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[/] [usb2uart/] [trunk/] [rtl/] [lib/] [generic_fifo_sc_a.v] - Blame information for rev 5

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/////////////////////////////////////////////////////////////////////
////                                                             ////
////  Universal FIFO Single Clock                                ////
////                                                             ////
////                                                             ////
////  Author: Rudolf Usselmann                                   ////
////          rudi@asics.ws                                      ////
////                                                             ////
////                                                             ////
////  D/L from: http://www.opencores.org/cores/generic_fifos/    ////
////                                                             ////
/////////////////////////////////////////////////////////////////////
////                                                             ////
//// Copyright (C) 2000-2002 Rudolf Usselmann                    ////
////                         www.asics.ws                        ////
////                         rudi@asics.ws                       ////
////                                                             ////
//// This source file may be used and distributed without        ////
//// restriction provided that this copyright statement is not   ////
//// removed from the file and that any derivative work contains ////
//// the original copyright notice and the associated disclaimer.////
////                                                             ////
////     THIS SOFTWARE IS PROVIDED ``AS IS'' AND WITHOUT ANY     ////
//// EXPRESS OR IMPLIED WARRANTIES, INCLUDING, BUT NOT LIMITED   ////
//// TO, THE IMPLIED WARRANTIES OF MERCHANTABILITY AND FITNESS   ////
//// FOR A PARTICULAR PURPOSE. IN NO EVENT SHALL THE AUTHOR      ////
//// OR CONTRIBUTORS BE LIABLE FOR ANY DIRECT, INDIRECT,         ////
//// INCIDENTAL, SPECIAL, EXEMPLARY, OR CONSEQUENTIAL DAMAGES    ////
//// (INCLUDING, BUT NOT LIMITED TO, PROCUREMENT OF SUBSTITUTE   ////
//// GOODS OR SERVICES; LOSS OF USE, DATA, OR PROFITS; OR        ////
//// BUSINESS INTERRUPTION) HOWEVER CAUSED AND ON ANY THEORY OF  ////
//// LIABILITY, WHETHER IN  CONTRACT, STRICT LIABILITY, OR TORT  ////
//// (INCLUDING NEGLIGENCE OR OTHERWISE) ARISING IN ANY WAY OUT  ////
//// OF THE USE OF THIS SOFTWARE, EVEN IF ADVISED OF THE         ////
//// POSSIBILITY OF SUCH DAMAGE.                                 ////
////                                                             ////
/////////////////////////////////////////////////////////////////////
 
//  CVS Log
//
//  $Id: generic_fifo_sc_a.v,v 1.1.1.1 2002-09-25 05:42:06 rudi Exp $
//
//  $Date: 2002-09-25 05:42:06 $
//  $Revision: 1.1.1.1 $
//  $Author: rudi $
//  $Locker:  $
//  $State: Exp $
//
// Change History:
//               $Log: not supported by cvs2svn $
//
//
//
//
//
//
//
//
//
//
 
`include "timescale.v"
 
/*
 
Description
===========
 
I/Os
----
rst     low active, either sync. or async. master reset (see below how to select)
clr     synchronous clear (just like reset but always synchronous), high active
re      read enable, synchronous, high active
we      read enable, synchronous, high active
din     Data Input
dout    Data Output
 
full    Indicates the FIFO is full (combinatorial output)
full_r  same as above, but registered output (see note below)
empty   Indicates the FIFO is empty
empty_r same as above, but registered output (see note below)
 
full_n          Indicates if the FIFO has space for N entries (combinatorial output)
full_n_r        same as above, but registered output (see note below)
empty_n         Indicates the FIFO has at least N entries (combinatorial output)
empty_n_r       same as above, but registered output (see note below)
 
level           indicates the FIFO level:
                2'b00   0-25%    full
                2'b01   25-50%   full
                2'b10   50-75%   full
                2'b11   %75-100% full
 
combinatorial vs. registered status outputs
-------------------------------------------
Both the combinatorial and registered status outputs have exactly the same
synchronous timing. Meaning they are being asserted immediately at the clock
edge after the last read or write. The combinatorial outputs however, pass
through several levels of logic before they are output. The registered status
outputs are direct outputs of a flip-flop. The reason both are provided, is
that the registered outputs require quite a bit of additional logic inside
the FIFO. If you can meet timing of your device with the combinatorial
outputs, use them ! The FIFO will be smaller. If the status signals are
in the critical pass, use the registered outputs, they have a much smaller
output delay (actually only Tcq).
 
