coder.float2fixed.skip

Exclude functions from fixed-point conversion

Since R2024b

Syntax

coder.float2fixed.skip({'fcn'})

Description

coder.float2fixed.skip({'fcn'}) excludes the function fcn from fixed-point conversion when you use the -float2fixed option with codegen or fiaccel, or the HDL Coder™ Workflow Advisor.

Use coder.float2fixed.skip for designs that contain functions that do not support fixed-point inputs, or that contain custom floating-point or fixed-point functions that do not need to be converted to fixed point.

To skip functions with floating-point types when you generate HDL code, you must enable native floating point. For information about generating code from floating-point designs, see Getting Started with HDL Coder Native Floating-Point Support.

Examples

Exclude Function from Fixed-Point Conversion

Select a design for fixed-point conversion that contains unsupported constructs. This example uses a design called skipFcn, shown below.

function out = skipFcn(inp)
out = localFcn(inp);
end


function y = localFcn(u)
y = 2*exp(u);
end

The skipFcn design calls exp, a MATLAB® function that does not support fixed-point data types. To exclude exp from fixed-point conversion, add a call to coder.float2fixed.skip. Specify localFcn, which contains the call to exp, as the function to exclude.

function out = skipFcn(inp)
coder.float2fixed.skip({'localFcn'});
out = localFcn(inp);
end


function y = localFcn(u)
y = 2*exp(u);
end

To generate fixed-point code, create a coder.FixPtConfig object fixptcfg with default settings.

fixptcfg = coder.config("fixpt");

Specify a test bench. The test bench used in this example is skipFcn_tb.

fixptcfg.TestBenchName = 'skipFcn_tb';

Generate fixed-point code.

codegen -float2fixed fixptcfg skipFcn

===================================================
Design Name: skipFcn
Test Bench Name: skipFcn_tb
===================================================

Input types not specified for design(s) 'skipFcn', inferring types by simulating the first test bench: 'skipFcn_tb' in the base workspace.

============= Step1: Analyze floating-point code ==============

Code generation successful.



============= Step1a: Verify Floating Point ==============

### Analyzing the design 'skipFcn'
### Analyzing the test bench(es) 'skipFcn_tb'
### Begin Floating Point Simulation (Instrumented)
### Floating Point Simulation Completed in   1.8153 sec(s)
### Elapsed Time:             2.6461 sec(s)

============= Step2: Propose Types based on Range Information ==============


============= Step3: Generate Fixed Point Code ==============

### Generating Fixed Point MATLAB Code skipFcn_fixpt using Proposed Types
### Generating Fixed Point MATLAB Design Wrapper skipFcn_wrapper_fixpt
### Generating Mex file for ' skipFcn_wrapper_fixpt '
Code generation successful: View report
### Generating Type Proposal Report for 'skipFcn' skipFcn_report.html

===================================================
Code generation successful.

Open the Code Generation Report Viewer by clicking View report in the code generation output.

On the left side, under MATLAB Source, select skipFcn_fixpt from the function list to view the generated fixed-point code. Point to localFcn to view the expression information and note that the class is double. The function returns a fixed-point output by converting the output of localFcn to fixed point.

Input Arguments

fcn — Function name

cell array

Name of the function to exclude from fixed-point conversion, specified as a cell array. You can specify multiple functions.

Example: coder.float2fixed.skip({'fcn1','fcn2'})

Data Types: cell

Version History

Introduced in R2024b