fixup: better understandable enable/disable decision tree

Author: rleh

src/modm/platform/dma/stm32/module.lb

@@ -21,6 +21,8 @@ def init(module):
 def prepare(module, options):
     device = options[":target"]
 
+    module.depends(":cmsis:device", ":platform:rcc")
+
     if (not device.has_driver("dma")) or device.get_driver("dma")["type"] not in \
             [
             "stm32-channel-request",
@@ -31,37 +33,37 @@ def prepare(module, options):
     did = device.identifier
 
     # Enable DMA for all but some devices...
-    if not (
-        (did["family"] in ["f0"]
-         # STM32F09x has shared interrupts between DMA1 and DMA2, not supported...
-         and did["name"] not in ["30", "71", "72", "78", "91", "98"])
-        or (did["family"] in ["f1"] and
-            (did["name"] in ["02", "05", "07"]
-             or
-             (did["name"] in ["00", "01", "03"]
-              and did["pin"] in ["r", "v", "z"]
-              and did["size"] in ["c", "d", "e", "f", "g"]
-             )
-            )
-           )
-        or (did["family"] in ["f3"] and
-            did["name"] not in ["73", "78"]
-            and
-            (did["name"] in ["02"]
-             and did["pin"] not in ["c"]
-             and did["size"] not in ["b", "c"]
-             )
-            )
-        or (did["family"] in ["l0"])
-        or (did["family"] in ["l1"]
-            and did["size"] not in ["c"])
-        or (did["family"] in ["l4"])
-    ):
+
+    if did["family"] in ["f0"]:
+        if did["name"] in ["30", "71", "72", "78", "91", "98"]:
+            # STM32F09x has shared interrupts between DMA1 and DMA2, not supported...
+            return False
+        return True
+
+    if did["family"] in ["f1"]:
+        if did["name"] in ["02", "05", "07"]:
+            return True
+        if did["name"] in ["00", "01", "03"] and did["pin"] in ["r", "v", "z"] and did["size"] in ["c", "d", "e", "f", "g"]:
+            return True
         return False
 
-    module.depends(":cmsis:device", ":platform:rcc")
+    if did["family"] in ["f3"]:
+        if did["name"] in ["73", "78"]:
+            return False
+        if did["name"] in ["02"] and did["pin"] in ["c"] and did["size"] in ["b", "c"]:
+            return False
+        return True
+
+    if did["family"] in ["l0", "l4"]:
+        return True
+
+    if did["family"] in ["l1"]:
+        if did["size"] in ["c"]:
+            return False
+        return True
+
+    return False
 
-    return True
 
 def build(env):
     device = env[":target"]