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// See LICENSE for license details.
/** Enum generators, allowing circuit constants to have more meaningful names.
*/
package chisel3.util
import chisel3._
object Enum {
/** Returns a sequence of Bits subtypes with values from 0 until n. Helper method. */
private def createValues[T <: Bits](nodeType: T, n: Int): Seq[T] =
(0 until n).map(x => nodeType.fromInt(x, log2Up(n)))
/** Returns n unique values of the specified type. Can be used with unpacking to define enums.
*
* @example {{{
* val state_on :: state_off :: Nil = Enum(UInt(), 2)
* val current_state = UInt()
* switch (current_state) {
* is (state_on) {
* ...
* }
* if (state_off) {
* ...
* }
* }
* }}}
*
*/
def apply[T <: Bits](nodeType: T, n: Int): List[T] = createValues(nodeType, n).toList
/** Returns a map of the input symbols to unique values of the specified type.
*
* @example {{{
* val states = Enum(UInt(), 'on, 'off)
* val current_state = UInt()
* switch (current_state) {
* is (states('on)) {
* ...
* }
* if (states('off)) {
* ..
* }
* }
* }}}
*/
def apply[T <: Bits](nodeType: T, l: Symbol *): Map[Symbol, T] = (l zip createValues(nodeType, l.length)).toMap
/** Returns a map of the input symbols to unique values of the specified type.
*/
def apply[T <: Bits](nodeType: T, l: List[Symbol]): Map[Symbol, T] = (l zip createValues(nodeType, l.length)).toMap
}
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