asc2bcd.cpp

ASCII码转BCD码算法

// Asc2BCD.cpp: implementation of the CAsc2BCD class.
//
//////////////////////////////////////////////////////////////////////

#include "Asc2BCD.h"

//////////////////////////////////////////////////////////////////////
// Construction/Destruction
//////////////////////////////////////////////////////////////////////

#define RIGHT_ALIGN	1
#define LEFT_ALIGN	2

/*
   Convert an ASCII/EBCDIC number string to BCD string
   Return the BCD string length
   "12345" -> 0x01,0x23,0x45  (right alignment) 
   "12345" -> 0x12,0x34,0x50  (left alignment)
   If error, return -1
*/
int CAsc2BCD::Asc2BCD(char *Nstr, int Nstr_len, char *BCDstr, int align)
{
  int  i, j, n;
  char *sn = Nstr, *sb = BCDstr;

  n = (Nstr_len + 1) / 2;  //字节数
  if(align == RIGHT_ALIGN)
  {
    for(i = Nstr_len - 1, j = n - 1; j >= 0; j--) 
    {
      if(i >= 0)//低字节
      {
        if(sn[i] < '0'||sn[i] > '9') return -1; 
        sb[j] = sn[i] - '0'; 
        
        i--;
      }
      if(i >= 0)//高字节
      {
        if(sn[i] < '0'||sn[i] > '9') return -1;
        sb[j] = (sn[i] - '0') << 4|sb[j]; 
        
        i--;
      }
    }
  }
  else /* LEFT_ALIGN */
  {
    for(i = 0, j = 0; i < Nstr_len; i++, j++)
    {
      if(sn[i] < '0'||sn[i] > '9') return -1;
      sb[j] = (sn[i] - '0') << 4;
      i++;
      if(i < Nstr_len)
      {
        if(sn[i] < '0'||sn[i] > '9') return -1;
        sb[j] = sb[j]|(sn[i] - '0');
      }
    }
  }
  return n;
}