Index: uspace/lib/c/generic/imath.c
===================================================================
--- uspace/lib/c/generic/imath.c	(revision 9624c35ea91c745dc2f54caa27c46504570192c7)
+++ uspace/lib/c/generic/imath.c	(revision 9624c35ea91c745dc2f54caa27c46504570192c7)
@@ -0,0 +1,123 @@
+/*
+ * Copyright (c) 2015 Jiri Svoboda
+ * All rights reserved.
+ *
+ * Redistribution and use in source and binary forms, with or without
+ * modification, are permitted provided that the following conditions
+ * are met:
+ *
+ * - Redistributions of source code must retain the above copyright
+ *   notice, this list of conditions and the following disclaimer.
+ * - Redistributions in binary form must reproduce the above copyright
+ *   notice, this list of conditions and the following disclaimer in the
+ *   documentation and/or other materials provided with the distribution.
+ * - The name of the author may not be used to endorse or promote products
+ *   derived from this software without specific prior written permission.
+ *
+ * THIS SOFTWARE IS PROVIDED BY THE AUTHOR ``AS IS'' AND ANY EXPRESS OR
+ * IMPLIED WARRANTIES, INCLUDING, BUT NOT LIMITED TO, THE IMPLIED WARRANTIES
+ * OF MERCHANTABILITY AND FITNESS FOR A PARTICULAR PURPOSE ARE DISCLAIMED.
+ * IN NO EVENT SHALL THE AUTHOR BE LIABLE FOR ANY DIRECT, INDIRECT,
+ * INCIDENTAL, SPECIAL, EXEMPLARY, OR CONSEQUENTIAL DAMAGES (INCLUDING, BUT
+ * NOT LIMITED TO, PROCUREMENT OF SUBSTITUTE GOODS OR SERVICES; LOSS OF USE,
+ * DATA, OR PROFITS; OR BUSINESS INTERRUPTION) HOWEVER CAUSED AND ON ANY
+ * THEORY OF LIABILITY, WHETHER IN CONTRACT, STRICT LIABILITY, OR TORT
+ * (INCLUDING NEGLIGENCE OR OTHERWISE) ARISING IN ANY WAY OUT OF THE USE OF
+ * THIS SOFTWARE, EVEN IF ADVISED OF THE POSSIBILITY OF SUCH DAMAGE.
+ */
+
+/** @addtogroup libc
+ * @{
+ */
+/**
+ * @file Integer mathematical functions
+ */
+
+#include <errno.h>
+#include <imath.h>
+#include <stdbool.h>
+#include <stdint.h>
+
+/** Compute integer power of 10, unsigned 64-bit result.
+ *
+ * Fast algorithm using binary digits of exp to compute 10^exp in
+ * time O(log exp).
+ *
+ * @param exp Exponent
+ * @param res Place to store result
+ * @return EOK on success, ERANGE if result does not fit into result type
+ */
+int ipow10_u64(unsigned exp, uint64_t *res)
+{
+	unsigned a;
+	uint64_t r;
+
+	r = 1;
+	a = 10;
+	while (true) {
+		if ((exp & 1) != 0) {
+			if ((r * a) / a != r)
+				return ERANGE;
+			r = r * a;
+		}
+
+		exp = exp >> 1;
+		if (exp == 0)
+			break;
+
+		if ((a * a) / a != a)
+			return ERANGE;
+		a = a * a;
+	}
+
+	*res = r;
+	return EOK;
+}
+
+/** Compute integer base 10 logarithm, unsigned 64-bit argument.
+ *
+ * For integer v, compute floor(log_10 v). Fast algorithm computing
+ * the binary digits of the result r in time O(log r).
+ *
+ * @param v Value to compute logarithm from
+ * @return Logarithm value
+ */
+unsigned ilog10_u64(uint64_t v)
+{
+	unsigned b;
+	unsigned e;
+	uint64_t p10p2[6];
+	uint64_t a;
+	unsigned r;
+
+	/* Determine largest b such that 10^2^b <= v */
+	b = 0;
+	e = 1;
+	a = 10;
+	p10p2[0] = a;
+
+	while (v / a >= a) {
+		++b;
+		a = a * a;
+		e = e + e;
+		p10p2[b] = a;
+	}
+
+	/* Determine the binary digits of largest e such that 10^e <= v */
+	r = 0;
+	while (true) {
+		if (v >= p10p2[b]) {
+			v = v / p10p2[b];
+			r = r ^ (1 << b);
+		}
+
+		if (b == 0)
+			break;
+		--b;
+	}
+
+	return r;
+}
+
+/** @}
+ */