Refactoring: Use data bits per symbol MCS table to calculate rates and

remove redundant HT MCS/rate table. Preparation for duration calculations
that will use this data as well.

Change-Id: Iee4fb2eefb00eaa53a6368eca4ed60f705ff49df
Reviewed-on: https://code.wireshark.org/review/12856
Reviewed-by: Michael Mann <mmann78@netscape.net>

1 files changed, 34 insertions, 389 deletions

diff --git a/epan/dissectors/packet-ieee80211-radio.c b/epan/dissectors/packet-ieee80211-radio.c
index b71e505c58..5b3af9dfcd 100644
--- a/epan/dissectors/packet-ieee80211-radio.c
+++ b/epan/dissectors/packet-ieee80211-radio.c
@@ -148,404 +148,48 @@ static const value_string fec_vals[] = {
 };
 
 /*
- * Data rates corresponding to a given 802.11n MCS index, bandwidth, and
- * guard interval.
- *
- * Indices are:
- *
- *  the MCS index (0-76);
- *
- *  0 for 20 MHz, 1 for 40 MHz;
- *
- *  0 for a long guard interval, 1 for a short guard interval.
+ * Lookup for the MCS index (0-76)
+ * returning the number of data bits per symbol
+ * assumes 52 subcarriers (20MHz)
+ * symbols are 4us for long guard interval, 3.6us for short guard interval
+ * Note: MCS 32 is special - only valid for 40Mhz channel.
  */
-WS_DLL_PUBLIC_DEF
-const float ieee80211_float_htrates[MAX_MCS_INDEX+1][2][2] = {
-  /* MCS  0  */
-  { /* 20 Mhz */ {    6.5f,   /* SGI */    7.2f, },
-    /* 40 Mhz */ {   13.5f,   /* SGI */   15.0f, },
-  },
-
-  /* MCS  1  */
-  { /* 20 Mhz */ {   13.0f,   /* SGI */   14.4f, },
-    /* 40 Mhz */ {   27.0f,   /* SGI */   30.0f, },
-  },
-
-  /* MCS  2  */
-  { /* 20 Mhz */ {   19.5f,   /* SGI */   21.7f, },
-    /* 40 Mhz */ {   40.5f,   /* SGI */   45.0f, },
-  },
-
-  /* MCS  3  */
-  { /* 20 Mhz */ {   26.0f,   /* SGI */   28.9f, },
-    /* 40 Mhz */ {   54.0f,   /* SGI */   60.0f, },
-  },
-
-  /* MCS  4  */
-  { /* 20 Mhz */ {   39.0f,   /* SGI */   43.3f, },
-    /* 40 Mhz */ {   81.0f,   /* SGI */   90.0f, },
-  },
-
-  /* MCS  5  */
-  { /* 20 Mhz */ {   52.0f,   /* SGI */   57.8f, },
-    /* 40 Mhz */ {  108.0f,   /* SGI */  120.0f, },
-  },
+WS_DLL_PUBLIC_DEF const guint16 ieee80211_ht_Dbps[MAX_MCS_INDEX+1] = {
+	/* MCS  0 - 1 stream */
+	26, 52, 78, 104, 156, 208, 234, 260,
 
-  /* MCS  6  */
-  { /* 20 Mhz */ {   58.5f,   /* SGI */   65.0f, },
-    /* 40 Mhz */ {  121.5f,   /* SGI */  135.0f, },
-  },
+	/* MCS  8 - 2 stream */
+	52, 104, 156, 208, 312, 416, 468, 520,
 
-  /* MCS  7  */
-  { /* 20 Mhz */ {   65.0f,   /* SGI */   72.2f, },
-    /* 40 Mhz */ {   135.0f,  /* SGI */  150.0f, },
-  },
+	/* MCS 16 - 3 stream */
+	78, 156, 234, 312, 468, 624, 702, 780,
 
-  /* MCS  8  */
-  { /* 20 Mhz */ {   13.0f,   /* SGI */   14.4f, },
-    /* 40 Mhz */ {   27.0f,   /* SGI */   30.0f, },
-  },
+	/* MCS 24 - 4 stream */
+	104, 208, 312, 416, 624, 832, 936, 1040,
 
