我不太理解以下code（bimpy.v）的无符号2位乘法操作。
编辑：根据我的一个朋友的评论，以下修改使用更少的逻辑也可以完成相同的操作！
代码与2位乘2位二进制乘法器门级图不匹配，请纠正我如果我错了。
编辑：根据我的一个朋友的评论，以下修改使用更少的逻辑也可以完成相同的操作！
o_r <= (i_a[0] ? i_b : 2'b0) + ((i_a[1] ? i_b : 2'b0) << 1);
assign w_r = { ((i_a[1])?i_b:{(BW){1'b0}}), 1'b0 }
^ { 1'b0, ((i_a[0])?i_b:{(BW){1'b0}}) };
assign c = { ((i_a[1])?i_b[(BW-2):0]:{(BW-1){1'b0}}) }
& ((i_a[0])?i_b[(BW-1):1]:{(BW-1){1'b0}});
代码与2位乘2位二进制乘法器门级图不匹配，请纠正我如果我错了。
我也附上了一个来自bimpy.v的工作波形，用于简单的2x2无符号乘法器。
我还为bimpy.v生成了门级表示图。
////////////////////////////////////////////////////////////////////////////////
//
// Filename: bimpy
//
// Project: A multiply core generator
//
// Purpose: An unsigned 2-bit multiply based upon the fact that LUT's allow
// 6-bits of input, but a 2x2 bit multiply will never carry more
// than one bit. While this multiply is hardware independent, it is
// really motivated by trying to optimize for a specific piece of
// hardware (Xilinx-7 series ...) that has 4-input LUT's with carry
// chains.
//
// Creator: Dan Gisselquist, Ph.D.
// Gisselquist Technology, LLC
//
////////////////////////////////////////////////////////////////////////////////
//
// Copyright (C) 2015,2017-2019, Gisselquist Technology, LLC
//
// This program is free software (firmware): you can redistribute it and/or
// modify it under the terms of the GNU General Public License as published
// by the Free Software Foundation, either version 3 of the License, or (at
// your option) any later version.
//
// This program is distributed in the hope that it will be useful, but WITHOUT
// ANY WARRANTY; without even the implied warranty of MERCHANTIBILITY or
// FITNESS FOR A PARTICULAR PURPOSE. See the GNU General Public License
// for more details.
//
// You should have received a copy of the GNU General Public License along
// with this program. If not, see <http://www.gnu.org/licenses/> for a
// copy.
//
// License: GPL, v3, as defined and found on www.gnu.org,
// http://www.gnu.org/licenses/gpl.html
//
//
////////////////////////////////////////////////////////////////////////////////
module bimpy(i_clk, i_reset, i_ce, i_a, i_b, o_r);
parameter BW=2, LUTB=2;
input i_clk, i_reset, i_ce;
input [(LUTB-1):0] i_a;
input [(BW-1):0] i_b;
output reg [(BW+LUTB-1):0] o_r;
wire [(BW+LUTB-2):0] w_r;
wire [(BW+LUTB-3):1] c;
assign w_r = { ((i_a[1])?i_b:{(BW){1'b0}}), 1'b0 }
^ { 1'b0, ((i_a[0])?i_b:{(BW){1'b0}}) };
assign c = { ((i_a[1])?i_b[(BW-2):0]:{(BW-1){1'b0}}) }
& ((i_a[0])?i_b[(BW-1):1]:{(BW-1){1'b0}});
initial o_r = 0;
always @(posedge i_clk)
if (i_reset)
o_r <= 0;
else if (i_ce)
o_r <= w_r + { c, 2'b0 };
endmodule