diff -r c065d196a2c8 -r 06091e067bee src/cx/buffer.h
--- a/src/cx/buffer.h	Fri Dec 20 13:13:38 2024 +0100
+++ b/src/cx/buffer.h	Fri Dec 20 15:00:05 2024 +0100
@@ -443,6 +443,32 @@
 );
 
 /**
+ * Appends data to a CxBuffer.
+ *
+ * The data is always appended to current data within the buffer,
+ * regardless of the current position.
+ * This is especially useful when the buffer is primarily meant for reading
+ * while additional data is added to the buffer occasionally.
+ * Consequently, the position of the buffer is unchanged after this operation.
+ *
+ * \note The signature is compatible with the fwrite() family of functions.
+ *
+ * @param ptr a pointer to the memory area containing the bytes to be written
+ * @param size the length of one element
+ * @param nitems the element count
+ * @param buffer the CxBuffer to write to
+ * @return the total count of elements written
+ * @see cxBufferWrite()
+ */
+cx_attr_nonnull
+size_t cxBufferAppend(
+        const void *ptr,
+        size_t size,
+        size_t nitems,
+        CxBuffer *buffer
+);
+
+/**
  * Reads data from a CxBuffer.
  *
  * The position of the buffer is increased by the number of bytes read.