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/*
* Convert ASCII numbers to or from BCD representations.
* $Id: bcd.c 1.2 Wed, 19 Mar 1997 12:44:53 -0500 dyfet $
* Copyright (c) 1997 by Tycho Softworks.
* For condititions of distribution and use, see product license.
*
* Abstract:
* BCD is a format for storing packed decimal data within a nibble.
* We assume "big endian" BCD, in that the high nibble contains the
* first digit within a byte. Any unused digits are filled with the
* nibble value of $F. This module provides the services needed to
* convert BCD data to and from ASCII strings.
*
* Functions:
* str2bcd() - convert ASCII string to packed bcd.
* bcd2str() - convert packed bcd to ASCII string.
*/
#include <other/strcvt.h>
/*
* Convert null terminated ASCII string to packed bcd data.
*
* Abstract:
* An ASCII input string is converted to binary packed decimal
* data. Any unused digits are filled with $f. The size specified
* for digits is filled, either with available digits from the input
* string, or with $f nibbles once no more digits are available.
*
* Paramaters:
* bcd - pointer to start of bcd data to store.
* str - null terminated input string.
* max - maximum number of digits in bcd data.
*
* Returns:
* pointer to first non-BCD digit in input string.
*
* Exceptions:
* If NULL input string, returns NULL. If more digits exist in
* the input string than are available in bcd storage (data
* overflow), the remaining digits are ignored.
*/
char *str2bcd(uchar *bcd, char *str, int max)
{
uchar packed = 0xff;
bool low = FALSE;
if(!str)
return NULL;
while(isdigit(*str))
{
packed = packed / 16;
packed |= ((*(str++) - '0') * 16);
if(low)
{
*(bcd++) = packed;
packed = 0xff;
if(!--max)
return str;
low = FALSE;
}
else
low = TRUE;
}
if(low)
{
*(bcd++) = packed;
--max;
}
while(max--)
*(bcd++) = 0xff;
return str;
}
/*
* Convert binary coded data to ASCII text.
*
* Abstract:
* A block of bcd data of up to a specified length is read, each
* digit being converted to an ASCII character code. If a $f is
* found before 'len' digits are examined, then the program
* completes with a shorter number.
*
* Paramaters:
* str - start of output string to receive converted data.
* bcd - bcd data input.
* len - maximum number of bcd digits.
*
* Return:
* pointer to next available bcd number in memory (or past end of
* bcd data block). The output string (str) is also given a null
* terminating byte.
*
* Exceptions:
* A NULL bcd pointer returns a NULL string.
*/
uchar *bcd2str(char *str, uchar *bcd, int len)
{
uchar nib1, nib2;
if(!bcd)
return NULL;
while(len--)
{
nib1 = *bcd / 16;
nib2 = *bcd % 16;
if(nib1 < 16)
*(str++) = nib1 + '0';
else
break;
if(nib2 < 16)
*(str++) = nib2 + '0';
else
break;
++bcd;
}
*str = 0;
return bcd;
}
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