diff --git a/src/MemoryUsage.cpp b/src/MemoryUsage.cpp
new file mode 100644
index 0000000000000000000000000000000000000000..e5383f6ecc9ae1580a973dc210af934a9722a3db
--- /dev/null
+++ b/src/MemoryUsage.cpp
@@ -0,0 +1,155 @@
+/**
+ * XMPP - libpurple transport
+ *
+ * Copyright (C) 2009, Jan Kaluza <hanzz@soc.pidgin.im>
+ *
+ * This program is free software; you can redistribute it and/or modify
+ * it under the terms of the GNU General Public License as published by
+ * the Free Software Foundation; either version 2 of the License, or
+ * (at your option) any later version.
+ *
+ * This program is distributed in the hope that it will be useful,
+ * but WITHOUT ANY WARRANTY; without even the implied warranty of
+ * MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE.  See the
+ * GNU General Public License for more details.
+ *
+ * You should have received a copy of the GNU General Public License
+ * along with this program; if not, write to the Free Software
+ * Foundation, Inc., 51 Franklin Street, Fifth Floor, Boston, MA  02111-1301  USA
+ */
+
+#include "transport/MemoryUsage.h"
+
+#include <iostream>
+#include <cstring>
+#include <sstream>
+#include <fstream>
+#include <algorithm>
+#include <boost/lexical_cast.hpp>
+#ifndef WIN32
+#include <sys/param.h>
+#else 
+#include <windows.h>
+#include <psapi.h>
+#endif
+#ifdef __MACH__
+#include <mach/mach.h>
+#elif BSD
+#include <sys/types.h>
+#include <sys/sysctl.h>
+#include <sys/param.h>
+#include <sys/sysctl.h>
+#include <sys/user.h>
+#endif
+
+namespace Transport {
+
+#ifndef WIN32
+#ifdef __MACH__
+
+void process_mem_usage(double& vm_usage, double& resident_set, pid_t pid) {
+
+	struct task_basic_info t_info;
+	mach_msg_type_number_t t_info_count = TASK_BASIC_INFO_COUNT;
+
+	if (KERN_SUCCESS != task_info(mach_task_self(),
+                              TASK_BASIC_INFO, (task_info_t)&t_info, 
+                              &t_info_count)) {
+		vm_usage = 0;
+		resident_set = 0;
+    		return;
+	}
+	vm_usage = t_info.virtual_size;
+	resident_set = t_info.resident_size;
+}
+#elif BSD
+void process_mem_usage(double& vm_usage, double& resident_set, pid_t pid) {
+	int mib[4];
+	size_t size;
+	mib[0] = CTL_KERN;
+	mib[1] = KERN_PROC;
+	mib[2] = KERN_PROC_PID;
+	if (pid == 0) {
+		mib[3] = getpid();
+	}
+	else {
+		mib[3] = pid;
+	}
+	struct kinfo_proc proc;
+
+	size = sizeof(struct kinfo_proc);
+
+	if (sysctl((int*)mib, 4, &proc, &size, NULL, 0) == -1) {
+		vm_usage = 0;
+		resident_set = 0;
+		return;
+	}
+
+	// sysctl stores 0 in the size if we can't find the process information.
+	// Set errno to ESRCH which will be translated in NoSuchProcess later on.
+	if (size == 0) {
+		vm_usage = 0;
+		resident_set = 0;
+		return;
+	}
+
+	int pagesize,cnt;
+
+	size = sizeof(pagesize);
+	sysctlbyname("hw.pagesize", &pagesize, &size, NULL, 0);
+
+	resident_set = (double) (proc.ki_rssize * pagesize / 1024);
+	vm_usage = (double) proc.ki_size;
+}
+#else /* BSD */
+void process_mem_usage(double& shared, double& resident_set, pid_t pid) {
+	using std::ios_base;
+	using std::ifstream;
+	using std::string;
+
+	shared       = 0.0;
+	resident_set = 0.0;
+
+	// 'file' stat seems to give the most reliable results
+	std::string f = "/proc/self/statm";
+	if (pid != 0) {
+		f = "/proc/" + boost::lexical_cast<std::string>(pid) + "/statm";
+	}
+	ifstream stat_stream(f.c_str(), ios_base::in);
+	if (!stat_stream.is_open()) {
+		shared = 0;
+		resident_set = 0;
+		return;
+	}
+
+	// dummy vars for leading entries in stat that we don't care about
+	//
+	string pid1, comm, state, ppid, pgrp, session, tty_nr;
+	string tpgid, flags, minflt, cminflt, majflt, cmajflt;
+	string utime, stime, cutime, cstime, priority, nice;
+	string O, itrealvalue, starttime;
+
+	// the two fields we want
+	//
+	unsigned long shared_;
+	long rss;
+
+	stat_stream >> O >> rss >> shared_; // don't care about the rest
+
+	long page_size_kb = sysconf(_SC_PAGE_SIZE) / 1024; // in case x86-64 is configured to use 2MB pages
+	shared     = shared_ * page_size_kb;
+	resident_set = rss * page_size_kb;
+}
+#endif /* else BSD */
+#else
+#define PSAPI_VERSION 1
+#define pid_t void*
+	void process_mem_usage(double& shared, double& resident_set, pid_t pid) {
+		PROCESS_MEMORY_COUNTERS_EX pmc;
+		GetProcessMemoryInfo(GetCurrentProcess(), (PROCESS_MEMORY_COUNTERS*)&pmc, sizeof(pmc));
+		shared =  (double)pmc.PrivateUsage;
+		resident_set = (double)pmc.WorkingSetSize;
+	}
+#endif /* WIN32 */
+
+}