Inherit Custom Data Types

Level-2 MATLAB^® S-functions do not support defining custom data types within the S-function. However, input and output ports can inherit their data types from a Simulink.NumericType or Simulink.AliasType object. For example, the S-function in the following model inherits its input data type from the Constant block:

The Constant block's Output data type field contains the value MyDouble, which is a Simulink.AliasType defined in the MATLAB workspace with the following line of code:

MyDouble = Simulink.AliasType('double');

The input and output ports of the Level-2 MATLAB S-function msfcn_inheritdt.m inherit their data types. When the Simulink^® engine performs data type propagation, it assigns the data type MyDouble to these ports.

You can define a fixed-point data type within a Level-2 MATLAB S-function, using one of the following three methods:

• RegisterDataTypeFxpBinaryPoint registers a fixed-point data type with binary point-only scaling

• RegisterDataTypeFxpFSlopeFixExpBias registers a fixed-point data type with [Slope Bias] scaling specified in terms of fractional slope, fixed exponent, and bias

• RegisterDataTypeFxpSlopeBias registers a data type with [Slope Bias] scaling

Note

If the registered data type is not one of the Simulink built-in data types, you must have a Fixed-Point Designer™ license.

If you have Fixed-Point Designer, inspect the example models and S-functions provided with the software for examples using the macros for defining fixed-point data types.