Allow for multiple synthesis directives in specials.

This is needed to specify timing constraints on some Lattice Diamond
library specials, like the EHXPLLL.

To keep backwards compatibility we allow the directive to still be a
single string. If it's not, we assume it's an iterable.

diff --git a/litex/gen/fhdl/specials.py b/litex/gen/fhdl/specials.py
index 4b7ab38698673c699813ee9ba63a688008012819..e3fdafdf8a919c74bd60af5cc71a480df9f4ca7b 100644 (file)
--- a/litex/gen/fhdl/specials.py
+++ b/litex/gen/fhdl/specials.py
@@ -181,11 +181,18 @@ class Instance(Special):
                 r += "\t." + name_inst + "(" + name_design + ")"
         if not firstp:
             r += "\n"
-        if instance.synthesis_directive is not None:
-            synthesis_directive = "/* synthesis {} */".format(instance.synthesis_directive)
-            r += ")" + synthesis_directive + ";\n\n"
-        else:
-            r += ");\n\n"
+
+        directives = instance.synthesis_directive
+        if directives is None:
+            directives = []
+        elif type(directives) == str :
+            directives = [directives,]
+
+        r += ")";
+        for directive in directives:
+            r += "\n\t/* synthesis {} */".format(directive)
+        r += ";\n\n"
+
         return r