From 695864f5716626a15a7798dae048d8301940a2db Mon Sep 17 00:00:00 2001
From: Jiuyang Liu
Date: Thu, 15 Jul 2021 02:32:06 +0800
Subject: Espresso Decoder (#1964)

Co-authored-by: Haoran Yuan <sinofp@tuta.io>
Co-authored-by: Boyang Han <yqszxx@gmail.com>---
 .../chisel3/util/experimental/decode/decoder.scala | 49 ++++++++++++++++++++++
 1 file changed, 49 insertions(+)

(limited to 'src/main/scala/chisel3/util/experimental/decode/decoder.scala')

diff --git a/src/main/scala/chisel3/util/experimental/decode/decoder.scala b/src/main/scala/chisel3/util/experimental/decode/decoder.scala
index 8168824f..42e374d1 100644
--- a/src/main/scala/chisel3/util/experimental/decode/decoder.scala
+++ b/src/main/scala/chisel3/util/experimental/decode/decoder.scala
@@ -10,6 +10,13 @@ import firrtl.annotations.Annotation
 import logger.LazyLogging
 
 object decoder extends LazyLogging {
+  /** Use a specific [[Minimizer]] to generated decoded signals.
+    *
+    * @param minimizer  specific [[Minimizer]], can be [[QMCMinimizer]] or [[EspressoMinimizer]].
+    * @param input      input signal that contains decode table input
+    * @param truthTable [[TruthTable]] to decode user input.
+    * @return decode table output.
+    */
   def apply(minimizer: Minimizer, input: UInt, truthTable: TruthTable): UInt = {
     val minimizedTable = getAnnotations().collect {
       case DecodeTableAnnotation(_, in, out) => TruthTable(in) -> TruthTable(out)
@@ -31,4 +38,46 @@ object decoder extends LazyLogging {
       plaOutput
     }
   }
+
+  /** Use [[EspressoMinimizer]] to generated decoded signals.
+    *
+    * @param input      input signal that contains decode table input
+    * @param truthTable [[TruthTable]] to decode user input.
+    * @return decode table output.
+    */
+  def espresso(input: UInt, truthTable: TruthTable): UInt = apply(EspressoMinimizer, input, truthTable)
+
+  /** Use [[QMCMinimizer]] to generated decoded signals.
+    *
+    * @param input      input signal that contains decode table input
+    * @param truthTable [[TruthTable]] to decode user input.
+    * @return decode table output.
+    */
+  def qmc(input: UInt, truthTable: TruthTable): UInt = apply(QMCMinimizer, input, truthTable)
+
+  /** try to use [[EspressoMinimizer]] to decode `input` by `truthTable`
+    * if `espresso` not exist in your PATH environment it will fall back to [[QMCMinimizer]], and print a warning.
+    *
+    * @param input      input signal that contains decode table input
+    * @param truthTable [[TruthTable]] to decode user input.
+    * @return decode table output.
+    */
+  def apply(input: UInt, truthTable: TruthTable): UInt = {
+    def qmcFallBack(input: UInt, truthTable: TruthTable) = {
+      """fall back to QMC.
+        |Quine-McCluskey is a NP complete algorithm, may run forever or run out of memory in large decode tables.
+        |To get rid of this warning, please use `decoder.qmc` directly, or add espresso to your PATH.
+        |""".stripMargin
+      qmc(input, truthTable)
+    }
+
+    try espresso(input, truthTable) catch {
+      case EspressoNotFoundException =>
+        logger.error(s"espresso is not found in your PATH:\n${sys.env("PATH").split(":").mkString("\n")}".stripMargin)
+        qmcFallBack(input, truthTable)
+      case e: java.io.IOException =>
+        logger.error(s"espresso failed to run with ${e.getMessage}")
+        qmcFallBack(input, truthTable)
+    }
+  }
 }
-- 
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