1 files changed, 79 insertions, 0 deletions
diff --git a/arch/x86/include/asm/word-at-a-time.h b/arch/x86/include/asm/word-at-a-time.h
new file mode 100644
index 000000000000..e58f03b206c3
--- /dev/null
+++ b/arch/x86/include/asm/word-at-a-time.h
@@ -0,0 +1,79 @@
+#ifndef _ASM_WORD_AT_A_TIME_H
+#define _ASM_WORD_AT_A_TIME_H
+
+/*
+ * This is largely generic for little-endian machines, but the
+ * optimal byte mask counting is probably going to be something
+ * that is architecture-specific. If you have a reliably fast
+ * bit count instruction, that might be better than the multiply
+ * and shift, for example.
+ */
+
+#ifdef CONFIG_64BIT
+
+/*
+ * Jan Achrenius on G+: microoptimized version of
+ * the simpler "(mask & ONEBYTES) * ONEBYTES >> 56"
+ * that works for the bytemasks without having to
+ * mask them first.
+ */
+static inline long count_masked_bytes(unsigned long mask)
+{
+	return mask*0x0001020304050608ul >> 56;
+}
+
+#else	/* 32-bit case */
+
+/* Carl Chatfield / Jan Achrenius G+ version for 32-bit */
+static inline long count_masked_bytes(long mask)
+{
+	/* (000000 0000ff 00ffff ffffff) -> ( 1 1 2 3 ) */
+	long a = (0x0ff0001+mask) >> 23;
+	/* Fix the 1 for 00 case */
+	return a & mask;
+}
+
+#endif
+
+#define REPEAT_BYTE(x)	((~0ul / 0xff) * (x))
+
+/* Return the high bit set in the first byte that is a zero */
+static inline unsigned long has_zero(unsigned long a)
+{
+	return ((a - REPEAT_BYTE(0x01)) & ~a) & REPEAT_BYTE(0x80);
+}
+
+/*
+ * Load an unaligned word from kernel space.
+ *
+ * In the (very unlikely) case of the word being a page-crosser
+ * and the next page not being mapped, take the exception and
+ * return zeroes in the non-existing part.
+ */
+static inline unsigned long load_unaligned_zeropad(const void *addr)
+{
+	unsigned long ret, dummy;
+
+	asm(
+		"1:\tmov %2,%0\n"
+		"2:\n"
+		".section .fixup,\"ax\"\n"
+		"3:\t"
+		"lea %2,%1\n\t"
+		"and %3,%1\n\t"
+		"mov (%1),%0\n\t"
+		"leal %2,%%ecx\n\t"
+		"andl %4,%%ecx\n\t"
+		"shll $3,%%ecx\n\t"
+		"shr %%cl,%0\n\t"
+		"jmp 2b\n"
+		".previous\n"
+		_ASM_EXTABLE(1b, 3b)
+		:"=&r" (ret),"=&c" (dummy)
+		:"m" (*(unsigned long *)addr),
+		 "i" (-sizeof(unsigned long)),
+		 "i" (sizeof(unsigned long)-1));
+	return ret;
+}
+
+#endif /* _ASM_WORD_AT_A_TIME_H */