byteIndex", SR.GetString(SR.OffsetExceedsBufferSize, bytes.Length))); if (byteCount < 0) throw System.Runtime.Serialization.DiagnosticUtility.ExceptionUtility.ThrowHelperError(new ArgumentOutOfRangeException("byteCount", SR.GetString(SR.ValueMustBeNonNegative))); if (byteCount > bytes.Length - byteIndex) throw System.Runtime.Serialization.DiagnosticUtility.ExceptionUtility.ThrowHelperError(new ArgumentOutOfRangeException("byteCount", SR.GetString(SR.SizeExceedsRemainingBufferSpace, bytes.Length - byteIndex))); int charCount = GetCharCount(bytes, byteIndex, byteCount); if (chars == null) throw System.Runtime.Serialization.DiagnosticUtility.ExceptionUtility.ThrowHelperError(new ArgumentNullException("chars")); if (charIndex < 0) throw System.Runtime.Serialization.DiagnosticUtility.ExceptionUtility.ThrowHelperError(new ArgumentOutOfRangeException("charIndex", SR.GetString(SR.ValueMustBeNonNegative))); if (charIndex > chars.Length) throw System.Runtime.Serialization.DiagnosticUtility.ExceptionUtility.ThrowHelperError(new ArgumentOutOfRangeException("charIndex", SR.GetString(SR.OffsetExceedsBufferSize, chars.Length))); if (charCount < 0 || charCount > chars.Length - charIndex) throw System.Runtime.Serialization.DiagnosticUtility.ExceptionUtility.ThrowHelperError(new ArgumentException(SR.GetString(SR.XmlArrayTooSmall), "chars")); // We've computed exactly how many chars there are and verified that // there's enough space in the char buffer, so we can proceed without // checking the charCount. if (byteCount > 0) { fixed (char* _val2char = val2char) { fixed (byte* _bytes = &bytes[byteIndex]) { fixed (char* _chars = &chars[charIndex]) { byte* pb = _bytes; byte* pbMax = pb + byteCount - 3; char* pch = _chars; // Convert chunks of 3 bytes to 4 chars while (pb <= pbMax) { // 76543210 76543210 76543210 // xx765432 xx107654 xx321076 xx543210 // Inspect the code carefully before you change this pch[0] = _val2char[(pb[0] >> 2)]; pch[1] = _val2char[((pb[0] & 0x03) << 4) | (pb[1] >> 4)]; pch[2] = _val2char[((pb[1] & 0x0F) << 2) | (pb[2] >> 6)]; pch[3] = _val2char[pb[2] & 0x3F]; pb += 3; pch += 4; } // Handle 1 or 2 trailing bytes if (pb - pbMax == 2) { // 1 trailing byte // 76543210 xxxxxxxx xxxxxxxx // xx765432 xx10xxxx xxxxxxxx xxxxxxxx pch[0] = _val2char[(pb[0] >> 2)]; pch[1] = _val2char[((pb[0] & 0x03) << 4)]; pch[2] = '='; pch[3] = '='; } else if (pb - pbMax == 1) { // 2 trailing bytes // 76543210 76543210 xxxxxxxx // xx765432 xx107654 xx3210xx xxxxxxxx pch[0] = _val2char[(pb[0] >> 2)]; pch[1] = _val2char[((pb[0] & 0x03) << 4) | (pb[1] >> 4)]; pch[2] = _val2char[((pb[1] & 0x0F) << 2)]; pch[3] = '='; } else { // 0 trailing bytes Fx.Assert(pb - pbMax == 3, ""); } } } } } return charCount; } [Fx.Tag.SecurityNote(Critical = "Contains unsafe code.", Safe = "Unsafe code is effectively encapsulated, all inputs are validated.")] [SecuritySafeCritical] unsafe public int GetChars(byte[] bytes, int byteIndex, int byteCount, byte[] chars, int charIndex) { if (bytes == null) throw System.Runtime.Serialization.DiagnosticUtility.ExceptionUtility.ThrowHelperError(new