forked from osmocom/wireshark
118 lines
2.8 KiB
C
118 lines
2.8 KiB
C
/* frequency-utils.c
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* Frequency conversion utility definitions
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*
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* Wireshark - Network traffic analyzer
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* By Gerald Combs <gerald@wireshark.org>
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* Copyright 2007 Gerald Combs
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*
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* SPDX-License-Identifier: GPL-2.0-or-later
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*/
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#include "config.h"
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#include <glib.h>
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#include "frequency-utils.h"
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typedef struct freq_cvt_s {
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guint fmin; /* Minimum frequency in MHz */
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guint fmax; /* Maximum frequency in MHz */
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gint cmin; /* Minimum/base channel */
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gboolean is_bg; /* B/G channel? */
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} freq_cvt_t;
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#define FREQ_STEP 5 /* MHz. This seems to be consistent, thankfully */
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/*
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* From IEEE Std 802.11-2012:
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*
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* section 16.4.6.3 "Channel Numbering of operating channels";
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*
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* section 17.4.6.3 "Channel Numbering of operating channels";
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*
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* section 18.3.8.4.2 "Channel numbering";
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*
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* Annex E.
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*
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* XXX - Japanese channels 182 through 196 actually have center
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* frequencies that are off by 2.5 MHz from these values, according
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* to the IEEE standard, although the table in ARIB STD T-71 version 5.2:
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*
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* http://www.arib.or.jp/english/html/overview/doc/1-STD-T71v5_2.pdf
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*
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* section 5.3.8.3.3 doesn't show that.
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*
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* XXX - what about the U.S. public safety 4.9 GHz band?
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*
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* XXX - what about 802.11ad?
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*/
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static freq_cvt_t freq_cvt[] = {
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{ 2412, 2472, 1, TRUE },
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{ 2484, 2484, 14, TRUE },
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{ 5000, 5995, 0, FALSE },
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{ 4910, 4980, 182, FALSE }
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};
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#define NUM_FREQ_CVT (sizeof(freq_cvt) / sizeof(freq_cvt_t))
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#define MAX_CHANNEL(fc) ( (gint) ((fc.fmax - fc.fmin) / FREQ_STEP) + fc.cmin )
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/*
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* Get channel number given a Frequency
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*/
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gint
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ieee80211_mhz_to_chan(guint freq) {
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guint i;
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for (i = 0; i < NUM_FREQ_CVT; i++) {
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if (freq >= freq_cvt[i].fmin && freq <= freq_cvt[i].fmax) {
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return ((freq - freq_cvt[i].fmin) / FREQ_STEP) + freq_cvt[i].cmin;
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}
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}
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return -1;
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}
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/*
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* Get Frequency given a Channel number
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*/
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guint
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ieee80211_chan_to_mhz(gint chan, gboolean is_bg) {
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guint i;
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for (i = 0; i < NUM_FREQ_CVT; i++) {
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if (is_bg == freq_cvt[i].is_bg &&
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chan >= freq_cvt[i].cmin && chan <= MAX_CHANNEL(freq_cvt[i])) {
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return ((chan - freq_cvt[i].cmin) * FREQ_STEP) + freq_cvt[i].fmin;
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}
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}
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return 0;
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}
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/*
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* Get channel representation string given a Frequency
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*/
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gchar*
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ieee80211_mhz_to_str(guint freq){
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gint chan = ieee80211_mhz_to_chan(freq);
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gboolean is_bg = FREQ_IS_BG(freq);
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if (chan < 0) {
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return g_strdup_printf("%u", freq);
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} else {
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return g_strdup_printf("%u [%s %u]", freq, is_bg ? "BG" : "A",
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chan);
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}
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}
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/*
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* Editor modelines
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*
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* Local Variables:
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* c-basic-offset: 4
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* tab-width: 8
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* indent-tabs-mode: nil
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* End:
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*
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* ex: set shiftwidth=4 tabstop=8 expandtab:
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* :indentSize=4:tabSize=8:noTabs=true:
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*/
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