Parameters
----------
The FIFO takes 3 parameters:
dw      Data bus width
aw      Address bus width (Determines the FIFO size by evaluating 2^aw)
n       N is a second status threshold constant for full_n and empty_n
        If you have no need for the second status threshold, do not
        connect the outputs and the logic should be removed by your
        synthesis tool.
 
Synthesis Results
-----------------
In a Spartan 2e a 8 bit wide, 8 entries deep FIFO, takes 85 LUTs and runs
at about 116 MHz (IO insertion disabled). The registered status outputs
are valid after 2.1NS, the combinatorial once take out to 6.5 NS to be
available.
 
 
Misc
----
This design assumes you will do appropriate status checking externally.
 
IMPORTANT ! writing while the FIFO is full or reading while the FIFO is
empty will place the FIFO in an undefined state.
 
*/
 
 
// Selecting Sync. or Async Reset
// ------------------------------
// Uncomment one of the two lines below. The first line for
// synchronous reset, the second for asynchronous reset
 
`define SC_FIFO_ASYNC_RESET                             // Uncomment for Syncr. reset
//`define SC_FIFO_ASYNC_RESET   or negedge rst          // Uncomment for Async. reset
 
 
module generic_fifo_sc_a(clk, rst, clr, din, we, dout, re,
                        full, empty, full_r, empty_r,
                        full_n, empty_n, full_n_r, empty_n_r,
                        level);
 
parameter dw=8;
parameter aw=8;
parameter n=32;
parameter max_size = 1<<aw;
 
input                   clk, rst, clr;
input   [dw-1:0] din;
input                   we;
output  [dw-1:0] dout;
input                   re;
output                  full, full_r;
output                  empty, empty_r;
output                  full_n, full_n_r;
output                  empty_n, empty_n_r;
output  [1:0]            level;
 
////////////////////////////////////////////////////////////////////
//
// Local Wires
//
 
reg     [aw-1:0] wp;
wire    [aw-1:0] wp_pl1;
wire    [aw-1:0] wp_pl2;
reg     [aw-1:0] rp;
wire    [aw-1:0] rp_pl1;
reg                     full_r;
reg                     empty_r;
reg                     gb;
reg                     gb2;
reg     [aw:0]           cnt;
wire                    full_n, empty_n;
reg                     full_n_r, empty_n_r;
 
////////////////////////////////////////////////////////////////////
//
// Memory Block
//
 
generic_dpram  #(aw,dw) u0(
        .rclk(          clk             ),
        .rrst(          !rst            ),
        .rce(           1'b1            ),
        .oe(            1'b1            ),
        .raddr(         rp              ),
        .do(            dout            ),
        .wclk(          clk             ),
        .wrst(          !rst            ),
        .wce(           1'b1            ),
        .we(            we              ),
        .waddr(         wp              ),
        .di(            din             )
        );
 
////////////////////////////////////////////////////////////////////
//
// Misc Logic
//
 
always @(posedge clk `SC_FIFO_ASYNC_RESET)
        if(!rst)        wp <= #1 {aw{1'b0}};
        else
        if(clr)         wp <= #1 {aw{1'b0}};
        else
        if(we)          wp <= #1 wp_pl1;
 
assign wp_pl1 = wp + { {aw-1{1'b0}}, 1'b1};
assign wp_pl2 = wp + { {aw-2{1'b0}}, 2'b10};
 
always @(posedge clk `SC_FIFO_ASYNC_RESET)
        if(!rst)        rp <= #1 {aw{1'b0}};
        else
        if(clr)         rp <= #1 {aw{1'b0}};
        else
        if(re)          rp <= #1 rp_pl1;
 
assign rp_pl1 = rp + { {aw-1{1'b0}}, 1'b1};
 
////////////////////////////////////////////////////////////////////
//
// Combinatorial Full & Empty Flags
//
 
assign empty = ((wp == rp) & !gb);
assign full  = ((wp == rp) &  gb);
 
// Guard Bit ...
always @(posedge clk `SC_FIFO_ASYNC_RESET)
        if(!rst)                        gb <= #1 1'b0;
        else
        if(clr)                         gb <= #1 1'b0;
        else
        if((wp_pl1 == rp) & we)         gb <= #1 1'b1;
        else
        if(re)                          gb <= #1 1'b0;
 
////////////////////////////////////////////////////////////////////
//
// Registered Full & Empty Flags
//
 
