Add --extract

Extract all files in the rom to the given directory.  Filename structure
is ###_Side_FileNumber_FileId.

cmd/fdslist.go

@@ -16,6 +16,7 @@ import (
 
 type Arguments struct {
 	Input string `arg:"positional,required"`
+	Extract string `arg:"--extract" help:"Extract files to the given directory"`
 }
 
 
@@ -49,6 +50,26 @@ func run(args *Arguments) error {
 
 	fmt.Println(rom.Info())
 
+	if args.Extract != "" {
+		err = os.MkdirAll(args.Extract, 0775)
+		if err != nil {
+			return err
+		}
+
+		num := 0
+		for _, side := range rom.Sides {
+			sideName := fmt.Sprintf("Side%d", side.Header.PhysicalSide)
+			for _, file := range side.Files {
+				fileName := filepath.Join(args.Extract, fmt.Sprintf("%03d_%s_%02d_%02X", num, sideName, file.Number, file.Id))
+				err := os.WriteFile(fileName, file.Data, 0664)
+				if err != nil {
+					return err
+				}
+				num++
+			}
+		}
+	}
+
 	return nil
 }