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// Copyright 2019 DeepMind Technologies Limited
//
// Licensed under the Apache License, Version 2.0 (the "License");
// you may not use this file except in compliance with the License.
// You may obtain a copy of the License at
//
// http://www.apache.org/licenses/LICENSE-2.0
//
// Unless required by applicable law or agreed to in writing, software
// distributed under the License is distributed on an "AS IS" BASIS,
// WITHOUT WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied.
// See the License for the specific language governing permissions and
// limitations under the License.
using System;
using System.IO;
using System.Runtime.InteropServices;
using System.Text;
using UnityEngine;
namespace Mujoco {
using static MujocoLib;
// A wrapper around Mujoco's native _mjVFS that simplifies the process of creating memory files.
public sealed class MjVfs : IDisposable {
private _mjVFS _managedVfs;
private IntPtr _unmanagedVfs;
// Managed version of the underlying _mjVFS structure.
public _mjVFS Data {
get {
_managedVfs = (_mjVFS)Marshal.PtrToStructure(_unmanagedVfs, typeof(_mjVFS));
return _managedVfs;
}
set {
_managedVfs = value;
Marshal.StructureToPtr(_managedVfs, _unmanagedVfs, fDeleteOld: false);
}
}
// Number of files added to the filesystem.
public int FilesCount {
get { return Data.nfile; }
}
// Adds a new file to the virtual filesystem.
public unsafe void AddFile(string filename, string contents) {
var result = mj_makeEmptyFileVFS(_unmanagedVfs.ToPointer(), filename, contents.Length);
if (result != 0) {
throw new Exception(
"VFS error (" + result + ") encountered while creating an empty file");
}
var fileIndex = mj_findFileVFS(_unmanagedVfs.ToPointer(), filename);
if (fileIndex < 0) {
throw new IndexOutOfRangeException("VFS didn't properly create the empty file.");
}
SetFileContents(fileIndex, contents);
}
// Searches the VFS for the specified file and returns its index.
// The index then can be used to retrieve the file contents from Data.filedata array.
public unsafe int FindFile(string filename) {
return mj_findFileVFS(_unmanagedVfs.ToPointer(), filename);
}
// Loads a model from the specified file.
// The file is assumed to be located in the filesystem. If it's not found, the method will throw
// an ArgumentException.
public unsafe MujocoLib.mjModel_* LoadXML(string filename) {
if (FindFile(filename) < 0) {
throw new ArgumentException($"File {filename} was not added to the VFS.");
}
var errorBuf = new StringBuilder(1024);
MujocoLib.mjModel_* model = MujocoLib.mj_loadXML(
filename, _unmanagedVfs.ToPointer(), errorBuf, errorBuf.Capacity);
if (model == null || errorBuf.Length > 0) {
throw new IOException($"Error loading the model: {errorBuf}");
}
return model;
}
private unsafe void SetFileContents(int fileIndex, string contents) {
var data = Data;
Marshal.FreeHGlobal(data.filedata[fileIndex]);
data.filedata[fileIndex] = Marshal.StringToHGlobalAnsi(contents);
Data = data;
}
public MjVfs() {
_managedVfs = new _mjVFS();
_unmanagedVfs = Marshal.AllocHGlobal(Marshal.SizeOf(_managedVfs));
Marshal.StructureToPtr(_managedVfs, _unmanagedVfs, true);
}
~MjVfs() {
ReleaseUnmanagedMemory();
}
public void Dispose() {
GC.SuppressFinalize(this);
ReleaseUnmanagedMemory();
}
private void ReleaseUnmanagedMemory() {
if (_unmanagedVfs != IntPtr.Zero) {
var data = Data;
for (var fileIndex = 0; fileIndex < data.nfile; ++fileIndex) {
Marshal.FreeHGlobal(data.filedata[fileIndex]);
}
Marshal.FreeHGlobal(_unmanagedVfs);
_unmanagedVfs = IntPtr.Zero;
}
}
}
}
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