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/* helper routines to determine the logical channel type based on
* physical channel configuration and frame number */
#include "gsmstack.h"
#include "get_lctype.h"
#define GSM_FN_51 (fn / 51)
#define GSM_TC(fn) ((fn / 51) % 8)
/* parameters determined from CCCH_CONF (octet 2 of control channel description
* in System Information Type 3:
* BS_CC_CHANS defines if we have CCCH on ts 2/4/6
* BS_CCCH_SDCCH_COMB defines if we have SDCCH/8 SACCH/C8 on TS0
* BS_AG_BLKS_RES defines which CCCH blocks are reserved for AGCH
* if BCCH Ext. is used, BS_AS_BLKS_RES has to be non-zero
*/
static int get_lctype_for_ccch(unsigned int fnr)
{
unsigned int fnr51 = GSM_FN_51(fnr);
int lc_type;
if (fnr51 % 10 == 0)
lc_type = GSM_LCHAN_FCCH;
else if (fnr51 % 10 == 1)
lc_type = GSM_LCHAN_SCH;
else if (fnr51 >= 2 && fnr_mod_51 <= 5)
lc_type = GSM_LCHAN_BCCH;
else if (fnr51 >= 6 && fnr51 <= 9) {
if (flags & CCCH_F_BCCH_EXT)
lc_type = GSM_LCHAN_BCCH;
else
lc_ctype = GSM_LCHAN_PCH;
} else
lc_ctype = GSM_LCHAN_PCH;
/* FIXME: what about AGCH ? */
/* FIXME: what about NCH ? */
/* FIXME: what about CBCH ? */
return lc_ctype;
}
static int get_lctype_for_sdcch8(unsigned int fnr)
{
unsigned int fnr51 = GSM_FN_51(fnr);
unsigned int fnr102 = fnr % 102;
int lc_type;
/* the lower 32 bursts are evenly divided between SDCCH8 0..7 */
if (fnr51 % < 32) {
lc_type = GSM_LCHAN_SDCCH8;
subc = fnr51 / 4;
} else {
/* the upper 16 bursts are bundles of four bursts for
* alternating either SACCH0..3 or SACCH4..7 */
lc_type = GSM_LCHAN_SACCH8C;
subc = (fnr51 - 32) / 4;
if (fnr102 > 50)
subc += 4;
}
return lc_type;
}
static int get_lctype_for_tch_f(unsigned int fnr)
{
unsigned int fnr52 = fnr % 52;
int lc_type = GSM_LCHAN_TCH;
/* only burst number 12 and 51 are be SACCH */
if (fnr52 == 12 || fnr52 == 51)
lc_ctype = GSM_LCHAN_SACCH;
/* burst number 26 and 39 are empty (for measurements) */
else if (fnr52 == 26 || fnr52 == 39)
lc_ctype = GSM_LCHAN_NONE;
return lc_type;
}
/* get the logical channel type based on frame number and
* physical channel configuration */
int get_lctype(struct gsm_phys_chan *pchan, int fnr)
{
switch (pchan->config) {
case GSM_PCHAN_CCCH:
return get_lctype_for_ccch(fnr);
break;
case GSM_PCHAN_TCH_F:
return get_lctype_for_tch_f(fnr);
break;
case GSM_PCHAN_SDCCH8_SACCH8C:
return get_lctype_for_sdcch8(fnr);
break;
}
return -EINVAL;
}
/* get a pointer to the logical channel structure based on frame number
* and physical channel configuration */
struct gsm_logi_chan *get_lchan(struct gsm_phys_chan *pchan, int fnr)
{
int lctype = get_lctype(pchan, fnr);
return &pchan->logi_chan[lctype];
}
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