flatbuffer base

flatbuffers/stream/stream.fbs

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+include "stream_reg.fbs";
+include "stream_data.fbs";
+
+namespace hmmmm.stream;
+
+// ── Client → Server ──────────────────────────────────────────────────────────
+
+union StreamClientPayload {
+    StreamRegRequest,
+    StreamDeregRequest,
+    StreamWritePush,
+}
+
+table StreamClientMessage {
+    payload: StreamClientPayload;
+}
+
+// ── Server → Client ──────────────────────────────────────────────────────────
+
+union StreamServerPayload {
+    StreamRegConfirm,
+    StreamDataPush,
+}
+
+table StreamServerMessage {
+    payload: StreamServerPayload;
+}

flatbuffers/stream/stream_data.fbs

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+namespace hmmmm.stream;
+
+// Server → Client: memory region snapshot pushed by the server.
+// tclk is the virtual clock tick at which this data became valid —
+// clients may buffer and apply it at the appropriate simulation point.
+table StreamDataPush {
+    stream_id: uint32;
+    tclk:      uint64;
+    data:      [ubyte];
+}
+
+// Client → Server: write into a registered write-mode stream.
+// offset is relative to the registered region start.
+table StreamWritePush {
+    stream_id: uint32;
+    offset:    uint32;
+    data:      [ubyte];
+}

flatbuffers/stream/stream_reg.fbs

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+namespace hmmmm.stream;
+
+enum StreamMode: byte {
+    mode_read  = 0,
+    mode_write = 1,
+}
+
+// Client → Server: subscribe to a memory region.
+table StreamRegRequest {
+    device_id: uint32;   // from DeviceIdMappingNotif
+    seg_id:    uint32;   // from DeviceIdMappingNotif
+    offset:    uint32;   // start offset within segment, in bytes
+    length:    uint32;   // region length, in bytes
+    mode:      StreamMode;
+}
+
+// Client → Server: cancel a stream subscription.
+// No confirmation is sent by the server.
+table StreamDeregRequest {
+    stream_id: uint32;
+}
+
+// Server → Client: subscription confirmed, stream_id assigned.
+// Echoes the original request fields for client-side reconciliation.
+table StreamRegConfirm {
+    stream_id: uint32;
+    device_id: uint32;
+    seg_id:    uint32;
+    offset:    uint32;
+    length:    uint32;
+    mode:      StreamMode;
+}