Add some decoder comments

src/main/scala/SpinalRiscv/Plugin/DecoderSimplePlugin.scala

@@ -11,8 +11,12 @@ import scala.collection.mutable.ArrayBuffer
 case class Masked(value : BigInt,care : BigInt){
   var isPrime = true
 
+  def < (that: Masked) = value < that.value || value == that.value && ~care < ~that.care
+
   def intersects(x: Masked) = ((value ^ x.value) & care & x.care) == 0
 
+  def covers(x: Masked) = ((value ^ x.value) & care | (~x.care) & care) == 0
+
   def setPrime(value : Boolean) = {
     isPrime = value
     this
@@ -173,22 +177,27 @@ class DecoderSimplePlugin(catchIllegalInstruction : Boolean) extends Plugin[VexR
 
 
 object Symplify{
-  val cache = mutable.HashMap[Bits,mutable.HashMap[Masked,Bool]]();
+  val cache = mutable.HashMap[Bits,mutable.HashMap[Masked,Bool]]()
   def getCache(addr : Bits) = cache.getOrElseUpdate(addr,mutable.HashMap[Masked,Bool]())
-  def logicOf(addr : Bits,terms : Seq[Masked]) = terms.map(t => getCache(addr).getOrElseUpdate(t,t === addr)).asBits.orR
   
-  def apply(addr: Bits, mapping: Iterable[(Masked, Masked)],resultWidth : Int) : Bits = {
-    val addrWidth = widthOf(addr)
+  //Generate terms logic for the given input
+  def logicOf(input : Bits,terms : Seq[Masked]) = terms.map(t => getCache(input).getOrElseUpdate(t,t === input)).asBits.orR
+
+  //Decode 'input' b using an mapping[key, decoding] specification
+  def apply(input: Bits, mapping: Iterable[(Masked, Masked)],resultWidth : Int) : Bits = {
+    val addrWidth = widthOf(input)
     (for(bitId <- 0 until resultWidth) yield{
       val trueTerm = mapping.filter { case (k,t) => (t.care.testBit(bitId) && t.value.testBit(bitId))}.map(_._1)
       val falseTerm = mapping.filter { case (k,t) => (t.care.testBit(bitId) &&  !t.value.testBit(bitId))}.map(_._1)
       val symplifiedTerms = SymplifyBit.getPrimeImplicants(trueTerm.toSeq, falseTerm.toSeq, addrWidth)
-      logicOf(addr, symplifiedTerms)
+      logicOf(input, symplifiedTerms)
     }).asBits
   }
 }
 
 object SymplifyBit{
+
+  //Return a new term with only one bit difference with 'term' and not included in falseTerms. above => 0 to 1 dif, else 1 to 0 diff
   def genImplicitDontCare(falseTerms: Seq[Masked], term: Masked, bits: Int, above: Boolean): Masked = {
     for (i <- 0 until bits; if term.care.testBit(i)) {
       var t: Masked = null
@@ -205,6 +214,7 @@ object SymplifyBit{
     null
   }
 
+  //Return primes implicants for the trueTerms, falseTerms spec. Default value is don't care
   def getPrimeImplicants(trueTerms: Seq[Masked],falseTerms: Seq[Masked],inputWidth : Int): Seq[Masked] = {
     val primes = ArrayBuffer[Masked]()
     trueTerms.foreach(_.isPrime = true)
@@ -233,9 +243,18 @@ object SymplifyBit{
         for (p <- r; if p.isPrime)
           primes += p
     }
+
+    verify(primes, trueTerms, falseTerms)
     primes
   }
 
+  //Verify that the 'terms' doesn't violate the trueTerms ++ falseTerms spec
+  def verify(terms : Seq[Masked], trueTerms : Seq[Masked], falseTerms : Seq[Masked]): Unit ={
+    require(trueTerms.forall(trueTerm => terms.exists(_ covers trueTerm)))
+    require(falseTerms.forall(falseTerm => !terms.exists(_ covers falseTerm)))
+  }
+
+  //Return primes implicants for the trueTerms, default value is False
   def getPrimeImplicants(trueTerms: Seq[Masked],inputWidth : Int): Seq[Masked] = {
     val primes = ArrayBuffer[Masked]()
     trueTerms.foreach(_.isPrime = true)

src/main/scala/SpinalRiscv/Plugin/ShiftPlugins.scala

@@ -92,8 +92,6 @@ class LightShifterPlugin extends Plugin[VexRiscv]{
     import pipeline.config._
     import IntAluPlugin._
 
