/* * \$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: * info@iptel.org * * 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., 51 Franklin Street, Fifth Floor, Boston, MA 02110-1301 USA * * History * ------ * 2004-04-25 created (janakj) */ #ifndef _QVALUE_H #define _QVALUE_H 1 #include /* * 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; } } /* * Convert qvalue_t to double */ static inline double q2double(qvalue_t q) { if (q == Q_UNSPECIFIED) { return -1; } else { return (double)((double)q / (double)1000); } } /* * Convert double to qvalue_t */ static inline qvalue_t double2q(double q) { if (q == -1) { return Q_UNSPECIFIED; } else { return q * 1000; } } /* * Convert q value to string */ static inline char* q2str(qvalue_t q, unsigned int* len) { static char buf[sizeof("0.123")]; char* p; p = buf; if (q == Q_UNSPECIFIED) { /* Do nothing */ } else if (q >= MAX_Q) { memcpy(p, MAX_Q_STR, MAX_Q_STR_LEN); p += MAX_Q_STR_LEN; } else if (q <= MIN_Q) { memcpy(p, MIN_Q_STR, MIN_Q_STR_LEN); p += MIN_Q_STR_LEN; } else { memcpy(p, Q_PREFIX, Q_PREFIX_LEN); p += Q_PREFIX_LEN; *p++ = q / 100 + '0'; q %= 100; if (!q) goto end; *p++ = q / 10 + '0'; q %= 10; if (!q) goto end; *p++ = q + '0'; } end: *p = '\0'; if (len) { *len = p - buf; } return buf; } /* * Convert string representation of q parameter in qvalue_t */ int str2q(qvalue_t* q, char* s, int len); #endif /* _QVALUE_H */