add hw2

node_modules/unbzip2-stream/index.js

@@ -0,0 +1,93 @@
+var through = require('through');
+var bz2 = require('./lib/bzip2');
+var bitIterator = require('./lib/bit_iterator');
+
+module.exports = unbzip2Stream;
+
+function unbzip2Stream() {
+    var bufferQueue = [];
+    var hasBytes = 0;
+    var blockSize = 0;
+    var broken = false;
+    var done = false;
+    var bitReader = null;
+    var streamCRC = null;
+
+    function decompressBlock(push){
+        if(!blockSize){
+            blockSize = bz2.header(bitReader);
+            //console.error("got header of", blockSize);
+            streamCRC = 0;
+            return true;
+        }else{
+            var bufsize = 100000 * blockSize;
+            var buf = new Int32Array(bufsize);
+            
+            var chunk = [];
+            var f = function(b) {
+                chunk.push(b);
+            };
+
+            streamCRC = bz2.decompress(bitReader, f, buf, bufsize, streamCRC);
+            if (streamCRC === null) {
+                // reset for next bzip2 header
+                blockSize = 0;
+                return false;
+            }else{
+                //console.error('decompressed', chunk.length,'bytes');
+                push(Buffer.from(chunk));
+                return true;
+            }
+        }
+    }
+
+    var outlength = 0;
+    function decompressAndQueue(stream) {
+        if (broken) return;
+        try {
+            return decompressBlock(function(d) {
+                stream.queue(d);
+                if (d !== null) {
+                    //console.error('write at', outlength.toString(16));
+                    outlength += d.length;
+                } else {
+                    //console.error('written EOS');
+                }
+            });
+        } catch(e) {
+            //console.error(e);
+            stream.emit('error', e);
+            broken = true;
+            return false;
+        }
+    }
+
+    return through(
+        function write(data) {
+            //console.error('received', data.length,'bytes in', typeof data);
+            bufferQueue.push(data);
+            hasBytes += data.length;
+            if (bitReader === null) {
+                bitReader = bitIterator(function() {
+                    return bufferQueue.shift();
+                });
+            }
+            while (!broken && hasBytes - bitReader.bytesRead + 1 >= ((25000 + 100000 * blockSize) || 4)){
+                //console.error('decompressing with', hasBytes - bitReader.bytesRead + 1, 'bytes in buffer');
+                decompressAndQueue(this);
+            }
+        },
+        function end(x) {
+            //console.error(x,'last compressing with', hasBytes, 'bytes in buffer');
+            while (!broken && bitReader && hasBytes > bitReader.bytesRead){
+                decompressAndQueue(this);
+            }
+            if (!broken) {
+                if (streamCRC !== null)
+                    this.emit('error', new Error("input stream ended prematurely"));
+                this.queue(null);
+            }
+        }
+    );
+}
+