diff --git a/src/fileio.cpp b/src/fileio.cpp
new file mode 100644
--- /dev/null
+++ b/src/fileio.cpp
@@ -0,0 +1,151 @@
+/* $Id$ */
+
+#include "stdafx.h"
+#include "openttd.h"
+#include "fileio.h"
+#include "functions.h"
+#include "string.h"
+#include "macros.h"
+#include "variables.h"
+
+/*************************************************/
+/* FILE IO ROUTINES ******************************/
+/*************************************************/
+
+#define FIO_BUFFER_SIZE 512
+
+typedef struct {
+	byte *buffer, *buffer_end;          ///< position pointer in local buffer and last valid byte of buffer
+	uint32 pos;                         ///< current (system) position in file
+	FILE *cur_fh;                       ///< current file handle
+	FILE *handles[64];                  ///< array of file handles we can have open
+	byte buffer_start[FIO_BUFFER_SIZE]; ///< local buffer when read from file
+} Fio;
+
+static Fio _fio;
+
+// Get current position in file
+uint32 FioGetPos(void)
+{
+	return _fio.pos + (_fio.buffer - _fio.buffer_start) - FIO_BUFFER_SIZE;
+}
+
+void FioSeekTo(uint32 pos, int mode)
+{
+	if (mode == SEEK_CUR) pos += FioGetPos();
+	_fio.buffer = _fio.buffer_end = _fio.buffer_start + FIO_BUFFER_SIZE;
+	_fio.pos = pos;
+	fseek(_fio.cur_fh, _fio.pos, SEEK_SET);
+}
+
+// Seek to a file and a position
+void FioSeekToFile(uint32 pos)
+{
+	FILE *f = _fio.handles[pos >> 24];
+	assert(f != NULL);
+	_fio.cur_fh = f;
+	FioSeekTo(GB(pos, 0, 24), SEEK_SET);
+}
+
+byte FioReadByte(void)
+{
+	if (_fio.buffer == _fio.buffer_end) {
+		_fio.pos += FIO_BUFFER_SIZE;
+		fread(_fio.buffer = _fio.buffer_start, 1, FIO_BUFFER_SIZE, _fio.cur_fh);
+	}
+	return *_fio.buffer++;
+}
+
+void FioSkipBytes(int n)
+{
+	for (;;) {
+		int m = min(_fio.buffer_end - _fio.buffer, n);
+		_fio.buffer += m;
+		n -= m;
+		if (n == 0) break;
+		FioReadByte();
+		n--;
+	}
+}
+
+uint16 FioReadWord(void)
+{
+	byte b = FioReadByte();
+	return (FioReadByte() << 8) | b;
+}
+
+uint32 FioReadDword(void)
+{
+	uint b = FioReadWord();
+	return (FioReadWord() << 16) | b;
+}
+
+void FioReadBlock(void *ptr, uint size)
+{
+	FioSeekTo(FioGetPos(), SEEK_SET);
+	_fio.pos += size;
+	fread(ptr, 1, size, _fio.cur_fh);
+}
+
+static inline void FioCloseFile(int slot)
+{
+	if (_fio.handles[slot] != NULL) {
+		fclose(_fio.handles[slot]);
+		_fio.handles[slot] = NULL;
+	}
+}
+
+void FioCloseAll(void)
+{
+	int i;
+
+	for (i = 0; i != lengthof(_fio.handles); i++)
+		FioCloseFile(i);
+}
+
+bool FioCheckFileExists(const char *filename)
+{
+	FILE *f = FioFOpenFile(filename);
+	if (f == NULL) return false;
+
+	fclose(f);
+	return true;
+}
+
+FILE *FioFOpenFile(const char *filename)
+{
+	FILE *f;
+	char buf[MAX_PATH];
+
+	snprintf(buf, lengthof(buf), "%s%s", _paths.data_dir, filename);
+
+	f = fopen(buf, "rb");
+#if !defined(WIN32)
+	if (f == NULL) {
+		strtolower(buf + strlen(_paths.data_dir) - 1);
+		f = fopen(buf, "rb");
+
+#if defined SECOND_DATA_DIR
+		// tries in the 2nd data directory
+		if (f == NULL) {
+			snprintf(buf, lengthof(buf), "%s%s", _paths.second_data_dir, filename);
+			strtolower(buf + strlen(_paths.second_data_dir) - 1);
+			f = fopen(buf, "rb");
+		}
+#endif
+	}
+#endif
+
+	return f;
+}
+
+void FioOpenFile(int slot, const char *filename)
+{
+	FILE *f = FioFOpenFile(filename);
+
+	if (f == NULL) error("Cannot open file '%s%s'", _paths.data_dir, filename);
+
+	FioCloseFile(slot); // if file was opened before, close it
+	_fio.handles[slot] = f;
+	FioSeekToFile(slot << 24);
+}