Merge branch 'topic/isa' into topic/misc

1 files changed, 68 insertions, 0 deletions

diff --git a/arch/tile/lib/memchr_32.c b/arch/tile/lib/memchr_32.c
new file mode 100644
index 00000000000..6235283b485
--- /dev/null
+++ b/arch/tile/lib/memchr_32.c
@@ -0,0 +1,68 @@
+/*
+ * Copyright 2010 Tilera Corporation. All Rights Reserved.
+ *
+ *   This program is free software; you can redistribute it and/or
+ *   modify it under the terms of the GNU General Public License
+ *   as published by the Free Software Foundation, version 2.
+ *
+ *   This program is distributed in the hope that it will be useful, but
+ *   WITHOUT ANY WARRANTY; without even the implied warranty of
+ *   MERCHANTABILITY OR FITNESS FOR A PARTICULAR PURPOSE, GOOD TITLE or
+ *   NON INFRINGEMENT.  See the GNU General Public License for
+ *   more details.
+ */
+
+#include <linux/types.h>
+#include <linux/string.h>
+#include <linux/module.h>
+
+void *memchr(const void *s, int c, size_t n)
+{
+	/* Get an aligned pointer. */
+	const uintptr_t s_int = (uintptr_t) s;
+	const uint32_t *p = (const uint32_t *)(s_int & -4);
+
+	/* Create four copies of the byte for which we are looking. */
+	const uint32_t goal = 0x01010101 * (uint8_t) c;
+
+	/* Read the first word, but munge it so that bytes before the array
+	 * will not match goal.
+	 *
+	 * Note that this shift count expression works because we know
+	 * shift counts are taken mod 32.
+	 */
+	const uint32_t before_mask = (1 << (s_int << 3)) - 1;
+	uint32_t v = (*p | before_mask) ^ (goal & before_mask);
+
+	/* Compute the address of the last byte. */
+	const char *const last_byte_ptr = (const char *)s + n - 1;
+
+	/* Compute the address of the word containing the last byte. */
+	const uint32_t *const last_word_ptr =
+	    (const uint32_t *)((uintptr_t) last_byte_ptr & -4);
+
+	uint32_t bits;
+	char *ret;
+
+	if (__builtin_expect(n == 0, 0)) {
+		/* Don't dereference any memory if the array is empty. */
+		return NULL;
+	}
+
+	while ((bits = __insn_seqb(v, goal)) == 0) {
+		if (__builtin_expect(p == last_word_ptr, 0)) {
+			/* We already read the last word in the array,
+			 * so give up.
+			 */
+			return NULL;
+		}
+		v = *++p;
+	}
+
+	/* We found a match, but it might be in a byte past the end
+	 * of the array.
+	 */
+	ret = ((char *)p) + (__insn_ctz(bits) >> 3);
+	return (ret <= last_byte_ptr) ? ret : NULL;
+}
+EXPORT_SYMBOL(memchr);