type context struct {
	table [256]byte
}

// Encodes data in place
func (c *context) encode(data []byte) {
	for index, value := range data {

		// Shortcut for sequential, equal values
		if c.table[0] == value {
			data[index] = 0
			continue
		}

		// Loop over the MTF table
		for j := byte(1); j != 0; j++ {
			if c.table[j] == value {
		for i := byte(0); i <= 255; i++ {
			if c.table[i] == value {
				// Output the value
				data[index] = j
				data[index] = i

				// Shift the table
				copy(c.table[1:], c.table[:j])
				copy(c.table[1:], c.table[:i])

				// Restore the value in front and break
				c.table[0] = value
				break
			}
		}
	}
}

// Decode data in place
func (c *context) decode(data []byte) {
	for index, value := range data {
		position := value

		// Shortcut for sequential, equal values
		if position == 0 {
			data[index] = c.table[0]
			continue
		}

		// Output the value
		data[index] = c.table[position]

		// Shift the table and restore the value in front
		copy(c.table[1:], c.table[:position])
		c.table[0] = data[index]
	}