VSC6134
Datasheet
Forney Algorithm
This block computes the correction vector to be applied to the original message. The uncorrected
symbols are presented by the codeword FIFO.
Codeword FIFO
This block stores the codewords presented to the decoder and passes them to the Forney block for
calculation of the corrected codeword.
Performance
This block is designed to decode continuous messages with 255 symbols, including 16 parity symbols.
It provides high-speed, low-latency decoding of Reed Solomon codes. The decoder meets G.975 and
G.709 ITU-T recommendations.
Coincidentally with the output of the code symbols, the correction statistics are also produced. These
statistics include a marker asserted coincidentally with output symbols that have been corrected, the
total number of errors corrected, and flag to indicate that the code now being output is correctable.
Core Pinout
The RS decoder pinout is listed in the following table. All signals are active high unless stated
otherwise.
Table 45. RS Decoder Pins
Signal
I/O
IN
IN
IN
Size
Description
Clk
1
1
1
Decoder clock. Rising edge active.
Asynchronous reset input. Active high.
Resn
Frame_Start_In
Frame start indicator. Asserted coincident with the first valid Data_in of a
block.
Data_In(7:0)
Data_Valid_In
Dec_En
IN
IN
8
1
1
1
1
8
Symbol data input. Data on the input is valid on the Clk rising edge when
Data_Valid_In is asserted.
Symbol data valid indicator. Asserted coincidentally while the symbol data
input is valid.
IN
When high, corrections are done to data; otherwise, uncorrected data is
output from this block at all times.
Data_Valid_Out
Fstart_Out
OUT
OUT
OUT
Output symbol data valid flag. Asserted coincidentally with data on
Data_Out generated on the rising edge of Clk.
Frame start output flag. Asserted coincident with the first valid output
symbol of a block.
Data_Out(7:0)
Symbol data output. Data is valid on the rising edge of Clk when
Data_Valid_Out is asserted. Data symbols are held valid for the complete
period between Data_Valid_Out pulses.
Uncorr
OUT
1
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VMDS-10185 Revision 4.0
July 2006
VITESSE [ VITESSE SEMICONDUCTOR CORPORATION ]
