38 lines
2 KiB
Text
38 lines
2 KiB
Text
|
<span class="hljs-meta">`<span class="hljs-meta-keyword">timescale</span> 1ns / 1ps</span>
|
||
|
|
|
||
|
|
<span class="hljs-comment">/**
|
||
|
|
* counter: a generic clearable up-counter
|
||
|
|
*/</span>
|
||
|
|
|
||
|
|
<span class="hljs-keyword">module</span> counter
|
||
|
|
#(<span class="hljs-keyword">parameter</span> WIDTH=<span class="hljs-number">64</span>)
|
||
|
|
(
|
||
|
|
<span class="hljs-keyword">input</span> clk,
|
||
|
|
<span class="hljs-keyword">input</span> ce,
|
||
|
|
<span class="hljs-keyword">input</span> arst_n,
|
||
|
|
<span class="hljs-keyword">output</span> <span class="hljs-keyword">reg</span> [WIDTH-<span class="hljs-number">1</span>:<span class="hljs-number">0</span>] q
|
||
|
|
);
|
||
|
|
|
||
|
|
<span class="hljs-comment">// some child</span>
|
||
|
|
clock_buffer <span class="hljs-variable">#(WIDTH)</span> buffer_inst (
|
||
|
|
<span class="hljs-variable">.clk</span>(clk),
|
||
|
|
<span class="hljs-variable">.ce</span>(ce),
|
||
|
|
<span class="hljs-variable">.reset</span>(arst_n)
|
||
|
|
);
|
||
|
|
|
||
|
|
<span class="hljs-comment">// Simple gated up-counter with async clear</span>
|
||
|
|
|
||
|
|
<span class="hljs-keyword">always</span> @(<span class="hljs-keyword">posedge</span> clk <span class="hljs-keyword">or</span> <span class="hljs-keyword">negedge</span> arst_n) <span class="hljs-keyword">begin</span>
|
||
|
|
<span class="hljs-keyword">if</span> (arst_n == <span class="hljs-number">1'b0</span>) <span class="hljs-keyword">begin</span>
|
||
|
|
q <= {WIDTH {<span class="hljs-number">1'b0</span>}};
|
||
|
|
<span class="hljs-keyword">end</span>
|
||
|
|
<span class="hljs-keyword">else</span> <span class="hljs-keyword">begin</span>
|
||
|
|
q <= q;
|
||
|
|
<span class="hljs-keyword">if</span> (ce == <span class="hljs-number">1'b1</span>) <span class="hljs-keyword">begin</span>
|
||
|
|
q <= q + <span class="hljs-number">1</span>;
|
||
|
|
<span class="hljs-keyword">end</span>
|
||
|
|
<span class="hljs-keyword">end</span>
|
||
|
|
<span class="hljs-keyword">end</span>
|
||
|
|
|
||
|
|
<span class="hljs-keyword">endmodule</span>
|