bit-twiddle - npm Package Compare versions

Comparing version 0.0.1 to 0.0.2

package.json

 {
   "name": "bit-twiddle",
-  "version": "0.0.1",
+  "version": "0.0.2",
   "description": "Bit twiddling hacks for JavaScript",
@@ -22,3 +22,22 @@ "main": "twiddle.js",
     "octree",
-    "quadtree"
+    "quadtree",
+    "math",
+    "nextPow2",
+    "log",
+    "shift",
+    "combination",
+    "permutation",
+    "trailing",
+    "zero",
+    "one",
+    "interleave",
+    "revere",
+    "parity",
+    "population",
+    "count",
+    "exponent",
+    "power",
+    "sign",
+    "min",
+    "max"
   ],
@@ -25,0 +44,0 @@ "author": "Mikola Lysenko",

README.md

@@ -58,4 +58,8 @@ bit-twiddle
 -------------
-Rounds v to the next power of 2.
+Rounds v up to the next power of 2.
 
+`prevPow2(v)`
+-------------
+Rounds v down to the previous power of 2.
+
 `parity(v)`
@@ -62,0 +66,0 @@ -----------

test/test.js

@@ -104,2 +104,16 @@ var test = require("tap").test
 
+
+test("prevPow2", function(t) {
+  for(var i=0; i<31; ++i) {
+    if(i > 0) {
+      t.equal(bits.prevPow2((1<<i)-1), 1<<(i-1));
+    }
+    t.equal(bits.prevPow2((1<<i)), 1<<i);
+    if(0<i && i < 30) {
+      t.equal(bits.prevPow2((1<<i)+1), 1<<i, "i=" + i + ", " + ((1<<i)+1));
+    }
+  }
+  t.end();
+});
+
 test("parity", function(t) {
@@ -106,0 +120,0 @@ t.equal(bits.parity(1), 1);

twiddle.js

@@ -96,2 +96,12 @@ /**
 
+//Rounds down to previous power of 2
+exports.prevPow2 = function(v) {
+  v |= v >>> 1;
+  v |= v >>> 2;
+  v |= v >>> 4;
+  v |= v >>> 8;
+  v |= v >>> 16;
+  return v - (v>>>1);
+}
+
 //Computes parity of word
@@ -98,0 +108,0 @@ exports.parity = function(v) {

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Improved metrics

Total package byte prevSize

11965

increased by7.35%

Lines of code

320

increased by7.02%

Number of lines in readme file

100

increased by4.17%

No dependency changes