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Merge pull request #4298 from povik/kogge-stone
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techmap: Add a Kogge-Stone option for `$lcu` mapping
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povik authored Apr 8, 2024
2 parents 8e8885e + 5f4d13e commit dc74608
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Showing 4 changed files with 57 additions and 1 deletion.
1 change: 1 addition & 0 deletions techlibs/common/Makefile.inc
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Expand Up @@ -35,3 +35,4 @@ $(eval $(call add_share_file,share,techlibs/common/abc9_map.v))
$(eval $(call add_share_file,share,techlibs/common/abc9_unmap.v))
$(eval $(call add_share_file,share,techlibs/common/cmp2lcu.v))
$(eval $(call add_share_file,share,techlibs/common/cmp2softlogic.v))
$(eval $(call add_share_file,share/choices,techlibs/common/choices/kogge-stone.v))
54 changes: 54 additions & 0 deletions techlibs/common/choices/kogge-stone.v
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@@ -0,0 +1,54 @@
/*
* yosys -- Yosys Open SYnthesis Suite
*
* Copyright (C) 2024 Martin Povišer <[email protected]>
*
* Permission to use, copy, modify, and/or distribute this software for any
* purpose with or without fee is hereby granted, provided that the above
* copyright notice and this permission notice appear in all copies.
*
* THE SOFTWARE IS PROVIDED "AS IS" AND THE AUTHOR DISCLAIMS ALL WARRANTIES
* WITH REGARD TO THIS SOFTWARE INCLUDING ALL IMPLIED WARRANTIES OF
* MERCHANTABILITY AND FITNESS. IN NO EVENT SHALL THE AUTHOR BE LIABLE FOR
* ANY SPECIAL, DIRECT, INDIRECT, OR CONSEQUENTIAL DAMAGES OR ANY DAMAGES
* WHATSOEVER RESULTING FROM LOSS OF USE, DATA OR PROFITS, WHETHER IN AN
* ACTION OF CONTRACT, NEGLIGENCE OR OTHER TORTIOUS ACTION, ARISING OUT OF
* OR IN CONNECTION WITH THE USE OR PERFORMANCE OF THIS SOFTWARE.
*
*/

(* techmap_celltype = "$lcu" *)
module _80_lcu_kogge_stone (P, G, CI, CO);
parameter WIDTH = 2;

(* force_downto *)
input [WIDTH-1:0] P, G;
input CI;

(* force_downto *)
output [WIDTH-1:0] CO;

integer i, j;
(* force_downto *)
reg [WIDTH-1:0] p, g;

wire [1023:0] _TECHMAP_DO_ = "proc; opt -fast";

always @* begin
p = P;
g = G;

// in almost all cases CI will be constant zero
g[0] = g[0] | (p[0] & CI);

for (i = 0; i < $clog2(WIDTH); i = i + 1) begin
// iterate in reverse so we don't confuse a result from this stage and the previous
for (j = WIDTH - 1; j >= 2**i; j = j - 1) begin
g[j] = g[j] | p[j] & g[j - 2**i];
p[j] = p[j] & p[j - 2**i];
end
end
end

assign CO = g;
endmodule
2 changes: 1 addition & 1 deletion techlibs/common/techmap.v
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Expand Up @@ -207,7 +207,7 @@ module _90_fa (A, B, C, X, Y);
endmodule

(* techmap_celltype = "$lcu" *)
module _90_lcu (P, G, CI, CO);
module _90_lcu_brent_kung (P, G, CI, CO);
parameter WIDTH = 2;

(* force_downto *)
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1 change: 1 addition & 0 deletions tests/techmap/kogge-stone.ys
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test_cell -s 1711533949 -n 10 -map +/techmap.v -map +/choices/kogge-stone.v $lcu

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