Use Case Block When Priority Encoder Not Needed - 2023.1 English

UltraFast Design Methodology Guide for FPGAs and SoCs (UG949)

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2023.1 English

When a priority encoding is not needed, use a case block instead of an if-then-else block or ternary operator.

Inefficient coding example:

if (reg1)
  val = reg_in1;
else if (reg2)
   val = reg_in2;
else if (reg3)
   val = reg_in3;
else val = reg_in4;

Correct coding example:

(* parallel_case *) casex ({reg1, reg2, reg3})
1xx: val = reg_in1 ;
01x: val = reg_in2 ;
001: val = reg_in3 ;
default: val = reg_in4 ;