AES-128 Sbox - Rom Issue

The solution is to simply use 4 synchronous ROMs, one for each "c". Or actually, 2 since each M*K block has two independent read ports.

So, AFAIK as I can see, you can use M*K blocks for your problem, without performance penalty.

To use them, you basically two options.

One, you can use a ROM function such as LPM_ROM or ALT_ROM.

LPM_ROM is portable, ALT_ROM has more features, such as 2 ports.

It will require some changes to your code and you need to write a .HEX/.MIF file for the ROM's contents.

The other solution, which I prefer, is to infer the ROM from your code.

This will require you to change your code to follow a ROM template Quartus can recognize, which may involve a bit of trial and error.

Take a look into the HDL coding guidelines to see which templates are supported and start from a simple case.

Also, Quartus may also decide that, despite your efforts, your ROM is best implemented in LUTs.