-  /* MCS  9  */
-  { /* 20 Mhz */ {   26.0f,   /* SGI */   28.9f, },
-    /* 40 Mhz */ {   54.0f,   /* SGI */   60.0f, },
-  },
+	/* MCS 32 - 1 stream */
+	12, /* only valid for 40Mhz - 11a/g DUP mode */
 
-  /* MCS 10  */
-  { /* 20 Mhz */ {   39.0f,   /* SGI */   43.3f, },
-    /* 40 Mhz */ {   81.0f,   /* SGI */   90.0f, },
-  },
-
-  /* MCS 11  */
-  { /* 20 Mhz */ {   52.0f,   /* SGI */   57.8f, },
-    /* 40 Mhz */ {  108.0f,   /* SGI */  120.0f, },
-  },
-
-  /* MCS 12  */
-  { /* 20 Mhz */ {   78.0f,   /* SGI */   86.7f, },
-    /* 40 Mhz */ {  162.0f,   /* SGI */  180.0f, },
-  },
-
-  /* MCS 13  */
-  { /* 20 Mhz */ {  104.0f,   /* SGI */  115.6f, },
-    /* 40 Mhz */ {  216.0f,   /* SGI */  240.0f, },
-  },
-
-  /* MCS 14  */
-  { /* 20 Mhz */ {  117.0f,   /* SGI */  130.0f, },
-    /* 40 Mhz */ {  243.0f,   /* SGI */  270.0f, },
-  },
-
-  /* MCS 15  */
-  { /* 20 Mhz */ {  130.0f,   /* SGI */  144.4f, },
-    /* 40 Mhz */ {  270.0f,   /* SGI */  300.0f, },
-  },
-
-  /* MCS 16  */
-  { /* 20 Mhz */ {   19.5f,   /* SGI */   21.7f, },
-    /* 40 Mhz */ {   40.5f,   /* SGI */   45.0f, },
-  },
+	/* MCS 33 - 2 stream */
+	156, 208, 260, 234, 312, 390,
 
-  /* MCS 17  */
-  { /* 20 Mhz */ {   39.0f,   /* SGI */   43.3f, },
-    /* 40 Mhz */ {   81.0f,   /* SGI */   90.0f, },
-  },
-
-  /* MCS 18  */
-  { /* 20 Mhz */ {   58.5f,   /* SGI */   65.0f, },
-    /* 40 Mhz */ {  121.5f,   /* SGI */  135.0f, },
-  },
-
-  /* MCS 19  */
-  { /* 20 Mhz */ {   78.0f,   /* SGI */   86.7f, },
-    /* 40 Mhz */ {  162.0f,   /* SGI */  180.0f, },
-  },
-
-  /* MCS 20  */
-  { /* 20 Mhz */ {  117.0f,   /* SGI */  130.0f, },
-    /* 40 Mhz */ {  243.0f,   /* SGI */  270.0f, },
-  },
-
-  /* MCS 21  */
-  { /* 20 Mhz */ {  156.0f,   /* SGI */  173.3f, },
-    /* 40 Mhz */ {  324.0f,   /* SGI */  360.0f, },
-  },
-
-  /* MCS 22  */
-  { /* 20 Mhz */ {  175.5f,   /* SGI */  195.0f, },
-    /* 40 Mhz */ {  364.5f,   /* SGI */  405.0f, },
-  },
-
-  /* MCS 23  */
-  { /* 20 Mhz */ {  195.0f,   /* SGI */  216.7f, },
-    /* 40 Mhz */ {  405.0f,   /* SGI */  450.0f, },
-  },
-
-  /* MCS 24  */
-  { /* 20 Mhz */ {   26.0f,   /* SGI */   28.9f, },
-    /* 40 Mhz */ {   54.0f,   /* SGI */   60.0f, },
-  },
-
-  /* MCS 25  */
-  { /* 20 Mhz */ {   52.0f,   /* SGI */   57.8f, },
-    /* 40 Mhz */ {  108.0f,   /* SGI */  120.0f, },
-  },
-
-  /* MCS 26  */
-  { /* 20 Mhz */ {   78.0f,   /* SGI */   86.7f, },
-    /* 40 Mhz */ {  162.0f,   /* SGI */  180.0f, },
-  },
-
-  /* MCS 27  */
-  { /* 20 Mhz */ {  104.0f,   /* SGI */  115.6f, },
-    /* 40 Mhz */ {  216.0f,   /* SGI */  240.0f, },
-  },
-
-  /* MCS 28  */
-  { /* 20 Mhz */ {  156.0f,   /* SGI */  173.3f, },
-    /* 40 Mhz */ {  324.0f,   /* SGI */  360.0f, },
-  },
-
-  /* MCS 29  */
-  { /* 20 Mhz */ {  208.0f,   /* SGI */  231.1f, },
-    /* 40 Mhz */ {  432.0f,   /* SGI */  480.0f, },
-  },
-
-  /* MCS 30  */
-  { /* 20 Mhz */ {  234.0f,   /* SGI */  260.0f, },
-    /* 40 Mhz */ {  486.0f,   /* SGI */  540.0f, },
-  },
-
-  /* MCS 31  */
-  { /* 20 Mhz */ {  260.0f,   /* SGI */  288.9f, },
-    /* 40 Mhz */ {  540.0f,   /* SGI */  600.0f, },
-  },
-
-  /* MCS 32  */
-  { /* 20 Mhz */ {    0.0f,   /* SGI */    0.0f, }, /* not valid */
-    /* 40 Mhz */ {    6.0f,   /* SGI */    6.7f, },
-  },
-
-  /* MCS 33  */
-  { /* 20 Mhz */ {   39.0f,   /* SGI */   43.3f, },
-    /* 40 Mhz */ {   81.0f,   /* SGI */   90.0f, },
-  },
-
-  /* MCS 34  */
-  { /* 20 Mhz */ {   52.0f,   /* SGI */   57.8f, },
-    /* 40 Mhz */ {  108.0f,   /* SGI */  120.0f, },
-  },
-
-  /* MCS 35  */
-  { /* 20 Mhz */ {   65.0f,   /* SGI */   72.2f, },
-    /* 40 Mhz */ {  135.0f,   /* SGI */  150.0f, },
-  },
-
-  /* MCS 36  */
-  { /* 20 Mhz */ {   58.5f,   /* SGI */   65.0f, },
-    /* 40 Mhz */ {  121.5f,   /* SGI */  135.0f, },
-  },
-
-  /* MCS 37  */
-  { /* 20 Mhz */ {   78.0f,   /* SGI */   86.7f, },
-    /* 40 Mhz */ {  162.0f,   /* SGI */  180.0f, },
-  },
+	/* MCS 39 - 3 stream */
+	208, 260, 260, 312, 364, 364, 416, 312, 390, 390, 468, 546, 546, 624,
 
