core: add nm_utils_10pow() utils

3 files changed, 85 insertions, 0 deletions

diff --git a/src/nm-core-utils.c b/src/nm-core-utils.c
index 25ca18853e..11b2085b2c 100644
--- a/src/nm-core-utils.c
+++ b/src/nm-core-utils.c
@@ -155,6 +155,37 @@ _nm_singleton_instance_register_destruction (GObject *instance)
 
 /*****************************************************************************/
 
+static double
+_10pow (guint16 ex)
+{
+	double v;
+
+	if (ex == 0)
+		return 1.0;
+
+	v = _10pow (ex / 2);
+	v = v * v;
+	if (ex % 2)
+		v *= 10;
+	return v;
+}
+
+/*/
+ * nm_utils_10pow:
+ * @ex: the exponent
+ *
+ * Returns: 10^ex or pow(10, ex)
+ */
+double
+nm_utils_10pow (gint16 ex)
+{
+	if (ex >= 0)
+		return _10pow (ex);
+	return 1.0 / _10pow (- ((gint32) ex));
+}
+
+/*****************************************************************************/
+
 /*
  * nm_ethernet_address_is_valid:
  * @addr: pointer to a binary or ASCII Ethernet address
diff --git a/src/nm-core-utils.h b/src/nm-core-utils.h
index f9fa88a29b..fbeecf7a21 100644
--- a/src/nm-core-utils.h
+++ b/src/nm-core-utils.h
@@ -97,6 +97,8 @@ in_addr_t nm_utils_ip4_address_clear_host_address (in_addr_t addr, guint8 plen);
 const struct in6_addr *nm_utils_ip6_address_clear_host_address (struct in6_addr *dst, const struct in6_addr *src, guint8 plen);
 gboolean nm_utils_ip6_address_same_prefix (const struct in6_addr *addr_a, const struct in6_addr *addr_b, guint8 plen);
 
+double nm_utils_10pow (gint16 e);
+
 /**
  * nm_utils_ip6_route_metric_normalize:
  * @metric: the route metric
diff --git a/src/tests/test-general.c b/src/tests/test-general.c
index 498615822e..abc1534003 100644
--- a/src/tests/test-general.c
+++ b/src/tests/test-general.c
@@ -23,6 +23,9 @@
 #include <string.h>
 #include <errno.h>
 
+/* need math.h for isinf() and INFINITY. No need to link with -lm */
+#include <math.h>
+
 #include "NetworkManagerUtils.h"
 #include "nm-core-internal.h"
 
@@ -1653,6 +1656,53 @@ test_stable_id_generated_complete (void)
 
 /*****************************************************************************/
 
+static void
+test_nm_utils_10pow (void)
+{
+#define FLOAT_CMP(a, b) \
+	G_STMT_START { \
+		double _a = (a); \
+		double _b = (b); \
+		\
+		if (isinf (_b)) \
+			g_assert (isinf (_a)); \
+		else if (_b >= 0.0 && _b <= 0.0) \
+			g_assert (_a >= 0.0 && _a <= 0.0); \
+		else { \
+			double _x = (_a) - (_b); \
+			g_assert (_b > 0.0); \
+			if (_x < 0.0) \
+				_x = -_x; \
+			g_assert (_x / _b <  1E-10); \
+		} \
+	} G_STMT_END
+
+	FLOAT_CMP (nm_utils_10pow (G_MININT16),  0.0);
+	FLOAT_CMP (nm_utils_10pow (-310),        0.0);
+	FLOAT_CMP (nm_utils_10pow (-309),        0.0);
+	FLOAT_CMP (nm_utils_10pow (-308),        1e-308);
+	FLOAT_CMP (nm_utils_10pow (-307),        1e-307);
+	FLOAT_CMP (nm_utils_10pow (-1),          1e-1);
+	FLOAT_CMP (nm_utils_10pow (-2),          1e-2);
+	FLOAT_CMP (nm_utils_10pow (0),           1e0);
+	FLOAT_CMP (nm_utils_10pow (1),           1e1);
+	FLOAT_CMP (nm_utils_10pow (2),           1e2);
+	FLOAT_CMP (nm_utils_10pow (3),           1e3);
+	FLOAT_CMP (nm_utils_10pow (4),           1e4);
+	FLOAT_CMP (nm_utils_10pow (5),           1e5);
+	FLOAT_CMP (nm_utils_10pow (6),           1e6);
+	FLOAT_CMP (nm_utils_10pow (7),           1e7);
+	FLOAT_CMP (nm_utils_10pow (122),         1e122);
+	FLOAT_CMP (nm_utils_10pow (200),         1e200);
+	FLOAT_CMP (nm_utils_10pow (307),         1e307);
+	FLOAT_CMP (nm_utils_10pow (308),         1e308);
+	FLOAT_CMP (nm_utils_10pow (309),         INFINITY);
+	FLOAT_CMP (nm_utils_10pow (310),         INFINITY);
+	FLOAT_CMP (nm_utils_10pow (G_MAXINT16),  INFINITY);
+}
+
+/*****************************************************************************/
+
 NMTST_DEFINE ();
 
 int
@@ -1666,6 +1716,8 @@ main (int argc, char **argv)
 	g_test_add_func ("/general/nm_utils_ip6_address_same_prefix", test_nm_utils_ip6_address_same_prefix);
 	g_test_add_func ("/general/nm_utils_log_connection_diff", test_nm_utils_log_connection_diff);
 
+	g_test_add_func ("/general/10pow", test_nm_utils_10pow);
+
 	g_test_add_func ("/general/connection-match/basic", test_connection_match_basic);
 	g_test_add_func ("/general/connection-match/ip6-method", test_connection_match_ip6_method);
 	g_test_add_func ("/general/connection-match/ip6-method-ignore", test_connection_match_ip6_method_ignore);