X-Git-Url: https://sigrok.org/gitweb/?a=blobdiff_plain;f=pv%2Futil.cpp;h=897254e12160fa59e60c7766efbd5e84f1d5fff5;hb=e23d7aa0d9980c3c269cbddb4cfbb32350d7425c;hp=49b9467c1642737a1a995df5adcb622e2bbddfa1;hpb=0cbadf1c6a80ec37481ae11ee3cb709eeffda3e7;p=pulseview.git

diff --git a/pv/util.cpp b/pv/util.cpp
index 49b9467c..897254e1 100644
--- a/pv/util.cpp
+++ b/pv/util.cpp
@@ -110,25 +110,31 @@ static QTextStream& operator<<(QTextStream& stream, const Timestamp& t)
 	return stream << QString::fromStdString(str);
 }
 
-QString format_time_si(const Timestamp& v, SIPrefix prefix,
-	unsigned int precision, QString unit, bool sign)
+SIPrefix determine_value_prefix(double v)
 {
-	if (prefix == SIPrefix::unspecified) {
-		// No prefix given, calculate it
-
-		if (v.is_zero()) {
-			prefix = SIPrefix::none;
-		} else {
-			int exp = exponent(SIPrefix::yotta);
-			prefix = SIPrefix::yocto;
-			while ((fabs(v) * pow(Timestamp(10), exp)) > 999 &&
-					prefix < SIPrefix::yotta) {
-				prefix = successor(prefix);
-				exp -= 3;
-			}
+	SIPrefix prefix;
+
+	if (v == 0) {
+		prefix = SIPrefix::none;
+	} else {
+		int exp = exponent(SIPrefix::yotta);
+		prefix = SIPrefix::yocto;
+		while ((fabs(v) * pow(10, exp)) > 999 &&
+				prefix < SIPrefix::yotta) {
+			prefix = successor(prefix);
+			exp -= 3;
 		}
 	}
 
+	return prefix;
+}
+
+QString format_time_si(const Timestamp& v, SIPrefix prefix,
+	unsigned int precision, QString unit, bool sign)
+{
+	if (prefix == SIPrefix::unspecified)
+		prefix = determine_value_prefix(v.convert_to<double>());
+
 	assert(prefix >= SIPrefix::yocto);
 	assert(prefix <= SIPrefix::yotta);
 
@@ -138,8 +144,8 @@ QString format_time_si(const Timestamp& v, SIPrefix prefix,
 	QTextStream ts(&s);
 	if (sign && !v.is_zero())
 		ts << forcesign;
-	ts << qSetRealNumberPrecision(precision) << (v * multiplier) << ' '
-		<< prefix << unit;
+	ts << qSetRealNumberPrecision(precision) << (v * multiplier);
+	ts << ' ' << prefix << unit;
 
 	return s;
 }
@@ -148,19 +154,11 @@ QString format_value_si(double v, SIPrefix prefix, unsigned precision,
 	QString unit, bool sign)
 {
 	if (prefix == SIPrefix::unspecified) {
-		// No prefix given, calculate it
-
-		if (v == 0) {
-			prefix = SIPrefix::none;
-		} else {
-			int exp = exponent(SIPrefix::yotta);
-			prefix = SIPrefix::yocto;
-			while ((fabs(v) * pow(Timestamp(10), exp)) > 999 &&
-					prefix < SIPrefix::yotta) {
-				prefix = successor(prefix);
-				exp -= 3;
-			}
-		}
+		prefix = determine_value_prefix(v);
+
+		const int prefix_order = -exponent(prefix);
+		precision = (prefix >= SIPrefix::none) ? max((int)(precision + prefix_order), 0) :
+			max((int)(precision - prefix_order), 0);
 	}
 
 	assert(prefix >= SIPrefix::yocto);