RL b,BCDE     Rotate Left Through Carry     Rabbit 4000 Instruction

Opcode	Instruction	Clocks	Operation
----	RL b,BCDE	4 (2,2)	{CF,BCDE} = {BCDE,CF}   b = b - 1 repeat while b != 0
DD 68	RL 1,BCDE	4 (2,2)	{CF,BCDE} = {BCDE,CF}   b = b - 1 repeat while b != 0
DD 69	RL 2,BCDE	4 (2,2)	{CF,BCDE} = {BCDE,CF}   b = b - 1 repeat while b != 0
DD 6B	RL 4,BCDE	4 (2,2)	{CF,BCDE} = {BCDE,CF}   b = b - 1 repeat while b != 0

Flags				ALTD			IOI/IOE
S	Z	L/V	C	F	R	SP	S	D
·	·	L	·	·	·

Description

Rotates BCDE to the left with the C flag. Each bit in the register moves to the next highest-order bit position (bit 0 moves to bit 1, etc.) while the C flag moves to bit 0 and bit 31 moves to the C flag. This operation happens b number of times.

Figure 2: Bit logic of the RL instruction