kernel: lib: Add memmove()

Signed-off-by: Ian Moffett <ian@osmora.org>

2 files changed, 51 insertions, 0 deletions

diff --git a/sys/include/lib/string.h b/sys/include/lib/string.h
index c138cf1..c09e6f4 100644
--- a/sys/include/lib/string.h
+++ b/sys/include/lib/string.h
@@ -47,5 +47,6 @@ int strcmp(const char *s1, const char *s2);
 
 int strncmp(const char *s1, const char *s2, size_t n);
 int atoi(char *s);
+void *memmove(void *s1, const void *s2, size_t n);
 
 #endif  /* !_LIB_STRING_H_ */
diff --git a/sys/lib/string/memmove.c b/sys/lib/string/memmove.c
new file mode 100644
index 0000000..f1271ee
--- /dev/null
+++ b/sys/lib/string/memmove.c
@@ -0,0 +1,50 @@
+/*
+ * Copyright (c) 2023-2025 Ian Marco Moffett and the Osmora Team.
+ * All rights reserved.
+ *
+ * Redistribution and use in source and binary forms, with or without
+ * modification, are permitted provided that the following conditions are met:
+ *
+ * 1. Redistributions of source code must retain the above copyright notice,
+ *    this list of conditions and the following disclaimer.
+ * 2. Redistributions in binary form must reproduce the above copyright
+ *    notice, this list of conditions and the following disclaimer in the
+ *    documentation and/or other materials provided with the distribution.
+ * 3. Neither the name of Hyra nor the names of its
+ *    contributors may be used to endorse or promote products derived from
+ *    this software without specific prior written permission.
+ *
+ * THIS SOFTWARE IS PROVIDED BY THE COPYRIGHT HOLDERS AND CONTRIBUTORS "AS IS"
+ * AND ANY EXPRESS OR IMPLIED WARRANTIES, INCLUDING, BUT NOT LIMITED TO, THE
+ * IMPLIED WARRANTIES OF MERCHANTABILITY AND FITNESS FOR A PARTICULAR PURPOSE
+ * ARE DISCLAIMED. IN NO EVENT SHALL THE COPYRIGHT OWNER OR CONTRIBUTORS BE
+ * LIABLE FOR ANY DIRECT, INDIRECT, INCIDENTAL, SPECIAL, EXEMPLARY, OR
+ * CONSEQUENTIAL DAMAGES (INCLUDING, BUT NOT LIMITED TO, PROCUREMENT OF
+ * SUBSTITUTE GOODS OR SERVICES; LOSS OF USE, DATA, OR PROFITS; OR BUSINESS
+ * INTERRUPTION) HOWEVER CAUSED AND ON ANY THEORY OF LIABILITY, WHETHER IN
+ * CONTRACT, STRICT LIABILITY, OR TORT (INCLUDING NEGLIGENCE OR OTHERWISE)
+ * ARISING IN ANY WAY OUT OF THE USE OF THIS SOFTWARE, EVEN IF ADVISED OF THE
+ * POSSIBILITY OF SUCH DAMAGE.
+ */
+
+#include <string.h>
+
+void *
+memmove(void *s1, const void *s2, size_t n)
+{
+	const char *f = s2;
+	char *t = s1;
+
+	if (f < t) {
+		f += n;
+		t += n;
+		while (n-- > 0) {
+			*--t = *--f;
+        }
+	} else {
+		while (n-- > 0) {
+			*t++ = *f++;
+        }
+    }
+	return s1;
+}