apply optimation supplied by Florian Schneider

[adam-singer]

diff --git a/lib/src/BigInteger_v8/big_integer.dart b/lib/src/BigInteger_v8/big_integer.dart
index 10cbea2..a0c1c45 100644
--- a/lib/src/BigInteger_v8/big_integer.dart
+++ b/lib/src/BigInteger_v8/big_integer.dart
@@ -111,7 +111,7 @@ class Montgomery {
       var u0 = (j*this.mpl+(((j*this.mph+(x_array[i]>>15)*this.mpl)&this.um)<<15))&BigInteger.BI_DM;
       // use am to combine the multiply-shift-add into one call
       j = i+this.m.t;
-      x_array[j] += this.m.am(0,u0,x,i,0,this.m.t);
+      x_array[j] += (this.m.am)(0,u0,x,i,0,this.m.t);
       // propagate carry
       while(x_array[j] >= BigInteger.BI_DV) { 
         x_array[j] -= BigInteger.BI_DV; 
@@ -227,6 +227,26 @@ class NullExp {

 // typedef AmplitudeModulation 

+
+/**
+ * This class wraps a Dart List and provides a JS-like behaviour.
+ * i.e. Storing an out-of-bounds element grows the list automatically.
+ */
+class JSArray<T> {
+  operator [](var index) {
+    return data[index];
+  }
+
+  operator []=(var index, var value) {
+    if (index > data.length - 1) {
+      data.length = index + 1;
+    }
+    return data[index] = value;
+  }
+
+  List<T> data = new List<T>();
+}
+
 /**
  * Basic dart [BigInteger] class. Implementation works across
  * dart and dart2js. 
@@ -272,7 +292,7 @@ class BigInteger {
    * support a rapid implementation. This will be replaced at a later
    * time for a [List] data structure.
    */ 
-  Map array; // TODO: create an array implementation that can handle out of bounds issues. 
+  var array;

   Function am;

@@ -322,8 +342,11 @@ class BigInteger {
     // Setup all the global scope js code here
     _setupDigitConversions();
     _lplim = (1<<26)~/_lowprimes[_lowprimes.length-1];
+    // am3 works better on x64, while am3 is faster on 32-bit platforms.
+    //_setupEngine(_am4, 26);
     _setupEngine(_am3, 28);
-    this.array = new Map();
+
+    this.array = new JSArray<int>();

     if (a != null) {
       if (a is int) {
@@ -358,7 +381,23 @@ class BigInteger {
     }
     return c;
   }
+ 
+  _am4(i,x,w,j,c,n) {
+    var this_array = this.array;
+    var w_array    = w.array;

+    var xl = x.toInt()&0x1fff, xh = x.toInt()>>13;
+    while(--n >= 0) {
+      var l = this_array[i]&0x1fff;
+      var h = this_array[i++]>>13;
+      var m = xh*l+h*xl;
+      l = xl*l+((m&0x1fff)<<13)+w_array[j]+c;
+      c = (l>>26)+(m>>13)+xh*h;
+      w_array[j++] = l&0x3ffffff;
+    }
+    return c;
+  }
+
   /**
    * am3/28 is best for SM, Rhino, but am4/26 is best for v8.
    * Kestrel (Opera 9.5) gets its best result with am4/26.
@@ -697,7 +736,7 @@ class BigInteger {
     var i = x.t;
     r.t = i+y.t;
     while(--i >= 0) r_array[i] = 0;
-    for(i = 0; i < y.t; ++i) r_array[i+x.t] = x.am(0,y_array[i],r,i,0,x.t);
+    for(i = 0; i < y.t; ++i) r_array[i+x.t] = (x.am)(0,y_array[i],r,i,0,x.t);
     r.s = 0;
     r.clamp();

@@ -716,13 +755,13 @@ class BigInteger {
     var i = r.t = 2*x.t;
     while(--i >= 0) r_array[i] = 0;
     for(i = 0; i < x.t-1; ++i) {
-      var c = x.am(i,x_array[i],r,2*i,0,1);
-      if((r_array[i+x.t]+=x.am(i+1,2*x_array[i],r,2*i+1,c,x.t-i-1)) >= BI_DV) {
+      var c = (x.am)(i,x_array[i],r,2*i,0,1);
+      if((r_array[i+x.t]+=(x.am)(i+1,2*x_array[i],r,2*i+1,c,x.t-i-1)) >= BI_DV) {
         r_array[i+x.t] -= BI_DV;
         r_array[i+x.t+1] = 1;
       }
     }
-    if(r.t > 0) r_array[r.t-1] += x.am(i,x_array[i],r,2*i,0,1);
+    if(r.t > 0) r_array[r.t-1] += (x.am)(i,x_array[i],r,2*i,0,1);
     r.s = 0;
     r.clamp();
   }
@@ -770,7 +809,7 @@ class BigInteger {
     while(--j >= 0) {
       // Estimate quotient digit
       var qd = (r_array[--i]==y0)?BI_DM:(r_array[i]*d1+(r_array[i-1]+e)*d2).floor();
-      if((r_array[i]+=y.am(0,qd,r,j,0,ys)) < qd) {  // Try it out
+      if((r_array[i]+=(y.am)(0,qd,r,j,0,ys)) < qd) {  // Try it out
         y.dlShiftTo(j,t);
         r.subTo(t,r);
         while(r_array[i] < --qd) r.subTo(t,r);
@@ -1290,7 +1329,7 @@ class BigInteger {
   /** this *= n, this >= 0, 1 < n < [BI_DV] */
   dMultiply(n) {
     var this_array = this.array;
-    this_array[this.t] = this.am(0,n-1,this,0,0,this.t);
+    this_array[this.t] = (this.am)(0,n-1,this,0,0,this.t);
     ++this.t;
     this.clamp();
   }
@@ -1325,8 +1364,8 @@ class BigInteger {
     r.t = i;
     while(i > 0) r_array[--i] = 0;
     var j;
-    for(j = r.t-this.t; i < j; ++i) r_array[i+this.t] = this.am(0,a_array[i],r,i,0,this.t);
-    for(j = Mathx.min(a.t,n); i < j; ++i) this.am(0,a_array[i],r,i,0,n-i);
+    for(j = r.t-this.t; i < j; ++i) r_array[i+this.t] = (this.am)(0,a_array[i],r,i,0,this.t);
+    for(j = Mathx.min(a.t,n); i < j; ++i) (this.am)(0,a_array[i],r,i,0,n-i);
     r.clamp();
   }

@@ -1342,7 +1381,7 @@ class BigInteger {
     r.s = 0; // assumes a,this >= 0
     while(--i >= 0) r_array[i] = 0;
     for(i = Mathx.max(n-this.t,0); i < a.t; ++i)
-      r_array[this.t+i-n] = this.am(n-i,a_array[i],r,0,0,this.t+i-n);
+      r_array[this.t+i-n] = (this.am)(n-i,a_array[i],r,0,0,this.t+i-n);
     r.clamp();
     r.drShiftTo(1,r);
   }