1 files changed, 68 insertions, 0 deletions
diff --git a/lib/libc/tests/stdbit/stdbit-test-kernel.c b/lib/libc/tests/stdbit/stdbit-test-kernel.c
new file mode 100644
index 000000000000..d584e391ff6f
--- /dev/null
+++ b/lib/libc/tests/stdbit/stdbit-test-kernel.c
@@ -0,0 +1,68 @@
+/*
+ * Copyright (c) 2025 Robert Clausecker <fuz@FreeBSD.org>
+ *
+ * SPDX-License-Identifier: BSD-2-Clause
+ */
+
+/*
+ * test kernel for stdbit functions.
+ * Requires the following macros to be defined:
+ *
+ * FUNCSTEM -- stem of the function name
+ * SUFFIX -- type suffic
+ * TYPE -- argument type
+ * MKREFFUNC(ref, type) -- reference function builder
+ */
+
+#define FUNC __CONCAT(FUNCSTEM, SUFFIX)
+#define REF __CONCAT(FUNCSTEM, __CONCAT(SUFFIX, _ref))
+
+MKREFFUNC(REF, TYPE)
+
+ATF_TC_WITHOUT_HEAD1(FUNCSTEM, SUFFIX);
+ATF_TC_BODY1(FUNCSTEM, SUFFIX, tc)
+{
+	uintmax_t has, want;
+	size_t i, j;
+	TYPE value;
+
+	/* test all single-bit patterns */
+	for (i = 0; i < TYPE_WIDTH; i++) {
+		value = (TYPE)1 << i;
+		has = FUNC(value);
+		want = REF(value);
+		ATF_CHECK_EQ_MSG(has, want, "%s(%#jx) == %#jx != %#jx == %s(%#jx)",
+		    __XSTRING(FUNC), (uintmax_t)value, has, want, __XSTRING(REF), (uintmax_t)value);
+	}
+
+	/* test all double-bit patterns */
+	for (i = 0; i < TYPE_WIDTH; i++) {
+		for (j = 0; j < i; j++) {
+			value = (TYPE)1 << i | (TYPE)1 << j;
+			has = FUNC(value);
+			want = REF(value);
+			ATF_CHECK_EQ_MSG(has, want, "%s(%#jx) == %#jx != %#jx == %s(%#jx)",
+			    __XSTRING(FUNC), (uintmax_t)value, has, want, __XSTRING(REF), (uintmax_t)value);
+		}
+	}
+
+	/* test all barber-pole patterns */
+	value = ~(TYPE)0;
+	for (i = 0; i < TYPE_WIDTH; i++) {
+		has = FUNC(value);
+		want = REF(value);
+		ATF_CHECK_EQ_MSG(has, want, "%s(%#jx) == %#jx != %#jx == %s(%#jx)",
+		    __XSTRING(FUNC), (uintmax_t)value, has, want, __XSTRING(REF), (uintmax_t)value);
+
+		value = ~value;		
+		has = FUNC(value);
+		want = REF(value);
+		ATF_CHECK_EQ_MSG(has, want, "%s(%#jx) == %#jx != %#jx == %s(%#jx)",
+		    __XSTRING(FUNC), (uintmax_t)value, has, want, __XSTRING(REF), (uintmax_t)value);
+
+		value = ~value << 1;
+	}
+}
+
+#undef REF
+#undef FUNC