Control Data Cyber 170 State Hardware Reference Manual page 114

CP ComparelMove Instructions
Corn pare/Move
The compare/move i n s t r u c t i o n s ( a l s o r e f e r r e d t o a s CMU i n s t r u c t i o n s ) a r e
provided f o r c o m p a t i b i l i t y with previous systems. For b e t t e r performance,
recompile jobs t o avoid use of i n s t r u c t i o n s .
( X U i n s t r u c t i o n s must appear i n p a r c e l 0 o r they a r e t r e a t e d as i l l e g a l
i n s t r u c t i o n s .
Data f i e l d s c o n s i s t i n g of 6-bit c h a r a c t e r s may
start
o r end with any c h a r a c t e r
p o s i t i o n ( o f f s e t ) of the t e n + b i t p o s i t i o n s i n each word.
The c h a r a c t e r
p o s i t i o n s a r e designated a s follows
:
For move i n s t r u c t i o n s , a K1 designator s p e c i f i e s which CM word contains the
f i r s t c h a r a c t e r of the source d a t a f i e l d , and
a
C 1 d e s i g n a t o r s p e c i f i e s t h e
c h a r a c t e r p o s i t i o n ( o f f s e t ) of t h e f i r s t c h a r a c t e r . The K2 d e s i g n a t o r
s p e c i f i e s t h e CM l o c a t i o n i n which t h e f i r s t c h a r a c t e r of t h e r e s u l t d a t a f i e l d
i s placed, and t h e C2 designator s p e c i f i e s t h e f i r s t c h a r a c t e r p o s i t i o n . For
compare i n s t r u c t i o n s , both d a t a f i e l d addresses s p e c i f y source f i e l d s .
Example :
If
t h e i n s t r u c t i o n i s Kl=1000 and C1' 3 , t h e f i r s t c h a r a c t e r of t h e source
f i e l d
i s
i n p o s i t i o n 3 of l o c a t i o n 1000.
Therefore, t h e f i r s t c h a r a c t e r of t h e source f i e l d i s 71.
An address i s out of range i f C 1 o r C2 i s g r e a t e r than 9 , K l p l u s N 1 i s g r e a t e r
than the program f i e l d l e n g t h f o r CM (FLc),
o r K2 p l u s N2 i s
g r e a t e r than FLC.
N 1 equals t h e number of CM r e f e r e n c e s made t o the source d a t a f i e l d s t a r t i n g a t
K1, and N 2 equals the number of CM r e f e r e n c e s made t o t h e r e s u l t d a t a f i e l d
s t a r t i n g a t K2. When an address-out-of-range c o n d i t i o n occurs, t h e
CMU
i n s t r u c t i o n i s not executed.
U i s t h e lower
4
b i t s , and LU i s t h e upper 9 b i t s of t h e f i e l d l e n g t h
designator i n numbers of c h a r a c t e r s .
The maximum l e n g t h of t h e d a t a f i e l d s f o r
t h e move d i r e c t and t h e compare i n s t r u c t i o n s i s 127 (177
c h a r a c t e r s . The
maximum data f i e l d l e n g t h f o r t h e move i n d i r e c t inatruct!?on i s 8191 (17777*)
c h a r a c t e r s . I f L (LU and
LZ,
combined) i s
0,
the i n s t r u c t i o n becomes a pass.
For overlapping move i n s t r u c t i o n s , the address of t h e source f i e l d ( s p e c i f i e d
by K1) must be g r e a t e r than the address of t h e r e s u l t f i e l d ( s p e c i f i e d by K 2 )
t o provide proper f i e l d overlap. I f
K1 i s
l e s s than K2, p a r t of the source
f i e l d
i s
changed during execution. The amount of change is determined by t h e
number of CM c o n f l i c t s encountered.
Overlapping f i e l d s should not contain more
than 377 ( o c t a l ) c h a r a c t e r s because an exchange jump i n t e r r u p t s any compare/
move operation having a decremented f i e l d l e n g t h g r e a t e r than 377 ( o c t a l ) .