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intel_alm: direct LUTRAM cell instantiation

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By instantiating the LUTRAM cell directly, we avoid a trip through
altsyncram, which speeds up Quartus synthesis time. This also gives
a little more flexibility, as Yosys can build RAMs out of individual
32x1 LUTRAM cells.

While working on this, I discovered that the mem_init0 parameter of
<family>_mlab_cell gets ignored by Quartus.
This commit is contained in:
Dan Ravensloft 2020-04-16 12:24:04 +01:00 • committed by Marcelina Kościelnicka
parent 0610424940
commit 5b779f7f4e
9 changed files with 163 additions and 52 deletions
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39
techlibs/intel_alm/common/quartus_rename.v
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@ -1,8 +1,10 @@
`ifdef cyclonev
`define LCELL cyclonev_lcell_comb
`define MLAB cyclonev_mlab_cell
`endif
`ifdef cyclone10gx
`define LCELL cyclone10gx_lcell_comb
`define MLAB cyclone10gx_mlab_cell
`endif
module __MISTRAL_VCC(output Q);
@ -80,3 +82,40 @@ parameter LUT1 = 16'h0000;
`LCELL #(.lut_mask({16'h0, LUT1, 16'h0, LUT0})) _TECHMAP_REPLACE_ (.dataa(A), .datab(B), .datac(C), .datad(D0), .dataf(D1), .cin(CI), .sumout(SO), .cout(CO));
endmodule
module MISTRAL_MLAB(input [4:0] A1ADDR, input A1DATA, A1EN, CLK1, input [4:0] B1ADDR, output B1DATA);
// Here we get to an unfortunate situation. The cell has a mem_init0 parameter,
// which takes in a hexadecimal string that could be used to initialise RAM.
// In the vendor simulation models, this appears to work fine, but Quartus,
// either intentionally or not, forgets about this parameter and initialises the
// RAM to zero.
//
// Because of this, RAM initialisation is presently disabled, but the source
// used to generate mem_init0 is kept (commented out) in case this gets fixed
// or an undocumented way to get Quartus to initialise from mem_init0 is found.
`MLAB #(
.logical_ram_name("MISTRAL_MLAB"),
.logical_ram_depth(32),
.logical_ram_width(1),
.mixed_port_feed_through_mode("Dont Care"),
.first_bit_number(0),
.first_address(0),
.last_address(31),
.address_width(5),
.data_width(1),
.byte_enable_mask_width(1),
.port_b_data_out_clock("NONE"),
// .mem_init0($sformatf("%08x", INIT))
) _TECHMAP_REPLACE_ (
.portaaddr(A1ADDR),
.portadatain(A1DATA),
.portbaddr(B1ADDR),
.portbdataout(B1DATA),
.ena0(A1EN),
.clk0(CLK1)
);
endmodule