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yosys/techlibs/xilinx/arith_map.v

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/*
* yosys -- Yosys Open SYnthesis Suite
*
* Copyright (C) 2012 Clifford Wolf <clifford@clifford.at>
*
* 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.
*
*/
// ============================================================================
// LCU
(* techmap_celltype = "$lcu" *)
module _80_xilinx_lcu (P, G, CI, CO);
parameter WIDTH = 2;
input [WIDTH-1:0] P, G;
input CI;
output [WIDTH-1:0] CO;
wire _TECHMAP_FAIL_ = WIDTH <= 2;
genvar i;
`ifdef _EXPLICIT_CARRY
wire [WIDTH-1:0] C = {CO, CI};
wire [WIDTH-1:0] S = P & ~G;
generate for (i = 0; i < WIDTH; i = i + 1) begin:slice
MUXCY muxcy (
.CI(C[i]),
.DI(G[i]),
.S(S[i]),
.O(CO[i])
);
end endgenerate
`else
localparam CARRY4_COUNT = (WIDTH + 3) / 4;
localparam MAX_WIDTH = CARRY4_COUNT * 4;
localparam PAD_WIDTH = MAX_WIDTH - WIDTH;
wire [MAX_WIDTH-1:0] S = {{PAD_WIDTH{1'b0}}, P & ~G};
wire [MAX_WIDTH-1:0] C = CO;
generate for (i = 0; i < CARRY4_COUNT; i = i + 1) begin:slice
// Partially occupied CARRY4
if ((i+1)*4 > WIDTH) begin
// First one
if (i == 0) begin
CARRY4 carry4_1st_part
(
.CYINIT(CI),
.CI (1'd0),
.DI (G [(WIDTH - 1):i*4]),
.S (S [(WIDTH - 1):i*4]),
.CO (CO[(WIDTH - 1):i*4]),
);
// Another one
end else begin
CARRY4 carry4_part
(
.CYINIT(1'd0),
.CI (C [i*4 - 1]),
.DI (G [(WIDTH - 1):i*4]),
.S (S [(WIDTH - 1):i*4]),
.CO (CO[(WIDTH - 1):i*4]),
);
end
// Fully occupied CARRY4
end else begin
// First one
if (i == 0) begin
CARRY4 carry4_1st_full
(
.CYINIT(CI),
.CI (1'd0),
.DI (G [((i+1)*4 - 1):i*4]),
.S (S [((i+1)*4 - 1):i*4]),
.CO (CO[((i+1)*4 - 1):i*4]),
);
// Another one
end else begin
CARRY4 carry4_full
(
.CYINIT(1'd0),
.CI (C [i*4 - 1]),
.DI (G [((i+1)*4 - 1):i*4]),
.S (S [((i+1)*4 - 1):i*4]),
.CO (CO[((i+1)*4 - 1):i*4]),
);
end
end
end endgenerate
`endif
endmodule
// ============================================================================
// ALU
(* techmap_celltype = "$alu" *)
module _80_xilinx_alu (A, B, CI, BI, X, Y, CO);
parameter A_SIGNED = 0;
parameter B_SIGNED = 0;
parameter A_WIDTH = 1;
parameter B_WIDTH = 1;
parameter Y_WIDTH = 1;
parameter _TECHMAP_CONSTVAL_CI_ = 0;
parameter _TECHMAP_CONSTMSK_CI_ = 0;
input [A_WIDTH-1:0] A;
input [B_WIDTH-1:0] B;
output [Y_WIDTH-1:0] X, Y;
input CI, BI;
output [Y_WIDTH-1:0] CO;
wire _TECHMAP_FAIL_ = Y_WIDTH <= 2;
wire [Y_WIDTH-1:0] A_buf, B_buf;
\$pos #(.A_SIGNED(A_SIGNED), .A_WIDTH(A_WIDTH), .Y_WIDTH(Y_WIDTH)) A_conv (.A(A), .Y(A_buf));
\$pos #(.A_SIGNED(B_SIGNED), .A_WIDTH(B_WIDTH), .Y_WIDTH(Y_WIDTH)) B_conv (.A(B), .Y(B_buf));
wire [Y_WIDTH-1:0] AA = A_buf;
wire [Y_WIDTH-1:0] BB = BI ? ~B_buf : B_buf;
genvar i;
`ifdef _EXPLICIT_CARRY
wire [Y_WIDTH-1:0] S = AA ^ BB;
wire [Y_WIDTH-1:0] DI = 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.
wire [Y_WIDTH-1:0] CO_CHAIN;
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(DI[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(DI[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(DI[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(DI[i]),
.S(S[i]),
.CO_CHAIN(CO_CHAIN[i]),
.O(Y[i])
);
end
else
begin
CARRY top_of_carry (
.CI(C[i]),
.DI(DI[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
`else
localparam CARRY4_COUNT = (Y_WIDTH + 3) / 4;
localparam MAX_WIDTH = CARRY4_COUNT * 4;
localparam PAD_WIDTH = MAX_WIDTH - Y_WIDTH;
wire [MAX_WIDTH-1:0] S = {{PAD_WIDTH{1'b0}}, AA ^ BB};
wire [MAX_WIDTH-1:0] DI = {{PAD_WIDTH{1'b0}}, AA & BB};
wire [MAX_WIDTH-1:0] C = CO;
genvar i;
generate for (i = 0; i < CARRY4_COUNT; i = i + 1) begin:slice
// Partially occupied CARRY4
if ((i+1)*4 > Y_WIDTH) begin
// First one
if (i == 0) begin
CARRY4 carry4_1st_part
(
.CYINIT(CI),
.CI (1'd0),
.DI (DI[(Y_WIDTH - 1):i*4]),
.S (S [(Y_WIDTH - 1):i*4]),
.O (Y [(Y_WIDTH - 1):i*4]),
.CO (CO[(Y_WIDTH - 1):i*4])
);
// Another one
end else begin
CARRY4 carry4_part
(
.CYINIT(1'd0),
.CI (C [i*4 - 1]),
.DI (DI[(Y_WIDTH - 1):i*4]),
.S (S [(Y_WIDTH - 1):i*4]),
.O (Y [(Y_WIDTH - 1):i*4]),
.CO (CO[(Y_WIDTH - 1):i*4])
);
end
// Fully occupied CARRY4
end else begin
// First one
if (i == 0) begin
CARRY4 carry4_1st_full
(
.CYINIT(CI),
.CI (1'd0),
.DI (DI[((i+1)*4 - 1):i*4]),
.S (S [((i+1)*4 - 1):i*4]),
.O (Y [((i+1)*4 - 1):i*4]),
.CO (CO[((i+1)*4 - 1):i*4])
);
// Another one
end else begin
CARRY4 carry4_full
(
.CYINIT(1'd0),
.CI (C [i*4 - 1]),
.DI (DI[((i+1)*4 - 1):i*4]),
.S (S [((i+1)*4 - 1):i*4]),
.O (Y [((i+1)*4 - 1):i*4]),
.CO (CO[((i+1)*4 - 1):i*4])
);
end
end
end endgenerate
`endif
assign X = S;
endmodule
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