diff --git a/runtime/src/main/java/org/capnproto/BufferedInputStreamWrapper.java b/runtime/src/main/java/org/capnproto/BufferedInputStreamWrapper.java
index 3a5bb68..69d6851 100644
--- a/runtime/src/main/java/org/capnproto/BufferedInputStreamWrapper.java
+++ b/runtime/src/main/java/org/capnproto/BufferedInputStreamWrapper.java
@@ -26,10 +26,12 @@ public final class BufferedInputStreamWrapper implements BufferedInputStream {
             return numBytes;
         } else {
             //# Copy current available into destination.
-            ByteBuffer slice = this.buf.slice();
             int fromFirstBuffer = cap - this.buf.position();
-            slice.limit(fromFirstBuffer);
-            dst.put(slice);
+            {
+                ByteBuffer slice = this.buf.slice();
+                slice.limit(fromFirstBuffer);
+                dst.put(slice);
+            }
 
             numBytes -= fromFirstBuffer;
             if (numBytes <= this.buf.capacity()) {
@@ -37,18 +39,22 @@ public final class BufferedInputStreamWrapper implements BufferedInputStream {
                 this.buf.rewind();
                 int n = readAtLeast(this.inner, this.buf, numBytes);
 
-                // ...
-                //ByteBuffer slice =
-                //dst.put(
+                this.buf.rewind();
+                ByteBuffer slice = this.buf.slice();
+                slice.limit(numBytes);
+                dst.put(slice);
 
                 this.cap = n;
                 this.buf.position(numBytes);
                 return fromFirstBuffer + numBytes;
             } else {
                 //# Forward large read to the underlying stream.
+
+                this.cap = 0;
+                this.buf.rewind();
+                return fromFirstBuffer + readAtLeast(this.inner, dst, numBytes);
             }
         }
-        throw new Error("unimplemented");
     }
 
     public final ByteBuffer getReadBuffer() {
diff --git a/runtime/src/main/java/org/capnproto/BufferedOutputStreamWrapper.java b/runtime/src/main/java/org/capnproto/BufferedOutputStreamWrapper.java
index 36acdc4..98f096c 100644
--- a/runtime/src/main/java/org/capnproto/BufferedOutputStreamWrapper.java
+++ b/runtime/src/main/java/org/capnproto/BufferedOutputStreamWrapper.java
@@ -26,13 +26,11 @@ public final class BufferedOutputStreamWrapper implements BufferedOutputStream {
             slice.limit(available);
             this.buf.put(slice);
 
-            // XXX This needs to be tested. Probably wrong.
-
             this.buf.rewind();
-            int n = this.inner.write(this.buf);
-            if (n != this.buf.capacity()) {
-                throw new IOException("failed to write all of the bytes");
+            while(this.buf.hasRemaining()) {
+                this.inner.write(this.buf);
             }
+            this.buf.rewind();
 
             src.position(src.position() + available);
             this.buf.put(src);
@@ -42,12 +40,13 @@ public final class BufferedOutputStreamWrapper implements BufferedOutputStream {
 
             int pos = this.buf.position();
             this.buf.rewind();
-            ByteBuffer slice = this.buf;
+            ByteBuffer slice = this.buf.slice();
             slice.limit(pos);
-            int n = this.inner.write(slice);
-            int m = this.inner.write(src);
-            if (n + m != size) {
-                throw new IOException("failed to write all of the bytes");
+            while (slice.hasRemaining()) {
+                this.inner.write(slice);
+            }
+            while (src.hasRemaining()) {
+                this.inner.write(src);
             }
         }
         return size;
diff --git a/runtime/src/main/java/org/capnproto/PackedInputStream.java b/runtime/src/main/java/org/capnproto/PackedInputStream.java
new file mode 100644
index 0000000..c15cfc1
--- /dev/null
+++ b/runtime/src/main/java/org/capnproto/PackedInputStream.java
@@ -0,0 +1,55 @@
+package org.capnproto;
+
+import java.io.IOException;
+import java.nio.channels.ReadableByteChannel;
+import java.nio.ByteBuffer;
+
+public final class PackedInputStream implements ReadableByteChannel {
+    final BufferedInputStream inner;
+
+    public PackedInputStream(BufferedInputStream input) {
+        this.inner = input;
+    }
+
+    public int read(ByteBuffer outBuf) throws IOException {
+
+        int len = outBuf.remaining();
+        if (len == 0) { return 0; }
+
+        if (len % 8 != 0) {
+            throw new Error("PackedInputStream reads must be word-aligned");
+        }
+
+        int out = outBuf.position();
+        int outEnd = out + len;
+
+        ByteBuffer inBuf = this.inner.getReadBuffer();
+
+
+        while (true) {
+
+            byte tag = 0;
+
+            //if (outBuf
+
+            if (inBuf.remaining() < 10) {
+                // TODO
+            }
+
+            // TODO
+
+
+            if (out == outEnd) {
+                return len;
+            }
+        }
+    }
+
+    public void close() throws IOException {
+        inner.close();
+    }
+
+    public boolean isOpen() {
+        return inner.isOpen();
+    }
+}
diff --git a/runtime/src/main/java/org/capnproto/PackedOutputStream.java b/runtime/src/main/java/org/capnproto/PackedOutputStream.java
new file mode 100644
index 0000000..fb7f304
--- /dev/null
+++ b/runtime/src/main/java/org/capnproto/PackedOutputStream.java
@@ -0,0 +1,29 @@
+package org.capnproto;
+
+import java.io.IOException;
+import java.nio.channels.WritableByteChannel;
+import java.nio.ByteBuffer;
+
+public final class PackedOutputStream implements WritableByteChannel {
+    final BufferedOutputStream inner;
+
+    public PackedOutputStream(BufferedOutputStream output) {
+        this.inner = output;
+    }
+
+    public int write(ByteBuffer src) throws IOException {
+        this.inner.getWriteBuffer();
+
+        // TODO
+
+        return 0;
+    }
+
+    public void close() throws IOException {
+        this.inner.close();
+    }
+
+    public boolean isOpen() {
+        return this.inner.isOpen();
+    }
+}