yosys/techlibs/nanoxplore/rf_rams_u.txt

ram distributed $__NX_XRFB_64x18_ {
    abits 6;
    width 18;
    cost 10;
    init no_undef;
    prune_rom;

    port sw "W" {
        clock anyedge;
    }
    port ar "R" {
    }
}

ram distributed $__NX_XRFB_32x36_ {
    abits 5;
    width 36;
    cost 10;
    init no_undef;
    prune_rom;

    port sw "W" {
        clock anyedge;
    }
    port ar "R" {
    }
}