core/src/main/scala/chisel3/IO.scala


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package chisel3

import chisel3.internal.requireIsChiselType // Fix ambiguous import
import chisel3.internal.Builder
import chisel3.internal.sourceinfo.SourceInfo

object IO {

  /** Constructs a port for the current Module
    *
    * This must wrap the datatype used to set the io field of any Module.
    * i.e. All concrete modules must have defined io in this form:
    * [lazy] val io[: io type] = IO(...[: io type])
    *
    * Items in [] are optional.
    *
    * The granted iodef must be a chisel type and not be bound to hardware.
    *
    * Also registers a Data as a port, also performing bindings. Cannot be called once ports are
    * requested (so that all calls to ports will return the same information).
    * Internal API.
    */
  def apply[T <: Data](iodef: T): T = {
    val module = Module.currentModule.get // Impossible to fail
    require(!module.isClosed, "Can't add more ports after module close")
    requireIsChiselType(iodef, "io type")

    // Clone the IO so we preserve immutability of data types
    val iodefClone =
      try {
        iodef.cloneTypeFull
      } catch {
        // For now this is going to be just a deprecation so we don't suddenly break everyone's code
        case e: AutoClonetypeException =>
          Builder.deprecated(e.getMessage, Some(s"${iodef.getClass}"))
          iodef
      }
    module.bindIoInPlace(iodefClone)
    iodefClone
  }
}