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chiselrocket-chip

comparing the value in a register to an int

I am trying to get the value of a reg and compare it with a number inside and if statement 

  val refill_addr    = Reg(UInt(width = paddrBits))
if ( refill_addr >  20000.U) 
   cacheable := true
   else 
       cacheable := false

but i get this error 

[error] /home/a/i-rocket-chip/src/main/scala/rocket/ICache.scala:365:18: type mismatch;
[error]  found   : chisel3.core.Bool
[error]  required: Boolean
[error] if ( refill_addr >  20000.U) 
[error]                  ^
[error] one error found
[error] (Compile / compileIncremental) Compilation failed
Solution

  • You should be using when/.otherwise here instead of if/else.

    when is a Chisel (hardware) construct that will eventually map to one or more multiplexers. if is a Scala construct and can be used for compile-time generation of hardware.

    when (refill_addr >  20000.U) {
  cacheable := true
} .otherwise {
  cacheable := false
}

    For some more info, there was a similar question here.