X-Git-Url: https://sigrok.org/gitweb/?a=blobdiff_plain;ds=sidebyside;f=src%2Fanalog.c;h=9fdece5df4a82a31333eb0577155b898e4bbea5d;hb=11e33196560a753b8af2486780dcb5f427a89177;hp=e2966875c3bbfb8c55212b19cd9ec2a110163347;hpb=8dc423b033678508ec08d7c473d883d4b3a58178;p=libsigrok.git

diff --git a/src/analog.c b/src/analog.c
index e2966875..9fdece5d 100644
--- a/src/analog.c
+++ b/src/analog.c
@@ -63,8 +63,8 @@ static struct unit_mq_string unit_strings[] = {
 	{ SR_UNIT_BOOLEAN, "" },
 	{ SR_UNIT_SECOND, "s" },
 	{ SR_UNIT_SIEMENS, "S" },
-	{ SR_UNIT_DECIBEL_MW, "dBu" },
-	{ SR_UNIT_DECIBEL_VOLT, "dBv" },
+	{ SR_UNIT_DECIBEL_MW, "dBm" },
+	{ SR_UNIT_DECIBEL_VOLT, "dBV" },
 	{ SR_UNIT_UNITLESS, "" },
 	{ SR_UNIT_DECIBEL_SPL, "dB" },
 	{ SR_UNIT_CONCENTRATION, "ppm" },
@@ -119,6 +119,7 @@ static struct unit_mq_string mq_strings[] = {
 	ALL_ZERO
 };
 
+/** @private */
 SR_PRIV int sr_analog_init(struct sr_datafeed_analog *analog,
 		struct sr_analog_encoding *encoding,
 		struct sr_analog_meaning *meaning,
@@ -306,8 +307,10 @@ SR_API int sr_analog_to_float(const struct sr_datafeed_analog *analog,
  */
 SR_API const char *sr_analog_si_prefix(float *value, int *digits)
 {
+/** @cond PRIVATE */
 #define NEG_PREFIX_COUNT 5  /* number of prefixes below unity */
 #define POS_PREFIX_COUNT (int)(ARRAY_SIZE(prefixes) - NEG_PREFIX_COUNT - 1)
+/** @endcond */
 	static const char *prefixes[] = { "f", "p", "n", "µ", "m", "", "k", "M", "G", "T" };
 
 	if (!value || !digits || isnan(*value))
@@ -329,6 +332,48 @@ SR_API const char *sr_analog_si_prefix(float *value, int *digits)
 	return prefixes[prefix + NEG_PREFIX_COUNT];
 }
 
+/**
+ * Check if a unit "accepts" an SI prefix.
+ *
+ * E.g. SR_UNIT_VOLT is SI prefix friendly while SR_UNIT_DECIBEL_MW or
+ * SR_UNIT_PERCENTAGE are not.
+ *
+ * @param[in] unit The unit to check for SI prefix "friendliness".
+ *
+ * @return TRUE if the unit "accept" an SI prefix.
+ *
+ * @since 0.5.0
+ */
+SR_API gboolean sr_analog_si_prefix_friendly(enum sr_unit unit)
+{
+	static const enum sr_unit prefix_friendly_units[] = {
+		SR_UNIT_VOLT,
+		SR_UNIT_AMPERE,
+		SR_UNIT_OHM,
+		SR_UNIT_FARAD,
+		SR_UNIT_KELVIN,
+		SR_UNIT_HERTZ,
+		SR_UNIT_SECOND,
+		SR_UNIT_SIEMENS,
+		SR_UNIT_VOLT_AMPERE,
+		SR_UNIT_WATT,
+		SR_UNIT_WATT_HOUR,
+		SR_UNIT_METER_SECOND,
+		SR_UNIT_HENRY,
+		SR_UNIT_GRAM
+	};
+	unsigned int i;
+
+	for (i = 0; i < ARRAY_SIZE(prefix_friendly_units); i++)
+		if (unit == prefix_friendly_units[i])
+			break;
+
+	if (unit != prefix_friendly_units[i])
+		return FALSE;
+
+	return TRUE;
+}
+
 /**
  * Convert the unit/MQ/MQ flags in the analog struct to a string.
  *