common: Move in bit operation helpers

travis-ci: success for Common headers Signed-off-by: Cyrill Gorcunov <gorcunov@openvz.org> Signed-off-by: Pavel Emelyanov <xemul@virtuozzo.com>
2025-08-31 22:35:33 +00:00 · 2016-10-24 14:58:09 +03:00
parent 4485723f80
commit 49883d681f
20 changed files with 21 additions and 13 deletions
--- a/include/common/asm-generic/bitops.h
+++ b/include/common/asm-generic/bitops.h
@@ -0,0 +1,123 @@
+/*
+ * Generic bits operations.
+ *
+ * Architectures that don't want their own implementation of those,
+ * should include this file into the arch/$ARCH/include/asm/bitops.h
+ */
+
+#ifndef __CR_GENERIC_BITOPS_H__
+#define __CR_GENERIC_BITOPS_H__
+
+#include "asm/bitsperlong.h"
+
+#define DIV_ROUND_UP(n,d)	(((n) + (d) - 1) / (d))
+#define BITS_TO_LONGS(nr)	DIV_ROUND_UP(nr, BITS_PER_LONG)
+
+#define DECLARE_BITMAP(name, bits)		\
+	unsigned long name[BITS_TO_LONGS(bits)]
+
+#if __GNUC__ < 4 || (__GNUC__ == 4 && __GNUC_MINOR__ < 1)
+/* Technically wrong, but this avoids compilation errors on some gcc
+   versions. */
+#define BITOP_ADDR(x) "=m" (*(volatile long *) (x))
+#else
+#define BITOP_ADDR(x) "+m" (*(volatile long *) (x))
+#endif
+
+#define ADDR				BITOP_ADDR(addr)
+
+static inline void set_bit(int nr, volatile unsigned long *addr) {
+	addr += nr / BITS_PER_LONG;
+	*addr |= (1 << (nr % BITS_PER_LONG));
+}
+
+static inline void change_bit(int nr, volatile unsigned long *addr)
+{
+	addr += nr / BITS_PER_LONG;
+	*addr ^= (1 << (nr % BITS_PER_LONG));
+}
+
+static inline int test_bit(int nr, volatile const unsigned long *addr)
+{
+	addr += nr / BITS_PER_LONG;
+	return (*addr & (1 << (nr % BITS_PER_LONG))) ? -1 : 0;
+}
+
+static inline void clear_bit(int nr, volatile unsigned long *addr)
+{
+	addr += nr / BITS_PER_LONG;
+	*addr &= ~(1 << (nr % BITS_PER_LONG));
+}
+
+/**
+ * __ffs - find first set bit in word
+ * @word: The word to search
+ *
+ * Undefined if no bit exists, so code should check against 0 first.
+ */
+static inline unsigned long __ffs(unsigned long word)
+{
+	int p = 0;
+
+	for (; p < 8*sizeof(word); ++p) {
+		if (word & 1) {
+			break;
+		}
+
+		word >>= 1;
+	}
+
+	return p;
+}
+
+#define BITOP_WORD(nr)		((nr) / BITS_PER_LONG)
+
+/*
+ * Find the next set bit in a memory region.
+ */
+static inline
+unsigned long find_next_bit(const unsigned long *addr, unsigned long size,
+			    unsigned long offset)
+{
+	const unsigned long *p = addr + BITOP_WORD(offset);
+	unsigned long result = offset & ~(BITS_PER_LONG-1);
+	unsigned long tmp;
+
+	if (offset >= size)
+		return size;
+	size -= result;
+	offset %= BITS_PER_LONG;
+	if (offset) {
+		tmp = *(p++);
+		tmp &= (~0UL << offset);
+		if (size < BITS_PER_LONG)
+			goto found_first;
+		if (tmp)
+			goto found_middle;
+		size -= BITS_PER_LONG;
+		result += BITS_PER_LONG;
+	}
+	while (size & ~(BITS_PER_LONG-1)) {
+		if ((tmp = *(p++)))
+			goto found_middle;
+		result += BITS_PER_LONG;
+		size -= BITS_PER_LONG;
+	}
+	if (!size)
+		return result;
+	tmp = *p;
+
+found_first:
+	tmp &= (~0UL >> (BITS_PER_LONG - size));
+	if (tmp == 0UL)		/* Are any bits set? */
+		return result + size;	/* Nope. */
+found_middle:
+	return result + __ffs(tmp);
+}
+
+#define for_each_bit(i, bitmask)				\
+	for (i = find_next_bit(bitmask, sizeof(bitmask), 0);	\
+	     i < sizeof(bitmask);				\
+	     i = find_next_bit(bitmask, sizeof(bitmask), i + 1))
+
+#endif /* __CR_GENERIC_BITOPS_H__ */