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Under the following conditions, CMSIS support for DSP blocks is available:
Input data type is single. (except for Discrete FIR Filter with 'Direct Form' Structure, where both single and fixedpoint data types are supported.)
Block is in single rate mode.
Input or output is real. (Support for complex input or output is available for FFT and IFFT blocks.)
Input is single channel.
Note: In the Fixedpoint mode of the CMSIS DSP (FIR) function, Wrap is used for intermediate MAC operations if accumulator result overflows. At the end, the accumulator is right shifted and saturated to the output data type. For discrete FIR block or system object, there is only one overflow setting for accumulator and output. So if overflow happens in accumulation, the simulation result will not match the CMSIS library result. 
DSP blocks supporting the ARMCortexM package require a set of conditions that would allow code replacement with the CMSIS Library, when generating C code from a model. The CMSIS library supports these DSP blocks only when you set specific parameters, as indicated in the following table. To use the CMSIS library with these blocks offering ARM support, you must follow these rules for specifying parameters.
The following table illustrates the rules under which CMSIS supports these blocks offering ARM support:
DSP Block  Block Parameters for CMSIS Support  Equivalent CMSIS Methods 

Discrete FIR Filter 


FIR Decimation 


FIR Interpolation 


LMS Filter 


Biquad Filter 


FFT 


IFFT 


CorrelationConvolution 


MeanRMSVarianceStandard deviation 

