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// SPDX-License-Identifier: Apache-2.0
/** Conditional blocks.
*/
package chisel3.util
import scala.language.reflectiveCalls
import scala.language.experimental.macros
import scala.reflect.macros.blackbox._
import chisel3._
import chisel3.internal.sourceinfo.SourceInfo
/** Implementation details for [[switch]]. See [[switch]] and [[chisel3.util.is is]] for the
* user-facing API.
* @note DO NOT USE. This API is subject to change without warning.
*/
class SwitchContext[T <: Element](cond: T, whenContext: Option[WhenContext], lits: Set[BigInt]) {
def is(
v: Iterable[T]
)(block: => Any
)(
implicit sourceInfo: SourceInfo,
compileOptions: CompileOptions
): SwitchContext[T] = {
if (!v.isEmpty) {
val newLits = v.map { w =>
require(w.litOption.isDefined, "is condition must be literal")
val value = w.litValue
require(!lits.contains(value), "all is conditions must be mutually exclusive!")
value
}
// def instead of val so that logic ends up in legal place
def p = v.map(_.asUInt === cond.asUInt).reduce(_ || _)
whenContext match {
case Some(w) => new SwitchContext(cond, Some(w.elsewhen(p)(block)), lits ++ newLits)
case None => new SwitchContext(cond, Some(when(p)(block)), lits ++ newLits)
}
} else {
this
}
}
def is(v: T)(block: => Any)(implicit sourceInfo: SourceInfo, compileOptions: CompileOptions): SwitchContext[T] =
is(Seq(v))(block)
def is(
v: T,
vr: T*
)(block: => Any
)(
implicit sourceInfo: SourceInfo,
compileOptions: CompileOptions
): SwitchContext[T] = is(v :: vr.toList)(block)
}
/** Use to specify cases in a [[switch]] block, equivalent to a [[when$ when]] block comparing to
* the condition variable.
*
* @note illegal outside a [[switch]] block
* @note must be a literal
* @note each is must be mutually exclusive
* @note dummy implementation, a macro inside [[switch]] transforms this into the actual
* implementation
*/
object is {
// TODO: Begin deprecation of non-type-parameterized is statements.
/** Executes `block` if the switch condition is equal to any of the values in `v`.
*/
def apply(v: Iterable[Element])(block: => Any) {
require(false, "The 'is' keyword may not be used outside of a switch.")
}
/** Executes `block` if the switch condition is equal to `v`.
*/
def apply(v: Element)(block: => Any) {
require(false, "The 'is' keyword may not be used outside of a switch.")
}
/** Executes `block` if the switch condition is equal to any of the values in the argument list.
*/
def apply(v: Element, vr: Element*)(block: => Any) {
require(false, "The 'is' keyword may not be used outside of a switch.")
}
}
/** Conditional logic to form a switch block. See [[is$ is]] for the case API.
*
* @example {{{
* switch (myState) {
* is (state1) {
* // some logic here that runs when myState === state1
* }
* is (state2) {
* // some logic here that runs when myState === state2
* }
* }
* }}}
*/
object switch {
def apply[T <: Element](cond: T)(x: => Any): Unit = macro impl
def impl(c: Context)(cond: c.Tree)(x: c.Tree): c.Tree = {
import c.universe._
val q"..$body" = x
val res = body.foldLeft(q"""new chisel3.util.SwitchContext($cond, None, Set.empty)""") {
case (acc, tree) =>
tree match {
// TODO: remove when Chisel compatibility package is removed
case q"Chisel.`package`.is.apply( ..$params )( ..$body )" => q"$acc.is( ..$params )( ..$body )"
case q"chisel3.util.is.apply( ..$params )( ..$body )" => q"$acc.is( ..$params )( ..$body )"
case b => throw new Exception(s"Cannot include blocks that do not begin with is() in switch.")
}
}
q"""{ $res }"""
}
}
|
