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Cleanup: return gasmix by value

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Currently, get_gasmix_from_event() and get_gasmix() return pointers
to either static or to (possibly changing) dive data. This seems like
a dangerous practice and the returned data should be used immediately.

Instead, return the gasmix by value. This is in preparation of
const-ifying input parameters of a number of core functions, which
will ultimately let the merge() function take const-arguments in
preparation of undo of dive-merging.

On common 64-bit systems gasmix (two "int"s) is the size of a pointer
and can be returned in a register.

On 32-bit systems a pointer to the struct to be filled out will be
passed.

Since get_gasmix() now returns a value, the first invocation is
tested by a NULL-initialized "struct event *". Document this in
a comment.

Signed-off-by: Berthold Stoeger <bstoeger@mail.tuwien.ac.at>
This commit is contained in:
Berthold Stoeger 2018-08-16 13:35:14 +02:00 • committed by Dirk Hohndel
parent b6187f73aa
commit f5b11daffd
10 changed files with 65 additions and 55 deletions
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30
core/dive.c
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@ -270,17 +270,16 @@ enum divemode_t get_current_divemode(struct divecomputer *dc, int time, struct e
return *divemode;
}
/* this returns a pointer to static variable - so use it right away after calling */
struct gasmix *get_gasmix_from_event(struct dive *dive, struct event *ev)
struct gasmix get_gasmix_from_event(struct dive *dive, struct event *ev)
{
static struct gasmix dummy;
struct gasmix dummy = { 0 };
if (ev && event_is_gaschange(ev)) {
int index = ev->gas.index;
if (index >= 0 && index < MAX_CYLINDERS)
return &dive->cylinder[index].gasmix;
return &ev->gas.mix;
return dive->cylinder[index].gasmix;
return ev->gas.mix;
}
return &dummy;
return dummy;
}
int get_pressure_units(int mb, const char **units)
@ -1073,7 +1072,7 @@ void update_setpoint_events(struct dive *dive, struct divecomputer *dc)
// So we make sure, this comes from a Predator or Petrel and we only remove
// pO2 values we would have computed anyway.
struct event *ev = get_next_event(dc->events, "gaschange");
struct gasmix *gasmix = get_gasmix_from_event(dive, ev);
struct gasmix gasmix = get_gasmix_from_event(dive, ev);
struct event *next = get_next_event(ev, "gaschange");
for (int i = 0; i < dc->samples; i++) {
@ -1083,7 +1082,7 @@ void update_setpoint_events(struct dive *dive, struct divecomputer *dc)
gasmix = get_gasmix_from_event(dive, ev);
next = get_next_event(ev, "gaschange");
}
fill_pressures(&pressures, calculate_depth_to_mbar(dc->sample[i].depth.mm, dc->surface_pressure, 0), gasmix ,0, dc->divemode);
fill_pressures(&pressures, calculate_depth_to_mbar(dc->sample[i].depth.mm, dc->surface_pressure, 0), &gasmix ,0, dc->divemode);
if (abs(dc->sample[i].setpoint.mbar - (int)(1000 * pressures.o2)) <= 50)
dc->sample[i].setpoint.mbar = 0;
}
@ -4288,19 +4287,24 @@ int dive_has_gps_location(struct dive *dive)
return dive_site_has_gps_location(get_dive_site_by_uuid(dive->dive_site_uuid));
}
struct gasmix *get_gasmix(struct dive *dive, struct divecomputer *dc, int time, struct event **evp, struct gasmix *gasmix)
struct gasmix get_gasmix(struct dive *dive, struct divecomputer *dc, int time, struct event **evp, struct gasmix *gasmix)
{
struct event *ev = *evp;
struct gasmix res;
if (!gasmix) {
if (!ev) {
/* on first invocation, get initial gas mix and first event (if any) */
int cyl = explicit_first_cylinder(dive, dc);
gasmix = &dive->cylinder[cyl].gasmix;
res = dive->cylinder[cyl].gasmix;
ev = dc ? get_next_event(dc->events, "gaschange") : NULL;
} else {
res = *gasmix;
}
while (ev && ev->time.seconds < time) {
gasmix = get_gasmix_from_event(dive, ev);
res = get_gasmix_from_event(dive, ev);
ev = get_next_event(ev->next, "gaschange");
}
*evp = ev;
return gasmix;
return res;
}