feat: add imm gen module impl

Author: maksyuki

rtl/tc_l3/src/main/scala/core/ImmGen.scala

@@ -0,0 +1,33 @@
+package treecorel3
+
+import chisel._
+import chiesl.uitl._
+
+class ImmGenIO(implicit p: Parameters) extends Bundle {
+  val inst = Input(UInt(xlen.W))
+  val sel  = Input(UInt(3.W))
+  val out  = Output(UInt(xlen.W))
+}
+
+class ImmGen(implicit p: Parameters) extends Module {
+  val io   = IO(new ImmGenIO)
+  val Iimm = io.inst(31, 20).asSInt
+  val Simm = Cat(io.inst(31, 25), io.inst(11, 7)).asSInt
+  val Bimm = Cat(io.inst(31), io.inst(7), io.inst(30, 25), io.inst(11, 8), 0.U(1.W)).asSInt
+  val Uimm = Cat(io.inst(31, 12), 0.U(12.W)).asSInt
+  val Jimm = Cat(io.inst(31), io.inst(19, 12), io.inst(20), io.inst(30, 25), io.inst(24, 21), 0.U(1.W)).asSInt
+  val Zimm = io.inst(19, 15).zext
+
+  io.out := MuxLookup(
+    io.sel,
+    Iimm & -2.S,
+    Seq(
+      IMM_I -> Iimm,
+      IMM_S -> Simm,
+      IMM_B -> Bimm,
+      IMM_U -> Uimm,
+      IMM_J -> Jimm,
+      IMM_Z -> Zimm
+    )
+  ).asUInt
+}