Opcode Table:

–INSTR– ZCRI –CON– –DEST– –SRC–	Z Result	C Result	Result	Clocks
000011 0001 1111 ddddddddd ------101	ID = 0	No Lock Free	Not Written	8..23

Concise Truth Table:

In					Out
Destination	Source¹	Z	C	Effects	Destination²	Z	C³
$0000_0000; 0	%0_00000101; 5	-	-	wr wz wc	$0000_0000; 0	1	0
$0000_0005; 5	%0_00000101; 5	-	-	wr wz wc	$0000_0005; 5	0	0
$0000_0008; 8 ⁴	%0_00000101; 5	-	-	wr wz wc	$0000_0000; 0	1	0

¹ Source is automatically set to immediate value 5 by the assembler to indicate that this is the LOCKRET hub instruction.
² Destination is not written unless the WR effect is given.
³ The C flag will be set (1) if all lock bits were allocated prior to executing the LOCKRET instruction.
⁴ Only the lowest 3 bits of Destination In are utilized, so a value of 8 is seen as lock bit ID 0.

Explanation

LOCKRET is one of four lock instructions (LOCKNEW, LOCKRET, LOCKSET, and LOCKCLR) used to manage resources that are user-defined and deemed mutually exclusive. LOCKRET returns a lock, by ID, back to the Hub's lock pool so that it may be reused by other cogs at a later time. The LOCKRET instruction behaves similar to Spin's LOCKRET command; see LOCKRET.

If the WZ effect is specified, the Z flag is set (1) if the ID of the returned lock is zero (0). If the WC effect is specified, the C flag is set (1) if all lock bits were allocated prior to executing this instruction. If the WR effect is specified, the ID of the returned lock is written to ID.

LOCKRET is a hub instruction. Hub instructions require 8 to 23 clock cycles to execute depending on the relation between the cog's hub access window and the instruction's moment of execution. See Hub for more information.