Moved hash_byte & hash_nbytes functions to common

Also fixed possible overflow on large payload hashing

src_common/hash_bytes.c

@@ -0,0 +1,22 @@
+#include "hash_bytes.h"
+
+/**
+ * Continue given progressive hash on given bytes
+ *
+ * @param[in] bytes_ptr pointer to bytes
+ * @param[in] n number of bytes to hash
+ * @param[in] hash_ctx pointer to the hashing context
+ */
+void hash_nbytes(const uint8_t *bytes_ptr, size_t n, cx_hash_t *hash_ctx) {
+    cx_hash(hash_ctx, 0, bytes_ptr, n, NULL, 0);
+}
+
+/**
+ * Continue given progressive hash on given byte
+ *
+ * @param[in] byte byte to hash
+ * @param[in] hash_ctx pointer to the hashing context
+ */
+void hash_byte(uint8_t byte, cx_hash_t *hash_ctx) {
+    hash_nbytes(&byte, 1, hash_ctx);
+}

src_common/hash_bytes.h

@@ -0,0 +1,10 @@
+#ifndef HASH_BYTES_H_
+#define HASH_BYTES_H_
+
+#include <stdint.h>
+#include "cx.h"
+
+void hash_nbytes(const uint8_t *const bytes_ptr, size_t n, cx_hash_t *hash_ctx);
+void hash_byte(uint8_t byte, cx_hash_t *hash_ctx);
+
+#endif  // HASH_BYTES_H_