pull17, magic writer: remove hardcoded technology name

* instead introduce the `magscale` parameter for `MagicWriter`
* use `magscale` parameter in the tech-file to set the correct scale

lclayout/writer/magic_writer.py

@@ -93,7 +93,8 @@ def store_layout_to_magic_file(tech_name: str,
                                top_cell: db.Cell,
                                output_file: str,
                                ignore_non_rectilinear: bool = False,
-                               scale_factor: int = 1):
+                               scale_factor: int = 1,
+                               magscale: Tuple[int, int] = (1, 10)):
     """
     Write the cell layout to a file in the Magic (.mag) format.
 
@@ -106,6 +107,8 @@ def store_layout_to_magic_file(tech_name: str,
     :return:
     """
 
+    assert len(magscale) == 2, "magscale must be a 2-tuple"
+
     layer_config = []
     for source_layer_name, destinations in output_map.items():
         assert isinstance(destinations, str) or isinstance(destinations, List), \
@@ -126,7 +129,7 @@ def store_layout_to_magic_file(tech_name: str,
     mag_lines = ["magic",
                  "# Generated by librecell",
                  "tech {}".format(tech_name),
-                 "magscale 1 10" if tech_name=='gf180mcuC' else "magscale 1 1", 
+                 f"magscale {magscale[0]} {magscale[1]}",
                  "timestamp {}".format(int(time.time()))
                  ]
 
@@ -197,7 +200,12 @@ def store_layout_to_magic_file(tech_name: str,
 
 class MagWriter(Writer):
 
-    def __init__(self, tech_name: str, output_map: Dict[str, str], scale_factor: float = 1):
+    def __init__(self,
+        tech_name: str, 
+        output_map: Dict[str, str], 
+        scale_factor: float = 1,
+        magscale: Tuple[int, int] = (1, 10)
+        ):
         """
 
         :param tech_name:
@@ -207,6 +215,7 @@ class MagWriter(Writer):
         self.tech_name = tech_name
         self.output_map = output_map
         self.scale_factor = scale_factor
+        self.magscale = magscale
 
     def write_layout(self,
                      layout: db.Layout,
@@ -225,4 +234,6 @@ class MagWriter(Writer):
             top_cell,
             mag_out_path,
             ignore_non_rectilinear=False,
-            scale_factor=self.scale_factor)
+            scale_factor=self.scale_factor,
+            magscale=self.magscale
+        )