add overflow detection to DIVS

overflow shouldn't occur when calling DIVS since it should have been
detected in the code calling DIVS to properly handle edge cases.

diff --git a/src/nmutil/divmod.py b/src/nmutil/divmod.py
index af5d2141a58e00b27e4b2ad62a860b478cda50d5..357fdcb2d905f31492ad961d94578bc73d1f83dd 100644 (file)
--- a/src/nmutil/divmod.py
+++ b/src/nmutil/divmod.py
@@ -17,6 +17,9 @@ def trunc_divs(n, d):
     res = copy(n)
     if (sign_n == sign_d):
         res.value = abs_q
+        if res.value & (1 << (res.bits - 1)) != 0:
+            # result should be positive but is negative
+            raise OverflowError()
         return res
     mask = (1 << res.bits) - 1
     res.value = (-abs_q) & mask