// Guard Bit ...
always @(posedge clk `SC_FIFO_ASYNC_RESET)
        if(!rst)                        gb2 <= #1 1'b0;
        else
        if(clr)                         gb2 <= #1 1'b0;
        else
        if((wp_pl2 == rp) & we)         gb2 <= #1 1'b1;
        else
        if((wp != rp) & re)             gb2 <= #1 1'b0;
 
always @(posedge clk `SC_FIFO_ASYNC_RESET)
        if(!rst)                                full_r <= #1 1'b0;
        else
        if(clr)                                 full_r <= #1 1'b0;
        else
        if(we & ((wp_pl1 == rp) & gb2) & !re)   full_r <= #1 1'b1;
        else
        if(re & ((wp_pl1 != rp) | !gb2) & !we)  full_r <= #1 1'b0;
 
always @(posedge clk `SC_FIFO_ASYNC_RESET)
        if(!rst)                                empty_r <= #1 1'b1;
        else
        if(clr)                                 empty_r <= #1 1'b1;
        else
        if(we & ((wp != rp_pl1) | gb2) & !re)   empty_r <= #1 1'b0;
        else
        if(re & ((wp == rp_pl1) & !gb2) & !we)  empty_r <= #1 1'b1;
 
////////////////////////////////////////////////////////////////////
//
// Combinatorial Full_n & Empty_n Flags
//
 
assign empty_n = cnt < n;
assign full_n  = !(cnt < (max_size-n+1));
assign level = {2{cnt[aw]}} | cnt[aw-1:aw-2];
 
// N entries status
always @(posedge clk `SC_FIFO_ASYNC_RESET)
        if(!rst)        cnt <= #1 {aw+1{1'b0}};
        else
        if(clr)         cnt <= #1 {aw+1{1'b0}};
        else
        if( re & !we)   cnt <= #1 cnt + { {aw{1'b1}}, 1'b1};
        else
        if(!re &  we)   cnt <= #1 cnt + { {aw{1'b0}}, 1'b1};
 
////////////////////////////////////////////////////////////////////
//
// Registered Full_n & Empty_n Flags
//
 
always @(posedge clk `SC_FIFO_ASYNC_RESET)
        if(!rst)                                empty_n_r <= #1 1'b1;
        else
        if(clr)                                 empty_n_r <= #1 1'b1;
        else
        if(we & (cnt >= (n-1) ) & !re)          empty_n_r <= #1 1'b0;
        else
        if(re & (cnt <= n ) & !we)              empty_n_r <= #1 1'b1;
 
always @(posedge clk `SC_FIFO_ASYNC_RESET)
        if(!rst)                                full_n_r <= #1 1'b0;
        else
        if(clr)                                 full_n_r <= #1 1'b0;
        else
        if(we & (cnt >= (max_size-n) ) & !re)   full_n_r <= #1 1'b1;
        else
        if(re & (cnt <= (max_size-n+1)) & !we)  full_n_r <= #1 1'b0;
 
////////////////////////////////////////////////////////////////////
//
// Sanity Check
//
 
// synopsys translate_off
always @(posedge clk)
        if(we & full)
                $display("%m WARNING: Writing while fifo is FULL (%t)",$time);
 
always @(posedge clk)
        if(re & empty)
                $display("%m WARNING: Reading while fifo is EMPTY (%t)",$time);
// synopsys translate_on
 
endmodule

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Subversion Repositories usb2uart

[/] [usb2uart/] [trunk/] [rtl/] [lib/] [generic_fifo_sc_a.v] - Blame information for rev 5

