-int ieee80211_get_hdrlen(u16 fc)
-{
- int hdrlen = 24;
-
- switch (fc & IEEE80211_FCTL_FTYPE) {
- case IEEE80211_FTYPE_DATA:
- if ((fc & IEEE80211_FCTL_FROMDS) && (fc & IEEE80211_FCTL_TODS))
- hdrlen = 30; /* Addr4 */
- /*
- * The QoS Control field is two bytes and its presence is
- * indicated by the IEEE80211_STYPE_QOS_DATA bit. Add 2 to
- * hdrlen if that bit is set.
- * This works by masking out the bit and shifting it to
- * bit position 1 so the result has the value 0 or 2.
- */
- hdrlen += (fc & IEEE80211_STYPE_QOS_DATA)
- >> (ilog2(IEEE80211_STYPE_QOS_DATA)-1);
- break;
- case IEEE80211_FTYPE_CTL:
- /*
- * ACK and CTS are 10 bytes, all others 16. To see how
- * to get this condition consider
- * subtype mask: 0b0000000011110000 (0x00F0)
- * ACK subtype: 0b0000000011010000 (0x00D0)
- * CTS subtype: 0b0000000011000000 (0x00C0)
- * bits that matter: ^^^ (0x00E0)
- * value of those: 0b0000000011000000 (0x00C0)
- */
- if ((fc & 0xE0) == 0xC0)
- hdrlen = 10;
- else
- hdrlen = 16;
- break;
- }
-
- return hdrlen;
-}
-EXPORT_SYMBOL(ieee80211_get_hdrlen);
-