diff --git a/dap/utils/__init__.py b/dap/utils/__init__.py
index 85850fe..26acf15 100644
--- a/dap/utils/__init__.py
+++ b/dap/utils/__init__.py
@@ -4,5 +4,6 @@ from .bits import read_bit
 from .bufjson import BufferedJSON
 from .filehandler import FileHandler
 from .randskip import randskip
+from .sorter import Sorter
 
 
diff --git a/dap/utils/sorter.py b/dap/utils/sorter.py
new file mode 100644
index 0000000..5f82095
--- /dev/null
+++ b/dap/utils/sorter.py
@@ -0,0 +1,75 @@
+
+class Sorter:
+
+    def __init__(self, window=1000):
+        """
+        window: max allowed gap in IDs
+        """
+        self.window = window
+        self.buffer = {}
+        self.max_ID = -1
+        self.next_ID = 0
+
+    def add(self, ID, data):
+        self.buffer[ID] = data
+        self.max_ID = max(self.max_ID, ID)
+
+    def flush_ready(self):
+        res = self._collect_contiguous_IDs()
+        self._skip_over_gap()
+        self._drop_old_entries()
+        return res
+
+    def _collect_contiguous_IDs(self):
+        res = []
+        while self.next_ID in self.buffer:
+            res.append(self.buffer.pop(self.next_ID))
+            self.next_ID += 1
+        return res
+
+    def _skip_over_gap(self):
+        self.next_ID = max(self.next_ID, self.max_ID - self.window)
+
+    def _drop_old_entries(self):
+        for i in list(self.buffer):
+            if i < self.next_ID:
+                del self.buffer[i]
+
+
+
+
+
+if __name__ == "__main__":
+    sorter = Sorter(window=5)
+
+    data = [
+        0, # contiguous case
+        2, # gap at 1
+        1, # fills gap, triggers flush: 1, 2
+        # gap between 3 and 7
+        8, 9, 10, 11,
+        3, # arrives too late
+        12, 13, 14
+    ]
+
+    expected = (
+        [0],
+        [],
+        [1, 2],
+        [],
+        [],
+        [],
+        [],
+        [],
+        [],
+        [],
+        [8, 9, 10, 11, 12, 13, 14]
+    )
+
+    for ID, exc in zip(data, expected):
+        sorter.add(ID, ID)
+        ready = sorter.flush_ready()
+        assert exc == ready, f"{exc} != {ready}"
+
+
+