Base64: кодирование и декодирование

const char Base64Table[64] =
  "ABCDEFGHIJKLMNOPQRSTUVWXYZabcdefghijklmnopqrstuvwxyz0123456789+/";
 
int __stdcall encode_b64(const unsigned char *buftoenc, int bufsize,
   unsigned char *encbuf)
  {
    // выделяем память под временный буфер
    unsigned char *buftemp = new unsigned char[bufsize + 3];
    memset(buftemp, '\0', bufsize+3);
    memcpy(buftemp, buftoenc, bufsize);
 
    int i = 0;
    int b64byte[5];
 
    while (i < bufsize)
      {
        b64byte[0] = buftemp[i] >> 2;
        b64byte[1] = ((buftemp[i] & 3) << 4)|(buftemp[i + 1] >> 4);
        b64byte[2] = ((buftemp[i + 1] & 0x0F) << 2)|(buftemp[i + 2] >> 6);
        b64byte[3] = buftemp[i + 2] & 0x3F;
        if(b64byte[0] == 0)
          encbuf[i + (i / 3)] = '=';
        else
          encbuf[i + (i / 3)] = Base64Table[b64byte[0]];
 
        if(b64byte[1] == 0)
          encbuf[i + (i / 3) + 1] = '=';
        else
          encbuf[i + (i / 3) + 1] = Base64Table[b64byte[1]];
 
        if(b64byte[2] == 0)
          encbuf[i + (i / 3) + 2] = '=';
        else
          encbuf[i + (i / 3) + 2] = Base64Table[b64byte[2]];
 
        if(b64byte[3] == 0)
          encbuf[i + (i / 3) + 3] = '=';
        else
          encbuf[i + (i / 3) + 3] = Base64Table[b64byte[3]];
        i += 3;
      }
 
    delete buftemp;
    return strlen(encbuf);
  }

const char Base64Table[64] =
  "ABCDEFGHIJKLMNOPQRSTUVWXYZabcdefghijklmnopqrstuvwxyz0123456789+/";
 
int __stdcall decode_b64(const unsigned char *buftodec, int bufsize,
  unsigned char *decbuf)
  {
  // выделяем память под временный буфер
  unsigned char *buftemp = new unsigned char [bufsize];
  memset(buftemp, '\0', bufsize);
  memcpy(buftemp, buftodec, bufsize);
 
  int i = 0;
  int cpos[5];
  unsigned char binbyte[4];
 
  while (i < bufsize)
    {
      if(buftemp[i] == '=')
        cpos[0] = 0;
      else
        cpos[0] = strchr(Base64Table, buftemp[i]) - Base64Table;
 
      if(buftemp[i + 1] == '=')
        cpos[1] = 0;
      else
        cpos[1] = strchr(Base64Table, buftemp[i + 1]) - Base64Table;
 
      if(buftemp[i + 2] == '=')
        cpos[2] = 0;
      else
        cpos[2] = strchr(Base64Table, buftemp[i + 2]) - Base64Table;
 
      if(buftemp[i + 3] == '=')
        cpos[3] = 0;
      else
        cpos[3] = strchr(Base64Table,buftemp[i + 3]) - Base64Table;
 
      binbyte[0] = ((cpos[0] << 2) | (cpos[1] >> 4));
      binbyte[1] = ((cpos[1] << 4) | (cpos[2] >> 2));
      binbyte[2] = (((cpos[2] & 0x03 )<< 6) | (cpos[3] & 0x3f));
      decbuf[i - (i / 4)] = binbyte[0];
      decbuf[i - (i / 4) + 1] = binbyte[1];
      decbuf[i - (i / 4) + 2] = binbyte[2];
      i += 4;
    }
 
    delete buftemp;
    return strlen(decbuf);
  }

new const g_abc[65] = "ABCDEFGHIJKLMNOPQRSTUVWXYZabcdefghijklmnopqrstuvwxyz0123456789+/"
 
stock base64_encode(in[], len, out[])
{   
    new i, j, buf[4]
    
    while(i < len)
    {
        buf[0] = in[i] >> 2
        buf[1] = ((in[i] & 3) << 4)|(in[i + 1] >> 4)
        buf[2] = ((in[i + 1] & 0x0F) << 2)|(in[i + 2] >> 6)
        buf[3] = in[i + 2] & 0x3F
        
        j = -1
        
        while(++j < 4)
        {
            if(!buf[j]) out[i + (i / 3) + j] = '='
            else out[i + (i / 3) + j] = g_abc[buf[j]]
        }
        i += 3
    }
    return strlen(out)
}
 
stock base64_decode(in[], len, out[])
{
    new i, j, buf[4], c[2]
    
    while(i < len)
    {
        j = -1
        
        while(++j < 4)
        {
            if(in[i + j] == '=') buf[j] = '^0'
            else
            {
                formatex(c, charsmax(c), "%c", in[i + j])
                buf[j] = contain(g_abc, c)
            }
        }
        out[i - (i / 4)] = ((buf[0] << 2) | (buf[1] >> 4))
        out[i - (i / 4) + 1] = ((buf[1] << 4) | (buf[2] >> 2))
        out[i - (i / 4) + 2] = (((buf[2] & 0x03 )<< 6) | (buf[3] & 0x3f))
        i += 4
    }
    return strlen(out)
}