qvalue related functions and types.

qvalue.h

@@ -0,0 +1,132 @@
+/*
+ * $Id$
+ *
+ * Handling of the q value
+ *
+ * Copyright (C) 2004 FhG FOKUS
+ *
+ * This file is part of ser, a free SIP server.
+ *
+ * ser is free software; you can redistribute it and/or modify
+ * it under the terms of the GNU General Public License as published by
+ * the Free Software Foundation; either version 2 of the License, or
+ * (at your option) any later version
+ *
+ * For a license to use the ser software under conditions
+ * other than those described here, or to purchase support for this
+ * software, please contact iptel.org by e-mail at the following addresses:
+ *    [email protected]
+ *
+ * ser is distributed in the hope that it will be useful,
+ * but WITHOUT ANY WARRANTY; without even the implied warranty of
+ * MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE.  See the
+ * GNU General Public License for more details.
+ *
+ * You should have received a copy of the GNU General Public License 
+ * along with this program; if not, write to the Free Software 
+ * Foundation, Inc., 59 Temple Place, Suite 330, Boston, MA  02111-1307  USA
+ *
+ * History
+ * ------
+ * 2004-04-25 created (janakj)
+ */
+
+#ifndef _QVALUE_H
+#define _QVALUE_H 1
+
+#include <string.h>
+
+/*
+ * The q value expresses the priority of a URI within a set of URIs 
+ * (Contact header field in the same SIP message or dset array in 
+ * ser. The higher is the q value of a URI the higher is the priority 
+ * of the URI.
+ *
+ * The q value is usually expressed as a floating point number with 
+ * limited number of decimal digits, for example 0.346. RFC3261 allows 
+ * 0-3 decimal digits.
+ *
+ * To speed things up we represent the q value as integer number, it 
+ * is then easier to handle/print the value. To convert float into 
+ * integer we multiply the q value by 1000, i.e. 
+ * (float)0.567 == (int)567. In the opposite direction, values 
+ * higher or equal to 1000 are converted to 1.0 and values below or 
+ * equal to 0 are converted to 0.
+ *
+ * Value Q_UNSPECIFIED (which is in fact -1) has a special meaning, it 
+ * means that the q value is not known and the parameter should not be 
+ * printed when printing Contacts, implementations will then use 
+ * implementation specific pre-defined values.
+ */
+
+typedef int qvalue_t;
+
+/*
+ * Use this if the value of q is not specified
+ */
+#define Q_UNSPECIFIED ((qvalue_t)-1)
+
+
+#define MAX_Q ((qvalue_t)1000)
+#define MIN_Q ((qvalue_t)0)
+
+#define MAX_Q_STR "1"
+#define MAX_Q_STR_LEN (sizeof(MAX_Q_STR) - 1)
+
+#define MIN_Q_STR "0"
+#define MIN_Q_STR_LEN (sizeof(MIN_Q_STR) - 1)
+
+#define Q_PREFIX "0."
+#define Q_PREFIX_LEN (sizeof(Q_PREFIX) - 1)
+
+
+/*
+ * Calculate the length of printed q
+ */
+static inline size_t len_q(qvalue_t q)
+{
+	if (q == Q_UNSPECIFIED) {
+		return 0;
+	} else if (q >= MAX_Q) {
+		return MAX_Q_STR_LEN;
+	} else if (q <= MIN_Q) {
+		return MIN_Q_STR_LEN;
+	} else if (q % 100 == 0) {
+		return Q_PREFIX_LEN + 1;
+	} else if (q % 10 == 0) {
+		return Q_PREFIX_LEN + 2;
+	} else {
+		return Q_PREFIX_LEN + 3;
+	}
+}
+
+
+/*
+ * Print the q parameter
+ */
+static inline size_t print_q(char* p, qvalue_t q)
+{
+	if (q == Q_UNSPECIFIED) {
+		return 0;
+	} else if (q >= MAX_Q) {
+		memcpy(p, MAX_Q_STR, MAX_Q_STR_LEN);
+		return MAX_Q_STR_LEN;
+	} else if (q <= MIN_Q) {
+		memcpy(p, MIN_Q_STR, MIN_Q_STR_LEN);
+		return MIN_Q_STR_LEN;
+	}
+	
+	memcpy(p, Q_PREFIX, Q_PREFIX_LEN);
+	p += Q_PREFIX_LEN;
+
+	*p++ = q / 100 + '0';
+	q %= 100;
+	if (!q) return Q_PREFIX_LEN + 1;
+	*p++ = q / 10 + '0';
+	q %= 10;
+	if (!q) return Q_PREFIX_LEN + 2;
+	*p = q + '0';
+	return Q_PREFIX_LEN + 3;
+}
+
+#endif /* _QVALUE_H */