Create BitInputStream

Author: CodeInSuits

BitInputStream

@@ -0,0 +1,65 @@
+import java.io.*;
+
+/*
+ * A BitInputStream lets you read in the contents of a binary file in
+ * units of: one bit (a single binary digit), one byte (8 bits), and
+ * one 4-byte word (32 bits). The bits that form a byte or a word do
+ * not have to be byte aligned.
+ */
+public class BitInputStream implements AutoCloseable {
+  private byte[] bytes;
+  private int index;
+
+  public BitInputStream(File in) throws FileNotFoundException, IOException {
+    this(new FileInputStream(in));
+  }
+
+  public BitInputStream(FileInputStream fileInputStream) throws IOException {
+    DataInputStream in = new DataInputStream(fileInputStream);
+    int size = in.available();
+    this.bytes = new byte[size];
+    this.index = 0;
+    in.read(bytes);
+    in.close();
+  }
+
+  /*
+   * Returns the file size as a count of bytes.
+   */
+  public int size() {
+    return bytes.length;
+  }
+
+  public byte[] allBytes() {
+    return bytes;
+  }
+
+  public int readBit() throws IOException {
+    byte b = bytes[index / 8];
+    int offset = index % 8;
+    final int mask = 1 << 7;
+    ++index;
+    return (b & (mask >>> offset)) == 0 ? 0 : 1;
+  }
+
+  public int readByte() throws IOException {
+    byte value = 0;
+    for (int i = 0; i < 8; ++i) {
+      value <<= 1;
+      value |= readBit();
+    }
+    return value & 0xFF;
+  }
+  
+  public int readInt() throws IOException {
+    int value = readByte();
+    value = (value << 8) | readByte();
+    value = (value << 8) | readByte();
+    value = (value << 8) | readByte();
+    return value;
+  }
+
+  public void close() throws IOException {
+    // intentionally left blank
+  }
+}