libcamera: utils: Add alignUp and alignDown functions

Add to libcamera utils library two functions to round up or down a
value to an alignment and add a test in test/utils.cpp for the two
new functions.

Reviewed-by: Kieran Bingham <kieran.bingham@ideasonboard.com>
Reviewed-by: Niklas Söderlund <niklas.soderlund@ragnatech.se>
Reviewed-by: Laurent Pinchart <laurent.pinchart@ideasonboard.com>
Signed-off-by: Jacopo Mondi <jacopo@jmondi.org>

3 files changed, 37 insertions, 0 deletions

diff --git a/include/libcamera/internal/utils.h b/include/libcamera/internal/utils.h
index 8d026cc6..45cd6f12 100644
--- a/include/libcamera/internal/utils.h
+++ b/include/libcamera/internal/utils.h
@@ -200,6 +200,16 @@ details::StringSplitter split(const std::string &str, const std::string &delim);
 std::string libcameraBuildPath();
 std::string libcameraSourcePath();
 
+constexpr unsigned int alignDown(unsigned int value, unsigned int alignment)
+{
+	return value / alignment * alignment;
+}
+
+constexpr unsigned int alignUp(unsigned int value, unsigned int alignment)
+{
+	return (value + alignment - 1) / alignment * alignment;
+}
+
 } /* namespace utils */
 
 } /* namespace libcamera */
diff --git a/src/libcamera/utils.cpp b/src/libcamera/utils.cpp
index 0567328f..615df46a 100644
--- a/src/libcamera/utils.cpp
+++ b/src/libcamera/utils.cpp
@@ -444,6 +444,22 @@ std::string libcameraSourcePath()
 	return path + "/";
 }
 
+/**
+ * \fn alignDown(unsigned int value, unsigned int alignment)
+ * \brief Align \a value down to \a alignment
+ * \param[in] value The value to align
+ * \param[in] alignment The alignment
+ * \return The value rounded down to the nearest multiple of \a alignment
+ */
+
+/**
+ * \fn alignUp(unsigned int value, unsigned int alignment)
+ * \brief Align \a value up to \a alignment
+ * \param[in] value The value to align
+ * \param[in] alignment The alignment
+ * \return The value rounded up to the nearest multiple of \a alignment
+ */
+
 } /* namespace utils */
 
 } /* namespace libcamera */
diff --git a/test/utils.cpp b/test/utils.cpp
index f482e6a1..08f29389 100644
--- a/test/utils.cpp
+++ b/test/utils.cpp
@@ -166,6 +166,17 @@ protected:
 			return TestFail;
 		}
 
+		/* utils::alignUp() and utils::alignDown() tests. */
+		if (utils::alignDown(6, 3) != 6 || utils::alignDown(7, 3) != 6) {
+			cerr << "utils::alignDown test failed" << endl;
+			return TestFail;
+		}
+
+		if (utils::alignUp(6, 3) != 6 || utils::alignUp(7, 3) != 9) {
+			cerr << "utils::alignUp test failed" << endl;
+			return TestFail;
+		}
+
 		return TestPass;
 	}
 };