@@ -4,18 +4,16 @@
 // 1 - 11, 2 - 011, 3 - 0011, 4 - 1011, 5 - 00011
 //
 // Incrementing input by one to allow for zero gives
 // 0 - 11, 1 - 011, 2 - 0011, 3 - 1011, 4 - 00011
 //
-// The codes are then reversed so that they are easily stored in uints
+// The codes are reversed so that they are easily stored in uints,
+// effectively avoiding the need to store the number of leading zeroes
 // 0 - 11, 1 - 110, 2 - 1100, 3 - 1101, 4 - 11000
-// (so that they are always comparable with each other as there is no need to
-//  store the leading number of zeroes which are otherwise required)
 package fibonacci
 
 import (
-	_ "fmt"
 	"io"
 )
 
 type Numbers []uint64
 
@@ -159,50 +157,62 @@
 		e.buffer = e.buffer[:0]
 	}
 	return total, err
 }
 
-// func Reader(source io.Reader) io.Reader {
-// 	var dec decoder
-// 	dec.Numbers = New(16)
-// 	dec.source = source
-// 	return &dec
-// }
-
-// type decoder struct {
-// 	Numbers
-// 	source io.Reader
-// 	buffer uint64
-// 	at     byte
-// }
-
-// func (d *decoder) Read(output []byte) (int, error) {
-// 	var (
-// 		total int
-// 		err   error
-// 	)
-
-// 	// While we have suitable buffered data and enough output space
-// 	for (len(output) > 0) && ((d.buffer & (d.buffer >> 1)) > 0) {
-// 		val, len := d.Decode(d.buffer)
-
-// 		// Store the decoded byte
-// 		output[0] = byte(val)
-
-// 		// Advance the internal and output buffers
-// 		output = output[1:]
-// 		d.buffer >>= len
-
-// 		// TODO - decrease d.at as well ?
-
-// 		total++
-// 	}
-
-// 	// Termination condition
-// 	if len(output) == 0 {
-// 		return total, nil
-// 	}
-
-// 	// count, err := d.source.Read(output)
-
-// 	return total, err
-// }
+func Reader(source io.Reader) io.Reader {
+	var dec decoder
+	dec.Numbers = New(16)
+	dec.source = source
+	return &dec
+}
+
+type decoder struct {
+	Numbers
+	source io.Reader
+	buffer uint64
+	at     byte
+}
+
+func (d *decoder) Read(output []byte) (int, error) {
+	var (
+		total int
+		err   error
+	)
+
+start:
+	// While we have suitable buffered data and enough output space
+	for (len(output) > 0) && ((d.buffer & (d.buffer >> 1)) > 0) {
+		val, len := d.Decode(d.buffer)
+
+		// Store the decoded byte
+		output[0] = byte(val)
+
+		// Advance the internal and output buffers
+		output = output[1:]
+		d.buffer >>= len
+		d.at -= len
+
+		total++
+	}
+
+	// Termination condition
+	if len(output) == 0 || err != nil {
+		return total, err
+	}
+
+	// We need to limit the output's size else we could end up with a lot of small values
+	// that fit neither in the output slice nor in the internal buffer
+	free := int((63 ^ d.at) >> 3)
+	if free > len(output) {
+		free = len(output)
+	}
+
+	// Read data and transfer to the internal buffer
+	count, err := d.source.Read(output[:free])
+	for _, v := range output[:count] {
+		d.buffer |= uint64(v) << d.at
+		d.at += 8
+	}
+
+	goto start
+}