-
-
     val immediateActions = List[(Stageable[_ <: BaseType],Any)](
       SRC1_CTRL                -> Src1CtrlEnum.RS,
       SRC2_CTRL                -> Src2CtrlEnum.IMI,

src/main/scala/SpinalRiscv/TopLevel.scala

@@ -26,7 +26,7 @@ import spinal.lib._
 object TopLevel {
   def main(args: Array[String]) {
     SpinalVerilog {
-      val config = VexRiscvConfig(
+      val configFull = VexRiscvConfig(
         pcWidth = 32
       )
 
@@ -41,7 +41,7 @@ object TopLevel {
 //      )
 
 
-      val csrConfig = MachineCsrConfig(
+      val csrConfigAll = MachineCsrConfig(
         mvendorid      = 11,
         marchid        = 22,
         mimpid         = 33,
@@ -77,7 +77,7 @@ object TopLevel {
 //        minstretAccess = CsrAccess.NONE
 //      )
 
-      config.plugins ++= List(
+      configFull.plugins ++= List(
         new PcManagerSimplePlugin(0x00000000l, false),
         new IBusSimplePlugin(
           interfaceKeepData = true,
@@ -126,7 +126,7 @@ object TopLevel {
 //        new HazardSimplePlugin(false, false, false, false),
         new MulPlugin,
         new DivPlugin,
-        new MachineCsr(csrConfig),
+        new MachineCsr(csrConfigAll),
         new BranchPlugin(
           earlyBranch = false,
           catchAddressMisaligned = true,
@@ -134,41 +134,49 @@ object TopLevel {
         )
       )
 
-//      config.plugins ++= List(
-//        new PcManagerSimplePlugin(0x00000000l, false),
-//        new IBusSimplePlugin(
-//          interfaceKeepData = true
-//        ),
-//        new DecoderSimplePlugin(
-//          catchIllegalInstruction = false
-//        ),
-//        new RegFilePlugin(
-//          regFileReadyKind = Plugin.SYNC,
-//          zeroBoot = false
-//        ),
-//        new IntAluPlugin,
-//        new SrcPlugin,
-////        new FullBarrielShifterPlugin,
-//        new LightShifterPlugin,
-//        new DBusSimplePlugin(
-//          catchUnalignedException = false
-//        ),
-////        new HazardSimplePlugin(true, true, true, true),
-//        //        new HazardSimplePlugin(false, true, false, true),
-//        new HazardSimplePlugin(false, false, false, false),
-////        new MulPlugin,
-////        new DivPlugin,
-////        new MachineCsr(csrConfig),
-//        new BranchPlugin(
-//          earlyBranch = false,
-//          catchUnalignedException = false,
-//          prediction = NONE
-//        )
-//      )
+      val configLight = VexRiscvConfig(
+        pcWidth = 32
+      )
 
-      val toplevel = new VexRiscv(config)
-      toplevel.decode.input(config.INSTRUCTION).addAttribute("verilator public")
-      toplevel.decode.input(config.PC).addAttribute("verilator public")
+      configLight.plugins ++= List(
+        new PcManagerSimplePlugin(0x00000000l, false),
+        new IBusSimplePlugin(
+          interfaceKeepData = true,
+          catchAccessFault = false
+        ),
+
+        new DBusSimplePlugin(
+          catchAddressMisaligned = false,
+          catchAccessFault = false
+        ),
+        new DecoderSimplePlugin(
+          catchIllegalInstruction = false
+        ),
+        new RegFilePlugin(
+          regFileReadyKind = Plugin.SYNC,
+          zeroBoot = false
+        ),
+        new IntAluPlugin,
+        new SrcPlugin,
+//        new FullBarrielShifterPlugin,
+        new LightShifterPlugin,
+//        new HazardSimplePlugin(true, true, true, true),
+        //        new HazardSimplePlugin(false, true, false, true),
+        new HazardSimplePlugin(false, false, false, false),
+//        new MulPlugin,
+//        new DivPlugin,
+//        new MachineCsr(csrConfig),
+        new BranchPlugin(
+          earlyBranch = false,
+          catchAddressMisaligned = false,
+          prediction = NONE
+        )
+      )
+
+      val toplevel = new VexRiscv(configFull)
+//      val toplevel = new VexRiscv(configLight)
+      toplevel.decode.input(toplevel.config.INSTRUCTION).addAttribute("verilator public")
+      toplevel.decode.input(toplevel.config.PC).addAttribute("verilator public")
       toplevel.decode.arbitration.isValid.addAttribute("verilator public")
 //      toplevel.writeBack.input(config.PC).addAttribute("verilator public")
 //      toplevel.service(classOf[DecoderSimplePlugin]).bench(toplevel)