kiwi-schema - npm Package Compare versions

Comparing version 0.0.10 to 0.0.11

kiwi.js

@@ -18,4 +18,4 @@ var kiwi = exports || kiwi || {}, exports;
 (function() {
-  var uint8 = new Uint8Array(4);
-  var float32 = new Float32Array(uint8.buffer);
+  var int32 = new Int32Array(1);
+  var float32 = new Float32Array(int32.buffer);
 
@@ -49,13 +49,29 @@ function ByteBuffer(data) {
 
-  ByteBuffer.prototype.readFloat = function() {
+  ByteBuffer.prototype.readVarFloat = function() {
     var index = this._index;
     var data = this._data;
-    if (index + 4 > data.length) {
+    var length = data.length;
+
+    // Optimization: use a single byte to store zero
+    if (index + 1 > length) {
       throw new Error('Index out of bounds');
     }
-    uint8[0] = data[index];
-    uint8[1] = data[index + 1];
-    uint8[2] = data[index + 2];
-    uint8[3] = data[index + 3];
+    var first = data[index];
+    if (first === 0) {
+      this._index = index + 1;
+      return 0;
+    }
+
+    // Endian-independent 32-bit read
+    if (index + 4 > length) {
+      throw new Error('Index out of bounds');
+    }
+    var bits = first | (data[index + 1] << 8) | (data[index + 2] << 16) | (data[index + 3] << 24);
     this._index = index + 4;
+
+    // Move the exponent back into place
+    bits = (bits << 23) | (bits >>> 9);
+
+    // Reinterpret as a floating-point number
+    int32[0] = bits;
     return float32[0];
@@ -137,11 +153,25 @@ };
 
-  ByteBuffer.prototype.writeFloat = function(value) {
+  ByteBuffer.prototype.writeVarFloat = function(value) {
     var index = this.length;
+
+    // Reinterpret as an integer
+    float32[0] = value;
+    var bits = int32[0];
+
+    // Move the exponent to the first 8 bits
+    bits = (bits >>> 23) | (bits << 9);
+
+    // Optimization: use a single byte to store zero and denormals (check for an exponent of 0)
+    if ((bits & 255) === 0) {
+      this.writeByte(0);
+      return;
+    }
+
+    // Endian-independent 32-bit write
     this._growBy(4);
     var data = this._data;
-    float32[0] = value;
-    data[index] = uint8[0];
-    data[index + 1] = uint8[1];
-    data[index + 2] = uint8[2];
-    data[index + 3] = uint8[3];
+    data[index] = bits;
+    data[index + 1] = bits >> 8;
+    data[index + 2] = bits >> 16;
+    data[index + 3] = bits >> 24;
   };
@@ -527,3 +557,3 @@
         case 'float': {
-          code = 'bb.readFloat()';
+          code = 'bb.readVarFloat()';
           break;
@@ -618,3 +648,3 @@ }
         case 'float': {
-          code = 'bb.writeFloat(value);';
+          code = 'bb.writeVarFloat(value);';
           break;
@@ -1006,3 +1036,3 @@ }
               case 'float': {
-                code = '_bb.writeFloat(' + value + ');';
+                code = '_bb.writeVarFloat(' + value + ');';
                 break;
@@ -1120,3 +1150,3 @@ }
               case 'float': {
-                code = '_bb.readFloat(' + value + ')';
+                code = '_bb.readVarFloat(' + value + ')';
                 break;
@@ -1123,0 +1153,0 @@ }

package.json

 {
   "name": "kiwi-schema",
-  "version": "0.0.10",
+  "version": "0.0.11",
   "description": "",
@@ -5,0 +5,0 @@ "main": "kiwi.js",

README.md

@@ -11,3 +11,3 @@ # Kiwi Message Format
 * *uint*: A 32-bit integer value stored using a variable-length encoding optimized for storing small non-negative numbers. Will use at most 5 bytes.
-* *float*: A 32-bit floating-point number. Will always use 4 bytes.
+* *float*: A 32-bit floating-point number. Normally uses 4 bytes but a value of zero uses 1 byte ([denormal numbers](https://en.wikipedia.org/wiki/Denormal_number) become zero when encoded).
 * *string*: A UTF-8 length-prefixed string. Will use at least 1 byte.
@@ -14,0 +14,0 @@ * *T[]*: Any type can be made into an array using the `[]` suffix.

test/test-schema.js

@@ -151,3 +151,3 @@ var test = exports || test || {}, exports;
 
-  result["x"] = bb.readFloat();
+  result["x"] = bb.readVarFloat();
   return result;
@@ -162,3 +162,3 @@ };
   if (value != null) {
-    bb.writeFloat(value);
+    bb.writeVarFloat(value);
   } else {
@@ -419,3 +419,3 @@ throw new Error("Missing required field \"x\"");
     case 1:
-      result["x"] = bb.readFloat();
+      result["x"] = bb.readVarFloat();
       break;
@@ -436,3 +436,3 @@
     bb.writeVarUint(1);
-    bb.writeFloat(value);
+    bb.writeVarFloat(value);
   }
@@ -711,3 +711,3 @@ bb.writeVarUint(0);
   var length = bb.readVarUint();
-  while (length-- > 0) values.push(bb.readFloat());
+  while (length-- > 0) values.push(bb.readVarFloat());
   return result;
@@ -726,3 +726,3 @@ };
       value = values[i];
-      bb.writeFloat(value);
+      bb.writeVarFloat(value);
     }
@@ -995,3 +995,3 @@ } else {
       var length = bb.readVarUint();
-      while (length-- > 0) values.push(bb.readFloat());
+      while (length-- > 0) values.push(bb.readVarFloat());
       break;
@@ -1016,3 +1016,3 @@
       value = values[i];
-      bb.writeFloat(value);
+      bb.writeVarFloat(value);
     }
@@ -1019,0 +1019,0 @@ }

test/test.js

@@ -84,10 +84,13 @@ var assert = require('assert');
     assert.deepEqual(Buffer(schema.encodeFloatStruct({x: i})), Buffer(o));
-    assert.deepEqual(schema.decodeFloatStruct(new Uint8Array(o)), {x: i});
+    assert.deepEqual(JSON.stringify(schema.decodeFloatStruct(new Uint8Array(o))), JSON.stringify({x: i}));
   }
 
-  check(0, [0, 0, 0, 0]);
-  check(1, [0, 0, 128, 63]);
-  check(-1, [0, 0, 128, 191]);
-  check(3.1415927410125732, [219, 15, 73, 64]);
-  check(-3.1415927410125732, [219, 15, 73, 192]);
+  check(0, [0]);
+  check(1, [127, 0, 0, 0]);
+  check(-1, [127, 1, 0, 0]);
+  check(3.1415927410125732, [128, 182, 31, 146]);
+  check(-3.1415927410125732, [128, 183, 31, 146]);
+  check(Infinity, [255, 0, 0, 0]);
+  check(-Infinity, [255, 1, 0, 0]);
+  check(NaN, [255, 0, 0, 128]);
 });
@@ -176,3 +179,3 @@
   check({}, [0]);
-  check({x: 3.1415927410125732}, [1, 219, 15, 73, 64, 0]);
+  check({x: 3.1415927410125732}, [1, 128, 182, 31, 146, 0]);
 });
@@ -179,0 +182,0 @@

No alert changes

Improved metrics

Total package byte prevSize

145424

increased by1.45%

Lines of code

2302

increased by1.1%

No dependency changes