1 files changed, 270 insertions, 0 deletions
diff --git a/lib/find_bit.c b/lib/find_bit.c
new file mode 100644
index 0000000000..32f99e9a67
--- /dev/null
+++ b/lib/find_bit.c
@@ -0,0 +1,270 @@
+// SPDX-License-Identifier: GPL-2.0-or-later
+/* bit search implementation
+ *
+ * Copyright (C) 2004 Red Hat, Inc. All Rights Reserved.
+ * Written by David Howells (dhowells@redhat.com)
+ *
+ * Copyright (C) 2008 IBM Corporation
+ * 'find_last_bit' is written by Rusty Russell <rusty@rustcorp.com.au>
+ * (Inspired by David Howell's find_next_bit implementation)
+ *
+ * Rewritten by Yury Norov <yury.norov@gmail.com> to decrease
+ * size and improve performance, 2015.
+ */
+
+#include <linux/bitops.h>
+#include <linux/bitmap.h>
+#include <linux/export.h>
+#include <linux/math.h>
+#include <linux/minmax.h>
+#include <linux/swab.h>
+
+/*
+ * Common helper for find_bit() function family
+ * @FETCH: The expression that fetches and pre-processes each word of bitmap(s)
+ * @MUNGE: The expression that post-processes a word containing found bit (may be empty)
+ * @size: The bitmap size in bits
+ */
+#define FIND_FIRST_BIT(FETCH, MUNGE, size)					\
+({										\
+	unsigned long idx, val, sz = (size);					\
+										\
+	for (idx = 0; idx * BITS_PER_LONG < sz; idx++) {			\
+		val = (FETCH);							\
+		if (val) {							\
+			sz = min(idx * BITS_PER_LONG + __ffs(MUNGE(val)), sz);	\
+			break;							\
+		}								\
+	}									\
+										\
+	sz;									\
+})
+
+/*
+ * Common helper for find_next_bit() function family
+ * @FETCH: The expression that fetches and pre-processes each word of bitmap(s)
+ * @MUNGE: The expression that post-processes a word containing found bit (may be empty)
+ * @size: The bitmap size in bits
+ * @start: The bitnumber to start searching at
+ */
+#define FIND_NEXT_BIT(FETCH, MUNGE, size, start)				\
+({										\
+	unsigned long mask, idx, tmp, sz = (size), __start = (start);		\
+										\
+	if (unlikely(__start >= sz))						\
+		goto out;							\
+										\
+	mask = MUNGE(BITMAP_FIRST_WORD_MASK(__start));				\
+	idx = __start / BITS_PER_LONG;						\
+										\
+	for (tmp = (FETCH) & mask; !tmp; tmp = (FETCH)) {			\
+		if ((idx + 1) * BITS_PER_LONG >= sz)				\
+			goto out;						\
+		idx++;								\
+	}									\
+										\
+	sz = min(idx * BITS_PER_LONG + __ffs(MUNGE(tmp)), sz);			\
+out:										\
+	sz;									\
+})
+
+#define FIND_NTH_BIT(FETCH, size, num)						\
+({										\
+	unsigned long sz = (size), nr = (num), idx, w, tmp;			\
+										\
+	for (idx = 0; (idx + 1) * BITS_PER_LONG <= sz; idx++) {			\
+		if (idx * BITS_PER_LONG + nr >= sz)				\
+			goto out;						\
+										\
+		tmp = (FETCH);							\
+		w = hweight_long(tmp);						\
+		if (w > nr)							\
+			goto found;						\
+										\
+		nr -= w;							\
+	}									\
+										\
+	if (sz % BITS_PER_LONG)							\
+		tmp = (FETCH) & BITMAP_LAST_WORD_MASK(sz);			\
+found:										\
+	sz = min(idx * BITS_PER_LONG + fns(tmp, nr), sz);			\
+out:										\
+	sz;									\
+})
+
+#ifndef find_first_bit
+/*
+ * Find the first set bit in a memory region.
+ */
+unsigned long _find_first_bit(const unsigned long *addr, unsigned long size)
+{
+	return FIND_FIRST_BIT(addr[idx], /* nop */, size);
+}
+EXPORT_SYMBOL(_find_first_bit);
+#endif
+
+#ifndef find_first_and_bit
+/*
+ * Find the first set bit in two memory regions.
+ */
+unsigned long _find_first_and_bit(const unsigned long *addr1,
+				  const unsigned long *addr2,
+				  unsigned long size)
+{
+	return FIND_FIRST_BIT(addr1[idx] & addr2[idx], /* nop */, size);
+}
+EXPORT_SYMBOL(_find_first_and_bit);
+#endif
+
+#ifndef find_first_zero_bit
+/*
+ * Find the first cleared bit in a memory region.
