RamFS In-Memory File System

RamFS is a lightweight in-memory file system module provided by LibXR. It supports unified management of files, directories, and device nodes, and is suitable for file access and debugging simulations in embedded systems.

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Main Features

• Organized using a red-black tree structure for files and directories;
• Supports read-only, read-write, and executable file types;
• Supports device nodes that bind to ReadPort / WritePort;
• Supports recursive search of files, directories, and devices;
• Type-safe data access for all files;
• All data resides entirely in memory, ideal for runtime construction and simulation.

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Core Structures

FsNode

The base class for all nodes, with a unified interface:

• name: node name
• type: node type (FILE / DIR / DEVICE)
• parent: parent directory

File

Created using CreateFile(), supporting:

• Read-only (READ_ONLY)
• Read-write (READ_WRITE)
• Executable (EXEC): has a Run(argc, argv) method

Dir

Directory class supports adding and finding:

• Add: Add(file), Add(dir), Add(device)
• Find: FindFile(name), FindDir(name), FindDevice(name), and their recursive variants with Rev

Device

Device class supports binding to ReadPort / WritePort, and accessing data through Read() / Write() methods.

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Usage Example

RamFS fs;

int counter = 0;

// Create executable file (increments counter each time it's run)
auto exec_file = RamFS::CreateFile<int*>(
  "runme",
  [](int* arg, int argc, char** argv) {
    UNUSED(argc);
    UNUSED(argv);
    (*arg)++;
    return 0;
  },
  &counter
);

// Create read/write file
auto data_file = RamFS::CreateFile("value", counter);

// Create directory and device
auto dir = RamFS::CreateDir("mydir");
auto dev = RamFS::Device("mydev");

// Build file system structure
fs.Add(data_file);  // Add to root directory
fs.Add(dir);
dir.Add(exec_file);
dir.Add(dev);

// Run exec file multiple times and verify count
for (int i = 1; i <= 5; ++i) {
  exec_file->Run(0, nullptr);
  ASSERT(data_file->GetData<int>() == i);
}

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Interface Overview

RamFS File System Interface

Method	Description
CreateFile(name, data)	Create a read-only or read-write file
CreateFile(name, exec, arg)	Create an executable file
CreateDir(name)	Create a directory
Add(file/dir/dev)	Add node to root directory
FindFile(name)	Recursively search for a file
FindDir(name)	Search for a directory
FindDevice(name)	Search for a device

File Interface

Method	Description
Run(argc, argv)	Run executable file (only for EXEC type)
GetData<T>()	Get a type-safe reference to file data

Dir Interface

Method	Description
Add(node)	Add a file, directory, or device
FindFile(name)	Find file in current directory
FindFileRev(name)	Recursively find file
FindDir(name)	Find subdirectory
FindDirRev(name)	Recursively find directory
FindDevice(name)	Find device
FindDeviceRev(name)	Recursively find device

Device Interface

Method	Description
Read(op, data)	Read data
Write(op, data)	Write data

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Application Scenarios

• Simulate file systems in embedded platforms;
• Virtual file access in debug mode;
• Build temporary config, log, or parameter nodes in memory;
• Simulate input/output interfaces of devices;

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Unit Test Reference

See [test_ramfs.cpp] for coverage of:

• Executable file execution
• Type-safe data access
• Adding and finding files, directories, and devices