summaryrefslogtreecommitdiffstats
path: root/kernel/arch/tile/lib/strnlen_32.c
diff options
context:
space:
mode:
Diffstat (limited to 'kernel/arch/tile/lib/strnlen_32.c')
-rw-r--r--kernel/arch/tile/lib/strnlen_32.c47
1 files changed, 47 insertions, 0 deletions
diff --git a/kernel/arch/tile/lib/strnlen_32.c b/kernel/arch/tile/lib/strnlen_32.c
new file mode 100644
index 000000000..1434141d9
--- /dev/null
+++ b/kernel/arch/tile/lib/strnlen_32.c
@@ -0,0 +1,47 @@
+/*
+ * Copyright 2013 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>
+
+size_t strnlen(const char *s, size_t count)
+{
+ /* Get an aligned pointer. */
+ const uintptr_t s_int = (uintptr_t) s;
+ const uint32_t *p = (const uint32_t *)(s_int & -4);
+ size_t bytes_read = sizeof(*p) - (s_int & (sizeof(*p) - 1));
+ size_t len;
+ uint32_t v, bits;
+
+ /* Avoid page fault risk by not reading any bytes when count is 0. */
+ if (count == 0)
+ return 0;
+
+ /* Read first word, but force bytes before the string to be nonzero. */
+ v = *p | ((1 << ((s_int << 3) & 31)) - 1);
+
+ while ((bits = __insn_seqb(v, 0)) == 0) {
+ if (bytes_read >= count) {
+ /* Read COUNT bytes and didn't find the terminator. */
+ return count;
+ }
+ v = *++p;
+ bytes_read += sizeof(v);
+ }
+
+ len = ((const char *) p) + (__insn_ctz(bits) >> 3) - s;
+ return (len < count ? len : count);
+}
+EXPORT_SYMBOL(strnlen);