From 0cc9b20c15460213e488bf5e70963b941482f628 Mon Sep 17 00:00:00 2001
From: William Harrington <kb0iic@berzerkula.org>
Date: Tue, 14 Jan 2025 16:06:02 -0600
Subject: Add source.

---
 sdk/other/bcd.c | 125 ++++++++++++++++++++++++++++++++++++++++++++++++++++++++
 1 file changed, 125 insertions(+)
 create mode 100644 sdk/other/bcd.c

(limited to 'sdk/other/bcd.c')

diff --git a/sdk/other/bcd.c b/sdk/other/bcd.c
new file mode 100644
index 0000000..3bd6144
--- /dev/null
+++ b/sdk/other/bcd.c
@@ -0,0 +1,125 @@
+/*
+ * 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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