add center info at fixed address in shm.

lichao

2021-05-14 9bf199a4770b08c03d553129757d960b605e598a

 .vscode/tasks.json

@@ -4,12 +4,9 @@
            "type": "cppbuild",
            "label": "C/C++: g++ build active file",
            "command": "ninja",
            "args": [
                "-C",
                "debug"
            ],
            "args": [],
            "options": {
                "cwd": "${workspaceFolder}"
                "cwd": "${workspaceFolder}/debug"
            },
            "problemMatcher": [
                "$gcc"