/* 
 * MandelFPGA
 * by Joshua Wise and Chris Lu
 * 
 * An implementation of a pipelined algorithm to calculate the Mandelbrot set
 * in real time on an FPGA.
 */
 
/* verilator lint_off WIDTH */

`define XRES 640
`define YRES 480
`define WHIRRRRR 27

module SyncGen(
	input pixclk,
	output reg vs, hs,
	output reg [11:0] xout = `WHIRRRRR, yout = 0,
	output wire [11:0] xoutreal, youtreal,
	output reg border);
	
	reg [11:0] x = 0, y = 0;	// Used for generating border and timing.
	assign xoutreal = x;
	assign youtreal = y;
	
	parameter XFPORCH = 16;
	parameter XSYNC = 96;
	parameter XBPORCH = 48;
	
	parameter YFPORCH = 10;
	parameter YSYNC = 2;
	parameter YBPORCH = 29;

	always @(posedge pixclk)
	begin
		if (x >= (`XRES + XFPORCH + XSYNC + XBPORCH))
		begin
			if (y >= (`YRES + YFPORCH + YSYNC + YBPORCH))
				y <= 0;
			else
				y <= y + 1;
			x <= 0;
		end else
			x <= x + 1;
			
		if (xout >= (`XRES + XFPORCH + XSYNC + XBPORCH))
		begin
			if (yout >= (`YRES + YFPORCH + YSYNC + YBPORCH))
				yout <= 0;
			else
				yout <= yout + 1;
			xout <= 0;
		end else
			xout <= xout + 1;
		hs <= (x >= (`XRES + XFPORCH)) && (x < (`XRES + XFPORCH + XSYNC));
		vs <= (y >= (`YRES + YFPORCH)) && (y < (`YRES + YFPORCH + YSYNC));
		border <= (x > `XRES) || (y > `YRES);
	end
endmodule

// bits: 1.12

module NaiveMultiplier(
	input clk,
	input [12:0] x, y,
	input xsign, ysign,
	output reg [12:0] out,
	output reg sign,
	output reg ovf);

	always @(posedge clk)
	begin
		{ovf,out} <=
			(((y[12] ? (x       ) : 0)   +
			  (y[11] ? (x[12:1]) : 0)   +
			  (y[10] ? (x[12:2]) : 0))  +
			(((y[9]  ? (x[12:3]) : 0)   +
			  (y[8]  ? (x[12:4]) : 0))  +
			 ((y[7]  ? (x[12:5]) : 0)   +
			  (y[6]  ? (x[12:6]) : 0))))+
			(((y[5]  ? (x[12:7]) : 0)   +
			  (y[4]  ? (x[12:8]) : 0)   +
			  (y[3]  ? (x[12:9]) : 0))  +
			 ((y[2]  ? (x[12:10]): 0)   +
			  (y[1]  ? (x[12:11]): 0)   +
			  (y[0]  ? (x[12]): 0)));
		sign <= xsign ^ ysign;
	end

endmodule

module Multiplier(
	input clk,
	input [12:0] x, y,
	input xsign, ysign,
	output wire [12:0] out,
	output wire sign,
	output wire overflow);

	NaiveMultiplier nm(clk, x, y, xsign, ysign, out, sign, overflow);

endmodule

// Yuq.
module MandelUnit(
	input clk,
	input [12:0] x, y,
	input xsign, ysign,
	input [14:0] r, i,
	input rsign, isign,
	input [7:0] ibail, icuriter,
	output reg [12:0] xout, yout,
	output reg xsout, ysout,
	output reg [14:0] rout, iout,
	output reg rsout, isout,
	output reg [7:0] obail, ocuriter);

	wire [13:0] r2, i2;
	wire [14:0] ri, diff;
	wire [15:0] twocdiff;
	wire r2sign, i2sign, risign, dsign;
	wire [14:0] bigsum;
	wire bigsum_ovf;

	reg [12:0] xd, yd;
	reg ineedbaild;
	reg xsd, ysd;
	reg [7:0] ibaild, curiterd;

	assign ri[0] = 0;

