Control Signed Left Shifts in Generated Code - MATLAB & Simulink (original) (raw)

Main Content

If you have an Embedded Coder® license, you can control whether MATLAB® Coder™ replaces multiplications by powers of two with signed left bitwise shifts. Some coding standards, such as MISRA™, do not allow bitwise operations on signed integers.

By default, MATLAB Coder replaces multiplication by powers of two with signed left shifts. Here is an example of generated C code that uses a signed left shift for multiplication by eight.

To increase the likelihood of generating MISRA C:2012 compliant code, disable the replacement of multiplication by powers of two with signed left shifts. Here is an example of generated C code that does not use a signed left shift for multiplication by eight:

Control Signed Left Shifts Using the MATLAB Coder App

  1. Set Build type to one of the following:
    • Static Library (.lib)
    • Dynamic Library (.dll)
    • Executable (.exe)
  2. Click Settings.
  3. On the Code Appearance tab, select or clear the Use signed shift left for fixed-point operations and multiplication by powers of 2 check box.

Control Signed Left Shifts Using the Command-Line Interface

  1. Create a code configuration object for 'lib', 'dll', or 'exe'. For example:
    cfg = coder.config('lib','ecoder',true); % or dll or exe
  2. Set the EnableSignedLeftShifts property to true or false. For example:
    cfg.EnableSignedLeftShifts = false;

See Also

coder.EmbeddedCodeConfig

Topics