-  /* MCS 38  */
-  { /* 20 Mhz */ {   97.5f,   /* SGI */  108.3f, },
-    /* 40 Mhz */ {  202.5f,   /* SGI */  225.0f, },
-  },
-
-  /* MCS 39  */
-  { /* 20 Mhz */ {   52.0f,   /* SGI */   57.8f, },
-    /* 40 Mhz */ {  108.0f,   /* SGI */  120.0f, },
-  },
-
-  /* MCS 40  */
-  { /* 20 Mhz */ {   65.0f,   /* SGI */   72.2f, },
-    /* 40 Mhz */ {  135.0f,   /* SGI */  150.0f, },
-  },
-
-  /* MCS 41  */
-  { /* 20 Mhz */ {   65.0f,   /* SGI */   72.2f, },
-    /* 40 Mhz */ {  135.0f,   /* SGI */  150.0f, },
-  },
-
-  /* MCS 42  */
-  { /* 20 Mhz */ {   78.0f,   /* SGI */   86.7f, },
-    /* 40 Mhz */ {  162.0f,   /* SGI */  180.0f, },
-  },
-
-  /* MCS 43  */
-  { /* 20 Mhz */ {   91.0f,   /* SGI */  101.1f, },
-    /* 40 Mhz */ {  189.0f,   /* SGI */  210.0f, },
-  },
-
-  /* MCS 44  */
-  { /* 20 Mhz */ {   91.0f,   /* SGI */  101.1f, },
-    /* 40 Mhz */ {  189.0f,   /* SGI */  210.0f, },
-  },
-
-  /* MCS 45  */
-  { /* 20 Mhz */ {  104.0f,   /* SGI */  115.6f, },
-    /* 40 Mhz */ {  216.0f,   /* SGI */  240.0f, },
-  },
-
-  /* MCS 46  */
-  { /* 20 Mhz */ {   78.0f,   /* SGI */   86.7f, },
-    /* 40 Mhz */ {  162.0f,   /* SGI */  180.0f, },
-  },
-
-  /* MCS 47  */
-  { /* 20 Mhz */ {   97.5f,   /* SGI */  108.3f, },
-    /* 40 Mhz */ {  202.5f,   /* SGI */  225.0f, },
-  },
-
-  /* MCS 48  */
-  { /* 20 Mhz */ {   97.5f,   /* SGI */  108.3f, },
-    /* 40 Mhz */ {  202.5f,   /* SGI */  225.0f, },
-  },
-
-  /* MCS 49  */
-  { /* 20 Mhz */ {  117.0f,   /* SGI */  130.0f, },
-    /* 40 Mhz */ {  243.0f,   /* SGI */  270.0f, },
-  },
-
-  /* MCS 50  */
-  { /* 20 Mhz */ {  136.5f,   /* SGI */  151.7f, },
-    /* 40 Mhz */ {  283.5f,   /* SGI */  315.0f, },
-  },
-
-  /* MCS 51  */
-  { /* 20 Mhz */ {  136.5f,   /* SGI */  151.7f, },
-    /* 40 Mhz */ {  283.5f,   /* SGI */  315.0f, },
-  },
-
-  /* MCS 52  */
-  { /* 20 Mhz */ {  156.0f,   /* SGI */  173.3f, },
-    /* 40 Mhz */ {  324.0f,   /* SGI */  360.0f, },
-  },
-
-  /* MCS 53  */
-  { /* 20 Mhz */ {   65.0f,   /* SGI */   72.2f, },
-    /* 40 Mhz */ {  135.0f,   /* SGI */  150.0f, },
-  },
-
-  /* MCS 54  */
-  { /* 20 Mhz */ {   78.0f,   /* SGI */   86.7f, },
-    /* 40 Mhz */ {  162.0f,   /* SGI */  180.0f, },
-  },
-
-  /* MCS 55  */
-  { /* 20 Mhz */ {   91.0f,   /* SGI */  101.1f, },
-    /* 40 Mhz */ {  189.0f,   /* SGI */  210.0f, },
-  },
-
-  /* MCS 56  */
-  { /* 20 Mhz */ {   78.0f,   /* SGI */   86.7f, },
-    /* 40 Mhz */ {  162.0f,   /* SGI */  180.0f, },
-  },
-
-  /* MCS 57  */