Line No.	Rev	Author	Line
1	5	dinesha	`/////////////////////////////////////////////////////////////////////`
2			`//// ////`
3			`//// Universal FIFO Single Clock ////`
4			`//// ////`
5			`//// ////`
6			`//// Author: Rudolf Usselmann ////`
7			`//// rudi@asics.ws ////`
8			`//// ////`
9			`//// ////`
10			`//// D/L from: http://www.opencores.org/cores/generic_fifos/ ////`
11			`//// ////`
12			`/////////////////////////////////////////////////////////////////////`
13			`//// ////`
14			`//// Copyright (C) 2000-2002 Rudolf Usselmann ////`
15			`//// www.asics.ws ////`
16			`//// rudi@asics.ws ////`
17			`//// ////`
18			`//// This source file may be used and distributed without ////`
19			`//// restriction provided that this copyright statement is not ////`
20			`//// removed from the file and that any derivative work contains ////`
21			`//// the original copyright notice and the associated disclaimer.////`
22			`//// ////`
23			//// THIS SOFTWARE IS PROVIDED ``AS IS'' AND WITHOUT ANY ////
24			`//// EXPRESS OR IMPLIED WARRANTIES, INCLUDING, BUT NOT LIMITED ////`
25			`//// TO, THE IMPLIED WARRANTIES OF MERCHANTABILITY AND FITNESS ////`
26			`//// FOR A PARTICULAR PURPOSE. IN NO EVENT SHALL THE AUTHOR ////`
27			`//// OR CONTRIBUTORS BE LIABLE FOR ANY DIRECT, INDIRECT, ////`
28			`//// INCIDENTAL, SPECIAL, EXEMPLARY, OR CONSEQUENTIAL DAMAGES ////`
29			`//// (INCLUDING, BUT NOT LIMITED TO, PROCUREMENT OF SUBSTITUTE ////`
30			`//// GOODS OR SERVICES; LOSS OF USE, DATA, OR PROFITS; OR ////`
31			`//// BUSINESS INTERRUPTION) HOWEVER CAUSED AND ON ANY THEORY OF ////`
32			`//// LIABILITY, WHETHER IN CONTRACT, STRICT LIABILITY, OR TORT ////`
33			`//// (INCLUDING NEGLIGENCE OR OTHERWISE) ARISING IN ANY WAY OUT ////`
34			`//// OF THE USE OF THIS SOFTWARE, EVEN IF ADVISED OF THE ////`
35			`//// POSSIBILITY OF SUCH DAMAGE. ////`
36			`//// ////`
37			`/////////////////////////////////////////////////////////////////////`
38
39			`// CVS Log`
40			`//`
41			`// $Id: generic_fifo_sc_a.v,v 1.1.1.1 2002-09-25 05:42:06 rudi Exp $`
42			`//`
43			`// $Date: 2002-09-25 05:42:06 $`
44			`// $Revision: 1.1.1.1 $`
45			`// $Author: rudi $`
46			`// $Locker: $`
47			`// $State: Exp $`
48			`//`
49			`// Change History:`
50			`// $Log: not supported by cvs2svn $`
51			`//`
52			`//`
53			`//`
54			`//`
55			`//`
56			`//`
57			`//`
58			`//`
59			`//`
60			`//`
61
62			`include "timescale.v"
63
64			`/*`
65
66			`Description`
67			`===========`
68
69			`I/Os`
70			`----`
71			`rst low active, either sync. or async. master reset (see below how to select)`
72			`clr synchronous clear (just like reset but always synchronous), high active`
73			`re read enable, synchronous, high active`
74			`we read enable, synchronous, high active`
75			`din Data Input`
76			`dout Data Output`
77
78			`full Indicates the FIFO is full (combinatorial output)`
79			`full_r same as above, but registered output (see note below)`
80			`empty Indicates the FIFO is empty`
81			`empty_r same as above, but registered output (see note below)`
82
83			`full_n Indicates if the FIFO has space for N entries (combinatorial output)`
84			`full_n_r same as above, but registered output (see note below)`
85			`empty_n Indicates the FIFO has at least N entries (combinatorial output)`
86			`empty_n_r same as above, but registered output (see note below)`
87
88			`level indicates the FIFO level:`
89			`2'b00 0-25% full`
90			`2'b01 25-50% full`
91			`2'b10 50-75% full`
92			`2'b11 %75-100% full`
93
94			`combinatorial vs. registered status outputs`
95			`-------------------------------------------`
96			`Both the combinatorial and registered status outputs have exactly the same`
