MacPlus_MiSTer/rtl/ps2_mouse.v

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2017-10-22 01:22:56 +00:00
`timescale 1ns / 100ps
/*
* PS2 mouse protocol
* Bit 7 6 5 4 3 2 1 0
* Byte 0: YOVR XOVR YSGN XSGN 1 MBUT RBUT LBUT
* Byte 1: XMOVE
* Byte 2: YMOVE
*/
/*
* PS2 Mouse to Mac interface module
*/
module ps2_mouse
(
input clk,
input ce,
input reset,
input [24:0] ps2_mouse,
output reg x1,
output reg y1,
output reg x2,
output reg y2,
output reg button
);
reg [9:0] xacc;
reg [9:0] yacc;
reg [11:0] clkdiv;
wire strobe = (old_stb != ps2_mouse[24]);
reg old_stb = 0;
always @(posedge clk) old_stb <= ps2_mouse[24];
/* Capture button state */
always@(posedge clk or posedge reset)
if (reset) button <= 1;
else if (strobe) button <= ~(|ps2_mouse[2:0]);
/* Clock divider to flush accumulators */
always@(posedge clk or posedge reset)
if (reset) clkdiv <= 0;
else if(ce) clkdiv <= clkdiv + 1'b1;
wire tick = (ce && clkdiv == 0);
/* Toggle output lines base on accumulator */
always@(posedge clk or posedge reset) begin
if (reset) begin
x1 <= 0;
x2 <= 0;
end else if (tick && xacc != 0) begin
x1 <= ~x1;
x2 <= ~x1 ^ ~xacc[9];
end
end
always@(posedge clk or posedge reset) begin
if (reset) begin
y1 <= 0;
y2 <= 0;
end else if (tick && yacc != 0) begin
y1 <= ~y1;
y2 <= ~y1 ^ ~yacc[9];
end
end
/* Movement accumulators. Needs tuning ! */
always@(posedge clk or posedge reset) begin
if (reset) xacc <= 0;
else begin
/* Add movement, convert to a 10-bit number if not over */
if (strobe && xacc[8] == xacc[9]) xacc <= xacc + { ps2_mouse[4], ps2_mouse[4], ps2_mouse[15:8] };
else
/* Decrement */
if (tick && xacc != 0) xacc <= xacc + { {9{~xacc[9]}}, 1'b1 };
end
end
always@(posedge clk or posedge reset) begin
if (reset) yacc <= 0;
else begin
/* Add movement, convert to a 10-bit number if not over*/
if (strobe && yacc[8] == yacc[9]) yacc <= yacc + { ps2_mouse[5], ps2_mouse[5], ps2_mouse[23:16] };
else
/* Decrement */
if (tick && yacc != 0) yacc <= yacc + { {9{~yacc[9]}}, 1'b1 };
end
end
endmodule