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//-----------------------------------------------------------------------------
// 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;
}
}
}
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