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Remove EXPLICIT_CARRY logic.

Browse source 
The symbiflow-arch-defs tool chain no longer needs the EXPLICIT_CARRY
within yosys itself.

Signed-off-by: Keith Rothman <537074+litghost@users.noreply.github.com>
This commit is contained in:
Keith Rothman 2019-08-19 08:42:09 -07:00 • committed by Marcelina Kościelnicka
parent 57af8499df
commit 819f1d8c20
3 changed files with 2 additions and 150 deletions
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114
techlibs/xilinx/arith_map.v
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@ -35,13 +35,7 @@ module _80_xilinx_lcu (P, G, CI, CO);
genvar i;
`ifdef _EXPLICIT_CARRY
localparam EXPLICIT_CARRY = 1'b1;
`else
localparam EXPLICIT_CARRY = 1'b0;
`endif
generate if (EXPLICIT_CARRY || `LUT_SIZE == 4) begin
generate if (`LUT_SIZE == 4) begin
(* force_downto *)
wire [WIDTH-1:0] C = {CO, CI};
@ -135,12 +129,6 @@ module _80_xilinx_alu (A, B, CI, BI, X, Y, CO);
genvar i;
`ifdef _EXPLICIT_CARRY
localparam EXPLICIT_CARRY = 1'b1;
`else
localparam EXPLICIT_CARRY = 1'b0;
`endif
generate if (`LUT_SIZE == 4) begin
(* force_downto *)
@ -163,106 +151,6 @@ generate if (`LUT_SIZE == 4) begin
);
end endgenerate
end else if (EXPLICIT_CARRY) begin
(* force_downto *)
wire [Y_WIDTH-1:0] S = AA ^ BB;
wire CINIT;
// Carry chain.
//
// VPR requires that the carry chain never hit the fabric. The CO input
// to this techmap is the carry outputs for synthesis, e.g. might hit the
// fabric.
//
// So we maintain two wire sets, CO_CHAIN is the carry that is for VPR,
// e.g. off fabric dedicated chain. CO is the carry outputs that are
// available to the fabric.
(* force_downto *)
wire [Y_WIDTH-1:0] CO_CHAIN;
(* force_downto *)
wire [Y_WIDTH-1:0] C = {CO_CHAIN, CINIT};
// If carry chain is being initialized to a constant, techmap the constant
// source. Otherwise techmap the fabric source.
generate for (i = 0; i < 1; i = i + 1) begin:slice
CARRY0 #(.CYINIT_FABRIC(1)) carry(
.CI_INIT(CI),
.DI(AA[0]),
.S(S[0]),
.CO_CHAIN(CO_CHAIN[0]),
.CO_FABRIC(CO[0]),
.O(Y[0])
);
end endgenerate
generate for (i = 1; i < Y_WIDTH-1; i = i + 1) begin:slice
if(i % 4 == 0) begin
CARRY0 carry (
.CI(C[i]),
.DI(AA[i]),
.S(S[i]),
.CO_CHAIN(CO_CHAIN[i]),
.CO_FABRIC(CO[i]),
.O(Y[i])
);
end
else
begin
CARRY carry (
.CI(C[i]),
.DI(AA[i]),
.S(S[i]),
.CO_CHAIN(CO_CHAIN[i]),
.CO_FABRIC(CO[i]),
.O(Y[i])
);
end
end endgenerate
generate for (i = Y_WIDTH-1; i < Y_WIDTH; i = i + 1) begin:slice
if(i % 4 == 0) begin
CARRY0 top_of_carry (
.CI(C[i]),
.DI(AA[i]),
.S(S[i]),
.CO_CHAIN(CO_CHAIN[i]),
.O(Y[i])
);
end
else
begin
CARRY top_of_carry (
.CI(C[i]),
.DI(AA[i]),
.S(S[i]),
.CO_CHAIN(CO_CHAIN[i]),
.O(Y[i])
);
end
// Turns out CO_FABRIC and O both use [ABCD]MUX, so provide
// a non-congested path to output the top of the carry chain.
// Registering the output of the CARRY block would solve this, but not
// all designs do that.
if((i+1) % 4 == 0) begin
CARRY0 carry_output (
.CI(CO_CHAIN[i]),
.DI(0),
.S(0),
.O(CO[i])
);
end
else
begin
CARRY carry_output (
.CI(CO_CHAIN[i]),
.DI(0),
.S(0),
.O(CO[i])
);
end
end endgenerate
end else begin
localparam CARRY4_COUNT = (Y_WIDTH + 3) / 4;