Hi Roman, 
 
It is my understanding that you are generating C code from MATLAB code that contains a “typecast” function. 
The generated C code uses “string.h” and “memcpy” function, which you want to avoid. 
Also, setting the options to the following value did not help;
- “Use memcpy for vector assignment”: No 
- “Use memset to initialize floats and doubles to 0.0”: No 
As a workaround, the Code Replacement Library (CRL) can be used. 
Please follow the workflow mentioned below to achieve the same. 
Creating Code Replacement Library for "memcpy"
- Download the attached scripts "crl_table_memcpy.m" and "rtwTargetInfo.m" and save them in the current working directory or in the folder that is in MATLAB Path. 
- To use your code replacement library, refresh your current MATLAB session with the command: 
    >> sl_refresh_customizations
          3. Verify the code replacement library by executing the command
    >> crviewer('CRL for memory function replacement') 
Code generation 
- In Generate Code stage of code generation using MATLAB Coder App, open more settings, and set the options' value as below; 
                a. “Code replacements”: Yes 
                b. “Code replacement library”: CRL for memory function replacement 
         2. Generate the code 
After using Code Replacement Library, it can be observe that “memcpy” is replaced with “my_memcpy”; 
Below are the links to detailed documentation of the steps mentioned above; 
 
Hope this helps! 
 
Regards, 
Shivam Malviya