core: replace IS_FP_SAME macro by inline function

No reason to keep this as a macro - a function is easier to
read, type safe and easier to debug. Moreover, give it the
more appropriate name "nearly_equal()". After all, it precisely
does NOT check floating points for equality.

Signed-off-by: Berthold Stoeger <bstoeger@mail.tuwien.ac.at>

core/parse-xml.c

@@ -161,7 +161,7 @@ static enum number_type parse_float(const char *buffer, double *res, const char
 	if (errno || *endp == buffer)
 		return NEITHER;
 	if (**endp == ',') {
-		if (IS_FP_SAME(val, rint(val))) {
+		if (nearly_equal(val, rint(val))) {
 			/* we really want to send an error if this is a Subsurface native file
 			 * as this is likely indication of a bug - but right now we don't have
 			 * that information available */
@@ -604,7 +604,7 @@ static void fahrenheit(char *buffer, temperature_t *temperature)
 
 	switch (integer_or_float(buffer, &val)) {
 	case FLOATVAL:
-		if (IS_FP_SAME(val.fp, 32.0))
+		if (nearly_equal(val.fp, 32.0))
 			break;
 		if (val.fp < 32.0)
 			temperature->mkelvin = C_to_mkelvin(val.fp);

core/settings/qPrefDisplay.cpp

@@ -96,7 +96,7 @@ void qPrefDisplay::disk_divelist_font(bool doSync)
 
 void qPrefDisplay::set_font_size(double value)
 {
-	if (!IS_FP_SAME(value, prefs.font_size)) {
+	if (!nearly_equal(value, prefs.font_size)) {
 		prefs.font_size = value;
 		disk_font_size(true);
 
@@ -121,7 +121,7 @@ void qPrefDisplay::disk_font_size(bool doSync)
 
 void qPrefDisplay::set_mobile_scale(double value)
 {
-	if (!IS_FP_SAME(value, prefs.mobile_scale)) {
+	if (!nearly_equal(value, prefs.mobile_scale)) {
 		prefs.mobile_scale = value;
 		disk_mobile_scale(true);
 
@@ -159,7 +159,7 @@ void qPrefDisplay::setCorrectFont()
 	// get the font from the settings or our defaults
 	// respect the system default font size if none is explicitly set
 	QFont defaultFont = qPrefPrivate::propValue(keyFromGroupAndName(group, "divelist_font"), prefs.divelist_font).value<QFont>();
-	if (IS_FP_SAME(system_divelist_default_font_size, -1.0)) {
+	if (nearly_equal(system_divelist_default_font_size, -1.0)) {
 		prefs.font_size = qApp->font().pointSizeF();
 		system_divelist_default_font_size = prefs.font_size; // this way we don't save it on exit
 	}

core/settings/qPrefPrivate.cpp

@@ -25,7 +25,7 @@ void qPrefPrivate::propSetValue(const QString &key, const QVariant &value, const
 #else
 	if (value.isValid() && value.type() == QVariant::Double)
 #endif
-		isDefault = IS_FP_SAME(value.toDouble(), defaultValue.toDouble());
+		isDefault = nearly_equal(value.toDouble(), defaultValue.toDouble());
 	else
 		isDefault = (value == defaultValue);
 

core/subsurface-string.h

@@ -5,6 +5,7 @@
 #include <stdbool.h>
 #include <string.h>
 #include <time.h>
+#include <math.h>
 
 // shared generic definitions and macros
 // mostly about strings, but a couple of math macros are here as well
@@ -22,13 +23,15 @@
 	(void) (&_max1 == &_max2);      \
 	_max1 > _max2 ? _max1 : _max2; })
 
-#define IS_FP_SAME(_a, _b) (fabs((_a) - (_b)) <= 0.000001 * MAX(fabs(_a), fabs(_b)))
-
-
 #ifdef __cplusplus
 extern "C" {
 #endif
 
+static inline bool nearly_equal(double a, double b)
+{
+	return fabs(a - b) <= 1e-6 * fmax(fabs(a), fabs(b));
+}
+
 static inline bool nearly_0(double fp)
 {
 	return fabs(fp) <= 1e-6;

desktop-widgets/downloadfromdivecomputer.cpp

@@ -183,7 +183,7 @@ void DownloadFromDCWidget::updateProgressBar()
 	if (empty_string(last_text)) {
 		// if we get the first actual text after the download is finished
 		// (which happens for example on the OSTC), then don't bother
-		if (!empty_string(progress_bar_text) && IS_FP_SAME(progress_bar_fraction, 1.0))
+		if (!empty_string(progress_bar_text) && nearly_equal(progress_bar_fraction, 1.0))
 			progress_bar_text = "";
 	}
 	if (!empty_string(progress_bar_text)) {

