Add a function to locate the closest element in a sorted v4l2_fract array.
The implementation is based on find_closest() macro in linux/util_macros.h
and the way to compare two v4l2_fract in vivid_vid_cap_s_parm in
drivers/media/platform/vivid/vivid-vid-cap.c.
Cc: Matt Ranostay <matt.ranos...@konsulko.com>
Cc: Sakari Ailus <sakari.ai...@linux.intel.com>
Cc: Hans Verkuil <hansv...@cisco.com>
Cc: Mauro Carvalho Chehab <mche...@kernel.org>
Signed-off-by: Akinobu Mita <akinobu.m...@gmail.com>
---
drivers/media/v4l2-core/v4l2-common.c | 26 ++++++++++++++++++++++++++
include/media/v4l2-common.h | 12 ++++++++++++
2 files changed, 38 insertions(+)
diff --git a/drivers/media/v4l2-core/v4l2-common.c
b/drivers/media/v4l2-core/v4l2-common.c
index b518b92..91bd460 100644
--- a/drivers/media/v4l2-core/v4l2-common.c
+++ b/drivers/media/v4l2-core/v4l2-common.c
@@ -387,6 +387,32 @@ __v4l2_find_nearest_size(const void *array, size_t
array_size,
}
EXPORT_SYMBOL_GPL(__v4l2_find_nearest_size);
+#define FRACT_CMP(a, OP, b) \
+ ((u64)(a).numerator * (b).denominator OP \
+ (u64)(b).numerator * (a).denominator)
+
+int v4l2_find_closest_fract(struct v4l2_fract x, const struct v4l2_fract
*array,
+ size_t num)
+{
+ int i;
+
+ for (i = 0; i < num - 1; i++) {
+ struct v4l2_fract a = array[i];
+ struct v4l2_fract b = array[i + 1];
+ struct v4l2_fract midpoint = {
+ .numerator = a.numerator * b.denominator +
+ b.numerator * a.denominator,
+ .denominator = 2 * a.denominator * b.denominator,
+ };
+
+ if (FRACT_CMP(x, <=, midpoint))
+ break;
+ }
+
+ return i;
+}
+EXPORT_SYMBOL_GPL(v4l2_find_closest_fract);
+
void v4l2_get_timestamp(struct timeval *tv)
{
struct timespec ts;
diff --git a/include/media/v4l2-common.h b/include/media/v4l2-common.h
index cdc87ec..e388f4e 100644
--- a/include/media/v4l2-common.h
+++ b/include/media/v4l2-common.h
@@ -350,6 +350,18 @@ __v4l2_find_nearest_size(const void *array, size_t
array_size,
size_t height_offset, s32 width, s32 height);
/**
+ * v4l2_find_closest_fract - locate the closest element in a sorted array
+ * @x: The reference value.
+ * @array: The array in which to look for the closest element. Must be sorted
+ * in ascending order.
+ * @num: number of elements in 'array'.
+ *
+ * Returns the index of the element closest to 'x'.
+ */
+int v4l2_find_closest_fract(struct v4l2_fract x, const struct v4l2_fract
*array,
+ size_t num);
+
+/**
* v4l2_get_timestamp - helper routine to get a timestamp to be used when
* filling streaming metadata. Internally, it uses ktime_get_ts(),
* which is the recommended way to get it.
--
2.7.4
