add new APIs to BitPat (#2076)

* add Y and N to BitPat.

* add ## for BitPat.

* add rawString API.

* use rawString in decoder

* add select and slice to BitPat.

1 files changed, 45 insertions, 8 deletions

diff --git a/src/main/scala/chisel3/util/BitPat.scala b/src/main/scala/chisel3/util/BitPat.scala
index 985d22da..0dcb2466 100644
--- a/src/main/scala/chisel3/util/BitPat.scala
+++ b/src/main/scala/chisel3/util/BitPat.scala
@@ -58,6 +58,22 @@ object BitPat {
     */
   def dontCare(width: Int): BitPat = BitPat("b" + ("?" * width))
 
+  /** Creates a [[BitPat]] of all 1 of the specified bitwidth.
+    *
+    * @example {{{
+    * val myY = BitPat.Y(4)  // equivalent to BitPat("b1111")
+    * }}}
+    */
+  def Y(width: Int = 1): BitPat = BitPat("b" + ("1" * width))
+
+  /** Creates a [[BitPat]] of all 0 of the specified bitwidth.
+    *
+    * @example {{{
+    * val myN = BitPat.N(4)  // equivalent to BitPat("b0000")
+    * }}}
+    */
+  def N(width: Int = 1): BitPat = BitPat("b" + ("0" * width))
+
   /** Allows BitPats to be used where a UInt is expected.
     *
     * @note the BitPat must not have don't care bits (will error out otherwise)
@@ -106,9 +122,11 @@ object BitPat {
   */
 sealed class BitPat(val value: BigInt, val mask: BigInt, width: Int) extends SourceInfoDoc {
   def getWidth: Int = width
+  def apply(x: Int): BitPat = macro SourceInfoTransform.xArg
+  def apply(x: Int, y: Int): BitPat = macro SourceInfoTransform.xyArg
   def === (that: UInt): Bool = macro SourceInfoTransform.thatArg
   def =/= (that: UInt): Bool = macro SourceInfoTransform.thatArg
-
+  def ## (that: BitPat): BitPat = macro SourceInfoTransform.thatArg
   override def equals(obj: Any): Boolean = {
     obj match {
       case y: BitPat => value == y.value && mask == y.mask && getWidth == y.getWidth
@@ -117,6 +135,18 @@ sealed class BitPat(val value: BigInt, val mask: BigInt, width: Int) extends Sou
   }
 
   /** @group SourceInfoTransformMacro */
+  def do_apply(x: Int)(implicit sourceInfo: SourceInfo, compileOptions: CompileOptions): BitPat = {
+    do_apply(x, x)
+  }
+
+  /** @group SourceInfoTransformMacro */
+  def do_apply(x: Int, y: Int)(implicit sourceInfo: SourceInfo, compileOptions: CompileOptions): BitPat = {
+    require(width > x && y >= 0, s"Invalid bit range ($x, $y), index should be bounded by (${width - 1}, 0)")
+    require(x >= y, s"Invalid bit range ($x, $y), x should be greater or equal to y.")
+    BitPat(s"b${rawString.slice(width - x - 1, width - y)}")
+  }
+
+  /** @group SourceInfoTransformMacro */
   def do_=== (that: UInt)
       (implicit sourceInfo: SourceInfo, compileOptions: CompileOptions): Bool = {
     value.asUInt === (that & mask.asUInt)
@@ -126,12 +156,19 @@ sealed class BitPat(val value: BigInt, val mask: BigInt, width: Int) extends Sou
       (implicit sourceInfo: SourceInfo, compileOptions: CompileOptions): Bool = {
     !(this === that)
   }
-
-  override def toString = {
-    "BitPat(" +
-      (0 until width).map(i =>
-        if (((mask >> i) & 1) == 1) if (((value >> i) & 1) == 1)  "1" else "0" else "?"
-      ).reverse.reduce(_ + _) +
-    ")"
+  /** @group SourceInfoTransformMacro */
+  def do_##(that: BitPat)(implicit sourceInfo: SourceInfo, compileOptions: CompileOptions): BitPat = {
+    new BitPat((value << that.getWidth) + that.value, (mask << that.getWidth) + that.mask, this.width + that.getWidth)
   }
+
+  /** Generate raw string of a BitPat. */
+  def rawString: String = Seq.tabulate(width) { i =>
+      (value.testBit(width - i - 1), mask.testBit(width - i - 1)) match {
+      case (true, true) => "1"
+      case (false, true) => "0"
+      case (_, false) => "?"
+    }
+  }.mkString
+
+  override def toString = s"BitPat($rawString)"
 }