	Multiplier r2m(clk, r[12:0], r[12:0], rsign, rsign, r2[12:0], r2sign, r2[13]);
	Multiplier i2m(clk, i[12:0], i[12:0], isign, isign, i2[12:0], i2sign, i2[13]);
	Multiplier rim(clk, r[12:0], i[12:0], rsign, isign, ri[13:1], risign, ri[14]);

	assign bigsum = r2[13:0] + i2[13:0];
	assign bigsum_ovf = bigsum[14];
	
	assign twocdiff = r2 - i2;
	assign diff = twocdiff[15] ? -twocdiff : twocdiff;
	assign dsign = twocdiff[15];
	
	wire [15:0] twocrout = xd - diff;
	wire [15:0] twociout = yd - ri;

	always @ (posedge clk)
	begin
		xd <= x;
		yd <= y;
		xsd <= xsign;
		ysd <= ysign;
		xout <= xd;
		yout <= yd;
		xsout <= xsd;
		ysout <= ysd;
		ibaild <= ibail;
		curiterd <= icuriter;
		ineedbaild <= r[13] | r[14] | i[13] | i[14];

		// r^2 - i^2 + x
		if (xsd ^ dsign) begin
			if (twocrout[15]) begin	// diff > xd
				rout <= -twocrout;
				rsout <= dsign;
			end else begin
				rout <= twocrout;
				rsout <= xsd;
			end
		end else begin
			rout <= diff + xd;
			rsout <= xsd;	// xsd == dsign
		end
		
		// 2 * r * i + y
		if (ysd ^ risign) begin
			if (twociout[15]) begin	// ri > yd
				iout <= -twociout;
				isout <= risign;
			end else begin
				iout <= twociout;
				isout <= ysd;
			end
		end else begin
			iout <= ri + yd;
			isout <= ysd;
		end
		
		// If we haven't bailed out, and we meet any of the bailout conditions,
		// bail out now.  Otherwise, leave the bailout at whatever it was before.
		if ((ibaild == 255) && (bigsum_ovf | ineedbaild))
			obail <= curiterd;
		else
			obail <= ibaild;
		ocuriter <= curiterd + 8'b1;
	end

endmodule

module Mandelbrot(
	input mclk,
	input pixclk,
	input [11:0] x, y,
	input [13:0] xofs, yofs,
	input [7:0] colorofs,
	input [2:0] scale,
	output reg [2:0] red, green, output reg [1:0] blue);

`define MAXOUTN 11
	
	wire [12:0] rx, ry;
	wire [13:0] nx, ny;
	wire rxsign, rysign;
	
	assign nx = {2'b0,x} + {2'b0,xofs};
	assign ny = {2'b0,y} + {2'b0,yofs};
	assign rx = (nx[13] ? -nx[12:0] : nx[12:0]) << scale;
	assign rxsign = nx[13];
	assign ry = (ny[13] ? -ny[12:0] : ny[12:0]) << scale;
	assign rysign = ny[13];

	wire [14:0] mr[`MAXOUTN:0], mi[`MAXOUTN:0];
	wire mrs[`MAXOUTN:0], mis[`MAXOUTN:0];
	wire [7:0] mb[`MAXOUTN:0];
	wire [12:0] xprop[`MAXOUTN:0], yprop[`MAXOUTN:0];
	wire xsprop[`MAXOUTN:0], ysprop[`MAXOUTN:0];
	wire [7:0] curiter[`MAXOUTN:0];
	
	reg [12:0] initx, inity;
	reg [14:0] initr, initi;
	reg [7:0] initci, initb;
	reg initxs, initys, initrs, initis;
	
	// Values after the number of iterations denoted by the subscript.
	reg [12:0] stagex [2:1], stagey [2:1];
	reg [14:0] stager [2:1], stagei [2:1];
	reg [7:0] stageci [2:1], stageb [2:1];
	reg stagexs [2:1], stageys [2:1], stagers [2:1], stageis [2:1];
	
	reg [2:0] state = 3'b001;	// One-hot encoded state.
	
