PERFORCE change 133244 for review

[Sepherosa Ziehau]

http://perforce.freebsd.org/chv.cgi?CH=133244

Change 133244 by sephe at sephe_zealot:sam_wifi on 2008/01/14 07:20:31

	- Correct control rate index mapping in turbog rate table
	- ieee80211_compute_duration() needs 802.11 rate code instead of
	  rate table's rate index

Affected files ...

.. //depot/projects/wifi/sys/net80211/ieee80211_phy.c#4 edit

Differences ...

==== //depot/projects/wifi/sys/net80211/ieee80211_phy.c#4 (text+ko) ====

@@ -204,8 +204,8 @@
 /*                               short            ctrl  */
 /*                            Preamble  dot11Rate Rate */
 /*   6 Mb */ {  TURBO,   6000,    0x00, (0x80|12),   0 },
-/*  12 Mb */ {  TURBO,  12000,    0x00, (0x80|24),   2 },
-/*  18 Mb */ {  TURBO,  18000,    0x00,        36,   2 },
+/*  12 Mb */ {  TURBO,  12000,    0x00, (0x80|24),   1 },
+/*  18 Mb */ {  TURBO,  18000,    0x00,        36,   1 },
 /*  24 Mb */ {  TURBO,  24000,    0x00, (0x80|48),   3 },
 /*  36 Mb */ {  TURBO,  36000,    0x00,        72,   3 },
 /*  48 Mb */ {  TURBO,  48000,    0x00,        96,   3 },
@@ -288,6 +288,7 @@
 	for (i = 0; i < rt->rateCount; i++) {
 		uint8_t code = rt->info[i].dot11Rate;
 		uint8_t cix = rt->info[i].ctlRateIndex;
+		uint8_t ctl_rate = rt->info[cix].dot11Rate;
 
 		rt->rateCodeToIndex[code] = i;
 		if (code & IEEE80211_RATE_BASIC) {
@@ -303,11 +304,15 @@
 		 *     depends on whether they are marked as basic rates;
 		 *     the static tables are setup with an 11b-compatible
 		 *     2Mb/s rate which will work but is suboptimal
+		 *
+		 * NB: Control rate is always less than or equal to the
+		 *     current rate, so control rate's reverse lookup entry
+		 *     has been installed and following call is safe.
 		 */
 		rt->info[i].lpAckDuration = ieee80211_compute_duration(rt,
-			WLAN_CTRL_FRAME_SIZE, cix, 0);
+			WLAN_CTRL_FRAME_SIZE, ctl_rate, 0);
 		rt->info[i].spAckDuration = ieee80211_compute_duration(rt,
-			WLAN_CTRL_FRAME_SIZE, cix, IEEE80211_F_SHPREAMBLE);
+			WLAN_CTRL_FRAME_SIZE, ctl_rate, IEEE80211_F_SHPREAMBLE);
 	}
 
 #undef WLAN_CTRL_FRAME_SIZE