string: make memcpy(), memset(), memmove()

1 files changed, 42 insertions, 0 deletions

diff --git a/kernel/string.c b/kernel/string.c
index d038c27..006b907 100644
--- a/kernel/string.c
+++ b/kernel/string.c
@@ -7,3 +7,45 @@ size_t strlen(const char *str)
 		len++;
 	return len;
 }
+
+/*
+	Copy bytes in memory. If copying takes place between objects
+	that overlap, the behavior is undefined.
+*/
+void *memcpy(void *dest, const void *src, size_t n)
+{
+	size_t i;
+	const char *s = src;
+	char *d = dest;
+
+	for(i = 0; i < n; i++)
+		d[i] = s[i];
+	return dest;
+}
+
+void *memset(void *dest, int c, size_t n)
+{
+	char *d = dest;
+	while(n--)
+		*d++ = c;
+	return dest;
+}
+
+/*
+	Copy bytes in memory with overlapping areas.
+*/
+void *memmove(void *dest, const void *src, size_t n)
+{
+	const char *s = src;
+	char *d = dest;
+
+	if(dest == src)
+		return dest;
+
+	if(dest < src)
+		return memcpy(dest, src, n);
+
+	while(n--)
+		d[n] = s[n];
+	return dest;
+}