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Diffstat (limited to 'arch/tile/lib/memchr_32.c')
-rw-r--r--arch/tile/lib/memchr_32.c68
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 000000000000..6235283b4859
--- /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);