[Minios-devel] [PATCH v2 21/47] mini-os: implement the memmove/memchr

[Huang Shijie <shijie.huang@xxxxxxx>]

This patch is split from the Chen Baozi's old patch:

"This activates the ARM code added in the previous patches. On
 ARM, Mini-OS will boot and display some output on the console. Tested with:"

Note: The code is copied from FreeBSD code:
      freebsd/contrib/ldns/compat/memmove.c

Signed-off-by: Huang Shijie <shijie.huang@xxxxxxx>
---
 Makefile      |  1 +
 lib/memmove.c | 44 ++++++++++++++++++++++++++++++++++++++++++++
 lib/string.c  | 12 ++++++++++++
 3 files changed, 57 insertions(+)
 create mode 100644 lib/memmove.c

diff --git a/Makefile b/Makefile
index 88315c4..43075e1 100644
--- a/Makefile
+++ b/Makefile
@@ -61,6 +61,7 @@ src-y += lib/math.c
 src-y += lib/printf.c
 src-y += lib/stack_chk_fail.c
 src-y += lib/string.c
+src-y += lib/memmove.c
 src-y += lib/sys.c
 src-y += lib/xmalloc.c
 src-$(CONFIG_XENBUS) += lib/xs.c
diff --git a/lib/memmove.c b/lib/memmove.c
new file mode 100644
index 0000000..28f2706
--- /dev/null
+++ b/lib/memmove.c
@@ -0,0 +1,44 @@
+/*
+ *     memmove.c: memmove compat implementation.
+ *
+ *     Copyright (c) 2001-2008, NLnet Labs. All rights reserved.
+ *
+ * See COPYING for the license.
+*/
+#include <os.h>
+#include <mini-os/lib.h>
+
+#ifndef HAVE_LIBC
+
+void *memmove(void *dest, const void *src, size_t n)
+{
+       uint8_t* from = (uint8_t*) src;
+       uint8_t* to = (uint8_t*) dest;
+
+       if (from == to || n == 0)
+               return dest;
+       if (to > from && to-from < (int)n) {
+               /* to overlaps with from */
+               /*  <from......>         */
+               /*         <to........>  */
+               /* copy in reverse, to avoid overwriting from */
+               int i;
+               for(i=n-1; i>=0; i--)
+                       to[i] = from[i];
+               return dest;
+       }
+       if (from > to  && from-to < (int)n) {
+               /* to overlaps with from */
+               /*        <from......>   */
+               /*  <to........>         */
+               /* copy forwards, to avoid overwriting from */
+               size_t i;
+               for(i=0; i<n; i++)
+                       to[i] = from[i];
+               return dest;
+       }
+       memcpy(dest, src, n);
+       return dest;
+}
+
+#endif
diff --git a/lib/string.c b/lib/string.c
index 8b24146..c96ca41 100644
--- a/lib/string.c
+++ b/lib/string.c
@@ -225,4 +225,16 @@ int ffs(int i)
    return 0;
 }
 
+void *memchr(const void *s, int c, size_t n)
+{
+    if (n != 0) {
+        const unsigned char *p = s;
+
+        do {
+            if (*p++ == (unsigned char)c)
+                return ((void *)(uintptr_t)(p - 1));
+        } while (--n != 0);
+    }
+    return (NULL);
+}
 #endif
-- 
2.7.4


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