From f9cbcaf20f1f574098c0e8fe00604747b5dab8d4 Mon Sep 17 00:00:00 2001
From: supersurviveur <julien.thillard38@gmail.com>
Date: Tue, 11 Nov 2025 19:12:12 +0100
Subject: [PATCH] Add BSwitch macro and update gtkwave config

---
 build.sc                            | 12 +++++
 common/config.gtkw                  |  2 +-
 macros/src/utils/BSwitchMacro.scala | 77 +++++++++++++++++++++++++++++
 3 files changed, 90 insertions(+), 1 deletion(-)
 create mode 100644 macros/src/utils/BSwitchMacro.scala

diff --git a/build.sc b/build.sc
index 3093bbb..ccfc53b 100644
--- a/build.sc
+++ b/build.sc
@@ -13,6 +13,17 @@ import mill.bsp._
 // to properly generate and handle test directories and output files.
 // See: https://github.com/com-lihaoyi/mill/issues/3840
 
+object macros extends ScalaModule {
+    def scalaVersion = "2.13.16"
+    def scalacOptions = Seq[String]()
+    override def ivyDeps = Agg(
+        ivy"org.chipsalliance::chisel:7.2.0"
+    )
+    override def scalacPluginIvyDeps = Agg(
+        ivy"org.chipsalliance:::chisel-plugin:7.2.0"
+    )
+}
+
 object `TPchisel` extends SbtModule { m =>
     override def millSourcePath = super.millSourcePath / os.up
     override def scalaVersion = "2.13.16"
@@ -27,6 +38,7 @@ object `TPchisel` extends SbtModule { m =>
         "-Ywarn-dead-code",
         "-Ywarn-unused"
     )
+    override def moduleDeps = Seq(macros)
     override def ivyDeps = Agg(
         ivy"org.chipsalliance::chisel:7.2.0"
     )
diff --git a/common/config.gtkw b/common/config.gtkw
index 4d03d84..578db16 100644
--- a/common/config.gtkw
+++ b/common/config.gtkw
@@ -17,7 +17,7 @@ TOP.svsimTestbench.dut.core.wbVal[31:0]
 TOP.svsimTestbench.dut.core.clock
 TOP.svsimTestbench.dut.core.reset
 @22
-TOP.svsimTestbench.dut.io_x31[31:0]
+TOP.svsimTestbench.dut.io_x31[63:0]
 @28
 TOP.svsimTestbench.dut.io_valid_x31
 TOP.svsimTestbench.dut.core.rdValid
diff --git a/macros/src/utils/BSwitchMacro.scala b/macros/src/utils/BSwitchMacro.scala
new file mode 100644
index 0000000..d300903
--- /dev/null
+++ b/macros/src/utils/BSwitchMacro.scala
@@ -0,0 +1,77 @@
+package macros.utils
+
+import scala.language.experimental.macros
+import scala.reflect.macros.blackbox._
+import chisel3._
+import chisel3.experimental.SourceInfo
+import chisel3.util.BitPat
+
+object bis {
+
+    /** Executes `block` if the bswitch condition matchs `v`.
+      */
+    def apply(v: BitPat)(block: => Any): Unit = {
+        locally((v, block))
+        require(
+            false,
+            "The 'bis' keyword may not be used outside of a bswitch."
+        )
+    }
+}
+
+class BSwitchContext(
+    cond: UInt,
+    whenContext: Option[WhenContext],
+    lits: Set[BitPat]
+) {
+    def bis(
+        pat: BitPat
+    )(block: => Any)(implicit
+        sourceInfo: SourceInfo
+    ): BSwitchContext = {
+        require(
+            !lits.exists(w => {
+                w.overlap(pat)
+            }),
+            "all bis conditions must be mutually exclusive!"
+        )
+
+        // def instead of val so that logic ends up in legal place
+        def p = (cond === pat)
+        whenContext match {
+            case Some(w) =>
+                new BSwitchContext(
+                    cond,
+                    Some(w.elsewhen(p)(block)),
+                    lits + pat
+                )
+            case None =>
+                new BSwitchContext(
+                    cond,
+                    Some(when(p)(block)),
+                    lits + pat
+                )
+        }
+    }
+}
+
+object bswitch {
+    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"..$body" = x
+        val res = body.foldLeft(
+            q"""new macros.utils.BSwitchContext($cond, None, Set.empty)"""
+        ) { case (acc, tree) =>
+            tree match {
+                case q"macros.utils.bis.apply( ..$params )( ..$body )" =>
+                    q"$acc.bis( ..$params )( ..$body )"
+                case _ =>
+                    throw new Exception(
+                        s"Cannot include blocks that do not begin with bis() in bswitch."
+                    )
+            }
+        }
+        q"""{ $res }"""
+    }
+}