volatile string fns

include/string.h

@@ -51,6 +51,38 @@ extern void *memmove(void *restrict dest, const void *restrict src, size_t n);
  */
 extern void *memset(void *restrict dest, int c, size_t n);
 
+/**
+ * Copy the first n bytes from memory area src to memory area dest. The memory
+ * areas must not overlap.
+ * @param dest - the destination
+ * @param src - the source
+ * @param n - the byte count
+ * @returns a pointer to dest
+ */
+extern void *memcpyv(volatile void *restrict dest,
+					 const volatile void *restrict src, size_t n);
+
+/**
+ * Copy the first n bytes from memory area src to memory area dest. The memory
+ * areas may overlap; memmove behaves as though the bytes are first copied to a
+ * temporary array.
+ * @param dest - the destination
+ * @param src - the source
+ * @param n - the byte count
+ * @returns a pointer to dest
+ */
+extern void *memmovev(volatile void *restrict dest,
+					  const volatile void *restrict src, size_t n);
+
+/**
+ * Fill the first n bytes of the memory region dest with the constant byte c.
+ * @param dest - the destination
+ * @param c - the byte to write
+ * @param n - the byte count
+ * @returns a pointer to dest
+ */
+extern void *memsetv(volatile void *restrict dest, int c, size_t n);
+
 /**
  * Calculates the length of the string pointed to by str, excluding
  * the terminating null byte

lib/memcpyv.c

@@ -0,0 +1,11 @@
+#include <string.h>
+
+void *memcpyv(volatile void *restrict dest, const volatile void *restrict src,
+			  size_t n)
+{
+	char *d = dest;
+	const char *s = src;
+	for (; n; n--)
+		*d++ = *s++;
+	return dest;
+}

lib/memmovev.c

@@ -0,0 +1,20 @@
+#include <string.h>
+
+void *memmovev(volatile void *dest, const volatile void *src, size_t n)
+{
+	char *d = dest;
+	const char *s = src;
+
+	if (d == s)
+		return d;
+
+	if (d < s) {
+		for (; n; n--)
+			*d++ = *s++;
+	} else {
+		while (n)
+			n--, d[n] = s[n];
+	}
+
+	return dest;
+}

lib/memsetv.c

@@ -0,0 +1,10 @@
+#include <string.h>
+
+void *memsetv(volatile void *dest, int c, size_t n)
+{
+	unsigned char *d = dest;
+	for (; n; n--) {
+		*d++ = c;
+	};
+	return dest;
+}