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intel_alm: re-enable carry chains for ABC9

This commit is contained in:
Lofty 2023-05-25 16:17:09 +01:00
parent 52c8c28d2c
commit 00b0e850db
2 changed files with 5 additions and 7 deletions

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@ -1,5 +1,5 @@
// The core logic primitive of the Cyclone V/10GX is the Adaptive Logic Module
// (ALM). Each ALM is made up of an 8-input, 2-output look-up table, covered
// (ALM). Each ALM is made up of an 8-input, 2-output look-up table, covered
// in this file, connected to combinational outputs, a carry chain, and four
// D flip-flops (which are covered as MISTRAL_FF in dff_sim.v).
//
@ -283,10 +283,8 @@ assign Q = ~A;
endmodule
// Despite the abc9_carry attributes, this doesn't seem to stop ABC9 adding illegal fanout to the carry chain that nextpnr cannot handle.
// So we treat it as a total blackbox from ABC9's perspective for now.
// (* abc9_box, lib_whitebox *)
module MISTRAL_ALUT_ARITH(input A, B, C, D0, D1, /* (* abc9_carry *) */ input CI, output SO, /* (* abc9_carry *) */ output CO);
(* abc9_box, lib_whitebox *)
module MISTRAL_ALUT_ARITH(input A, B, C, D0, D1, (* abc9_carry *) input CI, output SO, (* abc9_carry *) output CO);
parameter LUT0 = 16'h0000;
parameter LUT1 = 16'h0000;