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1 | // ========== Copyright Header Begin ========================================== |
2 | // | |
3 | // OpenSPARC T2 Processor File: wptr_full.v | |
4 | // Copyright (C) 1995-2007 Sun Microsystems, Inc. All Rights Reserved | |
5 | // 4150 Network Circle, Santa Clara, California 95054, U.S.A. | |
6 | // | |
7 | // * DO NOT ALTER OR REMOVE COPYRIGHT NOTICES OR THIS FILE HEADER. | |
8 | // | |
9 | // This program is free software; you can redistribute it and/or modify | |
10 | // it under the terms of the GNU General Public License as published by | |
11 | // the Free Software Foundation; version 2 of the License. | |
12 | // | |
13 | // This program is distributed in the hope that it will be useful, | |
14 | // but WITHOUT ANY WARRANTY; without even the implied warranty of | |
15 | // MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE. See the | |
16 | // GNU General Public License for more details. | |
17 | // | |
18 | // You should have received a copy of the GNU General Public License | |
19 | // along with this program; if not, write to the Free Software | |
20 | // Foundation, Inc., 59 Temple Place, Suite 330, Boston, MA 02111-1307 USA | |
21 | // | |
22 | // For the avoidance of doubt, and except that if any non-GPL license | |
23 | // choice is available it will apply instead, Sun elects to use only | |
24 | // the General Public License version 2 (GPLv2) at this time for any | |
25 | // software where a choice of GPL license versions is made | |
26 | // available with the language indicating that GPLv2 or any later version | |
27 | // may be used, or where a choice of which version of the GPL is applied is | |
28 | // otherwise unspecified. | |
29 | // | |
30 | // Please contact Sun Microsystems, Inc., 4150 Network Circle, Santa Clara, | |
31 | // CA 95054 USA or visit www.sun.com if you need additional information or | |
32 | // have any questions. | |
33 | // | |
34 | // ========== Copyright Header End ============================================ | |
35 | module wptr_full ( wfull,waddr,wptr,wrptr2,winc,wclk,wrst_n); | |
36 | parameter ADDRSIZE = 6; | |
37 | output wfull; | |
38 | output [ADDRSIZE-1:0] waddr; | |
39 | output [ADDRSIZE:0] wptr; | |
40 | input [ADDRSIZE:0] wrptr2; | |
41 | input winc,wclk,wrst_n; | |
42 | reg [ADDRSIZE:0] wptr,wbin,wgnext,wbnext; | |
43 | reg wfull,waddrmsb; | |
44 | ||
45 | // graystyle pointer | |
46 | ||
47 | always @(posedge wclk or negedge wrst_n) | |
48 | if ( !wrst_n ) begin | |
49 | wptr <= 0; | |
50 | waddrmsb <= 0; | |
51 | wgnext <= 0; | |
52 | wbnext <= 0; | |
53 | wbin <=0; | |
54 | end | |
55 | else begin | |
56 | wptr <= wgnext; | |
57 | waddrmsb <= wgnext[ADDRSIZE]^wgnext[ADDRSIZE-1]; | |
58 | end | |
59 | ||
60 | always @(wptr or winc) begin : Gray_inc | |
61 | integer i; | |
62 | for ( i=0; i<ADDRSIZE; i=i+1) | |
63 | wbin[i] <= ^(wptr>>i); | |
64 | if ( !wfull ) wbnext <= wbin + winc; | |
65 | else wbnext <= wbin; | |
66 | wgnext <= ( wbnext >> 1 ) ^ wbnext; | |
67 | end | |
68 | ||
69 | ||
70 | // memory wirte address pointer | |
71 | ||
72 | assign waddr = {waddrmsb,wptr[ADDRSIZE-2:0]}; | |
73 | ||
74 | wire w_2ndmsb = wgnext[ADDRSIZE] ^ wgnext[ADDRSIZE-1]; | |
75 | wire wr_2ndmsb = wrptr2[ADDRSIZE] ^ wrptr2[ADDRSIZE-1]; | |
76 | ||
77 | always @(posedge wclk or negedge wrst_n) | |
78 | if ( !wrst_n ) wfull <=0; | |
79 | else wfull <=((wgnext[ADDRSIZE] != wrptr2[ADDRSIZE]) && | |
80 | (w_2ndmsb == wr_2ndmsb ) && | |
81 | (wgnext[ADDRSIZE-2:0] == wrptr2[ADDRSIZE-2:0])); | |
82 | ||
83 | endmodule |