X, Y, Z, T are different jobs. Ex, X = Multiplexer( ... )
if ( empty1 )
if ( empty2 )
if ( empty3 )
if ( empty4 )
// Do nothing
else
X
else
Y
else
Z
else
T
EDIT : emptyA is a number 1 or 0, and A is member of the set { 1, 2, 3, 4 }
How can I rewrite that program segment so as to get minimum comparison cost
You have Verilog/HDL tags so assuming this is for synthesizable logic:
//This may be more readable
wire [3:0] empties = {empty4,empty3,empty2,empty1};
casex (empties)
4'xxx0: blah = T;
4'xx01: blah = Z;
4'x011: blah = Y;
4'0111: blah = X;
default: blah = something_else; //Shouldn't do nothing
endcase
The logic cost is going to depend on other factors than just this code.
if(!empty1)
T
else if (!empty2)
Z
else if (!empty3)
Y
else if (!empty4)
X
You can't reduce the comparisions as you have an action that is executed if the return value is false for all cases.
