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// SPDX-License-Identifier: Apache-2.0
package chisel3
import chisel3.internal._
import chisel3.internal.Builder.pushOp
import chisel3.internal.firrtl._
import chisel3.internal.firrtl.PrimOp._
object Mux {
/** Creates a mux, whose output is one of the inputs depending on the
* value of the condition.
*
* @param cond condition determining the input to choose
* @param con the value chosen when `cond` is true
* @param alt the value chosen when `cond` is false
* @example
* {{{
* val muxOut = Mux(data_in === 3.U, 3.U(4.W), 0.U(4.W))
* }}}
*/
def apply[T <: Data](
cond: Bool,
con: T,
alt: T
): T = {
requireIsHardware(cond, "mux condition")
requireIsHardware(con, "mux true value")
requireIsHardware(alt, "mux false value")
val d = cloneSupertype(Seq(con, alt), "Mux")
val conRef = con match { // this matches chisel semantics (DontCare as object) to firrtl semantics (invalidate)
case DontCare =>
val dcWire = Wire(d)
dcWire := DontCare
dcWire.ref
case _ => con.ref
}
val altRef = alt match {
case DontCare =>
val dcWire = Wire(d)
dcWire := DontCare
dcWire.ref
case _ => alt.ref
}
pushOp(DefPrim(d, MultiplexOp, cond.ref, conRef, altRef))
}
}
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