Merge b7fc06892a into beb352d47c

When computing the suggested switch depth for a gas,
we should take the next stop depth above the MOD, i.e.
round down. Otherwise we can produce MOD violation warnings.

We need, however, a bit of fudge as otherwise we do not
suggest to switch to o2 at 6m.

TestPlan uses the MOD to determine the depth to switch to
Tx21/35. This happens to be 65.378m. Therefore, switching
at 66m violates the MOD, the switch should be at 63m.
This then affects the gas usage.

Signed-off-by: Robert C. Helling <helling@atdotde.de>

core/dive.cpp

@@ -2457,7 +2457,9 @@ int dive::mbar_to_depth(int mbar) const
 depth_t dive::gas_mod(struct gasmix mix, pressure_t po2_limit, int roundto) const
 {
 	double depth = (double) mbar_to_depth(po2_limit.mbar * 1000 / get_o2(mix));
-	return depth_t { .mm = int_cast<int>(depth / roundto) * roundto };
+	// Rounding should be towards lower=safer depths but we give a bit
+	// of fudge to all to switch to o2 at 6m. So from .9 we round up.
+	return depth_t { .mm = (int)(depth / roundto + 0.1) * roundto };
 }
 
 /* Maximum narcotic depth rounded to multiples of roundto mm */

tests/testplan.cpp

@@ -865,17 +865,17 @@ void TestPlan::testVpmbMetricRepeat()
 
 	// check minimum gas result
 	dp = std::find_if(testPlan.dp.begin(), testPlan.dp.end(), [](auto &dp) { return dp.minimum_gas.mbar != 0; });
-	QCOMPARE(lrint(dp == testPlan.dp.end() ? 0.0 : dp->minimum_gas.mbar / 1000.0), 80l);
+	QCOMPARE(lrint(dp == testPlan.dp.end() ? 0.0 : dp->minimum_gas.mbar / 1000.0), 85l);
 	// print first ceiling
 	printf("First ceiling %.1f m\n", dive.mbar_to_depth(test_deco_state.first_ceiling_pressure.mbar) * 0.001);
 	QVERIFY(dive.dcs[0].events.size() >= 3);
-	// check first gas change to 21/35 at 66m
+	// check first gas change to 21/35 at 63m
 	struct event *ev = &dive.dcs[0].events[0];
 	QVERIFY(ev != NULL);
 	QCOMPARE(ev->gas.index, 1);
 	QCOMPARE(ev->gas.mix.o2.permille, 210);
 	QCOMPARE(ev->gas.mix.he.permille, 350);
-	QCOMPARE(get_depth_at_time(&dive.dcs[0], ev->time.seconds), 66000);
+	QCOMPARE(get_depth_at_time(&dive.dcs[0], ev->time.seconds), 63000);
 	// check second gas change to EAN50 at 21m
 	ev = &dive.dcs[0].events[1];
 	QCOMPARE(ev->gas.index, 2);