1 files changed, 36 insertions, 0 deletions
diff --git a/src/lib/bits.c b/src/lib/bits.c
new file mode 100644
index 0000000..6366cf2
--- /dev/null
+++ b/src/lib/bits.c
@@ -0,0 +1,36 @@
+/* Copyright (c) 2001-2018 Dovecot authors, see the included COPYING file */
+
+#include "lib.h"
+
+/*
+ * We could use bits_required64() unconditionally, but that's unnecessary
+ * and way more heavy weight on 32-bit systems.
+ */
+#ifdef _LP64
+#define BITS_REQUIRED(x)	bits_required64(x)
+#else
+#define BITS_REQUIRED(x)	bits_required32(x)
+#endif
+
+size_t nearest_power(size_t num)
+{
+	i_assert(num <= ((size_t)1 << (CHAR_BIT*sizeof(size_t) - 1)));
+
+	if (num == 0)
+		return 1;
+
+	return 1UL << BITS_REQUIRED(num - 1);
+}
+
+#if __GNUC__ > 3 || (__GNUC__ == 3 && __GNUC_MINOR__ >= 4)
+/* Lucky you, it's all inline intrinsics */
+#else
+unsigned int bits_required8(uint8_t num)
+{
+	int ret = 0;
+	if (num > 0xf) { ret += 4; num >>= 4; }
+	if (num > 0x3) { ret += 2; num >>= 2; }
+	num &= ~(num>>1); /* 3->2, else unchanged */
+	return ret + num;
+}
+#endif