volatile string fns

4 files changed, 73 insertions, 0 deletions

diff --git a/include/string.h b/include/string.h
index 4d32f57..e376918 100644
--- a/include/string.h
+++ b/include/string.h
@@ -52,6 +52,38 @@ 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
  * @param str - the string pointer
diff --git a/lib/memcpyv.c b/lib/memcpyv.c
new file mode 100644
index 0000000..205d9c1
--- /dev/null
+++ b/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;
+}
diff --git a/lib/memmovev.c b/lib/memmovev.c
new file mode 100644
index 0000000..d2fc683
--- /dev/null
+++ b/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;
+}
diff --git a/lib/memsetv.c b/lib/memsetv.c
new file mode 100644
index 0000000..9039cb7
--- /dev/null
+++ b/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;
+}