4Links EtherSpaceLink Series, Руководство пользователя

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EtherSpaceLink-RG408
EtherSpaceLink family User Manual
14. 6 .1 2 .
EtherSpaceLink_read_packet_special_callback()
S ynops i s
void EtherSpaceLink_read_packet_special_callback
( EtherSpaceLink ESL_unit,
void * callback_buffer,
int callback_buffer_length,
void (*callback) ( int length,
int complete,
int data_buffer_position
)
)
D esc ri pt i on
EtherSpaceLink_read_packet_special_callback()
r e gi ste r s
a
b
u ff
e r
a
nd
a ca ll
b
ac k
p r o c ed u r e t ha t m a y be ca ll ed , i f en a b l ed , w h en a s p e c i a l p ac k et i s r e c e iv ed i n t h e m i dd l e o f r e c e p t i o n o f
a
n
o
r m
a l
d
a
t
a p ac k
et.
Th
i s
p
e r m i ts t
h
e
a
s
y
n
ch
r
o
n
ou
s
ha
nd
l
i n g
o f
s
p
e
c
i
a l p ac k
ets
w
i t
h ou
t t
h
e need
f o
r
a n o r m a l d a t a r e a d t o acc e p t a nd p r o c ess s u ch p ac k ets.
Wh
en
ca
ll ed , t
h
e
ca
ll b
ac
k p r o
c
ed u r e i s p
a
ssed t
h
r ee p
a
r
a
mete r s:
length
i nd i
ca
tes t
h
e n
u
mbe r
o f
b
y
tes
o f
s
p
e
c
i
a l
d
a
t
a ac
t
u a lly
i n t
h
e
ca ll
b
ac k
b
u ff
e r .
complete
i nd i ca tes w h et h e r t h e p ac k et i n t h e ca ll b ac k b u ff e r i s c o m pl ete (1 ) o r n o t ( 0) . Th e
p ac k
et
w
i
ll
be i n
c o
m
pl
ete
o
n
ly
i
f
i t i s
l a
rg e r t
ha
n t
h
e
ca ll
b
ac k
b
u ff
e r, i n
w h
i
ch ca
se r et
u
r n i n g
f
r
o
m
t h e ca ll b ac k p r o c ed u r e w i ll r es ul t i n t ha t p r o c ed u r e be i n g ca ll ed a g a i n w i t h t h e ne x t se g ment , o r
t
h
e r est
o f
, t
h
e s
p
e
c
i
a l p ac k
et.
data_buffer_position
i nd i ca tes t h e i nde x o f t h e ne x t d a t a b y te t ha t w i ll be w ri tten t o t h e
n
o
r m
a l
d
a
t
a
b
u ff
e r
a
nd t
h u
s se rv es t
o
i nd i
ca
te t
h
e r e
l a
t iv e
po
s i t i
o
n
o f
t
h
i s s
p
e
c
i
a l p ac k
et. F
o
r
e x a m pl e , t i me - t a g s m a y o cc u r be f o r e t h e f ir st b y te o f a d a t a p ac k et (d a t a _b u ff e r _ po s i t i o n == 0),
be
f o
r e e
ach o
t
h
e r d
a
t
a
b
y
te (d
a
t
a
_b
u ff
e r _
po
s i t i
o
n
>
0)
a
nd be
f o
r e t
h
e end
o f p ac k
et m
a
r
k
e r
( i .e. af te r t h e l a st d a t a b y te , d a t a _b u ff e r _ po s i t i o n == N w h e r e t h e r e a r e N d a t a b y tes a t po s i t i o ns 0
t
o N-
1 ) .
I nput p ara mete r s
ESL_unit
t
h
e
ha
nd
l
e r et
u
r ned b
y a
s
u cc
ess
f ul
EtherSpaceLink_open()
c o
mm
a
nd.
callback_buffer
a
b
u ff
e r t
o c o
nt
a
i n r e
c
e iv ed s
p
e
c
i
a l
d
a
t
a
.
callback_buffer_length
t
h
e s i
z
e
o f
t
h
e r e
c
e iv e b
u ff
e r .
callback
a p r o c ed u r e t o ca ll .
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