-  { /* 20 Mhz */ {   91.0f,   /* SGI */  101.1f, },
-    /* 40 Mhz */ {  189.0f,   /* SGI */  210.0f, },
-  },
-
-  /* MCS 58  */
-  { /* 20 Mhz */ {  104.0f,   /* SGI */  115.6f, },
-    /* 40 Mhz */ {  216.0f,   /* SGI */  240.0f, },
-  },
-
-  /* MCS 59  */
-  { /* 20 Mhz */ {  117.0f,   /* SGI */  130.0f, },
-    /* 40 Mhz */ {  243.0f,   /* SGI */  270.0f, },
-  },
-
-  /* MCS 60  */
-  { /* 20 Mhz */ {  104.0f,   /* SGI */  115.6f, },
-    /* 40 Mhz */ {  216.0f,   /* SGI */  240.0f, },
-  },
-
-  /* MCS 61  */
-  { /* 20 Mhz */ {  117.0f,   /* SGI */  130.0f, },
-    /* 40 Mhz */ {  243.0f,   /* SGI */  270.0f, },
-  },
-
-  /* MCS 62  */
-  { /* 20 Mhz */ {  130.0f,   /* SGI */  144.4f, },
-    /* 40 Mhz */ {  270.0f,   /* SGI */  300.0f, },
-  },
-
-  /* MCS 63  */
-  { /* 20 Mhz */ {  130.0f,   /* SGI */  144.4f, },
-    /* 40 Mhz */ {  270.0f,   /* SGI */  300.0f, },
-  },
-
-  /* MCS 64  */
-  { /* 20 Mhz */ {  143.0f,   /* SGI */  158.9f, },
-    /* 40 Mhz */ {  297.0f,   /* SGI */  330.0f, },
-  },
-
-  /* MCS 65  */
-  { /* 20 Mhz */ {   97.5f,   /* SGI */  108.3f, },
-    /* 40 Mhz */ {  202.5f,   /* SGI */  225.0f, },
-  },
-
-  /* MCS 66  */
-  { /* 20 Mhz */ {  117.0f,   /* SGI */  130.0f, },
-    /* 40 Mhz */ {  243.0f,   /* SGI */  270.0f, },
-  },
-
-  /* MCS 67  */
-  { /* 20 Mhz */ {  136.5f,   /* SGI */  151.7f, },
-    /* 40 Mhz */ {  283.5f,   /* SGI */  315.0f, },
-  },
-
-  /* MCS 68  */
-  { /* 20 Mhz */ {  117.0f,   /* SGI */  130.0f, },
-    /* 40 Mhz */ {  243.0f,   /* SGI */  270.0f, },
-  },
-
-  /* MCS 69  */
-  { /* 20 Mhz */ {  136.5f,   /* SGI */  151.7f, },
-    /* 40 Mhz */ {  283.5f,   /* SGI */  315.0f, },
-  },
-
-  /* MCS 70  */
-  { /* 20 Mhz */ {  156.0f,   /* SGI */  173.3f, },
-    /* 40 Mhz */ {  324.0f,   /* SGI */  360.0f, },
-  },
-
-  /* MCS 71  */
-  { /* 20 Mhz */ {  175.5f,   /* SGI */  195.0f, },
-    /* 40 Mhz */ {  364.5f,   /* SGI */  405.0f, },
-  },
-
-  /* MCS 72  */
-  { /* 20 Mhz */ {  156.0f,   /* SGI */  173.3f, },
-    /* 40 Mhz */ {  324.0f,   /* SGI */  360.0f, },
-  },
-
-  /* MCS 73  */
-  { /* 20 Mhz */ {  175.5f,   /* SGI */  195.0f, },
-    /* 40 Mhz */ {  364.5f,   /* SGI */  405.0f, },
-  },
-
-  /* MCS 74  */
-  { /* 20 Mhz */ {  195.0f,   /* SGI */  216.7f, },
-    /* 40 Mhz */ {  405.0f,   /* SGI */  450.0f, },
-  },
+	/* MCS 53 - 4 stream */
+	260, 312, 364, 312, 364, 416, 468, 416, 468, 520, 520, 572,
+	390, 468, 546, 468, 546, 624, 702, 624, 702, 780, 780, 858
+};
 