+ */
+unsigned long _find_first_zero_bit(const unsigned long *addr, unsigned long size)
+{
+	return FIND_FIRST_BIT(~addr[idx], /* nop */, size);
+}
+EXPORT_SYMBOL(_find_first_zero_bit);
+#endif
+
+#ifndef find_next_bit
+unsigned long _find_next_bit(const unsigned long *addr, unsigned long nbits, unsigned long start)
+{
+	return FIND_NEXT_BIT(addr[idx], /* nop */, nbits, start);
+}
+EXPORT_SYMBOL(_find_next_bit);
+#endif
+
+unsigned long __find_nth_bit(const unsigned long *addr, unsigned long size, unsigned long n)
+{
+	return FIND_NTH_BIT(addr[idx], size, n);
+}
+EXPORT_SYMBOL(__find_nth_bit);
+
+unsigned long __find_nth_and_bit(const unsigned long *addr1, const unsigned long *addr2,
+				 unsigned long size, unsigned long n)
+{
+	return FIND_NTH_BIT(addr1[idx] & addr2[idx], size, n);
+}
+EXPORT_SYMBOL(__find_nth_and_bit);
+
+unsigned long __find_nth_andnot_bit(const unsigned long *addr1, const unsigned long *addr2,
+				 unsigned long size, unsigned long n)
+{
+	return FIND_NTH_BIT(addr1[idx] & ~addr2[idx], size, n);
+}
+EXPORT_SYMBOL(__find_nth_andnot_bit);
+
+unsigned long __find_nth_and_andnot_bit(const unsigned long *addr1,
+					const unsigned long *addr2,
+					const unsigned long *addr3,
+					unsigned long size, unsigned long n)
+{
+	return FIND_NTH_BIT(addr1[idx] & addr2[idx] & ~addr3[idx], size, n);
+}
+EXPORT_SYMBOL(__find_nth_and_andnot_bit);
+
+#ifndef find_next_and_bit
+unsigned long _find_next_and_bit(const unsigned long *addr1, const unsigned long *addr2,
+					unsigned long nbits, unsigned long start)
+{
+	return FIND_NEXT_BIT(addr1[idx] & addr2[idx], /* nop */, nbits, start);
+}
+EXPORT_SYMBOL(_find_next_and_bit);
+#endif
+
+#ifndef find_next_andnot_bit
+unsigned long _find_next_andnot_bit(const unsigned long *addr1, const unsigned long *addr2,
+					unsigned long nbits, unsigned long start)
+{
+	return FIND_NEXT_BIT(addr1[idx] & ~addr2[idx], /* nop */, nbits, start);
+}
+EXPORT_SYMBOL(_find_next_andnot_bit);
+#endif
+
+#ifndef find_next_or_bit
+unsigned long _find_next_or_bit(const unsigned long *addr1, const unsigned long *addr2,
+					unsigned long nbits, unsigned long start)
+{
+	return FIND_NEXT_BIT(addr1[idx] | addr2[idx], /* nop */, nbits, start);
+}
+EXPORT_SYMBOL(_find_next_or_bit);
+#endif
+
+#ifndef find_next_zero_bit
+unsigned long _find_next_zero_bit(const unsigned long *addr, unsigned long nbits,
+					 unsigned long start)
+{
+	return FIND_NEXT_BIT(~addr[idx], /* nop */, nbits, start);
+}
+EXPORT_SYMBOL(_find_next_zero_bit);
+#endif
+
+#ifndef find_last_bit
+unsigned long _find_last_bit(const unsigned long *addr, unsigned long size)
+{
+	if (size) {
+		unsigned long val = BITMAP_LAST_WORD_MASK(size);
+		unsigned long idx = (size-1) / BITS_PER_LONG;
+
+		do {
+			val &= addr[idx];
+			if (val)
+				return idx * BITS_PER_LONG + __fls(val);
+
+			val = ~0ul;
+		} while (idx--);
+	}
+	return size;
+}
+EXPORT_SYMBOL(_find_last_bit);
+#endif
+
+unsigned long find_next_clump8(unsigned long *clump, const unsigned long *addr,
+			       unsigned long size, unsigned long offset)
+{
+	offset = find_next_bit(addr, size, offset);
+	if (offset == size)
+		return size;
+
+	offset = round_down(offset, 8);
+	*clump = bitmap_get_value8(addr, offset);
+
+	return offset;
+}
+EXPORT_SYMBOL(find_next_clump8);
+
+#ifdef __BIG_ENDIAN
+
+#ifndef find_first_zero_bit_le
+/*
+ * Find the first cleared bit in an LE memory region.
+ */
+unsigned long _find_first_zero_bit_le(const unsigned long *addr, unsigned long size)
+{
+	return FIND_FIRST_BIT(~addr[idx], swab, size);
+}
+EXPORT_SYMBOL(_find_first_zero_bit_le);
+
+#endif
+
+#ifndef find_next_zero_bit_le
+unsigned long _find_next_zero_bit_le(const unsigned long *addr,
+					unsigned long size, unsigned long offset)
+{
+	return FIND_NEXT_BIT(~addr[idx], swab, size, offset);
+}
+EXPORT_SYMBOL(_find_next_zero_bit_le);
+#endif
+
+#ifndef find_next_bit_le
+unsigned long _find_next_bit_le(const unsigned long *addr,
+				unsigned long size, unsigned long offset)
+{
+	return FIND_NEXT_BIT(addr[idx], swab, size, offset);
+}
+EXPORT_SYMBOL(_find_next_bit_le);
+
+#endif
+
+#endif /* __BIG_ENDIAN */