diff --git a/av1/encoder/buf_ans.c b/av1/encoder/buf_ans.c
new file mode 100644
index 0000000..f87c1e1
--- /dev/null
+++ b/av1/encoder/buf_ans.c
@@ -0,0 +1,41 @@
+/*
+ *  Copyright (c) 2016 The WebM project authors. All Rights Reserved.
+ *
+ *  Use of this source code is governed by a BSD-style license
+ *  that can be found in the LICENSE file in the root of the source
+ *  tree. An additional intellectual property rights grant can be found
+ *  in the file PATENTS.  All contributing project authors may
+ *  be found in the AUTHORS file in the root of the source tree.
+ */
+
+#include <string.h>
+
+#include "av1/common/common.h"
+#include "av1/encoder/buf_ans.h"
+#include "av1/encoder/encoder.h"
+#include "aom_mem/vpx_mem.h"
+
+void vp10_buf_ans_alloc(struct BufAnsCoder *c, struct VP10Common *cm,
+                        int size_hint) {
+  c->cm = cm;
+  c->size = size_hint;
+  CHECK_MEM_ERROR(cm, c->buf, vpx_malloc(c->size * sizeof(*c->buf)));
+  // Initialize to overfull to trigger the assert in write.
+  c->offset = c->size + 1;
+}
+
+void vp10_buf_ans_free(struct BufAnsCoder *c) {
+  vpx_free(c->buf);
+  c->buf = NULL;
+  c->size = 0;
+}
+
+void vp10_buf_ans_grow(struct BufAnsCoder *c) {
+  struct buffered_ans_symbol *new_buf = NULL;
+  int new_size = c->size * 2;
+  CHECK_MEM_ERROR(c->cm, new_buf, vpx_malloc(new_size * sizeof(*new_buf)));
+  memcpy(new_buf, c->buf, c->size * sizeof(*c->buf));
+  vpx_free(c->buf);
+  c->buf = new_buf;
+  c->size = new_size;
+}