RSDEC-DBLK-XM-U3 Lattice, RSDEC-DBLK-XM-U3 Datasheet - Page 16

• Manufacturer Part Number: RSDEC-DBLK-XM-U3
• Description: Encoders, Decoders, Multiplexers & Demultiplexers Dynamic Block Reed Solomon Decoder
• Manufacturer: Lattice

Specifications of RSDEC-DBLK-XM-U3

• Factory Pack Quantity: 1

Lattice Semiconductor
IPUG52_01.6, December 2010
Table 2-2. Interface Signal Descriptions (Continued)
For Puncturing Mode (when Decoding mode is “Puncturing” and Number of puncture patterns is More than 1)
puncsel
For Erasure mode
ers
Optional I/Os
ce
sr
ddel
errcnt
erscnt
fail
Port
1 - 8
Bits
1-8
1-8
1
1
1
1
1
I/O
O
O
O
O
O
O
I
I
Puncture pattern select signal. The value on this port selects the puncturing pat-
tern from the number of predefined patterns for the current block of data. The
width of this port is defined as ceil(log2(Number of puncture patterns)).
The value at this port is read only when ibstart is high.
Erasure. Asserted to indicate the input data symbol at the din port is erased.
Clock enable. While this is de-asserted, the decoder will ignore all other syn-
chronous inputs and maintain its current state.
Synchronous reset. Asserted for at least one symbol duration in order to reini-
tialize the decoder state. Input data symbols sampled before sr is asserted are
not given at the output.
Original uncorrected data output. A delayed copy of the input data block. Data is
presented on ddel concurrently with the decoded block on dout. The wsymb
parameter defines the port width of this signal.
Error Counter. Provides the number of corrected errors in the most recent out-
put block. The bus width errwidth is equal to the number of bits required to
represent the maximum possible number of correctable errors, as given in the
following equation:
When Block size type is Constant, errwidth is defined as errwidth =
ciel(log2((n-k+1)/2)) when Error Decoding mode is selected.
errwidth = ciel(log2(n-k-0.5)) when Erasure or Puncturing Decoding mode is
selected.
When Block size type is Variable and Variable check symbols is No,
errwidth is defined as errwidth = ciel(log2((Number of check sym-
bols+1)/2)) when Error Decoding mode is selected.
errwidth = ciel(log2(Number of check symbols-0.5)) when Erasure or Punc-
turing Decoding mode is selected.
When Variable check symbols is Yes, errwidth is defined as errwidth =
ciel(log2((Max. number of check symbols+1)/2)) The operator ciel() stands for
the next higher integer.
Erasure Counter. Provides a count of the number of erasures fed into the
decoder in the most recent input data block. The bus width erswidth is equal
to the number of bits required to represent the maximum possible number of
correctable erasures, as given in the following equation:
When Block size type is Constant, erswidth is defined as erswidth =
ciel(log2(n-k-1.5)).
When Block size type is Variable, erswidth is defined as erswidth =
ciel(log2(Number of check symbols -1.5)) The operator ciel() stands for the next
higher integer.
Decoding failure indicator. Asserted at the same time obend is asserted to indi-
cate that the block has more errors than the decoder can correct.
16 Dynamic Block Reed-Solomon Decoder User’s Guide
Description
Functional Description