Move c_src dirs back to toplevel

[bcachefs-tools-debian] / linux / int_sqrt.c

diff --git a/linux/int_sqrt.c b/linux/int_sqrt.c
new file mode 100644 (file)
index 0000000..a8170bb
--- /dev/null
+++ b/linux/int_sqrt.c
@@ -0,0 +1,71 @@
+// SPDX-License-Identifier: GPL-2.0
+/*
+ * Copyright (C) 2013 Davidlohr Bueso <davidlohr.bueso@hp.com>
+ *
+ *  Based on the shift-and-subtract algorithm for computing integer
+ *  square root from Guy L. Steele.
+ */
+
+#include <linux/export.h>
+#include <linux/bitops.h>
+#include <linux/limits.h>
+#include <linux/math.h>
+
+/**
+ * int_sqrt - computes the integer square root
+ * @x: integer of which to calculate the sqrt
+ *
+ * Computes: floor(sqrt(x))
+ */
+unsigned long int_sqrt(unsigned long x)
+{
+       unsigned long b, m, y = 0;
+
+       if (x <= 1)
+               return x;
+
+       m = 1UL << (__fls(x) & ~1UL);
+       while (m != 0) {
+               b = y + m;
+               y >>= 1;
+
+               if (x >= b) {
+                       x -= b;
+                       y += m;
+               }
+               m >>= 2;
+       }
+
+       return y;
+}
+EXPORT_SYMBOL(int_sqrt);
+
+#if BITS_PER_LONG < 64
+/**
+ * int_sqrt64 - strongly typed int_sqrt function when minimum 64 bit input
+ * is expected.
+ * @x: 64bit integer of which to calculate the sqrt
+ */
+u32 int_sqrt64(u64 x)
+{
+       u64 b, m, y = 0;
+
+       if (x <= ULONG_MAX)
+               return int_sqrt((unsigned long) x);
+
+       m = 1ULL << ((fls64(x) - 1) & ~1ULL);
+       while (m != 0) {
+               b = y + m;
+               y >>= 1;
+
+               if (x >= b) {
+                       x -= b;
+                       y += m;
+               }
+               m >>= 2;
+       }
+
+       return y;
+}
+EXPORT_SYMBOL(int_sqrt64);
+#endif