Format NULL occurrences in CCM's Doxygen comments
diff --git a/include/mbedtls/ccm.h b/include/mbedtls/ccm.h
index 009231e..0eb1abe 100644
--- a/include/mbedtls/ccm.h
+++ b/include/mbedtls/ccm.h
@@ -84,7 +84,7 @@
* to make references valid, and prepare the context
* for mbedtls_ccm_setkey() or mbedtls_ccm_free().
*
- * \param ctx The CCM context to initialize. Must not be NULL.
+ * \param ctx The CCM context to initialize. Must not be \c NULL.
*/
void mbedtls_ccm_init( mbedtls_ccm_context *ctx );
@@ -92,9 +92,9 @@
* \brief This function initializes the CCM context set in the
* \p ctx parameter and sets the encryption key.
*
- * \param ctx The CCM context to initialize. Must not be NULL.
+ * \param ctx The CCM context to initialize. Must not be \c NULL.
* \param cipher The 128-bit block cipher to use.
- * \param key The encryption key. Must not be NULL.
+ * \param key The encryption key. Must not be \c NULL.
* \param keybits The key size in bits. This must be acceptable by the cipher.
*
* \return \c 0 on success.
@@ -109,7 +109,7 @@
* \brief This function releases and clears the specified CCM context
* and underlying cipher sub-context.
*
- * \param ctx The CCM context to clear. Must not be NULL.
+ * \param ctx The CCM context to clear. Must not be \c NULL.
*/
void mbedtls_ccm_free( mbedtls_ccm_context *ctx );
@@ -122,20 +122,20 @@
* \p tag = \p output + \p length, and make sure that the
* output buffer is at least \p length + \p tag_len wide.
*
- * \param ctx The CCM context to use for encryption. Must not be NULL.
+ * \param ctx The CCM context to use for encryption. Must not be \c NULL.
* \param length The length of the input data in Bytes.
- * \param iv Initialization vector (nonce). Must not be NULL.
+ * \param iv Initialization vector (nonce). Must not be \c NULL.
* \param iv_len The length of the nonce in Bytes: 7, 8, 9, 10, 11, 12,
* or 13. The length L of the message length field is
* 15 - \p iv_len.
- * \param add The additional data field. Must not be NULL.
+ * \param add The additional data field. Must not be \c NULL.
* \param add_len The length of additional data in Bytes.
* Must be less than 2^16 - 2^8.
- * \param input The buffer holding the input data. Must not be NULL.
+ * \param input The buffer holding the input data. Must not be \c NULL.
* \param output The buffer holding the output data.
* Must be at least \p length Bytes wide.
* \param tag The buffer holding the authentication field. Must not be
- * NULL.
+ * \c NULL.
* \param tag_len The length of the authentication field to generate in Bytes:
* 4, 6, 8, 10, 12, 14 or 16.
*
@@ -161,16 +161,16 @@
* the tag length has to be encoded into the \p iv passed to
* this function.
*
- * \param ctx The CCM context to use for encryption. Must not be NULL.
+ * \param ctx The CCM context to use for encryption. Must not be \c NULL.
* \param length The length of the input data in Bytes.
- * \param iv Initialization vector (nonce). Must not be NULL.
+ * \param iv Initialization vector (nonce). Must not be \c NULL.
* \param iv_len The length of the nonce in Bytes: 7, 8, 9, 10, 11, 12,
* or 13. The length L of the message length field is
* 15 - \p iv_len.
- * \param add The additional data field. Must not be NULL.
+ * \param add The additional data field. Must not be \c NULL.
* \param add_len The length of additional data in Bytes.
* Must be less than 2^16 - 2^8.
- * \param input The buffer holding the input data. Must not be NULL.
+ * \param input The buffer holding the input data. Must not be \c NULL.
* \param output The buffer holding the output data.
* Must be at least \p length Bytes wide.
* \param tag The buffer holding the authentication field. Must not be
@@ -194,16 +194,16 @@
* \brief This function performs a CCM authenticated decryption of a
* buffer.
*
- * \param ctx The CCM context to use for decryption. Must not be NULL.
+ * \param ctx The CCM context to use for decryption. Must not be \c NULL.
* \param length The length of the input data in Bytes.
- * \param iv Initialization vector (nonce). Must not be NULL.
+ * \param iv Initialization vector (nonce). Must not be \c NULL.
* \param iv_len The length of the nonce in Bytes: 7, 8, 9, 10, 11, 12,
* or 13. The length L of the message length field is
* 15 - \p iv_len.
- * \param add The additional data field. Must not be NULL.
+ * \param add The additional data field. Must not be \c NULL.
* \param add_len The length of additional data in Bytes.
* Must be less than 2^16 - 2^8.
- * \param input The buffer holding the input data. Must not be NULL.
+ * \param input The buffer holding the input data. Must not be \c NULL.
* \param output The buffer holding the output data.
* Must be at least \p length Bytes wide.
* \param tag The buffer holding the authentication field. Must not be
@@ -230,16 +230,16 @@
* this function as \p tag_len. (\p tag needs to be adjusted
* accordingly.)
*
- * \param ctx The CCM context to use for decryption. Must not be NULL.
+ * \param ctx The CCM context to use for decryption. Must not be \c NULL.
* \param length The length of the input data in Bytes.
- * \param iv Initialization vector (nonce). Must not be NULL.
+ * \param iv Initialization vector (nonce). Must not be \c NULL.
* \param iv_len The length of the nonce in Bytes: 7, 8, 9, 10, 11, 12,
* or 13. The length L of the message length field is
* 15 - \p iv_len.
- * \param add The additional data field. Must not be NULL.
+ * \param add The additional data field. Must not be \c NULL.
* \param add_len The length of additional data in Bytes.
* Must be less than 2^16 - 2^8.
- * \param input The buffer holding the input data. Must not be NULL.
+ * \param input The buffer holding the input data. Must not be \c NULL.
* \param output The buffer holding the output data.
* Must be at least \p length Bytes wide.
* \param tag The buffer holding the authentication field. Must not be