base64unit.cpp

指纹门禁机管理系统

//---------------------------------------------------------------------------


#pragma hdrstop

#include "Base64Unit.h"
//base64编码解码的函数


//base64编码的实现

int Base64Enc(char *buf, char*text,int size)
{
  static char *base64_encoding = "ABCDEFGHIJKLMNOPQRSTUVWXYZabcdefghijklmnopqrstuvwxyz0123456789+/";
  int buflen = 0;

  while(size>0)
  {
    *buf++ = base64_encoding[ (text[0] >> 2 ) & 0x3f];
    if(size>2)
    {
      *buf++ = base64_encoding[((text[0] & 3) << 4) | (text[1] >> 4)];
      *buf++ = base64_encoding[((text[1] & 0xF) << 2) | (text[2] >> 6)];
      *buf++ = base64_encoding[text[2] & 0x3F];
    }
    else
    {
      switch(size)
      {
        case 1:
        *buf++ = base64_encoding[(text[0] & 3) << 4 ];
        *buf++ = '=';
        *buf++ = '=';
        break;
        case 2:
        *buf++ = base64_encoding[((text[0] & 3) << 4) | (text[1] >> 4)];
        *buf++ = base64_encoding[((text[1] & 0x0F) << 2) | (text[2] >> 6)];
        *buf++ = '=';
        break;
      }
    }
    text +=3;
    size -=3;
    buflen +=4;
  }

  *buf = 0;
  return buflen;
}

//base64解码的实现

char GetBase64Value(char ch)
{
  if ((ch >= 'A') && (ch <= 'Z'))
    return ch - 'A';
  if ((ch >= 'a') && (ch <= 'z'))
    return ch - 'a' + 26;
  if ((ch >= '0') && (ch <= '9'))
    return ch - '0' + 52;
  switch (ch)
  {
    case '+':
    return 62;
    case '/':
    return 63;
    case '=': /* base64 padding */
    return 0;
    default:
    return 0;
  }
}

//进行base64解码输入应该是4的倍数(根据mime标准)
//如果不是4倍数返回错误
//注意 如果是最后一个字符 那么长度不准备 可能会多1
//返回buf长度
int Base64Dec(char *buf,char*text,int size)
{
  if(size%4)
    return -1;
  unsigned char chunk[4];
  int parsenum=0;

  while(size>0)
  {
    chunk[0] = GetBase64Value(text[0]);
    chunk[1] = GetBase64Value(text[1]);
    chunk[2] = GetBase64Value(text[2]);
    chunk[3] = GetBase64Value(text[3]);

    *buf++ = (chunk[0] << 2) | (chunk[1] >> 4);
    *buf++ = (chunk[1] << 4) | (chunk[2] >> 2);
    *buf++ = (chunk[2] << 6) | (chunk[3]);

    text+=4;
    size-=4;
    parsenum+=3;
  }
  return parsenum;
} 

//---------------------------------------------------------------------------

#pragma package(smart_init)