`default_nettype none

//  Top level io for this module should stay the same to fit into the scan_wrapper.
//  The pin connections within the user_module are up to you,
//  although (if one is present) it is recommended to place a clock on io_in[0].
//  This allows use of the internal clock divider if you wish.
//
//  so, just somehow calculate x^2+y^2 with random
//  0<x, y<1, and compare it with 1
//  using 8-bit fixed point, [7:0]x means x/2**8
//  0.0039 resolution is really coarse...
module user_module_341521390605697619(
	input [7:0] io_in, 
	output reg [7:0] io_out
);
	wire clk = io_in[0];
	wire rst = io_in[1];
	wire [5:0]sw1 = io_in[7:2];

	always @ (*) begin
		io_out = 0;
		case(sw1[1:0])
			0: io_out = cnt[7:0];
			1: io_out = cnt_in[7:0];
			2: io_out = {6'b0, cnt[0], cnt_in[0]};
			//2: io_out = {cnt[10:8], cnt_in[10:8], cnt[0], cnt_in[0]};
			//3: io_out = cnt_in[15:8];
			//4: io_out = {mulin1, mulin2};
			//5: io_out = mulout;
		endcase
	end

	reg [8:0]breg;
	reg [7:0]breg2; // shouldn't exceed 7:0 because x^2<1 when 0<x<1
	reg [7:0]x;

	reg [3:0]mulin1;
	reg [3:0]mulin2;
	wire [7:0]mulout;
	//mul_341521390605697619 #(.WIDTH(4)) mul_inst(
	mul4_341521390605697619 mul_inst(
		.a(mulin1),
		.b(mulin2),
		.c(mulout)
	);

	reg [7:0]addin1;
	reg [7:0]addin2;
	wire [8:0]addout;
	assign addout = addin1 + addin2;

	// not very random actually, should somehow 
	// receive seed from outside
	reg [7:0]random = 8'h01;
	//reg del = 0;
	always @ (posedge clk) begin
		//if (sw1[4] == 0) del <= ~del;
		//else del <= sw1[3];
		random <= {random[6:0], (random[7] ^ random[5] ^ random[4] ^ random[3])};
	end

	reg [3:0]sts;
	reg [7:0]cnt;
	reg [7:0]cnt_in;
	always @ (posedge clk) begin
		if (rst) begin
			sts <= 0;
			cnt <= 0;
			cnt_in <= 0;
			//x <= 0;
		end else begin
			if (sw1[5] == 0) begin
				case (sts)
					0: begin
						breg <= 0;
						x <= random;
					end
					4: begin
						x <= random;
						breg2 <= breg_in;
					end
					9: begin
						cnt <= cnt + 1;
						if (addout[8]) cnt_in <= cnt_in + 1;
					end
				endcase
				sts <= sts == 10 ? 0 : sts + 1;
				breg <= breg_in;
			end
		end
	end

	reg [8:0]breg_in;
	always @ (*) begin
		mulin1 = 0;
		mulin2 = 0;
		addin1 = 0;
		addin2 = 0;
		breg_in = 0;
		if (sts == 9) begin
			addin1 = breg;
			addin2 = breg2;
		end else begin
			case(sts[1:0])
				2'b01: begin
					mulin1 = x[3:0];
					mulin2 = x[3:0];
					breg_in = {1'b0, mulout};
				end
				2'b10: begin
					mulin1 = x[7:4];
					mulin2 = x[3:0];
					addin1 = {4'b0, breg[7:4]};
					addin2 = mulout;
					breg_in = addout;
				end
				2'b11: begin
					mulin1 = x[3:0];
					mulin2 = x[7:4];
					addin1 = breg[7:0];
					addin2 = mulout;
					breg_in = addout;
				end
				2'b00: begin
					mulin1 = x[7:4];
					mulin2 = x[7:4];
					addin1 = {3'b0, breg[8:4]};
					addin2 = mulout;
					breg_in = addout;
				end
			endcase
		end
	end
endmodule

module add_341521390605697619
#(parameter WIDTH = 8)
(
	input [WIDTH-1:0]a,
	input [WIDTH-1:0]b,
	output [WIDTH:0]c
);
assign c = a + b;
endmodule

