<s>
DSP/BIOS	B-Operating_System
Link	I-Operating_System
or	O
DSPLINK	O
is	O
an	O
interprocessor	O
or	O
inter-process	B-Operating_System
communication	I-Operating_System
(	O
IPC	O
)	O
scheme	O
to	O
pass	O
messages	O
and	O
data	O
in	O
multiprocessing	B-Operating_System
systems	O
.	O
</s>
<s>
In	O
the	O
case	O
of	O
the	O
DaVinci	B-General_Concept
digital	B-Architecture
signal	I-Architecture
processor	I-Architecture
(	O
DSP	O
)	O
family	O
from	O
Texas	O
Instruments	O
,	O
this	O
scheme	O
allows	O
passing	O
messages	O
and	O
data	O
between	O
an	O
ARM	B-Architecture
client	O
and	O
a	O
DSP	O
server	O
.	O
</s>
<s>
DSPLINK	O
can	O
be	O
used	O
to	O
implement	O
a	O
layer	O
of	O
software	O
abstraction	O
called	O
a	O
remote	B-Operating_System
procedure	I-Operating_System
call	I-Operating_System
(	O
RPC	O
)	O
that	O
allows	O
a	O
remote	O
function	O
on	O
the	O
DSP	O
to	O
appear	O
as	O
local	O
function	O
calls	O
in	O
the	O
ARM	B-Architecture
application	O
code	O
.	O
</s>
<s>
The	O
Codec	O
Engine	O
IPC	O
communication	O
layer	O
is	O
implemented	O
using	O
a	O
RPC	O
call	O
scheme	O
built	O
on	O
DSP/BIOS	B-Operating_System
LINK	I-Operating_System
.	O
</s>
<s>
DSP/BIOS	B-Operating_System
LINK	I-Operating_System
is	O
implemented	O
using	O
shared	B-Operating_System
memory	I-Operating_System
and	O
internal	O
interrupts	B-Application
from	O
the	O
ARM	B-Architecture
to	O
the	O
DSP	O
and	O
vice	O
versa	O
.	O
</s>
<s>
The	O
shared	B-Operating_System
memory	I-Operating_System
protocol	O
for	O
IPC	O
is	O
implemented	O
as	O
follows	O
:	O
</s>
<s>
The	O
ARM	B-Architecture
and	O
DSP	O
are	O
programmed	O
to	O
a	O
predetermined	O
memory	O
address	O
where	O
a	O
message	O
will	O
be	O
sent	O
from	O
the	O
ARM	B-Architecture
to	O
the	O
DSP	O
;	O
and	O
another	O
for	O
messages	O
sent	O
from	O
the	O
DSP	O
to	O
the	O
ARM	B-Architecture
.	O
</s>
<s>
One	O
processor	O
sends	O
messages	O
to	O
the	O
other	O
by	O
writing	O
the	O
message	O
into	O
the	O
pre-determined	O
address	O
and	O
then	O
sending	O
an	O
interrupt	B-Application
to	O
signal	O
the	O
other	O
processor	O
that	O
a	O
new	O
message	O
is	O
available	O
.	O
</s>
<s>
When	O
transferring	O
data	O
buffers	O
,	O
only	O
a	O
pointer	O
to	O
a	O
given	O
buffer	O
needs	O
to	O
be	O
passed	O
since	O
the	O
buffer	O
resides	O
in	O
shared	B-Operating_System
memory	I-Operating_System
that	O
is	O
accessible	O
to	O
both	O
the	O
processors	O
.	O
</s>
<s>
ARM	B-Architecture
buffer	O
addresses	O
must	O
be	O
translated	O
into	O
physical	O
addresses	O
when	O
being	O
presented	O
to	O
the	O
DSP	O
,	O
as	O
the	O
DSP	O
does	O
not	O
have	O
an	O
MMU	B-General_Concept
or	O
a	O
concept	O
of	O
virtual	B-General_Concept
addressing	I-General_Concept
.	O
</s>
<s>
Once	O
the	O
processor	O
receiving	O
the	O
message	O
has	O
read	O
it	O
,	O
it	O
marks	O
a	O
flag	O
in	O
shared	B-Operating_System
memory	I-Operating_System
to	O
indicate	O
that	O
the	O
message	O
memory	O
is	O
now	O
available	O
to	O
be	O
rewritten	O
with	O
another	O
message	O
.	O
</s>
<s>
The	O
DSP	O
included	O
in	O
many	O
DaVinci-based	O
devices	O
generally	O
runs	O
TI	O
's	O
DSP/BIOS	B-Operating_System
RTOS	B-Operating_System
.	O
</s>
<s>
DM644x	O
)	O
,	O
DSP/BIOS	B-Operating_System
Link	I-Operating_System
drivers	O
run	O
on	O
both	O
the	O
ARM	B-Architecture
processor	I-Architecture
and	O
the	O
DSP	O
to	O
provide	O
communication	O
between	O
the	O
two	O
.	O
</s>
<s>
A	O
number	O
of	O
ARM9	O
operating	O
systems	O
support	O
DSP/BIOS	B-Operating_System
Link	I-Operating_System
drivers	O
:	O
</s>
