From 9baea3e4cad8ada43fa6ccb8936d89ebee824b3a Mon Sep 17 00:00:00 2001
From: Damien Bergamini <damien@cvs.openbsd.org>
Date: Mon, 2 Jul 2007 16:46:45 +0000
Subject: initial bits for proper TIM support.

---
 sys/net80211/ieee80211_output.c | 39 ++++++++++++++++++++++++++++++++++++++-
 1 file changed, 38 insertions(+), 1 deletion(-)

(limited to 'sys/net80211/ieee80211_output.c')

diff --git a/sys/net80211/ieee80211_output.c b/sys/net80211/ieee80211_output.c
index 4e3535c7c49..b3c069ad513 100644
--- a/sys/net80211/ieee80211_output.c
+++ b/sys/net80211/ieee80211_output.c
@@ -1,4 +1,4 @@
-/*	$OpenBSD: ieee80211_output.c,v 1.31 2007/07/02 16:19:49 damien Exp $	*/
+/*	$OpenBSD: ieee80211_output.c,v 1.32 2007/07/02 16:46:44 damien Exp $	*/
 /*	$NetBSD: ieee80211_output.c,v 1.13 2004/05/31 11:02:55 dyoung Exp $	*/
 
 /*-
@@ -659,6 +659,43 @@ ieee80211_add_erp(u_int8_t *frm, struct ieee80211com *ic)
 	return frm;
 }
 
+/*
+ * Add a TIM element to a frame (see Annex L).
+ */
+u_int8_t *
+ieee80211_add_tim(u_int8_t *frm, struct ieee80211com *ic)
+{
+	u_int i, offset = 0, len;
+
+	/* find first non-zero octet in the virtual bit map */
+	for (i = 0; i < ic->ic_tim_len && ic->ic_tim_bitmap[i] == 0; i++);
+
+	/* clear the lsb as it is reserved for the broadcast indication bit */
+	if (i < ic->ic_tim_len)
+		offset = i & ~1;
+
+	/* find last non-zero octet in the virtual bit map */
+	for (i = ic->ic_tim_len - 1; i > 0 && ic->ic_tim_bitmap[i] != 0; i--);
+
+	len = i - offset + 1;
+
+	*frm++ = IEEE80211_ELEMID_TIM;
+	*frm++ = len + 3;		/* length */
+	*frm++ = ic->ic_dtim_count;	/* DTIM count */
+	*frm++ = ic->ic_dtim_period;	/* DTIM period */
+
+	/* Bitmap Control */
+	*frm = offset;
+	/* set broadcast/multicast indication bit if necessary */
+	if (ic->ic_dtim_count == 0 && ic->ic_tim_mcast)
+		*frm |= 0x01;
+	frm++;
+
+	/* Partial Virtual Bitmap */
+	memcpy(frm, &ic->ic_tim_bitmap[offset], len);
+	return frm + len;
+}
+
 /*
  * Add a QoS Capability element to a frame.
  */
-- 
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