[asterisk-dev] Reading codes - need help

[VoIP Newbie]

Hi there,

I have been reading and porting Zaptel to Windows TAPI. I don't quite
understand the following codes in wctdm.c:

.............
.............

  /* Go to half-duty FSYNC */
  __wctdm_setcreg(wc, WC_SYNC, 0x01);
  y = __wctdm_getcreg(wc, WC_SYNC);
.........
.........
 __wctdm_setcreg(wc, WC_SYNC, (wc->cardflag << 1) | 0x1);

...........

What do they do? In particular, why does wc->cardflag have to be shifted
left by 1?

Many thanks.
David
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