change Grey to Gray, as proper name for the enumeration encoding. also better documentation.

Author: Oron Port

compiler/ir/src/main/scala/dfhdl/compiler/printing/Printer.scala

@@ -421,7 +421,7 @@ class DFPrinter(using val getSet: MemberGetSet, val printerOptions: PrinterOptio
   val dfhdlOps: Set[String] = Set("<>", ":=", ":==")
   val dfhdlTypes: Set[String] = Set(
     "Bit", "Boolean", "Int", "UInt", "SInt", "Bits", "X", "Encoded", "Struct", "Opaque",
-    "StartAt", "OneHot", "Grey", "Unit", "Time", "Freq", "String", "fs", "ns", "ps", "us", "ms",
+    "StartAt", "OneHot", "Gray", "Unit", "Time", "Freq", "String", "fs", "ns", "ps", "us", "ms",
     "sec", "min", "hr", "Hz", "KHz", "MHz", "GHz"
   )
   def colorCode(cs: String): String =

core/src/main/scala/dfhdl/core/DFEnum.scala

@@ -18,7 +18,7 @@ object DFEncoding:
     val width: W
   abstract class Default extends StartAt(0)
 
-  abstract class Grey extends Auto:
+  abstract class Gray extends Auto:
     final def calcWidth(entryCount: Int): Int =
       (entryCount - 1).bitsWidth(false)
     final def encode(idx: Int): BigInt = BigInt(idx ^ (idx >>> 1))

core/src/main/scala/dfhdl/core/Width.scala

@@ -183,7 +183,7 @@ object Width extends WidthLP:
                     case _ => None
                 case '[DFEncoding.OneHot] =>
                   Some(entryCount)
-                case '[DFEncoding.Grey] =>
+                case '[DFEncoding.Gray] =>
                   Some((entryCount - 1).bitsWidth(false))
                 case '[DFEncoding.Manual[w]] =>
                   TypeRepr.of[w] match

core/src/test/scala/CoreSpec/DFEnumSpec.scala

@@ -10,7 +10,7 @@ class DFEnumSpec extends DFSpec:
     case Foo, Bar, Baz
   enum MyEnum3 extends Encoded.OneHot:
     case Foo, Bar, Baz
-  enum MyEnum4 extends Encoded.Grey:
+  enum MyEnum4 extends Encoded.Gray:
     case Foo, Bar, Baz
   enum MyEnum5(val value: UInt[8] <> CONST) extends Encoded.Manual(8):
     case Foo extends MyEnum5(200)

core/src/test/scala/CoreSpec/DFTypeSpec.scala

@@ -21,7 +21,7 @@ class DFTypeSpec extends DFSpec:
     case Foo, Bar, Baz
   enum MyEnum3 extends Encoded.OneHot:
     case Foo, Bar, Baz
-  enum MyEnum4 extends Encoded.Grey:
+  enum MyEnum4 extends Encoded.Gray:
     case Foo, Bar, Baz
   enum MyEnum5(val value: UInt[8] <> CONST) extends Encoded.Manual(8):
     case Foo extends MyEnum5(200)

docs/user-guide/type-system/index.md

@@ -1210,7 +1210,7 @@ DFHDL supports several encoding schemes for enums:
 1. **Binary Encoded** (default)
 ```scala
 enum MyEnum extends Encoded:
-  case A, B, C, D  // Encoded as 0,1,2,3
+  case A, B, C, D  // Encoded as 00,01,10,11
 ```
 
 2. **One-Hot Encoded**
@@ -1221,14 +1221,14 @@ enum MyEnum extends Encoded.OneHot:
 
 3. **Gray Encoded**
 ```scala
-enum MyEnum extends Encoded.Grey:
+enum MyEnum extends Encoded.Gray:
   case A, B, C  // Encoded as 00,01,11
 ```
 
 4. **Custom Start Value**
 ```scala
-enum MyEnum extends Encoded.StartAt(10):
-  case A, B, C  // Encoded as 10,11,12
+enum MyEnum extends Encoded.StartAt(4):
+  case A, B, C  // Encoded as 100,101,110
 ```
 
 5. **Manual Encoding**