ADDED   src/0dev.org/encoding/fibonacci/fib.go
Index: src/0dev.org/encoding/fibonacci/fib.go
==================================================================
--- /dev/null
+++ src/0dev.org/encoding/fibonacci/fib.go
@@ -0,0 +1,68 @@
+// Package provides a shifted, reversed fibonacci encoding of bytes
+//
+// http://en.wikipedia.org/wiki/Fibonacci_coding maps positive integers as
+// 1 - 11, 2 - 011, 3 - 0011, 4 - 1011, 5 - 00011
+//
+// Incrementing input bytes 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
+// 0 - 11, 1 - 110, 2 - 1100, 3 - 1101, 4 - 11000
+package fibonacci
+
+type Numbers []uint64
+
+// Returns the n-th fibonacci number
+// The result is stored after calculation
+func (f Numbers) Nth(index int) uint64 {
+	switch {
+	case index <= 1:
+		return 1
+	case f[index] > 0:
+		break
+	default:
+		f[index] = f.Nth(index-1) + f.Nth(index-2)
+	}
+	return f[index]
+}
+
+// Returns a fibonacci code for an integer as specified in the package doc.
+func (f Numbers) Code(value uint64) (result uint64) {
+	// Increment to encode zero as one
+	value++
+
+	// Find the nearest fibonacci number
+	i := 0
+	for f.Nth(i+1) <= value {
+		i++
+	}
+
+	// Leading bit that signals the start of a fibonacci-encoded integer
+	result |= 1
+
+	// Find the Zeckendorf's representation by raising a bit for each
+	// fibonacci number that is less or equal to the difference
+	// between the value and the previous such number
+	for ; i >= 1; i-- {
+		result <<= 1
+		if f.Nth(i) <= value {
+			result |= 1
+			value -= f.Nth(i)
+		}
+	}
+	return
+}
+
+// Returns an integer from a fibonacci code as specified in the package doc.
+func (f Numbers) Decode(value uint64) (result uint64) {
+	i := 1
+	for (value & 3) != 3 {
+		if (value & 1) == 1 {
+			result += f.Nth(i)
+		}
+		value >>= 1
+		i++
+	}
+	result += f.Nth(i) - 1
+	return
+}

ADDED   src/0dev.org/encoding/fibonacci/fib_test.go
Index: src/0dev.org/encoding/fibonacci/fib_test.go
==================================================================
--- /dev/null
+++ src/0dev.org/encoding/fibonacci/fib_test.go
@@ -0,0 +1,30 @@
+package fibonacci
+
+import (
+	"testing"
+)
+
+func TestNumbers(t *testing.T) {
+	n := make(Numbers, 32)
+
+	expected := []uint64{1, 1, 2, 3, 5, 8, 13, 21}
+
+	for i, v := range expected {
+
+		if f := n.Nth(i); f != v {
+			t.Error("Unexpected value for", i, f, "expected", v)
+		}
+	}
+}
+
+func TestCoding(t *testing.T) {
+	n := make(Numbers, 32)
+
+	for i := uint64(0); i < 1024; i++ {
+		enc := n.Code(i)
+		dec := n.Decode(enc)
+		if i != dec {
+			t.Errorf("Unexpected value for %d - enc is %b, dec is %d\n", i, enc, dec)
+		}
+	}
+}