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/* frequency-utils.c
* Frequency conversion utility definitions
*
* Wireshark - Network traffic analyzer
* By Gerald Combs <gerald@wireshark.org>
* Copyright 2007 Gerald Combs
*
* This program 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.
*
* This program 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.
*/
#include "config.h"
#include <glib.h>
#include "frequency-utils.h"
typedef struct freq_cvt_s {
guint fmin; /* Minimum frequency in MHz */
guint fmax; /* Maximum frequency in MHz */
gint cmin; /* Minimum/base channel */
gboolean is_bg; /* B/G channel? */
} freq_cvt_t;
#define FREQ_STEP 5 /* MHz. This seems to be consistent, thankfully */
/*
* From IEEE Std 802.11-2012:
*
* section 16.4.6.3 "Channel Numbering of operating channels";
*
* section 17.4.6.3 "Channel Numbering of operating channels";
*
* section 18.3.8.4.2 "Channel numbering";
*
* Annex E.
*
* XXX - Japanese channels 182 through 196 actually have center
* frequencies that are off by 2.5 MHz from these values, according
* to the IEEE standard, although the table in ARIB STD T-71 version 5.2:
*
* http://www.arib.or.jp/english/html/overview/doc/1-STD-T71v5_2.pdf
*
* section 5.3.8.3.3 doesn't show that.
*
* XXX - what about the U.S. public safety 4.9 GHz band?
*
* XXX - what about 802.11ad?
*/
static freq_cvt_t freq_cvt[] = {
{ 2412, 2472, 1, TRUE },
{ 2484, 2484, 14, TRUE },
{ 5000, 5995, 0, FALSE },
{ 4910, 4980, 182, FALSE }
};
#define NUM_FREQ_CVT (sizeof(freq_cvt) / sizeof(freq_cvt_t))
#define MAX_CHANNEL(fc) ( (gint) ((fc.fmax - fc.fmin) / FREQ_STEP) + fc.cmin )
/*
* Get channel number given a Frequency
*/
gint
ieee80211_mhz_to_chan(guint freq) {
guint i;
for (i = 0; i < NUM_FREQ_CVT; i++) {
if (freq >= freq_cvt[i].fmin && freq <= freq_cvt[i].fmax) {
return ((freq - freq_cvt[i].fmin) / FREQ_STEP) + freq_cvt[i].cmin;
}
}
return -1;
}
/*
* Get Frequency given a Channel number
*/
guint
ieee80211_chan_to_mhz(gint chan, gboolean is_bg) {
guint i;
for (i = 0; i < NUM_FREQ_CVT; i++) {
if (is_bg == freq_cvt[i].is_bg &&
chan >= freq_cvt[i].cmin && chan <= MAX_CHANNEL(freq_cvt[i])) {
return ((chan - freq_cvt[i].cmin) * FREQ_STEP) + freq_cvt[i].fmin;
}
}
return 0;
}
/*
* Get channel representation string given a Frequency
*/
gchar*
ieee80211_mhz_to_str(guint freq){
gint chan = ieee80211_mhz_to_chan(freq);
gboolean is_bg = FREQ_IS_BG(freq);
if (chan < 0) {
return g_strdup_printf("%u", freq);
} else {
return g_strdup_printf("%u [%s %u]", freq, is_bg ? "BG" : "A",
chan);
}
}
/*
* Editor modelines
*
* Local Variables:
* c-basic-offset: 4
* tab-width: 8
* indent-tabs-mode: nil
* End:
*
* ex: set shiftwidth=4 tabstop=8 expandtab:
* :indentSize=4:tabSize=8:noTabs=true:
*/
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