# ROtate Left and ROtate Right

```NAME
ROL, ROR -- Rotate left and rotate right

SYNOPSIS
ROd	Dx,Dy
ROd	#<data>,Dy
ROd	<ea>
where d is direction, L or R

Size = (Byte, Word, Long)

FUNCTION
Rotate the bits of the operand in the specified direction.
The rotation count may be specified in two different ways:

1. Immediate - the rotation count is specified in the instruction

2. Register  - the rotation count is contained in a data register
specified in the instruction

For a register, the size may be byte, word, or long, but for a memory
location, the size must be a word. The rotation count is also
restricted to one for a memory location.

.-------->--------.
ROL:      |                 |
C <------ OPERAND <---'
<---

ROR:     ,-------<-------.
|               |
`--> OPERAND -----> C
--->

FORMAT
In the case of the rotating of a register:
~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~
-----------------------------------------------------------------
|15 |14 |13 |12 |11 |10 | 9 | 8 | 7 | 6 | 5 | 4 | 3 | 2 | 1 | 0 |
|---|---|---|---|-----------|---|-------|---|---|---|-----------|
| 1 | 1 | 1 | 0 |  NUMBER/  |dr |  SIZE |i/r| 1 | 1 | REGISTER  |
|   |   |   |   |  REGISTER |   |       |   |   |   |           |
-----------------------------------------------------------------

In the case of the rotating of a memory area:
~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~
-----------------------------------------------------------------
|15 |14 |13 |12 |11 |10 | 9 | 8 | 7 | 6 | 5 | 4 | 3 | 2 | 1 | 0 |
|---|---|---|---|---|---|---|---|---|---|-----------|-----------|
| 1 | 1 | 1 | 0 | 0 | 1 | 1 |dr | 1 | 1 |    MODE   | REGISTER  |
----------------------------------------=========================
<ea>

NUMBER/REGISTER
Specifies number of rotating or number of register which contents
the number of rotating.
If i/r = 0, number of rotating is specified in the instruction as
immediate data
If i/r = 1, it's specified in the data register.
If dr = 0, right rotating
If dr = 1, left rotating

SIZE
00->one Byte operation
01->one Word operation
10->one Long operation

REGISTER
For a register rotating:
Indicates the number of data register on which rotating is applied.

For a memory rotating:
<ea> indicates operand which should be rotated.
Only addressing modes relatives to memory are allowed:

--------------------------------- -------------------------------
|-------------------------------| |-----------------------------|
|      Dn       | -  |     -    | |    Abs.W      |111 |  000   |
|-------------------------------| |-----------------------------|
|      An       | -  |     -    | |    Abs.L      |111 |  001   |
|-------------------------------| |-----------------------------|
|     (An)      |010 |N° reg. An| |   (d16,PC)    | -  |   -    |
|-------------------------------| |-----------------------------|
|     (An)+     |011 |N° reg. An| |   (d8,PC,Xi)  | -  |   -    |
|-------------------------------| |-----------------------------|
|    -(An)      |100 |N° reg. An| |   (bd,PC,Xi)  | -  |   -    |
|-------------------------------| |-----------------------------|
|    (d16,An)   |101 |N° reg. An| |([bd,PC,Xi],od)| -  |   -    |
|-------------------------------| |-----------------------------|
|   (d8,An,Xi)  |110 |N° reg. An| |([bd,PC],Xi,od)| -  |   -    |
|-------------------------------| |-----------------------------|
|   (bd,An,Xi)  |110 |N° reg. An| |    #data      | -  |   -    |
|-------------------------------| -------------------------------
|([bd,An,Xi]od) |110 |N° reg. An|
|-------------------------------|
|([bd,An],Xi,od)|110 |N° reg. An|
---------------------------------

RESULT
X - Not affected
N - Set if the result is negative. Cleared otherwise.
Z - Set if the result is zero. Cleared otherwise.
V - Always cleared
C - Set according to the last bit shifted out of the operand.