hdlcoder.TimingGenerator - Base class to implement custom tool and device support for critical path

        estimation reporting - MATLAB ([original](https://in.mathworks.com/help/hdlcoder/ref/hdlcoder.timinggenerator-class.html)) ([raw](?raw))

Namespace: hdlcoder

Base class to implement custom tool and device support for critical path estimation reporting

Since R2024a

Description

The hdlcoder.TimingGenerator class is an abstract base class you can use to implement custom tool and device support for critical path estimation reporting. You can use instances of this class as the input to thegenhdltdb function.

Because the hdlcoder.TimingGenerator class is an abstract class, you cannot create an instance of this class directly. You use thehandle class to derive other classes, which can be concrete classes whose instances are handle objects.

To define a handle class, derive your class fromhdlcoder.TimingGenerator using the syntax in this classdef code.

classdef MyHandleClass < hdlcoder.TimingGenerator ... end

When you create a derived class object fromhdlcoder.TimingGenerator, HDL Coder™ generates a comma-separated file calledtiming_info.txt. The file contains timing details related to the operation undergoing a timing analysis.

The hdlcoder.TimingGenerator class is a handle class.

Class Attributes

Abstract	true
HandleCompatible	true

For information on class attributes, see Class Attributes.

Events

Event Name	Trigger	Event Data	Event Attributes
ObjectBeingDestroyed	Triggered when the handle object is about to be destroyed, but before calling the delete method.	event.EventData	NotifyAccess=privateListenAccess=public

Examples

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In this example, you examine a custom timing generator subclass designed for Xilinx® Vivado® hardware. This class uses the synthesizeRTL method to run synthesis and timing analysis, and uses thehasDSPs method to characterize the DSPs on your device. If your device does not have DSPs or if you do not want to characterize them, sethasDSPs to false. After you create the class, you can pass the hdlcoder.TimingGenerator.XilinxVivado class as a name-value argument to the genhdltdb function to generate a timing database. To view the shipping custom class, at the MATLAB® Command Line, enter:

edit hdlcoder.TimingGenerator.XilinxVivado

XilinxVivado custom class definition.

classdef XilinxVivado < hdlcoder.TimingGenerator %

The synthesizeRTL method calls the project creation, synthesis, and timing analysis TCL scripts.

function [status, logTxt] = synthesizeRTL(obj) % add code for project creation, synthesis and timing analysis end

The postProcessTimingInfo method further processes the timing information reported by the synthesis tool. For example, you can use this method to remove setup and clock-to-Q delays. Use this method when TCL scripts cannot handle removing setup and hold delays that are not required.

function timingInfo = postProcessTimingInfo(obj, timingInfo) % add code here for your custom timing information analysis end

These methods account for and characterize the DSPs on the device.:

The hasDSPs method is set totrue to characterize the DSPs on the device
The countDSPs method counts and returns the number of DSPs during device synthesis
the dspSynthesisAttribute method uses name-value arguments in cell arrays to specify attributes to apply during HDL code generation
the dontTouchSynthesisAttribute method uses name-value arguments in cell arrays to specify attributes to apply during HDL code generation

function val = hasDSPs(~) val = true; end

    function val = countDSPs(~, synthesisLogText)
        val_str = regexp(synthesisLogText, '|DSP.\S*\s*\|\s*(\d+)', 'tokens', 'lineanchors');
        assert(isscalar(val_str));
        val = str2double(val_str{1}{1});
    end

    function val = dspSynthesisAttribute(~)
        val = {'USE_DSP', 'yes'};
    end

    function val = dontTouchSynthesisAttribute(~)
        val = {'DONT_TOUCH', 'TRUE'};
    end

Generate a timing database by using the genhdltdb function and passing the XilinxVivado class as a name-value argument to the function.

tg = XilinxVivado; genhdltdb("SynthesisDeviceConfiguration",{"Zynq","xc7z020","clg484","-1"}, ... "TimingDatabaseDirectory","C:\Work\database", ... "TimingGenerator",tg);

In this example, you examine a custom timing generator subclass designed for Cadence® Genus hardware. This class uses the synthesizeRTL method to run synthesis and timing analysis and uses thehasDSPs method to characterize the DSPs on the device. If your device does not have DSPs or if you do not want to characterize them, sethasDSPs to false. If you set hasDSPs totrue, you must define the countDSPs,dspSynthesisAttribute, anddontTouchSynthesisAttribute methods. After you create the class, you can pass the hdlcoder.TimingGenerator.CadenceGenus class as a name-value argument to the genhdltdb function to generate a timing database. To examine the completed custom class, at the MATLAB command line, enter:

edit hdlcoder.TimingGenerator.CadenceGenus

CadenceGenus custom class definition.