97			`synchronous timing. Meaning they are being asserted immediately at the clock`
98			`edge after the last read or write. The combinatorial outputs however, pass`
99			`through several levels of logic before they are output. The registered status`
100			`outputs are direct outputs of a flip-flop. The reason both are provided, is`
101			`that the registered outputs require quite a bit of additional logic inside`
102			`the FIFO. If you can meet timing of your device with the combinatorial`
103			`outputs, use them ! The FIFO will be smaller. If the status signals are`
104			`in the critical pass, use the registered outputs, they have a much smaller`
105			`output delay (actually only Tcq).`
106
107			`Parameters`
108			`----------`
109			`The FIFO takes 3 parameters:`
110			`dw Data bus width`
111			`aw Address bus width (Determines the FIFO size by evaluating 2^aw)`
112			`n N is a second status threshold constant for full_n and empty_n`
113			`If you have no need for the second status threshold, do not`
114			`connect the outputs and the logic should be removed by your`
115			`synthesis tool.`
116
117			`Synthesis Results`
118			`-----------------`
119			`In a Spartan 2e a 8 bit wide, 8 entries deep FIFO, takes 85 LUTs and runs`
120			`at about 116 MHz (IO insertion disabled). The registered status outputs`
121			`are valid after 2.1NS, the combinatorial once take out to 6.5 NS to be`
122			`available.`
123
124
125			`Misc`
126			`----`
127			`This design assumes you will do appropriate status checking externally.`
128
129			`IMPORTANT ! writing while the FIFO is full or reading while the FIFO is`
130			`empty will place the FIFO in an undefined state.`
131
132			`*/`
133
134
135			`// Selecting Sync. or Async Reset`
136			`// ------------------------------`
137			`// Uncomment one of the two lines below. The first line for`
138			`// synchronous reset, the second for asynchronous reset`
139
140			`define SC_FIFO_ASYNC_RESET // Uncomment for Syncr. reset
141			//`define SC_FIFO_ASYNC_RESET or negedge rst // Uncomment for Async. reset
142
143
144			`module generic_fifo_sc_a(clk, rst, clr, din, we, dout, re,`
145			`full, empty, full_r, empty_r,`
146			`full_n, empty_n, full_n_r, empty_n_r,`
147			`level);`
148
149			`parameter dw=8;`
150			`parameter aw=8;`
151			`parameter n=32;`
152			`parameter max_size = 1<<aw;`
153
154			`input clk, rst, clr;`
155			`input [dw-1:0] din;`
156			`input we;`
157			`output [dw-1:0] dout;`
158			`input re;`
159			`output full, full_r;`
160			`output empty, empty_r;`
161			`output full_n, full_n_r;`
162			`output empty_n, empty_n_r;`
163			`output [1:0] level;`
164
165			`////////////////////////////////////////////////////////////////////`
166			`//`
167			`// Local Wires`
168			`//`
169
170			`reg [aw-1:0] wp;`
171			`wire [aw-1:0] wp_pl1;`
172			`wire [aw-1:0] wp_pl2;`
173			`reg [aw-1:0] rp;`
174			`wire [aw-1:0] rp_pl1;`
175			`reg full_r;`
176			`reg empty_r;`
177			`reg gb;`
178			`reg gb2;`
179			`reg [aw:0] cnt;`
180			`wire full_n, empty_n;`
181			`reg full_n_r, empty_n_r;`
182
183			`////////////////////////////////////////////////////////////////////`
184			`//`
185			`// Memory Block`
186			`//`
187
188			`generic_dpram #(aw,dw) u0(`
189			`.rclk( clk ),`
190			`.rrst( !rst ),`
191			`.rce( 1'b1 ),`
192			`.oe( 1'b1 ),`
193			`.raddr( rp ),`
194			`.do( dout ),`
195			`.wclk( clk ),`
196			`.wrst( !rst ),`
197			`.wce( 1'b1 ),`
198			`.we( we ),`
199			`.waddr( wp ),`
200			`.di( din )`
201			`);`
202
203			`////////////////////////////////////////////////////////////////////`
204			`//`
205			`// Misc Logic`
206			`//`
207
208			always @(posedge clk `SC_FIFO_ASYNC_RESET)
209			`if(!rst) wp <= #1 {aw{1'b0}};`
210			`else`
211			`if(clr) wp <= #1 {aw{1'b0}};`
