1 files changed, 37 insertions, 0 deletions
diff --git a/src/aclk/mqtt_websockets/c-rbuf/cringbuffer_internal.h b/src/aclk/mqtt_websockets/c-rbuf/cringbuffer_internal.h
new file mode 100644
index 000000000..d32de187c
--- /dev/null
+++ b/src/aclk/mqtt_websockets/c-rbuf/cringbuffer_internal.h
@@ -0,0 +1,37 @@
+// Copyright: SPDX-License-Identifier:  GPL-3.0-only
+
+#ifndef CRINGBUFFER_INTERNAL_H
+#define CRINGBUFFER_INTERNAL_H
+
+struct rbuf_t {
+    char *data;
+
+    // points to next byte where we can write
+    char *head;
+    // points to oldest (next to be poped) readable byte
+    char *tail;
+
+    // to avoid calculating data + size
+    // all the time
+    char *end;
+
+    size_t size;
+    size_t size_data;
+};
+
+/* this exists so that it can be tested by unit tests
+ * without optimization that resets head and tail to
+ * beginning if buffer empty
+ */
+inline static int rbuf_bump_tail_noopt(rbuf_t buffer, size_t bytes)
+{
+    if (bytes > buffer->size_data)
+        return 0;
+    int i = buffer->tail - buffer->data;
+    buffer->tail = &buffer->data[(i + bytes) % buffer->size];
+    buffer->size_data -= bytes;
+
+    return 1;
+}
+
+#endif