module mul4_341521390605697619
(
	input [3:0] a,
	input [3:0] b,
	output [7:0] c
);
//assign c = {
	//ll,
	//t[3] ^ jj ^ kk,
	//z[3] ^ t[2] ^ gg ^ hh ^ ii,
	//y[3] ^ z[2] ^ t[1] ^ dd ^ ee ^ ff,
	//x[3] ^ y[2] ^ z[1] ^ t[0] ^ bb ^ cc,
	//x[2] ^ y[1] ^ z[0] ^ aa,
	//x[1] ^ y[0],
	//x[0]
	//};
wire [3:0]x = b[0] ? a : 0;
wire [3:0]y = b[1] ? a : 0;
wire [3:0]z = b[2] ? a : 0;
wire [3:0]t = b[3] ? a : 0;
//wire aa = x[1] & y[0];

assign c = {
	add3,
	add2[0],
	add1[0],
	x[0]
	};
wire [4:0]add1;
add_341521390605697619 #(.WIDTH(4)) add_1(
	.a({1'b0, x[3:1]}),
	.b(y),
	.c(add1)
);

wire [4:0]add2;
add_341521390605697619 #(.WIDTH(4)) add_2(
	.a(add1[4:1]),
	.b(z),
	.c(add2)
);

wire [4:0]add3;
add_341521390605697619 #(.WIDTH(4)) add_3(
	.a(add2[4:1]),
	.b(t),
	.c(add3)
);


//wire bb = (x[2] & y[1]) | ((x[2] ^ y[1]) & (z[0] ^ aa));
//wire cc = z[0] & aa;

//wire dd = x[3] & y[2] | ((x[3] ^ y[2]) & (z[1] ^ t[0]));
//wire ee = z[1] & t[0] | ((x[3] ^ y[2]) & (bb ^ cc));
//wire ff = bb & cc | ((bb ^ cc) & (z[1] ^ t[0]));

//wire gg = (y[3] ^ z[2]) | ();
//wire hh = (dd ^ ee) | ();
//wire ii = (t[2] ^ ff) | ();

//wire jj = z[3] ^ t[2];
//wire kk = (gg & (hh | ii)) || (hh & ii);

//wire ll = (t[3] & (jj | kk)) || (jj & kk);
endmodule
/*
 *  my_multiplier - an unoptimized multiplier
 *
 *  copyright (c) 2021  hirosh dabui <hirosh@dabui.de>
 *
 *  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.
 *
 */
//module mul_341521390605697619
//#(
	//parameter WIDTH = 16
//)
//(
	//input      [WIDTH-1:0]      a,
	//input      [WIDTH-1:0]      b,
	//output reg [(WIDTH<<1)-1:0] c = 0
//);

//reg [(WIDTH<<1)-1:0] tmp;

//reg  [(WIDTH<<1)-1:0] add_a[WIDTH-1:0];
//reg  [(WIDTH<<1)-1:0] add_b[WIDTH-1:0];
//wire [(WIDTH<<1)-1:0] add_y[WIDTH-1:0];

//genvar k;
//generate for (k = 0; k < WIDTH; k = k +1) begin
		//full_addr_341521390605697619 #(WIDTH<<1) full_addr_i(add_a[k], add_b[k], add_y[k]);
	//end endgenerate

//integer i;
//integer j;
//generate always @(*) begin
		//tmp = 0;
		//c   = 0;

		//[> generate parallel structure <]
		//for (j = 0; j < WIDTH; j = j + 1) begin
			//for (i = 0; i < WIDTH; i = i + 1) begin
				//tmp[i] = b[i] & a[j];
			//end
			//add_a[j] = c;
			//add_b[j] = (tmp << j);
			//c = add_y[j];
		//end
	//end endgenerate

//endmodule

//// carry ripple style
//module full_addr_341521390605697619
//#(
	//parameter WIDTH = 16
//)
//(
	//input      [WIDTH-1:0] a,
	//input      [WIDTH-1:0] b,
	//output reg [WIDTH-1:0] y = 0
//);

//integer i;
//reg [WIDTH-1:0] c = 1;
//generate always @(*) begin
		//c[0] = 0;
		//y[0] = c[0] ^ (a[0] ^ b[0]);
		//c[0] = a[0]&b[0] | b[0]&c[0] | a[0]&c[0];
		//for (i = 1; i < WIDTH; i = i +1) begin
			//y[i] = c[i -1] ^ (a[i] ^ b[i]);
			//c[i] = a[i]&b[i] | b[i]&c[i -1] | a[i]&c[i -1];
		//end
	//end endgenerate

//endmodule