	// States are advanced one from what they should be, so that they'll
	// get there on the _next_ mclk.
	always @(posedge mclk)
	begin
		initx <= (state[2]) ? rx :
	            (state[0]) ? stagex[1] :
	            (state[1]) ? stagex[2] : 0;
		inity <= (state[2]) ? ry :
	               (state[0]) ? stagey[1] :
	               (state[1]) ? stagey[2] : 0;
		initr <= (state[2]) ? {2'b0,rx} :
	               (state[0]) ? stager[1] :
	               (state[1]) ? stager[2] : 0;
		initi <= (state[2]) ? {2'b0,ry} :
	               (state[0]) ? stagei[1] :
	               (state[1]) ? stagei[2] : 0;
		initxs <= (state[2]) ? rxsign :
	                (state[0]) ? stagexs[1] :
	                (state[1]) ? stagexs[2] : 0;
		initys <= (state[2]) ? rysign :
	                (state[0]) ? stageys[1] :
	                (state[1]) ? stageys[2] : 0;
		initrs <= (state[2]) ? rxsign :
	                (state[0]) ? stagers[1] :
	                (state[1]) ? stagers[2] : 0;
		initis <= (state[2]) ? rysign :
	                (state[0]) ? stageis[1] :
	                (state[1]) ? stageis[2] : 0;
		initb <= (state[2]) ? 8'b11111111 :
	               (state[0]) ? stageb[1] :
	               (state[1]) ? stageb[2] : 0;
		initci <= (state[2]) ? 8'b00000000 :
	                (state[0]) ? stageci[1] : 
	                (state[1]) ? stageci[2] : 0;
	end
	
	reg [7:0] out;
	
	// We detect when the state should be poked by a high negedge followed
	// by a high posedge -- if that happens, then we're guaranteed that the
	// state following the current state will be 3'b100.
	reg lastneg;
	always @(negedge mclk)
		lastneg <= pixclk;
	
	always @(posedge mclk)
	begin
		if (lastneg && pixclk)	// If a pixclk has happened, the state should be reset.
			state <= 3'b100;
		else						// Otherwise, just poke it forward.
			case(state)
			3'b001: state <= 3'b010;
			3'b010: state <= 3'b100;
			3'b100: state <= 3'b001;
		`ifdef isim
			default: begin $display("invalid state"); $finish; end
		`endif
			endcase
	
		// Data output handling
		if (state[0]) begin
			{red, green, blue} <= {out[0],out[3],out[6],out[1],out[4],out[7],out[2],out[5]};
		end
		if (state[1]) begin
			out <= ~mb[`MAXOUTN] + colorofs;
		end
		
		if (state[0]) begin		// PnR0 in, PnR2 out
			stagex[2] <= xprop[`MAXOUTN];
			stagey[2] <= yprop[`MAXOUTN];
			stager[2] <= mr[`MAXOUTN];
			stagei[2] <= mi[`MAXOUTN];
			stagexs[2] <= xsprop[`MAXOUTN];
			stageys[2] <= ysprop[`MAXOUTN];
			stagers[2] <= mrs[`MAXOUTN];
			stageis[2] <= mis[`MAXOUTN];
			stageb[2] <= mb[`MAXOUTN];
			stageci[2] <= curiter[`MAXOUTN];
		end
		
		if (state[2]) begin	// PnR2 in, PnR1 out
			stagex[1] <= xprop[`MAXOUTN];
			stagey[1] <= yprop[`MAXOUTN];
			stager[1] <= mr[`MAXOUTN];
			stagei[1] <= mi[`MAXOUTN];
			stagexs[1] <= xsprop[`MAXOUTN];
			stageys[1] <= ysprop[`MAXOUTN];
			stagers[1] <= mrs[`MAXOUTN];
			stageis[1] <= mis[`MAXOUTN];
			stageb[1] <= mb[`MAXOUTN];
			stageci[1] <= curiter[`MAXOUTN];
		end
	end

	MandelUnit mu0(
		mclk,
		initx, inity, initxs, initys,
		initr, initi, initrs, initis,
		initb, initci,
		xprop[0], yprop[0], xsprop[0], ysprop[0],
		mr[0], mi[0], mrs[0], mis[0],
		mb[0], curiter[0]);
		
