synth_intel_alm: alternative synthesis for Intel FPGAs

By operating at a layer of abstraction over the rather clumsy Intel primitives,
we can avoid special hacks like `dffinit -highlow` in favour of simple techmapping.

This also makes the primitives much easier to manipulate, and more descriptive
(no more cyclonev_lcell_comb to mean anything from a LUT2 to a LUT6).

techlibs/intel_alm/common/lutram_mlab_map.v

@@ -0,0 +1,29 @@
+module __MISTRAL_MLAB(CLK1, CLK2, A1ADDR, A1DATA, A1EN, B1ADDR, B1DATA);
+
+parameter CFG_ABITS = 5;
+parameter CFG_DBITS = 20;
+
+input CLK1, CLK2;
+input [CFG_ABITS-1:0] A1ADDR, B1ADDR;
+input [CFG_DBITS-1:0] A1DATA;
+input A1EN;
+output [CFG_DBITS-1:0] B1DATA;
+
+altsyncram #(
+    .operation_mode("dual_port"),
+    .ram_block_type("mlab"),
+    .widthad_a(CFG_ABITS),
+    .width_a(CFG_DBITS),
+    .widthad_b(CFG_ABITS),
+    .width_b(CFG_DBITS),
+) _TECHMAP_REPLACE_ (
+    .address_a(A1ADDR),
+    .data_a(A1DATA),
+    .wren_a(A1EN),
+    .address_b(B1ADDR),
+    .q_b(B1DATA),
+    .clock0(CLK1),
+    .clock1(CLK1),
+);
+
+endmodule