stz.v
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/**************************************************************************
* *
* Copyright (C) 1994, Silicon Graphics, Inc. *
* *
* These coded instructions, statements, and computer programs contain *
* unpublished proprietary information of Silicon Graphics, Inc., and *
* are protected by Federal copyright law. They may not be disclosed *
* to third parties or copied or duplicated in any form, in whole or *
* in part, without the prior written consent of Silicon Graphics, Inc. *
* *
*************************************************************************/
// $Id: stz.v,v 1.2 2002/11/22 00:34:20 rws Exp $
/* Project Reality
RDP
Created by Mike M. Cai 5/30/94
*/
module stz( att_data_out,
att_data_in, dx, dy, x_offset, y_offset,
left_major, load, ncyc, clk, start_gclk);
output [17:0] att_data_out;
input [31:0] att_data_in, dx;
input [21:0] dy;
input [1:0] x_offset, y_offset;
input left_major, load, ncyc, clk, start_gclk;
wire [31:0] att_accum, dx_dir;
reg [31:0] att_cur_s;
wire [18:0] att_offset;
wire [17:0] att_clamp_value;
wire [17:0] att_clamped;
reg [17:0] att_data_out;
reg comp_new;
always @(posedge clk)
if (start_gclk) begin
att_cur_s <= load ? att_data_in : att_accum;
comp_new <= load ? ~ncyc : (ncyc ? ~comp_new : comp_new);
end
assign
dx_dir = (dx ~^ {32{left_major}}) & {32{comp_new}};
adder32b adder ( .sum(att_accum), .a(att_cur_s), .b(dx_dir),
.ci(~left_major & comp_new));
stzoffseti dooffset ( .att_data_out(att_offset), .att_data_in(att_cur_s[31:10]),
.dx(dx[31:10]), .dy(dy),
.x_offset(x_offset), .y_offset(y_offset));
assign
att_clamp_value = {18{~att_offset[17]}},
att_clamped = att_offset[18] ? att_clamp_value : att_offset[17:0];
always @(posedge clk)
if (start_gclk) begin
att_data_out <= att_clamped; // Z is always positive
end
endmodule // stz