Hi, Whoua ! lots of trials.
Nice to get it works, you may be lucky.
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I've tried making the process dependent on other signals.
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Mostly VHDL design employ
process(reset_n, clock) and other combinational logics. The clocked process insure that the design IS SYNCHRONOUS.
Making a design by using only combinational logics needs very (too) much rigorousness (to avoid glitches, latches, ringing....). I think 0.000000001% work with this.
If you make the process dependent on other signals, you build combinational logics. :-(
Maybe Read_ready and write_ready are asserted low !? Sometimes there are errors in manuals.