Table of Contents
Advertisement
Z:
Destination register
Xop:
X operand
Syntax:
[ IF cond ]
Permissible yops
AY0
AY1
AF
Example:
IF EQ AR = AY1 – 1 ;
Description:
Test the optional condition and if true, then decrement the
source operand by H#0001 and store in the destination location. If the
condition is not true then perform a no-operation. Omitting the condition
performs the decrement operation unconditionally. The source operand is
contained in the data register specified in the instruction.
Status Generated:
ASTAT:
7
6
SS MV AQ AS
–
–
AZ
Set if the result equals zero. Cleared otherwise.
AN
Set if the result is negative. Cleared otherwise.
AV
Set if an overflow is generated. Cleared otherwise.
AC
Set if a carry is generated. Cleared otherwise.
Instruction Format:
Conditional ALU/MAC Operation, Instruction Type 9:
23 22 21 20 19 18 17 16 15 14 13 12 11 10 9 8 7 6 5 4 3 2 1 0
0
0
1
0
0
AMF specifies the ALU or MAC operation. In this case,
AMF = 11000 for yop – 1 operation.
Note that the xop field is ignored for the decrement operation.
Yop:
COND: condition
AR
= yop – 1 ;
AF
Permissible conds (see Table 15.9)
EQ LE
NE NEG
GT POS
GE AV
LT NOT AV
5
4
3
AC AV AN AZ
–
–
*
Z
AMF
DECREMENT
Y operand
AC
NOT AC
MV
NOT MV
NOT CE
2
1
0
*
*
*
Yop
Xop
0 0 0 0
ALU
15
COND
15 – 37
- Quick Links:
- Overview
Hide quick links:
Advertisement
Table of Contents
