ROL

Basic Info
Addressing Mode	Opcode	Length	Speed
Accumulator	2A	1 byte	2 cycles
Absolute	2E	3 bytes	6 cycles*
Direct Page	26	2 bytes	5 cycles*
Absolute Indexed by X	3E	3 bytes	7 cycles*
Direct Page Indexed by X	36	2 bytes	6 cycles*

Flags Affected
N	V	M	X	D	I	Z	C
N	.	.	.	.	.	Z	C

ROL (Rotate Left) is a 65x instruction that rotates a value and the carry flag left one bit. The most significant bit is shifted into the carry flag. The carry flag is shifted into the least significant bit.

• When the accumulator is 8 bits wide, 9 bits are rotated.
• When the accumulator is 16 bits wide, 17 bits are rotated.

Syntax

ROL
ROL A
ROL addr
ROL dp
ROL addr, X
ROL dp, X

Cycle Penalties

• Except in accumulator addressing, ROL takes two extra cycles when the accumulator is 16 bits wide.
• In direct page addressing modes, ROL takes another extra cycle if the low byte of the direct page register is nonzero.

See Also

• ROR
• ASL
• ROL (SPC700)
• ROL (Super FX)

External Links

• Eyes & Lichty, page 490 on ROL
• lbid page 190 before & after diagram of ROL
• Labiak, page 174 on ROL
• 10.3 on MCS6500 Manual, page 149 on ROL
• Carr, page 269 on ROL
• Leventhal, page 3-85 on ROL
• snes9x implementation of ROL: https://github.com/snes9xgit/snes9x/blob/master/cpuops.cpp#L1011
• undisbeliever on ROL: https://undisbeliever.net/snesdev/65816-opcodes.html#rol-rotate-left
• Pickens, John. http://www.6502.org/tutorials/6502opcodes.html#ROL
• Clark, Bruce. http://www.6502.org/tutorials/65c816opcodes.html#6.1.3