515fceeb
 “wangming”
框架初始化
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using System;
using System.Text;
namespace Yi.Framework.Core.Helper
{
public sealed class Base32Helper
{
// the valid chars for the encoding
private static string ValidChars = "QAZ2WSX3" + "EDC4RFV5" + "TGB6YHN7" + "UJM8K9LP";
/// <summary>
/// Converts an array of bytes to a Base32-k string.
/// </summary>
public static string ToString(byte[] bytes)
{
StringBuilder sb = new StringBuilder(); // holds the base32 chars
byte index;
int hi = 5;
int currentByte = 0;
while (currentByte < bytes.Length)
{
// do we need to use the next byte?
if (hi > 8)
{
// get the last piece from the current byte, shift it to the right
// and increment the byte counter
index = (byte)(bytes[currentByte++] >> hi - 5);
if (currentByte != bytes.Length)
{
// if we are not at the end, get the first piece from
// the next byte, clear it and shift it to the left
index = (byte)((byte)(bytes[currentByte] << 16 - hi) >> 3 | index);
}
hi -= 3;
}
else if (hi == 8)
{
index = (byte)(bytes[currentByte++] >> 3);
hi -= 3;
}
else
{
// simply get the stuff from the current byte
index = (byte)((byte)(bytes[currentByte] << 8 - hi) >> 3);
hi += 5;
}
sb.Append(ValidChars[index]);
}
return sb.ToString();
}
/// <summary>
/// Converts a Base32-k string into an array of bytes.
/// </summary>
/// <exception cref="ArgumentException">
/// Input string <paramref name="s">s</paramref> contains invalid Base32-k characters.
/// </exception>
public static byte[] FromBase32String(string str)
{
int numBytes = str.Length * 5 / 8;
byte[] bytes = new byte[numBytes];
// all UPPERCASE chars
str = str.ToUpper();
int bit_buffer;
int currentCharIndex;
int bits_in_buffer;
if (str.Length < 3)
{
bytes[0] = (byte)(ValidChars.IndexOf(str[0]) | ValidChars.IndexOf(str[1]) << 5);
return bytes;
}
bit_buffer = ValidChars.IndexOf(str[0]) | ValidChars.IndexOf(str[1]) << 5;
bits_in_buffer = 10;
currentCharIndex = 2;
for (int i = 0; i < bytes.Length; i++)
{
bytes[i] = (byte)bit_buffer;
bit_buffer >>= 8;
bits_in_buffer -= 8;
while (bits_in_buffer < 8 && currentCharIndex < str.Length)
{
bit_buffer |= ValidChars.IndexOf(str[currentCharIndex++]) << bits_in_buffer;
bits_in_buffer += 5;
}
}
return bytes;
}
}
}
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