diff --git a/replay/Makefile.objs b/replay/Makefile.objs
index 7ea860f..1148f45 100755
--- a/replay/Makefile.objs
+++ b/replay/Makefile.objs
@@ -1 +1,2 @@
 obj-y += replay.o
+obj-y += replay-internal.o
diff --git a/replay/replay-internal.c b/replay/replay-internal.c
new file mode 100755
index 0000000..3865fa5
--- /dev/null
+++ b/replay/replay-internal.c
@@ -0,0 +1,141 @@
+/*
+ * replay-internal.c
+ *
+ * Copyright (c) 2010-2015 Institute for System Programming
+ *                         of the Russian Academy of Sciences.
+ *
+ * This work is licensed under the terms of the GNU GPL, version 2 or later.
+ * See the COPYING file in the top-level directory.
+ *
+ */
+
+#include "qemu-common.h"
+#include "replay-internal.h"
+
+unsigned int replay_data_kind = -1;
+unsigned int replay_has_unread_data;
+
+/* File for replay writing */
+FILE *replay_file;
+
+void replay_put_byte(uint8_t byte)
+{
+    if (replay_file) {
+        fwrite(&byte, sizeof(byte), 1, replay_file);
+    }
+}
+
+void replay_put_event(uint8_t event)
+{
+    replay_put_byte(event);
+}
+
+
+void replay_put_word(uint16_t word)
+{
+    if (replay_file) {
+        fwrite(&word, sizeof(word), 1, replay_file);
+    }
+}
+
+void replay_put_dword(uint32_t dword)
+{
+    if (replay_file) {
+        fwrite(&dword, sizeof(dword), 1, replay_file);
+    }
+}
+
+void replay_put_qword(int64_t qword)
+{
+    if (replay_file) {
+        fwrite(&qword, sizeof(qword), 1, replay_file);
+    }
+}
+
+void replay_put_array(const uint8_t *buf, size_t size)
+{
+    if (replay_file) {
+        fwrite(&size, sizeof(size), 1, replay_file);
+        fwrite(buf, 1, size, replay_file);
+    }
+}
+
+uint8_t replay_get_byte(void)
+{
+    uint8_t byte;
+    if (replay_file) {
+        fread(&byte, sizeof(byte), 1, replay_file);
+    }
+    return byte;
+}
+
+uint16_t replay_get_word(void)
+{
+    uint16_t word;
+    if (replay_file) {
+        fread(&word, sizeof(word), 1, replay_file);
+    }
+
+    return word;
+}
+
+uint32_t replay_get_dword(void)
+{
+    uint32_t dword;
+    if (replay_file) {
+        fread(&dword, sizeof(dword), 1, replay_file);
+    }
+
+    return dword;
+}
+
+int64_t replay_get_qword(void)
+{
+    int64_t qword;
+    if (replay_file) {
+        fread(&qword, sizeof(qword), 1, replay_file);
+    }
+
+    return qword;
+}
+
+void replay_get_array(uint8_t *buf, size_t *size)
+{
+    if (replay_file) {
+        fread(size, sizeof(*size), 1, replay_file);
+        fread(buf, 1, *size, replay_file);
+    }
+}
+
+void replay_get_array_alloc(uint8_t **buf, size_t *size)
+{
+    if (replay_file) {
+        fread(size, sizeof(*size), 1, replay_file);
+        *buf = g_malloc(*size);
+        fread(*buf, 1, *size, replay_file);
+    }
+}
+
+void replay_check_error(void)
+{
+    if (replay_file) {
+        if (feof(replay_file)) {
+            fprintf(stderr, "replay file is over\n");
+            exit(1);
+        } else if (ferror(replay_file)) {
+            fprintf(stderr, "replay file is over or something goes wrong\n");
+            exit(1);
+        }
+    }
+}
+
+void replay_fetch_data_kind(void)
+{
+    if (replay_file) {
+        if (!replay_has_unread_data) {
+            replay_data_kind = replay_get_byte();
+            replay_check_error();
+            replay_has_unread_data = 1;
+        }
+    }
+}
diff --git a/replay/replay-internal.h b/replay/replay-internal.h
new file mode 100755
index 0000000..dad5bc8
--- /dev/null
+++ b/replay/replay-internal.h
@@ -0,0 +1,50 @@
+#ifndef REPLAY_INTERNAL_H
+#define REPLAY_INTERNAL_H
+
+/*
+ * replay-internal.h
+ *
+ * Copyright (c) 2010-2015 Institute for System Programming
+ *                         of the Russian Academy of Sciences.
+ *
+ * This work is licensed under the terms of the GNU GPL, version 2 or later.
+ * See the COPYING file in the top-level directory.
+ *
+ */
+
+#include <stdio.h>
+
+extern unsigned int replay_data_kind;
+extern unsigned int replay_has_unread_data;
+
+/* File for replay writing */
+extern FILE *replay_file;
+
+void replay_put_byte(uint8_t byte);
+void replay_put_event(uint8_t event);
+void replay_put_word(uint16_t word);
+void replay_put_dword(uint32_t dword);
+void replay_put_qword(int64_t qword);
+void replay_put_array(const uint8_t *buf, size_t size);
+
+uint8_t replay_get_byte(void);
+uint16_t replay_get_word(void);
+uint32_t replay_get_dword(void);
+int64_t replay_get_qword(void);
+void replay_get_array(uint8_t *buf, size_t *size);
+void replay_get_array_alloc(uint8_t **buf, size_t *size);
+
+/*! Checks error status of the file. */
+void replay_check_error(void);
+
+/*! Reads data type from the file and stores it in the
+    replay_data_kind variable. */
+void replay_fetch_data_kind(void);
+
+/*! Saves queued events (like instructions and sound). */
+void replay_save_instructions(void);
+/*! Checks that the next data is corresponding to the desired kind.
+    Terminates the program in case of error. */
+void validate_data_kind(int kind);
+
+#endif
