# HG changeset patch
# User darwin.astudillo@enseeiht.fr
# Date 1318002897 -7200
# Node ID 96b20793ada3c55a76c7a43cfd98ae1aef3ecd6e
# Parent  fa9bc38208b6d07d6370a11aa622ba2199f9811c
Optimization of function CalculatePe

diff --git a/src/wifi/model/nist-error-rate-model.cc b/src/wifi/model/nist-error-rate-model.cc
--- a/src/wifi/model/nist-error-rate-model.cc
+++ b/src/wifi/model/nist-error-rate-model.cc
@@ -16,6 +16,7 @@
  * Foundation, Inc., 59 Temple Place, Suite 330, Boston, MA  02111-1307  USA
  *
  * Author: Gary Pei <guangyu.pei@boeing.com>
+ * Optimized by: Darwin Astudillo <darwin.astudillo@enseeiht.fr>
  */
 #include "nist-error-rate-model.h"
 #include "wifi-phy.h"
@@ -101,56 +102,126 @@
   double pms = pow (1 - pe, nbits);
   return pms;
 }
+
+//double NistErrorRateModel::powNist(double a, double b) {
+//    int tmp = (*(1 + (int *)&a));
+//    int tmp2 = (int)(b * (tmp - 1072632447) + 1072632447);
+//    double p = 0.0;
+//    *(1 + (int * )&p) = tmp2;
+//    return p;
+//}
+
 double
 NistErrorRateModel::CalculatePe (double p, uint32_t bValue) const
 {
   double D = sqrt (4.0 * p * (1.0 - p));
   double pe = 1.0;
+// The code modified below there is not beautiful but is fastest.
   if (bValue == 1)
     {
       // code rate 1/2, use table 3.1.1
-      pe = 0.5 * ( 36.0 * pow (D, 10.0)
-                   + 211.0 * pow (D, 12.0)
-                   + 1404.0 * pow (D, 14.0)
-                   + 11633.0 * pow (D, 16.0)
-                   + 77433.0 * pow (D, 18.0)
-                   + 502690.0 * pow (D, 20.0)
-                   + 3322763.0 * pow (D, 22.0)
-                   + 21292910.0 * pow (D, 24.0)
-                   + 134365911.0 * pow (D, 26.0)
-                   );
+//      pe = 0.5 * ( 36.0 * pow (D, 10.0)
+//                   + 211.0 * pow (D, 12.0)
+//                   + 1404.0 * pow (D, 14.0)
+//                   + 11633.0 * pow (D, 16.0)
+//                   + 77433.0 * pow (D, 18.0)
+//                   + 502690.0 * pow (D, 20.0)
+//                   + 3322763.0 * pow (D, 22.0)
+//                   + 21292910.0 * pow (D, 24.0)
+//                   + 134365911.0 * pow (D, 26.0)
+//                   );
+	  double multi = D * D;
+	  double acum = multi * multi * multi * multi * multi;
+	  double pe = 18.0 * acum;
+	  acum *= multi;	// 12
+	  pe += 105.5 * acum;
+	  acum *= multi;	// 14
+	  pe += 702.0 * acum;
+	  acum *= multi;	// 16
+	  pe += 5816.5 * acum;
+	  acum *= multi;	// 18
+	  pe += 38716.5 * acum;
+	  acum *= multi;	// 20
+	  pe += 251345 * acum;
+	  acum *= multi;	// 22
+	  pe += 1661381.5 * acum;
+	  acum *= multi;	// 24
+	  pe += 10646455.0 * acum;
+	  acum *= multi;	// 26
+	  pe += 67182955.5 * acum;
     }
   else if (bValue == 2)
     {
       // code rate 2/3, use table 3.1.2
-      pe = 1.0 / (2.0 * bValue) *
-        ( 3.0 * pow (D, 6.0)
