UseRAM parameter: The UseRAM implementation parameter in Simulink HDL block option enables using RAM-based mapping for an integer delay block.
web(fullfile(docroot, 'hdlcoder/ug/block-implementation-parameters.html#bs04098'))
You can also use array of persistent variables and map it to RAM in MATLAB to HDL
web(fullfile(docroot, 'hdlcoder/ug/how-to-map-persistent-arrays-to-ram.html'))