From 4abab5ad6c8465a7528ccdd5f49367da05f78bbd Mon Sep 17 00:00:00 2001
From: Vladimir Azarov <avm@intermediate-node.net>
Date: Tue, 1 Oct 2024 15:47:05 +0200
Subject: Initial version

---
 src/string/memmove.c | 42 ++++++++++++++++++++++++++++++++++++++++++
 1 file changed, 42 insertions(+)
 create mode 100644 src/string/memmove.c

(limited to 'src/string/memmove.c')

diff --git a/src/string/memmove.c b/src/string/memmove.c
new file mode 100644
index 0000000..5dc9cdb
--- /dev/null
+++ b/src/string/memmove.c
@@ -0,0 +1,42 @@
+#include <string.h>
+#include <stdint.h>
+
+#ifdef __GNUC__
+typedef __attribute__((__may_alias__)) size_t WT;
+#define WS (sizeof(WT))
+#endif
+
+void *memmove(void *dest, const void *src, size_t n)
+{
+	char *d = dest;
+	const char *s = src;
+
+	if (d==s) return d;
+	if ((uintptr_t)s-(uintptr_t)d-n <= -2*n) return memcpy(d, s, n);
+
+	if (d<s) {
+#ifdef __GNUC__
+		if ((uintptr_t)s % WS == (uintptr_t)d % WS) {
+			while ((uintptr_t)d % WS) {
+				if (!n--) return dest;
+				*d++ = *s++;
+			}
+			for (; n>=WS; n-=WS, d+=WS, s+=WS) *(WT *)d = *(WT *)s;
+		}
+#endif
+		for (; n; n--) *d++ = *s++;
+	} else {
+#ifdef __GNUC__
+		if ((uintptr_t)s % WS == (uintptr_t)d % WS) {
+			while ((uintptr_t)(d+n) % WS) {
+				if (!n--) return dest;
+				d[n] = s[n];
+			}
+			while (n>=WS) n-=WS, *(WT *)(d+n) = *(WT *)(s+n);
+		}
+#endif
+		while (n) n--, d[n] = s[n];
+	}
+
+	return dest;
+}
-- 
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