Add TRS-80 Model 1 and 3 support

src/main/scala/millfork/Platform.scala

@@ -284,10 +284,15 @@ object Platform {
       case "length_be" => AllocatedDataLengthBe(0)
       case "d88" => D88Output
       case "tap" => TapOutput
+      case "trscmd" => TrsCmdOutput
       case n => n.split(":").filter(_.nonEmpty) match {
         case Array(b, s, e) => BankFragmentOutput(b, parseNumber(s), parseNumber(e))
         case Array(s, e) => CurrentBankFragmentOutput(parseNumber(s), parseNumber(e))
-        case Array(b) => ConstOutput(parseNumber(b).toByte)
+        case Array(b) => try {
+          ConstOutput(parseNumber(b).toByte)
+        } catch {
+          case _:NumberFormatException => log.fatal(s"Invalid output format: `$b`")
+        }
         case x => log.fatal(s"Invalid output format: `$x`")
       }
     }.toList)

src/main/scala/millfork/output/TrsCmdOutput.scala

@@ -0,0 +1,22 @@
+package millfork.output
+
+/**
+  * @author Karol Stasiak
+  */
+object TrsCmdOutput extends OutputPackager {
+  override def packageOutput(mem: CompiledMemory, bank: String): Array[Byte] = {
+    val b = mem.banks(bank)
+    val start = b.start
+    b.output.slice(start, b.end + 1).grouped(256).zipWithIndex.flatMap{ case (chunk, index) =>
+      // chunk type 1: data
+      // chunk length: 1 byte, includes the load address, goes 3-258
+      // load address: 2 bytes, little-endian
+      Array[Byte](1, (chunk.length + 2).toByte, start.toByte, start.>>(8).+(index).toByte) ++ chunk
+    }.toArray ++ Array[Byte](
+      // chunk type 2: relocation address
+      // chunk length: for type 2, it's always 2 bytes
+      // relocation address: 2 bytes, little-endian
+      2, 2, b.start.toByte, b.start.>>(8).toByte
+    )
+  }
+}