Integer-Output RS Decoder HDL Optimized
Decode data using a Reed-Solomon decoder
Library
Block sublibrary of Error Correction and Detection
Description
Reed-Solomon encoding follows the same standards as any other cyclic redundancy code. The Integer-Output RS Decoder HDL Optimized block can be used to model many communication system Forward Error Correcting (FEC) codes.
For more about the Reed-Solomon decoder, see the Integer-Output RS Decoder block reference. For more information on representing data for Reed-Solomon codes, see Integer Format (Reed-Solomon Only).
Signal Attributes
The Integer-Output RS Decoder HDL Optimized block has four input ports and six output ports (5 required, 1 optional).
| Port | Direction | Description | Data Type |
|---|---|---|---|
dataIn | Input | Message data, one symbol at a time. | Integer or fixdt with any binary point scaling. double is
allowed for simulation but not for HDL code generation. |
startIn | Input | Indicates the start of a frame of data. | boolean or fixdt(0,1) |
endIn | Input | Indicates the end of a frame of data. | boolean or fixdt(0,1) |
validIn | Input | Indicates that input data is valid. | boolean or fixdt(0,1) |
dataOut | Output | Message data with the checksum appended. The data width is the same as the input data port. | Same as dataIn |
startOut | Output | Indicates the start of a frame of data. | boolean or fixdt(0,1) |
endOut | Output | Indicates the end of a frame of data, including checksum. | boolean or fixdt(0,1) |
validOut | Output | Indicates that output data is valid. | boolean or fixdt(0,1) |
errOut | Output | Indicates the corruption of the received data when error is high. | boolean |
numErrors | Output (optional) | Count of detected errors. | uint8 |
Troubleshooting
Each input frame must contain more than
(N-K)*2symbols, and fewer than or equal toNsymbols. A shortened code is inferred when the number of valid data samples betweenstartInandendInis less thanN. A shortened code still requiresNcycles to perform the Chien search. If the input is less thanNsymbols, leave a guard interval of at leastN-sizeinactive cycles before starting the next frame.The decoder can operate on up to 4 messages at a time. If the block receives the start of a fifth message before completely decoding the first message, the block drops data samples from the first message. To avoid this issue, increase the number of inactive cycles between input messages.
The generator polynomial is not specified explicitly. However, it is defined by the code word length, the message length, and the B value for the starting exponent of the roots. To get the value of B from a generator polynomial, use the
genpoly2bfunction.
Parameters
- Codeword length
The length of the code word,
N, must be equal to2M-1, whereMis the input word length.Mcan be between 3 and 16 bits.- Message length
The message length,
K. The number of parity symbols,N-K, must be a positive even integer, greater than or equal to the input word length,M.- Source of primitive polynomial
Select
Propertyto enable the Primitive polynomial parameter.- Primitive polynomial
Binary row vector representing the primitive polynomial in descending order of powers. When you provide a primitive polynomial, the number of input bits must be an integer multiple of K times the order of the primitive polynomial instead.
This parameter applies when only when
Propertyis selected for Primitive polynomial.- Source of B, the starting power for roots of the primitive polynomial
Select
Propertyto enable the B value parameter.- B value
The starting exponent of the roots.
This field is available only when you select
Propertyfor Source of B, the starting power for roots of the primitive polynomial.- Enable number of errors output
Check this box to enable the
numErrorsoutput port. This port outputs the detected error count.
Algorithm
Timing Diagram
HDL Code Generation
This block supports HDL code generation using HDL Coder™. HDL Coder provides additional configuration options that affect HDL implementation and synthesized logic. For more information on implementations, properties, and restrictions for HDL code generation, see Integer-Output RS Decoder HDL Optimized in the HDL Coder documentation.