mobile-widgets/themeinterface.cpp

@@ -81,7 +81,7 @@ double ThemeInterface::currentScale()
 
 void ThemeInterface::set_currentScale(double newScale)
 {
-	if (!IS_FP_SAME(newScale, qPrefDisplay::mobile_scale())) {
+	if (!nearly_equal(newScale, qPrefDisplay::mobile_scale())) {
 		qPrefDisplay::set_mobile_scale(newScale);
 		emit currentScaleChanged();
 		m_needSignals = true;

profile-widget/divecartesianaxis.cpp

@@ -442,7 +442,7 @@ double DiveCartesianAxis::posAtValue(double value, double max, double min) const
 
 	double screenFrom = position == Position::Bottom ? m.x1() : m.y1();
 	double screenTo = position == Position::Bottom ? m.x2() : m.y2();
-	if (IS_FP_SAME(min, max))
+	if (nearly_equal(min, max))
 		return (screenFrom + screenTo) / 2.0;
 	if ((position == Position::Bottom) == inverted)
 		std::swap(screenFrom, screenTo);

profile-widget/qmlprofile.cpp

@@ -96,7 +96,7 @@ void QMLProfile::setDevicePixelRatio(qreal dpr)
 // don't update the profile here, have the user update x and y and then manually trigger an update
 void QMLProfile::setXOffset(qreal value)
 {
-	if (IS_FP_SAME(value, m_xOffset))
+	if (nearly_equal(value, m_xOffset))
 		return;
 	m_xOffset = value;
 	emit xOffsetChanged();
@@ -105,7 +105,7 @@ void QMLProfile::setXOffset(qreal value)
 // don't update the profile here, have the user update x and y and then manually trigger an update
 void QMLProfile::setYOffset(qreal value)
 {
-	if (IS_FP_SAME(value, m_yOffset))
+	if (nearly_equal(value, m_yOffset))
 		return;
 	m_yOffset = value;
 	emit yOffsetChanged();

tests/testunitconversion.cpp

@@ -5,23 +5,23 @@
 
 void TestUnitConversion::testUnitConversions()
 {
-	QCOMPARE(IS_FP_SAME(grams_to_lbs(1000), 2.204586), true);
+	QCOMPARE(nearly_equal(grams_to_lbs(1000), 2.204586), true);
 	QCOMPARE(lbs_to_grams(1), 454);
-	QCOMPARE(IS_FP_SAME(ml_to_cuft(1000), 0.0353147), true);
+	QCOMPARE(nearly_equal(ml_to_cuft(1000), 0.0353147), true);
-	QCOMPARE(IS_FP_SAME(cuft_to_l(1), 28.316847), true);
+	QCOMPARE(nearly_equal(cuft_to_l(1), 28.316847), true);
-	QCOMPARE(IS_FP_SAME(mm_to_feet(1000), 3.280840), true);
+	QCOMPARE(nearly_equal(mm_to_feet(1000), 3.280840), true);
 	QCOMPARE(feet_to_mm(1), 305L);
 	QCOMPARE(to_feet((depth_t){1000}), 3);
-	QCOMPARE(IS_FP_SAME(mkelvin_to_C(647000), 373.85), true);
+	QCOMPARE(nearly_equal(mkelvin_to_C(647000), 373.85), true);
-	QCOMPARE(IS_FP_SAME(mkelvin_to_F(647000), 704.93), true);
+	QCOMPARE(nearly_equal(mkelvin_to_F(647000), 704.93), true);
 	QCOMPARE(F_to_mkelvin(704.93), 647000UL);
 	QCOMPARE(C_to_mkelvin(373.85), 647000UL);
-	QCOMPARE(IS_FP_SAME(psi_to_bar(14.6959488), 1.01325), true);
+	QCOMPARE(nearly_equal(psi_to_bar(14.6959488), 1.01325), true);
 	QCOMPARE(psi_to_mbar(14.6959488), 1013L);
-	QCOMPARE(IS_FP_SAME(to_PSI((pressure_t){1013}), 14.6923228594), true);
+	QCOMPARE(nearly_equal(to_PSI((pressure_t){1013}), 14.6923228594), true);
-	QCOMPARE(IS_FP_SAME(bar_to_atm(1.013), 1.0), true);
+	QCOMPARE(nearly_equal(bar_to_atm(1.013), 1.0), true);
-	QCOMPARE(IS_FP_SAME(mbar_to_atm(1013), 1.0), true);
+	QCOMPARE(nearly_equal(mbar_to_atm(1013), 1.0), true);
-	QCOMPARE(IS_FP_SAME(mbar_to_PSI(1013), 14.6923228594), true);
+	QCOMPARE(nearly_equal(mbar_to_PSI(1013), 14.6923228594), true);
 }
 
 QTEST_GUILESS_MAIN(TestUnitConversion)