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