Altera Viterbi Compiler User Manual
Page 33
Signal Name
Avalon-ST
Name
Direction
Description
eras_
sym[Nmax
:1]
dat
Input
When asserted,
eras_sym
Indicates an erased symbol. Both
rr
and
eras_sym
are Avalon-ST
dat
inputs
rr
dat
Input
Data input, which takes in n symbols, each softbits wide per
clock. In TCM mode the
rr
width is (2N × softbits:1); in
Viterbi mode the
rr
width is (nmax × softbits:1).Both
rr
and
eras_sym
are Avalon-ST
dat
inputs
sink_eop
eop
Input
End of packet (block) signal.
sink_eop
delineates the packet
boundaries on the
rr
bus. When
sink_eop
is high, the end
of the packet is present on the
dat
bus.
sink_eop
is asserted
on the last transfer of every packet. This signal applies to
block decoding only.
sink_rdy
ready
Output
Data transfer enable signal.The interface sink drives
sink_
rdy
and controls the flow of data across the interface.
sink_
rdy
behaves as a read enable from sink to source. When the
source observes
sink_rdy
asserted on the
clk
rising edge, it
can drive the Avalon-ST data interface signals and assert
sink_val
as early as the next clock cycle, if data is available.
In the hybrid architecture,
sink_rdy
is asserted for one
clock cycle at a time. If data is not available at the time, you
have to wait for the next
sink_rdy
pulse.
sink_sop
sop
Input
Start of packet (block) signal.
sop
delineates the packet
boundaries on the
rr
bus. When
sink_sop
is high, the start
of the packet is present on the
rr
bus.
sink_sop
is asserted
on the first transfer of every packet This signal applies to
block decoding only.
sink_val
val
Input
Data valid signal.
sink_val
indicates the validity of the data
signals.
sink_val
is updated on every clock edge where
sink_rdy
is sampled asserted, and holds its current value
along with the
dat
bus where
sink_rdy
is sampled
deasserted. When
sink_val
is asserted, the Avalon-ST data
interface signals are valid. When
sink_va
l is deasserted, the
Avalon-ST data interface signals are invalid and you must
disregard them. To determine whether new data has been
received, the sink qualifies the
sink_val
signal with the
previous state of the
sink_rdy
signal.
UG-VITERBI
2014.12.15
Avalon-ST Sink Signals
3-15
Viterbi IP Core Functional Description
Altera Corporation