quick sketch of java/io/*

classpath/java/io/BufferedInputStream.java

@@ -0,0 +1,68 @@
+package java.io;
+
+public class BufferedInputStream extends InputStream {
+  private final InputStream in;
+  private final byte[] buffer;
+  private int position;
+  private int limit;
+
+  public BufferedInputStream(InputStream in, int size) {
+    this.in = in;
+    this.buffer = new byte[size];
+  }
+  
+  public BufferedInputStream(InputStream in) {
+    this(in, 32);
+  }
+
+  private void fill() throws IOException {
+    position = 0;
+    limit = in.read(buffer);
+  }
+
+  public int read() throws IOException {
+    if (position >= limit) {
+      fill();
+      if (limit == -1) {
+        return -1;
+      }
+    }
+
+    return buffer[position++];
+  }
+
+  public int read(byte[] b, int offset, int length) throws IOException {
+    int count = 0;
+
+    if (position < limit) {
+      int remaining = limit - position;
+      if (remaining > length) {
+        remaining = length;
+      }
+
+      System.arraycopy(buffer, position, b, offset, remaining);
+
+      count += remaining;
+      position += remaining;
+      offset += remaining;
+      length -= remaining;
+    }
+
+    if (length > 0) {
+      int c = in.read(b, offset, length);
+      if (c == -1) {
+        if (count == 0) {
+          count = -1;
+        }
+      } else {
+        count += c;
+      }
+    }
+
+    return count;
+  }
+
+  public void close() throws IOException {
+    in.close();
+  }
+}