Finish (?) importing the Linux ext2fs files that our GPL'ed ext2fs

files seem to be based on.  Don't bother importing <asm-i386/string.h>
just to get the Linux implementation of memscan() which is appended
to our i386-bitops.h.  The BSD skpc() should have been used instead
of memscan().

Obtained from:	Linux 1.2.2 distribution

sys/gnu/ext2fs/i386-bitops.h

@@ -0,0 +1,135 @@
+#ifndef _I386_BITOPS_H
+#define _I386_BITOPS_H
+
+/*
+ * Copyright 1992, Linus Torvalds.
+ */
+
+/*
+ * These have to be done with inline assembly: that way the bit-setting
+ * is guaranteed to be atomic. All bit operations return 0 if the bit
+ * was cleared before the operation and != 0 if it was not.
+ *
+ * bit 0 is the LSB of addr; bit 32 is the LSB of (addr+1).
+ */
+
+/*
+ * Some hacks to defeat gcc over-optimizations..
+ */
+struct __dummy { unsigned long a[100]; };
+#define ADDR (*(struct __dummy *) addr)
+
+extern __inline__ int set_bit(int nr, void * addr)
+{
+	int oldbit;
+
+	__asm__ __volatile__("btsl %2,%1\n\tsbbl %0,%0"
+		:"=r" (oldbit),"=m" (ADDR)
+		:"r" (nr));
+	return oldbit;
+}
+
+extern __inline__ int clear_bit(int nr, void * addr)
+{
+	int oldbit;
+
+	__asm__ __volatile__("btrl %2,%1\n\tsbbl %0,%0"
+		:"=r" (oldbit),"=m" (ADDR)
+		:"r" (nr));
+	return oldbit;
+}
+
+extern __inline__ int change_bit(int nr, void * addr)
+{
+	int oldbit;
+
+	__asm__ __volatile__("btcl %2,%1\n\tsbbl %0,%0"
+		:"=r" (oldbit),"=m" (ADDR)
+		:"r" (nr));
+	return oldbit;
+}
+
+/*
+ * This routine doesn't need to be atomic, but it's faster to code it
+ * this way.
+ */
+extern __inline__ int test_bit(int nr, void * addr)
+{
+	int oldbit;
+
+	__asm__ __volatile__("btl %2,%1\n\tsbbl %0,%0"
+		:"=r" (oldbit)
+		:"m" (ADDR),"r" (nr));
+	return oldbit;
+}
+
+/*
+ * Find-bit routines..
+ */
+extern inline int find_first_zero_bit(void * addr, unsigned size)
+{
+	int res;
+
+	if (!size)
+		return 0;
+	__asm__("
+		cld
+		movl $-1,%%eax
+		repe; scasl
+		je 1f
+		subl $4,%%edi
+		movl (%%edi),%%eax
+		notl %%eax
+		bsfl %%eax,%%edx
+		jmp 2f
+1:		xorl %%edx,%%edx
+2:		subl %%ebx,%%edi
+		shll $3,%%edi
+		addl %%edi,%%edx"
+		:"=d" (res)
+		:"c" ((size + 31) >> 5), "D" (addr), "b" (addr)
+		:"ax", "bx", "cx", "di");
+	return res;
+}
+
+extern inline int find_next_zero_bit (void * addr, int size, int offset)
+{
+	unsigned long * p = ((unsigned long *) addr) + (offset >> 5);
+	int set = 0, bit = offset & 31, res;
+	
+	if (bit) {
+		/*
+		 * Look for zero in first byte
+		 */
+		__asm__("
+			bsfl %1,%0
+			jne 1f
+			movl $32, %0
+1:			"
+			: "=r" (set)
+			: "r" (~(*p >> bit)));
+		if (set < (32 - bit))
+			return set + offset;
+		set = 32 - bit;
+		p++;
+	}
+	/*
+	 * No zero yet, search remaining full bytes for a zero
+	 */
+	res = find_first_zero_bit (p, size - 32 * (p - (unsigned long *) addr));
+	return (offset + set + res);
+}
+
+/*
+ * ffz = Find First Zero in word. Undefined if no zero exists,
+ * so code should check against ~0UL first..
+ */
+extern inline unsigned long ffz(unsigned long word)
+{
+	__asm__("bsfl %1,%0"
+		:"=r" (word)
+		:"r" (~word));
+	return word;
+}
+
+#endif /* _I386_BITOPS_H */