diff --git a/libsrc/bits.c b/libsrc/bits.c
new file mode 100644
index 0000000..bd4282e
--- /dev/null
+++ b/libsrc/bits.c
@@ -0,0 +1,91 @@
+/* bits.c - information about bitops implementation.
+ *
+ * Copyright (C) 2021-2022 Bruno Raoult ("br")
+ * Licensed under the GNU General Public License v3.0 or later.
+ * Some rights reserved. See COPYING.
+ *
+ * You should have received a copy of the GNU General Public License along with this
+ * program. If not, see <https://www.gnu.org/licenses/gpl-3.0-standalone.html>.
+ *
+ * SPDX-License-Identifier: GPL-3.0-or-later <https://spdx.org/licenses/GPL-3.0-or-later.html>
+ *
+ */
+
+#include "bits.h"
+#include "debug.h"
+
+/**
+ * bits_implementation - display bitops implementation.
+ *
+ * For basic bitops (popcount, ctz, etc...), print the implementation
+ * (builtin, emulated).
+ */
+void bits_implementation(void)
+{
+    log(0, "bitops implementation: ");
+
+    log(0, "popcount64: ");
+#   if __has_builtin(__builtin_popcountl)
+    log(0, "builtin, ");
+#   else
+    log(0, "emulated, ");
+#   endif
+
+    log(0, "popcount32: ");
+#   if __has_builtin(__builtin_popcount)
+    log(0, "builtin, ");
+#   else
+    log(0, "emulated, ");
+#   endif
+
+    log(0, "ctz64: ");
+#   if __has_builtin(__builtin_ctzl)
+    log(0, "builtin, ");
+#   elif __has_builtin(__builtin_clzl)
+    log(0, "builtin (clzl), ");
+#   else
+    log(0, "emulated, ");
+#   endif
+
+    log(0, "ctz32: ");
+#   if __has_builtin(__builtin_ctz)
+    log(0, "builtin, ");
+#   elif __has_builtin(__builtin_clz)
+    log(0, "builtin (clz), ");
+#   else
+    log(0, "emulated, ");
+#   endif
+
+    log(0, "clz64: ");
+#   if __has_builtin(__builtin_clzl)
+    log(0, "builtin, ");
+#   else
+    log(0, "emulated, ");
+#   endif
+
+    log(0, "clz32: ");
+#   if __has_builtin(__builtin_clz)
+    log(0, "builtin, ");
+#   else
+    log(0, "emulated, ");
+#   endif
+
+    log(0, "ffs64: ");
+#   if __has_builtin(__builtin_ffsl)
+    log(0, "builtin, ");
+#   elif __has_builtin(__builtin_ctzl)
+    log(0, "builtin (ctzl), ");
+#   else
+    log(0, "emulated, ");
+#   endif
+
+    log(0, "ffs32: ");
+#   if __has_builtin(__builtin_ffs)
+    log(0, "builtin, ");
+#   elif __has_builtin(__builtin_ctz)
+    log(0, "builtin (ctzl), ");
+#   else
+    log(0, "emulated, ");
+#   endif
+    log(0, "\n");
+}