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-rw-r--r--lib/reciprocal_div.c27
1 files changed, 27 insertions, 0 deletions
diff --git a/lib/reciprocal_div.c b/lib/reciprocal_div.c
new file mode 100644
index 000000000..464152410
--- /dev/null
+++ b/lib/reciprocal_div.c
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+#include <linux/kernel.h>
+#include <asm/div64.h>
+#include <linux/reciprocal_div.h>
+#include <linux/export.h>
+
+/*
+ * For a description of the algorithm please have a look at
+ * include/linux/reciprocal_div.h
+ */
+
+struct reciprocal_value reciprocal_value(u32 d)
+{
+ struct reciprocal_value R;
+ u64 m;
+ int l;
+
+ l = fls(d - 1);
+ m = ((1ULL << 32) * ((1ULL << l) - d));
+ do_div(m, d);
+ ++m;
+ R.m = (u32)m;
+ R.sh1 = min(l, 1);
+ R.sh2 = max(l - 1, 0);
+
+ return R;
+}
+EXPORT_SYMBOL(reciprocal_value);