ewattadder.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* unpublished proprietary information of Silicon Graphics, Inc., and *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: ewattadder.v,v 1.2 2002/11/22 00:34:20 rws Exp $
/////////////////////////////////////////////////////////////////////////
//
// Project Reality
//
// module: ewattadders
// description: two 16-bit adders to compute attributes at triangle
// edge.
//
// designer: Mike M. Cai 6/18/94
//
/////////////////////////////////////////////////////////////////////////
module ewattadder(wa_data,
in_att, in_dade,
cs_ew_data,
add32b, add_clear, ld_a,
ew_stall_attr, clk, start_gclk);
output [31:0] wa_data; // data write to Attribute port of RF
input [31:0] in_att, in_dade;
input [31:0] cs_ew_data;
input add32b, add_clear;
input ld_a;
input ew_stall_attr, clk, start_gclk;
wire [31:0] sum;
wire msbcarryin, lsbcarryin;
wire msbcarryout, lsbcarryout;
reg msbcarryout_s, lsbcarryout_s;
reg [31:0] sum_att;
wire [31:0] sum_att_delay;
wire [31:0] wa_data;
adder16bi addermsb(.sum(sum[31:16]), .co(msbcarryout), .a(in_att[31:16]),
.b(in_dade[31:16]), .ci(msbcarryin)),
adderlsb(.sum(sum[15:0]), .co(lsbcarryout), .a(in_att[15:0]),
.b(in_dade[15:0]), .ci(lsbcarryin));
always @(posedge clk)
if (start_gclk) begin
msbcarryout_s <= ew_stall_attr ? msbcarryout_s : msbcarryout;
lsbcarryout_s <= ew_stall_attr ? lsbcarryout_s : lsbcarryout;
sum_att <= ew_stall_attr ? sum_att : sum;
end
ewrfdelay delaywdata(.out_data(sum_att_delay), .in_data(sum_att));
assign
wa_data = ld_a ? cs_ew_data : sum_att_delay,
msbcarryin = add32b ? lsbcarryout: (msbcarryout_s & ~add_clear),
lsbcarryin = lsbcarryout_s & ~add_clear;
endmodule // ewattadder