Fix bit_count for Python <= 3.9.

1 files changed, 10 insertions, 2 deletions

diff --git a/pyecsca/sca/attack/leakage_model.py b/pyecsca/sca/attack/leakage_model.py
index 84d927e..e589940 100644
--- a/pyecsca/sca/attack/leakage_model.py
+++ b/pyecsca/sca/attack/leakage_model.py
@@ -1,9 +1,17 @@
 import abc
+import sys
 from typing import Literal, ClassVar
 
 from numpy.random import default_rng
 from public import public
 
+if sys.version_info[0] < 3 or sys.version_info[0] == 3 and sys.version_info[1] < 10:
+    def hw(i):
+        return bin(i).count("1")
+else:
+    def hw(i):
+        return i.bit_count()
+
 
 @public
 class NormalNoice:
@@ -73,7 +81,7 @@ class HammingWeight(LeakageModel):
     num_args = 1
 
     def __call__(self, *args, **kwargs) -> int:
-        return int(args[0]).bit_count()
+        return hw(int(args[0]))
 
 
 @public
@@ -81,7 +89,7 @@ class HammingDistance(LeakageModel):
     num_args = 2
 
     def __call__(self, *args, **kwargs) -> int:
-        return (int(args[0]) ^ int(args[1])).bit_count()
+        return hw(int(args[0]) ^ int(args[1]))
 
 
 @public