// SPDX-License-Identifier: Apache-2.0

package chisel3.util

import scala.language.experimental.macros

import chisel3._
import chisel3.experimental.SourceInfo
import chisel3.internal.sourceinfo.SourceInfoTransform

/** Concatenates elements of the input, in order, together.
  *
  * @example {{{
  * Cat("b101".U, "b11".U)  // equivalent to "b101 11".U
  * Cat(myUIntWire0, myUIntWire1)
  *
  * Cat(Seq("b101".U, "b11".U))  // equivalent to "b101 11".U
  * Cat(mySeqOfBits)
  * }}}
  */
object Cat {

  /** Concatenates the argument data elements, in argument order, together. The first argument
    * forms the most significant bits, while the last argument forms the least significant bits.
    */
  def apply[T <: Bits](a: T, r: T*): UInt = macro SourceInfoTransform.arArg

  /** @group SourceInfoTransformMacro */
  def do_apply[T <: Bits](a: T, r: T*)(implicit sourceInfo: SourceInfo, compileOptions: CompileOptions): UInt =
    _apply_impl(a :: r.toList)

  /** Concatenates the data elements of the input sequence, in reverse sequence order, together.
    * The first element of the sequence forms the most significant bits, while the last element
    * in the sequence forms the least significant bits.
    *
    * Equivalent to r(0) ## r(1) ## ... ## r(n-1).
    * @note This returns a `0.U` if applied to a zero-element `Vec`.
    */
  def apply[T <: Bits](r: Seq[T]): UInt = macro SourceInfoTransform.rArg

  /** @group SourceInfoTransformMacro */
  def do_apply[T <: Bits](r: Seq[T])(implicit sourceInfo: SourceInfo, compileOptions: CompileOptions): UInt =
    _apply_impl(r)

  private def _apply_impl[T <: Bits](r: Seq[T])(implicit sourceInfo: SourceInfo, compileOptions: CompileOptions): UInt =
    SeqUtils.asUInt(r.reverse)
}
