Cyberun: Routine at F591

F591: Swap Players

Used by the routines at StartNewGame, LoseLife and GameOver. Does nothing if the second player has no ships. Otherwise it swaps the state of the two players, and the records for the scores and the numbers of ships that are printed at the top of the screen, so that the state of the player who is up is always at CurrentPlayerState. If the flag at CA1C is 99 it goes no further. If not it changes the number of the player, prints it and clears the playfield.
SwapPlayers	F591	LD A,($F656)	The other player's ships.
	F594	AND A	Return if A is zero.
	F595	RET Z	Return if A is zero.
	F596	LD DE,$F5E7	The current player state.
	F599	LD HL,$F650	The other player state.
	F59C	LD B,$69	B=69.
	F59E	CALL SwapBytes	Call SwapBytes.
	F5A1	LD DE,$C9EC	The player 1 score text.
	F5A4	LD HL,$C9FC	The player 2 score text.
	F5A7	LD B,$10	B=10.
	F5A9	CALL SwapBytes	Call SwapBytes.
	F5AC	LD A,($CA1C)	The current player.
	F5AF	CP $99	Return if A is 99.
	F5B1	RET Z	Return if A is 99.
	F5B2	XOR %00000001	Flip the bits of A that are set in 01.
	F5B4	LD ($CA1C),A	The other player is now up.
	F5B7	CALL PrintPlayer	Call PrintPlayer.
	F5BA	LD B,$08	B=08.
SwapPlayers_Delay	F5BC	CALL Delay	Call Delay.
	F5BF	DJNZ SwapPlayers_Delay	Decrease B and jump to SwapPlayers_Delay until none remain.
	F5C1	JP ClearPlayfield	Jump to ClearPlayfield.