212			`else`
213			`if(we) wp <= #1 wp_pl1;`
214
215			`assign wp_pl1 = wp + { {aw-1{1'b0}}, 1'b1};`
216			`assign wp_pl2 = wp + { {aw-2{1'b0}}, 2'b10};`
217
218			always @(posedge clk `SC_FIFO_ASYNC_RESET)
219			`if(!rst) rp <= #1 {aw{1'b0}};`
220			`else`
221			`if(clr) rp <= #1 {aw{1'b0}};`
222			`else`
223			`if(re) rp <= #1 rp_pl1;`
224
225			`assign rp_pl1 = rp + { {aw-1{1'b0}}, 1'b1};`
226
227			`////////////////////////////////////////////////////////////////////`
228			`//`
229			`// Combinatorial Full & Empty Flags`
230			`//`
231
232			`assign empty = ((wp == rp) & !gb);`
233			`assign full = ((wp == rp) & gb);`
234
235			`// Guard Bit ...`
236			always @(posedge clk `SC_FIFO_ASYNC_RESET)
237			`if(!rst) gb <= #1 1'b0;`
238			`else`
239			`if(clr) gb <= #1 1'b0;`
240			`else`
241			`if((wp_pl1 == rp) & we) gb <= #1 1'b1;`
242			`else`
243			`if(re) gb <= #1 1'b0;`
244
245			`////////////////////////////////////////////////////////////////////`
246			`//`
247			`// Registered Full & Empty Flags`
248			`//`
249
250			`// Guard Bit ...`
251			always @(posedge clk `SC_FIFO_ASYNC_RESET)
252			`if(!rst) gb2 <= #1 1'b0;`
253			`else`
254			`if(clr) gb2 <= #1 1'b0;`
255			`else`
256			`if((wp_pl2 == rp) & we) gb2 <= #1 1'b1;`
257			`else`
258			`if((wp != rp) & re) gb2 <= #1 1'b0;`
259
260			always @(posedge clk `SC_FIFO_ASYNC_RESET)
261			`if(!rst) full_r <= #1 1'b0;`
262			`else`
263			`if(clr) full_r <= #1 1'b0;`
264			`else`
265			`if(we & ((wp_pl1 == rp) & gb2) & !re) full_r <= #1 1'b1;`
266			`else`
267			`if(re & ((wp_pl1 != rp) \| !gb2) & !we) full_r <= #1 1'b0;`
268
269			always @(posedge clk `SC_FIFO_ASYNC_RESET)
270			`if(!rst) empty_r <= #1 1'b1;`
271			`else`
272			`if(clr) empty_r <= #1 1'b1;`
273			`else`
274			`if(we & ((wp != rp_pl1) \| gb2) & !re) empty_r <= #1 1'b0;`
275			`else`
276			`if(re & ((wp == rp_pl1) & !gb2) & !we) empty_r <= #1 1'b1;`
277
278			`////////////////////////////////////////////////////////////////////`
279			`//`
280			`// Combinatorial Full_n & Empty_n Flags`
281			`//`
282
283			`assign empty_n = cnt < n;`
284			`assign full_n = !(cnt < (max_size-n+1));`
285			`assign level = {2{cnt[aw]}} \| cnt[aw-1:aw-2];`
286
287			`// N entries status`
288			always @(posedge clk `SC_FIFO_ASYNC_RESET)
289			`if(!rst) cnt <= #1 {aw+1{1'b0}};`
290			`else`
291			`if(clr) cnt <= #1 {aw+1{1'b0}};`
292			`else`
293			`if( re & !we) cnt <= #1 cnt + { {aw{1'b1}}, 1'b1};`
294			`else`
295			`if(!re & we) cnt <= #1 cnt + { {aw{1'b0}}, 1'b1};`
296
297			`////////////////////////////////////////////////////////////////////`
298			`//`
299			`// Registered Full_n & Empty_n Flags`
300			`//`
301
302			always @(posedge clk `SC_FIFO_ASYNC_RESET)
303			`if(!rst) empty_n_r <= #1 1'b1;`
304			`else`
305			`if(clr) empty_n_r <= #1 1'b1;`
306			`else`
307			`if(we & (cnt >= (n-1) ) & !re) empty_n_r <= #1 1'b0;`
308			`else`
309			`if(re & (cnt <= n ) & !we) empty_n_r <= #1 1'b1;`
310
311			always @(posedge clk `SC_FIFO_ASYNC_RESET)
312			`if(!rst) full_n_r <= #1 1'b0;`
313			`else`
314			`if(clr) full_n_r <= #1 1'b0;`
315			`else`
316			`if(we & (cnt >= (max_size-n) ) & !re) full_n_r <= #1 1'b1;`
317			`else`
318			`if(re & (cnt <= (max_size-n+1)) & !we) full_n_r <= #1 1'b0;`
319
320			`////////////////////////////////////////////////////////////////////`
321			`//`
322			`// Sanity Check`
323			`//`
324
325			`// synopsys translate_off`
326			`always @(posedge clk)`
327			`if(we & full)`
328			`$display("%m WARNING: Writing while fifo is FULL (%t)",$time);`
329
330			`always @(posedge clk)`
331			`if(re & empty)`
332			`$display("%m WARNING: Reading while fifo is EMPTY (%t)",$time);`
333			`// synopsys translate_on`
334
335			`endmodule`