Decode data using a Reed-Solomon decoder

Block sublibrary of Error Correction and Detection

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).

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` |

Each input frame must contain more than

`(N-K)*2`

symbols, and fewer than or equal to`N`

symbols. A shortened code is inferred when the number of valid data samples between`startIn`

and`endIn`

is less than`N`

. A shortened code still requires`N`

cycles to perform the Chien search. If the input is less than`N`

symbols, leave a guard interval of at least`N-size`

inactive 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

`genpoly2b`

function.

**Codeword length**The length of the code word,

`N`

, must be equal to`2`

, where^{M}-1`M`

is the input word length.`M`

can 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

`Property`

to 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

`Property`

is selected for**Primitive polynomial**.**Source of B, the starting power for roots of the primitive polynomial**Select

`Property`

to enable the**B value**parameter.**B value**The starting exponent of the roots.

This field is available only when you select

`Property`

for**Source of B, the starting power for roots of the primitive polynomial**.**Enable number of errors output**Check this box to enable the

`numErrors`

output port. This port outputs the detected error count.

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.

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