Specify Properties of Entry-Point Function Inputs

Why You Must Specify Input Properties

Fixed-Point Designer™ must determine the properties of all variables in the MATLAB^® files at compile time. To infer variable properties in MATLAB files, Fixed-Point Designer must be able to identify the properties of the inputs to the primary function, also known as the top-level or entry-point function. Therefore, if your primary function has inputs, you must specify the properties of these inputs, to Fixed-Point Designer. If your primary function has no input parameters, Fixed-Point Designer can compile your MATLAB file without modification. You do not need to specify properties of inputs to local functions or external functions called by the primary function.

Note

Your primary function cannot be within a MATLAB namespace. Create a wrapper function as the primary function outside the namespace. Call the desired function within the new function as the primary function.

Methods of Input-Type Specification

Method Advantages Disadvantages

Method	Advantages	Disadvantages
Define Input Properties at the Command Line Note You cannot use this method if you define input properties by using `assert` statements in your MATLAB code	Easy to use Does not alter original MATLAB code Designed for prototyping a function that has few primary inputs	Must be specified at the command line every time you generate code (unless you use a script) Not efficient for specifying memory-intensive inputs such as large structures and arrays
Specify Input Types Using assert Statements in MATLAB Code	Integrated with MATLAB code Documents argument specifications in the MATLAB entry-point function Efficient for specifying memory-intensive inputs such as large structures	Uses complex syntax Project files do not currently recognize properties defined programmatically. If you are using a project, you must reenter the input types in the project.

Define Input Properties at the Command Line

Note

You cannot use this method if you define input properties by using assert statements in your MATLAB code

Easy to use
Does not alter original MATLAB code
Designed for prototyping a function that has few primary inputs

Must be specified at the command line every time you generate code (unless you use a script)
Not efficient for specifying memory-intensive inputs such as large structures and arrays

Specify Input Types Using assert Statements in MATLAB Code

Integrated with MATLAB code
Documents argument specifications in the MATLAB entry-point function
Efficient for specifying memory-intensive inputs such as large structures

Uses complex syntax
Project files do not currently recognize properties defined programmatically. If you are using a project, you must reenter the input types in the project.

Properties to Specify

If your primary function has inputs, you must specify the following properties for each input.

For	Specify properties
	Class	Size	Complexity	numerictype	fimath
Fixed-point inputs
Each field in a structure input	Specify properties for each field according to its class When a primary input is a structure, the code generator treats each field as a separate input. Therefore, you must specify properties for all fields of a primary structure input in the order that they appear in the structure definition: For each field of input structures, specify class, size, and complexity. For each field that is fixed-point class, also specify `numerictype`, and `fimath`.
Other inputs

Default Property Values

Fixed-Point Designer assigns the following default values for properties of primary function inputs.

Property	Default
class	`double`
size	`scalar`
complexity	`real`
`numerictype`	No default
`fimath`	MATLAB default `fimath` object

Supported Classes

The following table presents the class names supported by Fixed-Point Designer.

Class Name	Description
`logical`	Logical array of true and false values
`char`	Character array
`int8`	8-bit signed integer array
`uint8`	8-bit unsigned integer array
`int16`	16-bit signed integer array
`uint16`	16-bit unsigned integer array
`int32`	32-bit signed integer array
`uint32`	32-bit unsigned integer array
`int64`	64-bit signed integer array
`uint64`	64–bit unsigned integer array
`single`	Single-precision floating-point or fixed-point number array
`double`	Double-precision floating-point or fixed-point number array
`struct`	Structure array
`embedded.fi`	Fixed-point number array

Rules for Specifying Properties of Primary Inputs

When specifying the properties of primary inputs, follow these rules:

The order of elements in the cell array must correspond to the order in which inputs appear in the primary function signature. For example, the first element in the cell array defines the properties of the first primary function input.
To generate fewer arguments than those arguments that occur in the MATLAB function, specify properties for only the number of arguments that you want in the generated function.
If the MATLAB function has input arguments, to generate a function that has no input arguments, pass an empty cell array to -args.
For each primary function input whose class is fixed point (fi), specify the input numerictype and fimath properties.
For each primary function input whose class is struct, specify the properties of each of its fields in the order that they appear in the structure definition.
If you generate a MEX, SIL, or PIL function that accepts an empty array with a given shape, the generated function accepts empty arrays of other shapes as well. The MEX, SIL, or PIL function reshapes the empty run-time input array to match the shape of the array that was specified at code generation time.