Integer-Input RS Encoder HDL Optimized

Encode data using a Reed-Solomon (RS) encoder

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Libraries:
Communications Toolbox HDL Support / Error Detection and Correction / Block

Description

The Integer-Input RS Encoder HDL Optimized block encodes data using the RS encoder. The RS encoding follows the same standards as any other cyclic redundancy code. Use this block to model communications system forward error correction (FEC) codes. The block provides an architecture suitable for HDL code generation and hardware deployment.

For more information about the RS encoder, see the Integer-Input RS Encoder block. For more information on representing data for RS codes, see Integer Format (Reed-Solomon Only).

Examples

Using HDL Optimized RS Encoder/Decoder Library Blocks

Implement encoder and decoder for the IEEE® 802.16 standard [ 1 ] using the HDL Optimized Reed-Solomon (RS) Encoder and Decoder library blocks.

• Open Model

Ports

Input

dataIn — Input data

scalar

Input data, specified as a scalar representing one symbol. For binary point scaling, the input data type must be an unsigned integer or an unsigned fixed point. The word length of each symbol must be equal to ceil(log₂(Codeword length) + 1. The double data type is allowed for simulation, but not for HDL code generation.

Data Types: double | uint8 | uint16 | uint32 | uint64 | fixed point

startIn — Start of input frame indicator

scalar

Start of input frame indicator, specified as a Boolean scalar.

Data Types: Boolean

endIn — End of input frame indicator

scalar

End of input frame indicator, specified as a Boolean scalar.

Data Types: Boolean

validIn — Valid input data indicator

scalar

Valid input data indicator, specified as a Boolean scalar.

This is a control signal that indicates if the data on the dataIn port is valid.

Data Types: Boolean

Output

dataOut — Output data

scalar

Output data, returned as a scalar. This output data width is the same as the input data width.

Data Types: double | uint8 | uint16 | uint32 | uint64 | fixed point

startOut — Start of output frame indicator

scalar

Start of output frame indicator, returned as a Boolean scalar.

Data Types: Boolean

endOut — End of output frame indicator

scalar

End of output frame indicator, returned as a Boolean scalar.

Data Types: Boolean

validOut — Valid output data indicator

scalar

Valid output data indicator, returned as a Boolean scalar.

This is a control signal that indicates if the data on the dataOut port is valid.

Data Types: Boolean

Parameters

Codeword length — Length of codeword

7 (default) | range from 7 to 65, 535

Specify the codeword length.

The codeword length N must be an integer equal to 2^M – 1, where M is an integer in the range from 3 to 16. For more information on representing data for RS codes, see Integer Format (Reed-Solomon Only).

Message length — Length of message

3 (default) | positive integer

Specify the length of the message.

For more information on representing data for RS codes, see Integer Format (Reed-Solomon Only).

Each input frame, that is, the number of valid data samples between startIn and endIn port values, must contain more than N– K symbols and less than or equal to K symbols. A shortened code is inferred anytime the number of input data samples in a frame is less than K.

Source of primitive polynomial — Primitive polynomial source

Auto (default) | Property

Specify the source of the primitive polynomial.

• Select Auto to specify the primitive polynomial based on the Codeword length parameter value. The degree of the primitive polynomial is calculated as M = ceil(log₂(Codeword length).

• Select Property to specify the primitive polynomial using the Primitive polynomial parameter.

Primitive polynomial — Primitive polynomial provider

[ 1 0 1 1 ] (default) | binary row vector

Specify a binary row vector representing the primitive polynomial in descending order of powers.

For more information on how to specify a primitive polynomial, see Primitive Polynomials and Element Representations.

Dependencies

To enable this parameter, set the Source of primitive polynomial parameter to Property.

Source of puncture pattern — Puncture pattern source

None (default) | Property

Select Property to enable the Puncture pattern vector parameter.

Puncture pattern vector — Puncture vector

[ones(2,1); zeros(2,1)] (default) | binary column vector

Specify a column vector of length N–K. In a puncture vector, a value of 1 represents that the data symbol passes unaltered. A value of 0 represents that the data symbol is punctured, or removed, from the data stream.

Dependencies

To enable this parameter, set the Source of puncture pattern parameter to Property.

Source of B, the starting power for roots of the primitive polynomial — Starting power for roots of primitive polynomial

Auto (default) | Property

Specify the source of the starting power for roots of the primitive polynomial.

• Select Property to enable the B value parameter.

• Select Auto, to use the B value parameter default value of 1.

B value — Starting exponent of roots

1 (default) | positive integer

The starting exponent of the roots.

Dependencies

To enable this parameter, set the Source of B, the starting power for roots of the primitive polynomial parameter to Property.

Algorithms

This figure shows a sample output of the Integer-Input RS Encoder HDL Optimized block with a default configuration and when the Source of puncture pattern parameter is set to None.

This figure shows a sample output of the Integer-Input RS Encoder HDL Optimized block with a default configuration and when the Source of puncture pattern parameter is set to Property.

Points to Consider

• Each input frame must contain symbols less than or equal to Message length. A shortened code is inferred when the number of valid data samples between startIn and endIn is less than Message length.

• To receive a proper output for two sequential input frames, the gap between the frames must be greater than or equal to the sum of the block latency and the parity length, where parity length is equal to (Codeword length – Message length – Number of punctured symbols).

• The block does not allow you to specify the generator polynomial explicitly. It defines the generator polynomial based on the parameter values Codeword length, Message length, and the B value for the starting exponent of the roots.

Performance

The performance of the synthesized HDL code varies with the target and synthesis options. It also varies based on the input data type.

This table shows the resource and performance data synthesis results when you provide an input data type of uint8, specify the Code length parameter as 255, and Message length parameter as 223. The generated HDL is targeted to the AMD^® Zynq^®- 7000 ZC706 evaluation board. The design achieves a clock frequency of 363.75 MHz.

Resource	Number Used
Slice LUTs	416
Slice Registers	354
DSPs	0
Block RAMs	10

Extended Capabilities

C/C++ Code Generation

Generate C and C++ code using Simulink® Coder™.

Usage notes and limitations:

• Not recommended for production code.

HDL Code Generation

Generate VHDL, Verilog and SystemVerilog code for FPGA and ASIC designs using HDL Coder™.

HDL Coder™ provides additional configuration options that affect HDL implementation and synthesized logic.

HDL Architecture

This block has one default HDL architecture.

HDL Block Properties

ConstrainedOutputPipeline	Number of registers to place at the outputs by moving existing delays within your design. Distributed pipelining does not redistribute these registers. The default is 0. For more details, see ConstrainedOutputPipeline (HDL Coder).
InputPipeline	Number of input pipeline stages to insert in the generated code. Distributed pipelining and constrained output pipelining can move these registers. The default is 0. For more details, see InputPipeline (HDL Coder).
OutputPipeline	Number of output pipeline stages to insert in the generated code. Distributed pipelining and constrained output pipelining can move these registers. The default is 0. For more details, see OutputPipeline (HDL Coder).

Restrictions

You cannot generate HDL for this block inside a Resettable Synchronous Subsystem (HDL Coder).

Version History

Introduced in R2012b

R2023b: Added resource and performance data synthesis results

Added a new section with resource and performance data synthesis results for the Integer-Input RS Encoder HDL Optimized block.