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Maximum word length

Description

Specify a maximum word length, in bits, for which the code generation process generates system-defined multiword type definitions.

Category: Code Generation > Interface

Settings

Default: 256 for ERT targets, 2048 for GRT targets

Specify a maximum word length, in bits, for which the code generation process generates multiword type definitions into the file multiword_types.h. All multiword type definitions up to and including this number of bits are generated. If you select 0, multiword type definitions are not generated into the file multiword_types.h.

The maximum word length for multiword types only determines the type definitions generated and does not impact the efficiency of the generated code. If the maximum word length for multiword types is set to 0 or too small, an error occurs when the generated code is compiled. This error is caused by the generated code using a type that does not have the required type definition. To resolve the error, increase the maximum word length and regenerate the code. If the maximum word length for multiword types is larger than required, then multiword_types.h might contain unused type definitions. Unused type definitions do not consume target resources.

Tips

  • Adding a model to a model hierarchy or changing an existing model in the hierarchy can result in updates to the shared multiword_types.h file during code generation. These updates occur when the new model uses multiword types of length greater than those of the other models. You must then recompile and, depending on your development process, reverify previously generated code. To prevent updates to multiword_types.h, determine a maximum word length sufficiently big to cover the needs of all models in the hierarchy. Configure every model in the hierarchy to use that same maximum word length.

  • The majority of embedded designs do not need multiword types. By setting maximum word length for multiword types to 0, you can prevent use of multiword variables on the target. If you use multiword variables with a maximum word length that is 0 or smaller than required, you are alerted with an error when the generated code is compiled.

Dependencies

  • This parameter requires an Embedded Coder® license when generating code.

  • This parameter is enabled by selecting the value User defined for the parameter Multiword type definitions.

Command-Line Information

Parameter: MultiwordLength
Type: integer
Value: valid quantity of bits representing a word size
Default: 256 for ERT targets, 2048 for GRT targets

Recommended Settings

ApplicationSetting
DebuggingNo impact
TraceabilityNo impact
EfficiencyNo impact
Safety precaution

No recommendation

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