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authorPatrick McHardy <kaber@trash.net>2014-12-13 07:50:35 +0000
committerPatrick McHardy <kaber@trash.net>2014-12-16 18:20:54 +0100
commit8a5697cf51937b54fc9a2c1f0d22f19dafe4d61e (patch)
tree8f70de50a72d3ed9d0c8c9534b6fc3bb486e0444
parent51425ecaa06296c467fded2ad5bf1b23f8a90cdd (diff)
utils: add fls()
Signed-off-by: Patrick McHardy <kaber@trash.net>
-rw-r--r--include/utils.h37
1 files changed, 37 insertions, 0 deletions
diff --git a/include/utils.h b/include/utils.h
index 15b2e393..45cb5a70 100644
--- a/include/utils.h
+++ b/include/utils.h
@@ -76,6 +76,43 @@
(void) (&_max1 == &_max2); \
_max1 > _max2 ? _max1 : _max2; })
+
+/**
+ * fls - find last (most-significant) bit set
+ * @x: the word to search
+ *
+ * This is defined the same way as ffs.
+ * Note fls(0) = 0, fls(1) = 1, fls(0x80000000) = 32.
+ */
+static inline int fls(int x)
+{
+ int r = 32;
+
+ if (!x)
+ return 0;
+ if (!(x & 0xffff0000u)) {
+ x <<= 16;
+ r -= 16;
+ }
+ if (!(x & 0xff000000u)) {
+ x <<= 8;
+ r -= 8;
+ }
+ if (!(x & 0xf0000000u)) {
+ x <<= 4;
+ r -= 4;
+ }
+ if (!(x & 0xc0000000u)) {
+ x <<= 2;
+ r -= 2;
+ }
+ if (!(x & 0x80000000u)) {
+ x <<= 1;
+ r -= 1;
+ }
+ return r;
+}
+
extern void __memory_allocation_error(const char *filename, uint32_t line) __noreturn;
#define memory_allocation_error() \