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Assembler

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:

Immediate - the rotation count is specified in the instruction
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/REGISTER			dr	SIZE		i/r	1	1	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

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:

Addressing Mode	Mode	Register
Dn	-	-
An	-	-
(An)	010	No reg. An
(An)+	011	No reg. An
-(An)	100	No reg. An
(d16,An)	101	No reg. An
(d8,An,Xi)	110	No reg. An
(bd,An,Xi)	110	No reg. An
([bd,An,Xi]od)	110	No reg. An
([bd,An],Xi,od)	110	No reg. An

Addressing Mode	Mode	Register
Abs.W	111	000
Abs.L	111	001
(d16,PC)	-	-
(d8,PC,Xi)	-	-
(bd,PC,Xi)	-	-
([bd,PC,Xi],od)	-	-
([bd,PC],Xi,od)	-	-
#data	-	-

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.

English version not yet available.

Änderungen und Irrtümer vorbehalten. Letzte Änderung:
13 Dezember 2004.
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