The synthesizeRTL method calls the project creation, synthesis, and timing analysis TCL scripts.

function [status, logTxt] = synthesizeRTL(obj) % add code here for project creation, synthesis, and timing analysis
end

The useSynchronousReset method tells HDL Coder to specify what to set the global reset options to. For example, Cadence Genus supports asynchronous resets, souseSynchronousReset is set to false to perform asynchronous resets.

function val = useSynchronousReset(~) val = false; end

In this example, this class targets a device that does not have DSPs. ThehasDSPs method is set tofalse.

function val = hasDSPs(~) val = false; end

Generate a timing database by using the genhdltdb function. Pass the CadenceGenus class as a name-value argument to the function.

tg = CadenceGenus; genhdltdb("SynthesisDevicePart","tutorial.lib", ... "TimingDatabaseDirectory","C:\Work\database", ... "TimingGenerator",tg);

More About

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When you create a custom hdlcoder.TimingGenerator object, you must create an abstract synthesizeRTL method that you call to run synthesis and create a timing analysis, and an abstracthasDSPs method to characterize the DSPs on your device. If your device does not have DSPs, or you do not want to characterize the DSPs on the device, set hasDSPs to false. ThesynthesizeRTL method includes calls to functions to generate TCL scripts that create projects, run synthesis, and perform a timing analysis on all input, output, and internal register paths. Because critical path estimation includes timing information in the presence of delay blocks, you must remove:

Hold time from input-to-internal paths
Setup time from internal-to-output paths
Setup and hold times from input-to-output paths

When you set hasDSPs to true, you must define:

A countDSPs method to count and return the number of DSPs during device synthesis.
A dspSynthesisAttribute method and use name-value arguments in cell arrays to apply during HDL code generation.
A dontTouchSynthesisAttribute method and use name-value arguments in cell arrays to apply during HDL code generation.

You can also include an optionalpostProcessTimingInfo method to further process the timing info reported by the synthesis tool. Provide the name of the timing report generated by the synthesis tool by using the ReportFile property of the derived class object.

When you derive a hdlcoder.TimingGenerator object, these object parameters are pre-defined in the derived object and are copied from the basehdlcoder.TimingGenerator class:

ReportFile — Name of file that stores the timing report generated by the synthesis tool. ThepostprocessTimingInfo method uses this file. The default value is'mathworks_report_timing_groups.log'.
CsvFile — Name of the comma-separated value (CSV) file that contains the timing information of the register-to-register paths used to build the timing database. The default value is timing_info.txt.
RegSuffix — Wildcard option to query register names in the synthesis tool. This wildcard option includes all registers that have the same name and different numbers. The default value is*.

The derived hdlcoder.TimingGenerator class object receives these inputs from the characterization infrastructure:

obj.TargetInfo.deviceFullName — You can populate this field with information from any of these values:SynthesisDevicePart,SynthesisDeviceConfiguration,SynthesisDeviceName,SynthesisDeviceSpeedGrade, orSynthesisDevicePackage.

obj.ModelInfo— This field is a structure with these elements, which are populated by the characterization infrastructure:

Field Name	Description
obj.ModelInfo.topSubsystem	Name of design under test (DUT) subsystem
obj.ModelInfo.blockSubsystem	Name of subsystem that contains the block to be characterized
obj.ModelInfo.portRegisters.in.values	Cell array of DUT input register names
obj.ModelInfo.portRegisters.out.values	Cell array of DUT output register names

The output of the derived hdlcoder.TimingGenerator class is a CSV file named timing_info.txt. The file contains information in this format:DelayInfo, source_type, destination_type, propagation delay (ns).

The source_type or destination_type fields are of type:

mw_internal_registers — Any internal register inside the subsystem that contains the block to be characterized.
mw_inport_# — Numbered input to the operator starting at index zero. For example, mw_inport_0,mw_inport_1, and so on.
mw_outport_# — Numbered output from the operator starting at index zero. For example, mw_outport_0,mw_outport_1, and so on.

The propagation delay (ns) field is the value in nanoseconds for either internal-to-internal, input-to-internal, internal-to-output, or input-to-output propagation delays. If a timing path does not exist , this value isinf. This field contains the timing information for every path. This image shows the contents of an example timing_info.txt file:

Comma separate value file containing propagation delays between various registers

Version History

Introduced in R2024a