2 * yosys -- Yosys Open SYnthesis Suite
4 * Copyright (C) 2012 Claire Xen <claire@symbioticeda.com>
5 * Copyright (C) 2018 David Shah <dave@ds0.me>
7 * Permission to use, copy, modify, and/or distribute this software for any
8 * purpose with or without fee is hereby granted, provided that the above
9 * copyright notice and this permission notice appear in all copies.
11 * THE SOFTWARE IS PROVIDED "AS IS" AND THE AUTHOR DISCLAIMS ALL WARRANTIES
12 * WITH REGARD TO THIS SOFTWARE INCLUDING ALL IMPLIED WARRANTIES OF
13 * MERCHANTABILITY AND FITNESS. IN NO EVENT SHALL THE AUTHOR BE LIABLE FOR
14 * ANY SPECIAL, DIRECT, INDIRECT, OR CONSEQUENTIAL DAMAGES OR ANY DAMAGES
15 * WHATSOEVER RESULTING FROM LOSS OF USE, DATA OR PROFITS, WHETHER IN AN
16 * ACTION OF CONTRACT, NEGLIGENCE OR OTHER TORTIOUS ACTION, ARISING OUT OF
17 * OR IN CONNECTION WITH THE USE OR PERFORMANCE OF THIS SOFTWARE.
21 (* techmap_celltype = "$alu" *)
22 module _80_nexus_alu (A, B, CI, BI, X, Y, CO);
23 parameter A_SIGNED = 0;
24 parameter B_SIGNED = 0;
25 parameter A_WIDTH = 1;
26 parameter B_WIDTH = 1;
27 parameter Y_WIDTH = 1;
30 input [A_WIDTH-1:0] A;
32 input [B_WIDTH-1:0] B;
34 output [Y_WIDTH-1:0] X, Y;
38 output [Y_WIDTH-1:0] CO;
40 wire _TECHMAP_FAIL_ = Y_WIDTH <= 4;
43 wire [Y_WIDTH-1:0] A_buf, B_buf;
44 \$pos #(.A_SIGNED(A_SIGNED), .A_WIDTH(A_WIDTH), .Y_WIDTH(Y_WIDTH)) A_conv (.A(A), .Y(A_buf));
45 \$pos #(.A_SIGNED(B_SIGNED), .A_WIDTH(B_WIDTH), .Y_WIDTH(Y_WIDTH)) B_conv (.A(B), .Y(B_buf));
47 function integer round_up2;
50 round_up2 = ((N + 1) / 2) * 2;
54 localparam Y_WIDTH2 = round_up2(Y_WIDTH);
57 wire [Y_WIDTH2-1:0] AA = A_buf;
59 wire [Y_WIDTH2-1:0] BB = BI ? ~B_buf : B_buf;
61 wire [Y_WIDTH2-1:0] BX = B_buf;
63 wire [Y_WIDTH2+1:0] FCO, Y1;
73 .A0(1'b1), .B0(1'b1), .C0(1'b1), .D0(1'b1),
74 .A1(CI), .B1(1'b1), .C1(1'b1), .D1(1'b1),
78 generate for (i = 0; i < Y_WIDTH2; i = i + 2) begin:slice
85 .A0(AA[i]), .B0(BX[i]), .C0(BI), .D0(1'b1),
86 .A1(AA[i+1]), .B1(BX[i+1]), .C1(BI), .D1(1'b1),
87 .S0(Y[i]), .S1(Y1[i]),
91 assign CO[i] = (AA[i] && BB[i]) || ((Y[i] ^ AA[i] ^ BB[i]) && (AA[i] || BB[i]));
92 if (i+1 < Y_WIDTH) begin
93 assign CO[i + 1] = (AA[i] && BB[i]) || ((Y[i] ^ AA[i] ^ BB[i]) && (AA[i] || BB[i]));
94 assign Y[i+1] = Y1[i];