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25 lines
1.0 KiB
25 lines
1.0 KiB
SUBDESIGN dec_count |
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( |
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enc, ent, clk : INPUT; % two enables and the clock % |
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clear : INPUT; % Synchronous clear % |
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value[3..0] : OUTPUT; % Four output bits % |
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rco : OUTPUT; % ripple carry out % |
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) |
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VARIABLE |
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count[3..0] : DFF; % locally define 4 D-Flip-Flops for the count % |
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BEGIN |
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count[].clk = clk; % Connect the clock input to the DFF’s clock % |
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value[] = count[]; % connect the outputs of the DFFs to the outputs % |
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IF (clear) THEN % if clear is true clear the count i.e. % |
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count[].d = 1; % load the flipflops with zero % |
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ELSIF (enc & ent & (count[].q != 9)) THEN |
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% if both enables are true and the count does not % |
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count[].d = count[].q + 1; % equal nine then add one to the count value % |
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ELSIF (enc & ent & (count[].q == 9)) THEN |
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% if both enables are true and the count does % |
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count[].d = 1; % equal nine then load the flip flops with zero % |
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ELSE % with no enable keep the flips flops at the same value % |
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count[].d = count[].q; |
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END IF; |
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rco = ((count[].q == 9) & ent);% generate the rco when the count is nine and ent is true % |
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END;
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