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intel_alm: Fix illegal carry chains

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Signed-off-by: gatecat <gatecat@ds0.me>
This commit is contained in:
gatecat 2021-05-15 14:40:37 +01:00
parent eb106732d9
commit 34a08750fa
4 changed files with 9 additions and 7 deletions
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6
techlibs/intel_alm/common/alm_sim.v
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@ -230,8 +230,10 @@ assign Q = ~A;
endmodule
(* abc9_box, lib_whitebox *)
module MISTRAL_ALUT_ARITH(input A, B, C, D0, D1, (* abc9_carry *) input CI, output SO, (* abc9_carry *) output CO);
// 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);
parameter LUT0 = 16'h0000;
parameter LUT1 = 16'h0000;

2
techlibs/intel_alm/common/arith_alm_map.v
View file

@ -34,7 +34,7 @@ wire [Y_WIDTH:0] ALM_CARRY;
// Start of carry chain
generate
if (_TECHMAP_CONSTMSK_CI_ == 1) begin
if (_TECHMAP_CONSTMSK_CI_ == 1 && _TECHMAP_CONSTVAL_CI_ == 1'b0) begin
assign ALM_CARRY[0] = _TECHMAP_CONSTVAL_CI_;
end else begin
MISTRAL_ALUT_ARITH #(