[v2 01/10] utils_macro: introduce find_closest_unsorted()

Andrea Merello
2021-10-28T10:19:13Z

This is similar to find_closest() and find_closest_descending(), but, it
doesn't make any assumption about the array being ordered.

Signed-off-by: Andrea Merello <andrea.merello@iit.it>
---
include/linux/util_macros.h | 26 ++++++++++++++++++++++++++
1 file changed, 26 insertions(+)

diff --git a/include/linux/util_macros.h b/include/linux/util_macros.h
index 72299f261b25..b48f80ceb380 100644
--- a/include/linux/util_macros.h
+++ b/include/linux/util_macros.h
@@ -2,6 +2,8 @@
#ifndef _LINUX_HELPER_MACROS_H_
#define _LINUX_HELPER_MACROS_H_

+#include <linux/math.h>
+
#define __find_closest(x, a, as, op) \
({ \
typeof(as) __fc_i, __fc_as = (as) - 1; \
@@ -38,4 +40,28 @@
*/
#define find_closest_descending(x, a, as) __find_closest(x, a, as, >=)

+/**
+ * find_closest_unsorted - locate the closest element in a unsorted array
+ * @x: The reference value.
+ * @a: The array in which to look for the closest element.
+ * @as: Size of 'a'.
+ *
+ * Similar to find_closest() but 'a' has no requirement to being sorted
+ */
+#define find_closest_unsorted(x, a, as) \
+({ \
+ typeof(x) __fc_best_delta, __fc_delta; \
+ typeof(as) __fc_i, __fc_best_idx; \
+ bool __fc_first = true; \
+ for (__fc_i = 0; __fc_i < (as); __fc_i++) { \
+ __fc_delta = abs(a[__fc_i] - (x)); \
+ if (__fc_first || __fc_delta < __fc_best_delta) { \
+ __fc_best_delta = __fc_delta; \
+ __fc_best_idx = __fc_i; \
+ } \
+ __fc_first = false; \
+ } \
+ (__fc_best_idx); \
+})
+
#endif
--
2.17.1