Directly taken from Linux Kernel.
Signed-off-by: Sascha Hauer <s.hauer@xxxxxxxxxxxxxx>
---
include/linux/string.h | 2 ++
lib/string.c | 59 ++++++++++++++++++++++++++++++++++++++++++++++++++
2 files changed, 61 insertions(+)
diff --git a/include/linux/string.h b/include/linux/string.h
index 658264c..5df8c50 100644
--- a/include/linux/string.h
+++ b/include/linux/string.h
@@ -106,6 +106,8 @@ extern char * skip_spaces(const char *);
extern char *strim(char *);
+void *memchr_inv(const void *start, int c, size_t bytes);
+
#ifdef __cplusplus
}
#endif
diff --git a/lib/string.c b/lib/string.c
index f544b23..eeec137 100644
--- a/lib/string.c
+++ b/lib/string.c
@@ -666,3 +666,62 @@ char *strim(char *s)
return s;
}
EXPORT_SYMBOL(strim);
+
+static void *check_bytes8(const u8 *start, u8 value, unsigned int bytes)
+{
+ while (bytes) {
+ if (*start != value)
+ return (void *)start;
+ start++;
+ bytes--;
+ }
+ return NULL;
+}
+
+/**
+ * memchr_inv - Find an unmatching character in an area of memory.
+ * @start: The memory area
+ * @c: Find a character other than c
+ * @bytes: The size of the area.
+ *
+ * returns the address of the first character other than @c, or %NULL
+ * if the whole buffer contains just @c.
+ */
+void *memchr_inv(const void *start, int c, size_t bytes)
+{
+ u8 value = c;
+ u64 value64;
+ unsigned int words, prefix;
+
+ if (bytes <= 16)
+ return check_bytes8(start, value, bytes);
+
+ value64 = value;
+ value64 |= value64 << 8;
+ value64 |= value64 << 16;
+ value64 |= value64 << 32;
+
+ prefix = (unsigned long)start % 8;
+ if (prefix) {
+ u8 *r;
+
+ prefix = 8 - prefix;
+ r = check_bytes8(start, value, prefix);
+ if (r)
+ return r;
+ start += prefix;
+ bytes -= prefix;
+ }
+
+ words = bytes / 8;
+
+ while (words) {
+ if (*(u64 *)start != value64)
+ return check_bytes8(start, value, 8);
+ start += 8;
+ words--;
+ }
+
+ return check_bytes8(start, value, bytes % 8);
+}
+EXPORT_SYMBOL(memchr_inv);
--
1.8.3.2
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