Added bitLength, clamp(), toDouble(), toSigned(), toUnsigned().

pkg/fixnum/lib/src/int64.dart

Index: pkg/fixnum/lib/src/int64.dart
diff --git a/pkg/fixnum/lib/src/int64.dart b/pkg/fixnum/lib/src/int64.dart
index aed28a24d9402cd24a1f355f428bffe1e6c7b847..3fb57ccc8ae2a75a1d0f28924067758129ee9e90 100644
--- a/pkg/fixnum/lib/src/int64.dart
+++ b/pkg/fixnum/lib/src/int64.dart
@@ -516,6 +516,21 @@ class Int64 implements IntX {
   bool get isOdd => (_l & 0x1) == 1;
   bool get isZero => _h == 0 && _m == 0 && _l == 0;
 
+  int get bitLength {
+    if (isZero) return 0;
+    int a0 = _l, a1 = _m, a2 = _h;
+    if (isNegative) {
+      a0 = ~a0 & _MASK;

[sra1, 2013/09/24 02:58:04]

a0 = _MASK & a0

to help dart2js inference and consistency with most places.

[Chris Bracken, 2013/09/24 20:16:00]

Done.

+      a1 = ~a1 & _MASK;
+      a2 = ~a2 & _MASK2;
+    }
+    int len = a2.bitLength;
+    if (len > 0) return len + _BITS01;

[sra1, 2013/09/24 02:58:04]

if a2 is nonzero, we don't use len.

How about
  if (a2 != 0) return _BITS01 + a2.bitLength;
  if (a1 != 0) return _BITS + a2.bitLength;
  return a0.bitLength;

[Chris Bracken, 2013/09/24 20:16:00]

Done.

+    len = a1.bitLength;
+    if (len > 0) return len + _BITS;
+    return a0.bitLength;
+  }
+
   /**
    * Returns a hash code based on all the bits of this [Int64].
    */
@@ -531,6 +546,21 @@ class Int64 implements IntX {
     return this.isNegative ? -this : this;
   }
 
+  Int64 clamp(lowerLimit, upperLimit) {
+    Int64 lower = _promote(lowerLimit);
+    Int64 upper = _promote(upperLimit);
+    if (this < lowerLimit) {

[sra1, 2013/09/24 02:58:04]

Use the promoted values :-)

[Chris Bracken, 2013/09/24 20:16:00]

Done. Looks like I got two lines into cleaning this up then got distracted by
something!

+      if (lowerLimit is IntX) return lowerLimit.toInt64();
+      if (lowerLimit is int) return new Int64.fromInt(lowerLimit);
+      throw new ArgumentError(lowerLimit);
+    } else if (this > upperLimit) {
+      if (upperLimit is IntX) return upperLimit.toInt64();
+      if (upperLimit is int) return new Int64.fromInt(upperLimit);
+      throw new ArgumentError(upperLimit);
+    }
+    return this;
+  }
+
   /**
    * Returns the number of leading zeros in this [Int64] as an [int]
    * between 0 and 64.
@@ -572,6 +602,35 @@ class Int64 implements IntX {
     return 64;
   }
 
+  Int64 toSigned(int width) {
+    if (width < 1 || width > 64) throw new ArgumentError(width);
+    if (width > _BITS01) {
+      return Int64._masked(_l, _m, _h.toSigned(width - _BITS01));
+    } else if (width > _BITS) {
+      int m = _m.toSigned(width - _BITS);
+      return m.isNegative ? Int64._masked(_l, m, _MASK2) :
+          new Int64._bits(_l, m, 0);
+    } else {
+      int l = _l.toSigned(width);
+      return l.isNegative ? Int64._masked(l, _MASK, _MASK2) :
+          new Int64._bits(l, 0, 0);
+    }
+  }
+
+  Int64 toUnsigned(int width) {
+    if (width < 0 || width > 64) throw new ArgumentError(width);
+    if (width > 2 * _BITS) {
+      int h = _h.toUnsigned(width - 2 * _BITS);
+      return Int64._masked(_l, _m, h);
+    } else if (width > _BITS) {
+      int m = _m.toUnsigned(width - _BITS);
+      return Int64._masked(_l, m, 0);
+    } else {
+      int l = _l.toUnsigned(width);
+      return Int64._masked(l, 0, 0);
+    }
+  }
+
   List<int> toBytes() {
     List<int> result = new List<int>(8);
     result[0] = _l & 0xff;
@@ -585,6 +644,8 @@ class Int64 implements IntX {
     return result;
   }
 
+  double toDouble() => toInt().toDouble();

[sra1, 2013/09/24 02:58:04]

I think this can round incorrectly.

The problem lies in dart2js using doubles for the arithmetic on line 665 and
667.
Doing:
  big2 = (big1 + small1) + small2;
can cause both small1 and small2 to be effectively ignored.
We need to do
  big2 = big1 + (small1 + small2)
which can be written
  big2 = small1 + small2 + big1;

[Chris Bracken, 2013/09/24 20:16:00]

Done.

+
   int toInt() {
     int l = _l;
     int m = _m;