`define MAKE_UNIT(name, num) \
	MandelUnit name(mclk, \
		xprop[(num)], yprop[(num)], xsprop[(num)], ysprop[(num)], mr[(num)], mi[(num)], mrs[(num)], mis[(num)], mb[(num)], curiter[(num)], \
		xprop[(num)+1], yprop[(num)+1], xsprop[(num)+1], ysprop[(num)+1], mr[(num)+1], mi[(num)+1], mrs[(num)+1], mis[(num)+1], mb[(num)+1], curiter[(num)+1])

	`MAKE_UNIT(mu1, 0);
	`MAKE_UNIT(mu2, 1);
	`MAKE_UNIT(mu3, 2);
	`MAKE_UNIT(mu4, 3);
	`MAKE_UNIT(mu5, 4);
	`MAKE_UNIT(mu6, 5);
	`MAKE_UNIT(mu7, 6);
	`MAKE_UNIT(mu8, 7);
	`MAKE_UNIT(mu9, 8);
	`MAKE_UNIT(mua, 9);
	`MAKE_UNIT(mub, 10);
endmodule

module Logo(
	input pixclk,
	input [11:0] x, y,
	output wire enb,
	output wire [2:0] red, green, output wire [1:0] blue);
	
	reg [1:0] logo[8191:0];
	initial $readmemb("logo.readmemb", logo);
	
	assign enb = (x < 96) && (y < 64);
	wire [12:0] addr = {y[5:0], x[6:0]};
	wire [1:0] data = logo[addr];
	assign {red, green, blue} = 
		 (data == 2'b00) ? 8'b00000000 :
		((data == 2'b01) ? 8'b00011100 :
		((data == 2'b10) ? 8'b11100000 :
		                    8'b11111111));
endmodule

module MandelTop(
`ifdef verilator
	input pixclk, mclk,
`else
	input gclk, output wire dcmok,
`endif
	output wire vs, hs,
	output wire [2:0] red, green, output [1:0] blue,
	input left, right, up, down, rst, cycle, logooff,
	input [2:0] scale);
	
`ifdef verilator
`else
	wire pixclk, mclk, clk;
	wire dcm1ok, dcm2ok;
	assign dcmok = dcm1ok && dcm2ok;
	
	IBUFG iclkbuf(.O(clk), .I(gclk));
	
	pixDCM dcm(					// CLKIN is 50MHz xtal, CLKFX_OUT is 25MHz
		.CLKIN_IN(clk), 
		.CLKFX_OUT(pixclk),
		.LOCKED_OUT(dcm1ok)
		);
	
	mandelDCM dcm2(
		.CLKIN_IN(clk),
		.CLKFX_OUT(mclk),
		.LOCKED_OUT(dcm2ok)
		);
`endif

	wire border;
	wire [11:0] x, y;
	reg [13:0] xofs = -`XRES/2, yofs = -`YRES/2;
	reg [5:0] slowctr = 0;
	reg [7:0] colorcycle = 0;
	wire [11:0] realx, realy;
	
	wire logoenb;
	wire [2:0] mandelr, mandelg, logor, logog;
	wire [1:0] mandelb, logob;
	
	SyncGen sync(pixclk, vs, hs, x, y, realx, realy, border);
	Mandelbrot mandel(mclk, pixclk, x, y, xofs, yofs, cycle ? colorcycle : 8'b0, scale, mandelr, mandelg, mandelb);
	Logo logo(pixclk, realx, realy, logoenb, logor, logog, logob);
	
	assign {red,green,blue} =
		border ? 8'b00000000 :
		(!logooff && logoenb) ? {logor, logog, logob} : {mandelr, mandelg, mandelb};
	
	always @(posedge vs)
	begin
		if (rst)
		begin
			xofs <= -`XRES/2;
			yofs <= -`YRES/2;
			colorcycle <= 0;
		end else begin
			if (up) yofs <= yofs + 1;
			else if (down) yofs <= yofs - 1;
			
			if (left) xofs <= xofs + 1;
			else if (right) xofs <= xofs - 1;
			
			if (slowctr == 0)
				colorcycle <= colorcycle + 1;
		end
		
		if (slowctr == 12)
			slowctr <= 0;
		else
			slowctr <= slowctr + 1;
	end
endmodule