-          + 70.0 * pow (D, 7.0)
-          + 285.0 * pow (D, 8.0)
-          + 1276.0 * pow (D, 9.0)
-          + 6160.0 * pow (D, 10.0)
-          + 27128.0 * pow (D, 11.0)
-          + 117019.0 * pow (D, 12.0)
-          + 498860.0 * pow (D, 13.0)
-          + 2103891.0 * pow (D, 14.0)
-          + 8784123.0 * pow (D, 15.0)
-        );
+//      pe = 1.0 / (2.0 * bValue) *
+//        ( 3.0 * pow (D, 6.0)
+//          + 70.0 * pow (D, 7.0)
+//          + 285.0 * pow (D, 8.0)
+//          + 1276.0 * pow (D, 9.0)
+//          + 6160.0 * pow (D, 10.0)
+//          + 27128.0 * pow (D, 11.0)
+//          + 117019.0 * pow (D, 12.0)
+//          + 498860.0 * pow (D, 13.0)
+//          + 2103891.0 * pow (D, 14.0)
+//          + 8784123.0 * pow (D, 15.0)
+//        );
+	  double acum = D * D * D * D * D * D;
+      pe = 0.75 * acum;
+      acum *= D;  // 7
+      pe =+ 17.5 * acum;
+      acum *= D;  // 8
+      pe =+ 71.25 * acum;
+      acum *= D;  // 9
+      pe =+ 319.0 * acum;
+      acum *= D;  // 10
+      pe =+ 1540.0 * acum;
+      acum *= D;  // 11
+      pe =+ 6782.0 * acum;
+      acum *= D;  // 12
+      pe =+ 29254.75 * acum;
+      acum *= D;  // 13
+      pe =+ 124715.0 * acum;
+      acum *= D;  // 14
+      pe =+ 525972.75 * acum;
+      acum *= D;  // 15
+      pe =+ 2196030.75 * acum;
     }
   else if (bValue == 3)
     {
       // code rate 3/4, use table 3.1.2
-      pe = 1.0 / (2.0 * bValue) *
-        ( 42.0 * pow (D, 5.0)
-          + 201.0 * pow (D, 6.0)
-          + 1492.0 * pow (D, 7.0)
-          + 10469.0 * pow (D, 8.0)
-          + 62935.0 * pow (D, 9.0)
-          + 379644.0 * pow (D, 10.0)
-          + 2253373.0 * pow (D, 11.0)
-          + 13073811.0 * pow (D, 12.0)
-          + 75152755.0 * pow (D, 13.0)
-          + 428005675.0 * pow (D, 14.0)
-        );
+//      pe = 1.0 / (2.0 * bValue) *
+//        ( 42.0 * pow (D, 5.0)
+//          + 201.0 * pow (D, 6.0)
+//          + 1492.0 * pow (D, 7.0)
+//          + 10469.0 * pow (D, 8.0)
+//          + 62935.0 * pow (D, 9.0)
+//          + 379644.0 * pow (D, 10.0)
+//          + 2253373.0 * pow (D, 11.0)
+//          + 13073811.0 * pow (D, 12.0)
+//          + 75152755.0 * pow (D, 13.0)
+//          + 428005675.0 * pow (D, 14.0)
+//        );
+	  double acum = D * D * D * D * D;
+      pe = 42.0 * acum;
+      acum *= D;  // 6
+      pe += 201.0 * acum;
+      acum *= D;  // 7
+      pe += 1492.0 * acum;
+      acum *= D;  // 8
+      pe += 10469.0 * acum;
+      acum *= D;  // 9
+      pe += 62935.0 * acum;
+      acum *= D;  // 10
+      pe += 379644.0 * acum;
+      acum *= D;  // 11
+      pe += 2253373.0 * acum;
+      acum *= D;  // 12
+      pe += 13073811.0 * acum;
+      acum *= D;  // 13
+      pe += 75152755.0 * acum;
+      acum *= D;  // 14
+      pe += 428005675.0 * acum;
+      pe *= 1.0 / 6.0;
     }
   else
     {