ArgumentNullException("bytes")); if (byteIndex < 0) throw System.Runtime.Serialization.DiagnosticUtility.ExceptionUtility.ThrowHelperError(new ArgumentOutOfRangeException("byteIndex", SR.GetString(SR.ValueMustBeNonNegative))); if (byteIndex > bytes.Length) throw System.Runtime.Serialization.DiagnosticUtility.ExceptionUtility.ThrowHelperError(new ArgumentOutOfRangeException("byteIndex", SR.GetString(SR.OffsetExceedsBufferSize, bytes.Length))); if (byteCount < 0) throw System.Runtime.Serialization.DiagnosticUtility.ExceptionUtility.ThrowHelperError(new ArgumentOutOfRangeException("byteCount", SR.GetString(SR.ValueMustBeNonNegative))); if (byteCount > bytes.Length - byteIndex) throw System.Runtime.Serialization.DiagnosticUtility.ExceptionUtility.ThrowHelperError(new ArgumentOutOfRangeException("byteCount", SR.GetString(SR.SizeExceedsRemainingBufferSpace, bytes.Length - byteIndex))); int charCount = GetCharCount(bytes, byteIndex, byteCount); if (chars == null) throw System.Runtime.Serialization.DiagnosticUtility.ExceptionUtility.ThrowHelperError(new ArgumentNullException("chars")); if (charIndex < 0) throw System.Runtime.Serialization.DiagnosticUtility.ExceptionUtility.ThrowHelperError(new ArgumentOutOfRangeException("charIndex", SR.GetString(SR.ValueMustBeNonNegative))); if (charIndex > chars.Length) throw System.Runtime.Serialization.DiagnosticUtility.ExceptionUtility.ThrowHelperError(new ArgumentOutOfRangeException("charIndex", SR.GetString(SR.OffsetExceedsBufferSize, chars.Length))); if (charCount < 0 || charCount > chars.Length - charIndex) throw System.Runtime.Serialization.DiagnosticUtility.ExceptionUtility.ThrowHelperError(new ArgumentException(SR.GetString(SR.XmlArrayTooSmall), "chars")); // We've computed exactly how many chars there are and verified that // there's enough space in the char buffer, so we can proceed without // checking the charCount. if (byteCount > 0) { fixed (byte* _val2byte = val2byte) { fixed (byte* _bytes = &bytes[byteIndex]) { fixed (byte* _chars = &chars[charIndex]) { byte* pb = _bytes; byte* pbMax = pb + byteCount - 3; byte* pch = _chars; // Convert chunks of 3 bytes to 4 chars while (pb <= pbMax) { // 76543210 76543210 76543210 // xx765432 xx107654 xx321076 xx543210 // Inspect the code carefully before you change this pch[0] = _val2byte[(pb[0] >> 2)]; pch[1] = _val2byte[((pb[0] & 0x03) << 4) | (pb[1] >> 4)]; pch[2] = _val2byte[((pb[1] & 0x0F) << 2) | (pb[2] >> 6)]; pch[3] = _val2byte[pb[2] & 0x3F]; pb += 3; pch += 4; } // Handle 1 or 2 trailing bytes if (pb - pbMax == 2) { // 1 trailing byte // 76543210 xxxxxxxx xxxxxxxx // xx765432 xx10xxxx xxxxxxxx xxxxxxxx pch[0] = _val2byte[(pb[0] >> 2)]; pch[1] = _val2byte[((pb[0] & 0x03) << 4)]; pch[2] = (byte)'='; pch[3] = (byte)'='; } else if (pb - pbMax == 1) { // 2 trailing bytes // 76543210 76543210 xxxxxxxx // xx765432 xx107654 xx3210xx xxxxxxxx pch[0] = _val2byte[(pb[0] >> 2)]; pch[1] = _val2byte[((pb[0] & 0x03) << 4) | (pb[1] >> 4)]; pch[2] = _val2byte[((pb[1] & 0x0F) << 2)]; pch[3] = (byte)'='; } else { // 0 trailing bytes Fx.Assert(pb - pbMax == 3, ""); } } } } } return charCount; } } }