fix REQ-51

arch/x86/kernel/include/arch-bitops.h

@@ -0,0 +1,96 @@
+/**
+ * \file arch-bitops.h
+ *  License details are found in the file LICENSE.
+ * \brief
+ *  Find last set bit in word.
+ * \author Taku Shimosawa  <shimosawa@is.s.u-tokyo.ac.jp> \par
+ *      Copyright (C) 2011 - 2012  Taku Shimosawa
+ */
+/*
+ * HISTORY
+ */
+
+#ifndef HEADER_X86_COMMON_ARCH_BITOPS_H
+#define HEADER_X86_COMMON_ARCH_BITOPS_H
+
+static inline int fls(int x)
+{
+	int r;
+	asm("bsrl %1,%0\n\t"
+	    "jnz 1f\n\t"
+	    "movl $-1,%0\n"
+	    "1:" : "=r" (r) : "rm" (x));
+
+	return r + 1;
+}
+
+/**
+ * ffs - find first set bit in word
+ * @x: the word to search
+ *
+ * This is defined the same way as the libc and compiler builtin ffs
+ * routines, therefore differs in spirit from the other bitops.
+ *
+ * ffs(value) returns 0 if value is 0 or the position of the first
+ * set bit if value is nonzero. The first (least significant) bit
+ * is at position 1.
+ */
+static inline int ffs(int x)
+{
+	int r;
+	asm("bsfl %1,%0\n\t"
+	    "jnz 1f\n\t"
+	    "movl $-1,%0\n"
+	    "1:" : "=r" (r) : "rm" (x));
+	return r + 1;
+}
+
+
+/**
+ * __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)
+{
+	asm("bsf %1,%0"
+		: "=r" (word)
+		: "rm" (word));
+	return word;
+}
+
+/**
+ * ffz - find first zero bit in word
+ * @word: The word to search
+ *
+ * Undefined if no zero exists, so code should check against ~0UL first.
+ */
+static inline unsigned long ffz(unsigned long word)
+{
+	asm("bsf %1,%0"
+		: "=r" (word)
+		: "r" (~word));
+	return word;
+}
+
+
+#define ADDR (*(volatile long *)addr)
+
+static inline void set_bit(int nr, volatile unsigned long *addr)
+{
+	asm volatile("lock; btsl %1,%0"
+		     : "+m" (ADDR)
+		     : "Ir" (nr)
+		     : "memory");
+}
+
+static inline void clear_bit(int nr, volatile unsigned long *addr)
+{
+	asm volatile("lock; btrl %1,%0"
+		     : "+m" (ADDR)
+		     : "Ir" (nr)
+		     : "memory");
+}
+
+#endif