Table of Contents
Advertisement
OBee
Operation:
Assembler
Syntax:
Attributes:
Test Condition, Decrement, and Branch
If condition false then On - 1
=>
On;
If On :;t:-1 then PC + d
=>
PC
OBcc On, (label)
Size
=
(Word)
OBee
Description:
Controls a loop of instructions. The parameters are a condition code, a data register
(counter), and a displacement value. The instruction first tests the condition (for termination); if it
is true, no operation is performed. If the termination condition is not true, the low-order 16 bits of
the counter data register are decremented by one. If the result is -1, execution continues with
the next instruction. If the result is not equal to -1, execution continues at the location indicated
by the current value of the PC, plus the sign-extended 16-bit displacement. The value in the PC
is the address of the instruction word of the OBcc instruction plus two. The displacement is a twos
complement integer that represents the relative distance in bytes from the current PC to the
destination PC.
Condition code cc specifies one of the following conditions:
cc
Name
Code
Description
cc
Name
CC
Carry Clear
0100
C
LS
Low or Same
CS
Carry Set
0101
C
LT
Less Than
EQ
Equal
0111
Z
MI
Minus
F
Never equal
0001
0
NE
Not Equal
GE
Greater or Equal
1100
N.V+N.V
PL
Plus
GT
Greater Than
1110
N.V.Z+N.V.Z T
Always true
HI
High
0010
C.Z
VC
Overflow Clear
LE
Less or Equal
1111
Z+N.V+N.V
VS
Overflow Set
Condition Codes:
Not affected.
CPU32 REFERENCE MANUAL
INSTRUCTION SET
Code
0011
1101
1011
0110
1010
0000
1000
1001
Description
C+Z
N.V+N.V
N
Z
N
V
V
MOTOROLA
4-69
III
Advertisement
Table of Contents
