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drivers: video: common: optimizations for video_closest_frmival()

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In video_closest_frmival(), immediately stop searching when an exact
match is found, as a small performance optimization. Variables
that could be computed only once were moved further outside.

Signed-off-by: Josuah Demangeon <me@josuah.net>
This commit is contained in:
Josuah Demangeon 2025-05-08 15:13:49 +00:00 • committed by Benjamin Cabé
commit ee21d397d2
1 changed files with 13 additions and 6 deletions
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19
drivers/video/video_common.c
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@ -128,16 +128,18 @@ void video_closest_frmival_stepwise(const struct video_frmival_stepwise *stepwis
void video_closest_frmival(const struct device *dev, enum video_endpoint_id ep, void video_closest_frmival(const struct device *dev, enum video_endpoint_id ep,
struct video_frmival_enum *match) struct video_frmival_enum *match)
{ {
uint64_t best_diff_nsec = INT32_MAX;
struct video_frmival desired = match->discrete; struct video_frmival desired = match->discrete;
struct video_frmival_enum fie = {.format = match->format}; struct video_frmival_enum fie = {.format = match->format};
uint64_t best_diff_nsec = INT32_MAX;
uint64_t goal_nsec = video_frmival_nsec(&desired);
__ASSERT(match->type != VIDEO_FRMIVAL_TYPE_STEPWISE, __ASSERT(match->type != VIDEO_FRMIVAL_TYPE_STEPWISE,
"cannot find range matching the range, only a value matching the range"); "cannot find range matching the range, only a value matching the range");
for (fie.index = 0; video_enum_frmival(dev, ep, &fie) == 0; fie.index++) { for (fie.index = 0; video_enum_frmival(dev, ep, &fie) == 0; fie.index++) {
struct video_frmival tmp = {0}; struct video_frmival tmp = {0};
uint64_t diff_nsec = 0, a, b; uint64_t diff_nsec = 0;
uint64_t tmp_nsec;
switch (fie.type) { switch (fie.type) {
case VIDEO_FRMIVAL_TYPE_DISCRETE: case VIDEO_FRMIVAL_TYPE_DISCRETE:
@ -150,13 +152,18 @@ void video_closest_frmival(const struct device *dev, enum video_endpoint_id ep,
__ASSERT(false, "invalid answer from the queried video device"); __ASSERT(false, "invalid answer from the queried video device");
} }
a = video_frmival_nsec(&desired); tmp_nsec = video_frmival_nsec(&tmp);
b = video_frmival_nsec(&tmp); diff_nsec = tmp_nsec > goal_nsec ? tmp_nsec - goal_nsec : goal_nsec - tmp_nsec;
diff_nsec = a > b ? a - b : b - a;
if (diff_nsec < best_diff_nsec) { if (diff_nsec < best_diff_nsec) {
best_diff_nsec = diff_nsec; best_diff_nsec = diff_nsec;
match->index = fie.index; match->index = fie.index;
memcpy(&match->discrete, &tmp, sizeof(tmp)); match->discrete = tmp;
}
if (diff_nsec == 0) {
/* Exact match, stop searching a better match */
break;
} }
} }
} }