libcamera: utils: Add clamp()

C++11 does not support std::clamp(), add a custom implementation in
utils.

Signed-off-by: Niklas Söderlund <niklas.soderlund@ragnatech.se>
Reviewed-by: Laurent Pinchart <laurent.pinchart@ideasonboard.com>

src/libcamera/include/utils.h

@@ -7,6 +7,7 @@
 #ifndef __LIBCAMERA_UTILS_H__
 #define __LIBCAMERA_UTILS_H__
 
+#include <algorithm>
 #include <memory>
 
 #define ARRAY_SIZE(a)	(sizeof(a) / sizeof(a[0]))
@@ -45,6 +46,13 @@ unsigned int set_overlap(InputIt1 first1, InputIt1 last1,
 	return count;
 }
 
+/* C++11 doesn't provide std::clamp */
+template <typename T>
+const T& clamp(const T& v, const T& lo, const T& hi)
+{
+	return std::max(lo, std::min(v, hi));
+}
+
 } /* namespace utils */
 
 } /* namespace libcamera */

src/libcamera/utils.cpp

@@ -85,6 +85,14 @@ char *secure_getenv(const char *name)
  * \return The number of elements in the intersection of the two ranges
  */
 
+/**
+ * \fn libcamera::utils::clamp(const T& v, const T& lo, const T& hi)
+ * \param[in] v The value to clamp
+ * \param[in] lo The lower boundary to clamp v to
+ * \param[in] hi The higher boundary to clamp v to
+ * \return lo if v is less than lo, hi if v is greater than hi, otherwise v
+ */
+
 } /* namespace utils */
 
 } /* namespace libcamera */