10-1 DSP C Specifications
If you specify the dsp option in the SuperH C/C++ compiler, it can handle fixed point data.Data transfer and multiplication and accumulation can be executed in parallel with optimization.

DSP-C has the modifiers shown in this table.

A numeric value can be shown to be a fixed point constant by attaching a constant suffix.

Please refer to the manual regarding fixed point type conversion rules or libraries that can be used.