-  /* MCS 75  */
-  { /* 20 Mhz */ {  195.0f,   /* SGI */  216.7f, },
-    /* 40 Mhz */ {  405.0f,   /* SGI */  450.0f, },
-  },
+/*
+ * Calculates data rate corresponding to a given 802.11n MCS index,
+ * bandwidth, and guard interval.
+ */
+float ieee80211_htrate(int mcs_index, gboolean bandwidth, gboolean short_gi)
+{
+    return (float)(ieee80211_ht_Dbps[mcs_index] * (bandwidth ? 108 : 52) / 52.0 / (short_gi ? 3.6 : 4.0));
+}
 
-  /* MCS 76  */
-  { /* 20 Mhz */ {  214.5f,   /* SGI */  238.3f, },
-    /* 40 Mhz */ {  445.5f,   /* SGI */  495.0f, },
-  },
-};
 
 #define MAX_MCS_VHT_INDEX     9
 
@@ -648,6 +292,7 @@ static const struct mcs_vht_info ieee80211_vhtinfo[MAX_MCS_VHT_INDEX+1] = {
   }
 };
 
+
 static gint ett_wlan_radio = -1;
 static gint ett_wlan_radio_11ac_user = -1;
 
@@ -783,7 +428,7 @@ dissect_wlan_radio (tvbuff_t * tvb, packet_info * pinfo, proto_tree * tree, void
               (phdr->phy_info.info_11n.bandwidth == PHDR_802_11_BANDWIDTH_40_MHZ) ?
                1 : 0;
             if (phdr->phy_info.info_11n.mcs_index < MAX_MCS_INDEX) {
-              data_rate = ieee80211_float_htrates[phdr->phy_info.info_11n.mcs_index][bandwidth_40][phdr->phy_info.info_11n.short_gi];
+              data_rate = ieee80211_htrate(phdr->phy_info.info_11n.mcs_index, bandwidth_40, phdr->phy_info.info_11n.short_gi);
               have_data_rate = TRUE;
             }
           }