CR50: move utility method reverse() to common/util.c

reverse() swaps the endian-ness of a buffer of
specified length.  This change moves the implementation
to a common location.

BRANCH=none
BUG=chrome-os-partner:43025,chrome-os-partner:47524
TEST=compilation succeeds

Change-Id: If8c97f53cc199d63c1caebbd999e1c099814387e
Signed-off-by: nagendra modadugu <ngm@google.com>
Reviewed-on: https://chromium-review.googlesource.com/331333
Commit-Ready: Nagendra Modadugu <ngm@google.com>
Tested-by: Nagendra Modadugu <ngm@google.com>
Reviewed-by: Vadim Bendebury <vbendeb@chromium.org>

chip/g/dcrypto/rsa.c

@@ -297,19 +297,6 @@ static int check_pkcs1_type1_pad(const uint8_t *msg, uint32_t msg_len,
 	return memcmp(msg, &padded[i], hash_size) == 0;
 }
 
-static void reverse(uint8_t *start, size_t len)
-{
-	int i;
-	uint8_t *end = start + len;
-
-	for (i = 0; i < len / 2; ++i) {
-		uint8_t tmp = *start;
-
-		*start++ = *--end;
-		*end = tmp;
-	}
-}
-
 static int check_modulus_params(const struct BIGNUM *N, uint32_t *out_len)
 {
 	if (bn_size(N) > RSA_MAX_BYTES)

common/util.c

@@ -305,6 +305,21 @@ void *memmove(void *dest, const void *src, size_t len)
 }
 
 
+void reverse(void *dest, size_t len)
+{
+	int i;
+	uint8_t *start = dest;
+	uint8_t *end = start + len;
+
+	for (i = 0; i < len / 2; ++i) {
+		uint8_t tmp = *start;
+
+		*start++ = *--end;
+		*end = tmp;
+	}
+}
+
+
 char *strzcpy(char *dest, const char *src, int len)
 {
 	char *d = dest;

include/util.h

@@ -146,6 +146,11 @@ int uint64divmod(uint64_t *v, int by);
  */
 int get_next_bit(uint32_t *mask);
 
+/**
+ * Reverse's the byte-order of the provided buffer.
+ */
+void reverse(void *dest, size_t len);
+
 
 /****************************************************************************/
 /* Conditional stuff.