From: Linus Torvalds <torvalds@linux-foundation.org>
Date: Thu, 10 Nov 2011 23:33:38 +0000 (-0200)
Subject: Make the sample-vs-cylinder pressure check more liberal
X-Git-Url: http://git.tdb.fi/?p=ext%2Fsubsurface.git;a=commitdiff_plain;h=b4938ec2de87c3a43b749a1607d3bacb17d37cff

Make the sample-vs-cylinder pressure check more liberal

This makes it consider them to be identical if they are within half a
bar of each other.  If you edit the pressures by hand and set them to
the same bar pressure as the samples, they may not be identical to the
last milli-bar, but clearly the manually entered cylinder pressure isn't
significantly different from the sample data, so consider it redundant.

We do want manual overrides of cylinder pressures to take precedence
over sample data (as Dirk so eloquently puts it, some dive computers
really don't have very reliable sample data), but at the same time the
sample data is the one we are expecting to be fairly accurate.  The
starting and ending pressure overrides are for when there is no sample
data, or when the sample data is totally wrong for some reason.

Signed-off-by: Linus Torvalds <torvalds@linux-foundation.org>
---

diff --git a/dive.c b/dive.c
index bd1b926..dad0e23 100644
--- a/dive.c
+++ b/dive.c
@@ -224,6 +224,16 @@ static void fixup_pressure(struct dive *dive, struct sample *sample)
 	cyl->sample_end.mbar = pressure;
 }
 
+/*
+ * If the cylinder tank pressures are within half a bar
+ * (about 8 PSI) of the sample pressures, we consider it
+ * to be a rounding error, and throw them away as redundant.
+ */
+static int same_rounded_pressure(pressure_t a, pressure_t b)
+{
+	return abs(a.mbar - b.mbar) <= 500;
+}
+
 struct dive *fixup_dive(struct dive *dive)
 {
 	int i;
@@ -287,9 +297,9 @@ struct dive *fixup_dive(struct dive *dive)
 	for (i = 0; i < MAX_CYLINDERS; i++) {
 		cylinder_t *cyl = dive->cylinder + i;
 		add_cylinder_description(&cyl->type);
-		if (cyl->sample_start.mbar == cyl->start.mbar)
+		if (same_rounded_pressure(cyl->sample_start, cyl->start))
 			cyl->start.mbar = 0;
-		if (cyl->sample_end.mbar == cyl->end.mbar)
+		if (same_rounded_pressure(cyl->sample_end, cyl->end))
 			cyl->end.mbar = 0;
 	}