Changeset 230 for lang/javascript/bloomfilter

Timestamp:

09/19/07 21:49:36 (6 years ago)

Author:

itkz

Message:

change bit length in a Number from 8 bit to 31 bit

Files:

• lang/javascript/bloomfilter/bloomfilter.js (modified) (3 diffs)

lang/javascript/bloomfilter/bloomfilter.js

@@ -15 +15 @@
                 this.error_rate = 0.001;
                 this.capacity = 100;
+                /* set up to 31 bits per a Number is used in filter table  */
+                this.bit_length = 31;
 
                 for(var key in params)
@@ -72 +74 @@
                         for(var j=0;j<cells.length;j++) {
                                 var cell = cells[j]
-                                var offset_of_byte = Math.floor(cell / 8);
+                                var offset_of_byte = Math.floor(cell / this.bit_length);
                                 this.filter[offset_of_byte] =
-                                        this.filter[offset_of_byte] | (1 << cell % 8);
+                                        this.filter[offset_of_byte] | (1 << cell % this.bit_length);
                         }
                         this.key_count++;
@@ -130 +132 @@
         },
         is_bit_on: function(offset){
-                return this.filter[Math.floor(offset / 8)] & (1 << offset % 8);
+                return
+                        this.filter[Math.floor(offset / this.bit_length)] &
+                        (1 << offset % this.bit_length);
         },
         _make_empty_filter: function(size){
-                var byte_length = Math.floor(size / 8 + (size % 8 ? 1 : 0));
+                var byte_length =
+                        Math.floor(size / this.bit_length + (size % this.bit_length ? 1 : 0));
                 var f = new Array(byte_length);
                 for(var i=0;i<byte_length;i++) f[i] = 0x00; // false