Import aom library

This is the reference implementation for the Alliance for Open Media's av1 video code.

The commit used was 4d668d7feb1f8abd809d1bca0418570a7f142a36.

third_party/aom/aom_dsp/buf_ans.c

@@ -0,0 +1,71 @@
+/*
+ * Copyright (c) 2016, Alliance for Open Media. All rights reserved
+ *
+ * This source code is subject to the terms of the BSD 2 Clause License and
+ * the Alliance for Open Media Patent License 1.0. If the BSD 2 Clause License
+ * was not distributed with this source code in the LICENSE file, you can
+ * obtain it at www.aomedia.org/license/software. If the Alliance for Open
+ * Media Patent License 1.0 was not distributed with this source code in the
+ * PATENTS file, you can obtain it at www.aomedia.org/license/patent.
+ */
+
+#include <string.h>
+
+#include "aom_dsp/buf_ans.h"
+#include "aom_mem/aom_mem.h"
+#include "aom/internal/aom_codec_internal.h"
+
+void aom_buf_ans_alloc(struct BufAnsCoder *c,
+                       struct aom_internal_error_info *error, int size) {
+  c->error = error;
+  c->size = size;
+  assert(c->size > 1);
+  AOM_CHECK_MEM_ERROR(error, c->buf, aom_malloc(c->size * sizeof(*c->buf)));
+  // Initialize to overfull to trigger the assert in write.
+  c->offset = c->size + 1;
+}
+
+void aom_buf_ans_free(struct BufAnsCoder *c) {
+  aom_free(c->buf);
+  c->buf = NULL;
+  c->size = 0;
+}
+
+#if !ANS_MAX_SYMBOLS
+void aom_buf_ans_grow(struct BufAnsCoder *c) {
+  struct buffered_ans_symbol *new_buf = NULL;
+  int new_size = c->size * 2;
+  AOM_CHECK_MEM_ERROR(c->error, new_buf,
+                      aom_malloc(new_size * sizeof(*new_buf)));
+  memcpy(new_buf, c->buf, c->size * sizeof(*c->buf));
+  aom_free(c->buf);
+  c->buf = new_buf;
+  c->size = new_size;
+}
+#endif
+
+void aom_buf_ans_flush(struct BufAnsCoder *const c) {
+  int offset;
+#if ANS_MAX_SYMBOLS
+  if (c->offset == 0) return;
+#endif
+  assert(c->offset > 0);
+  offset = c->offset - 1;
+  // Code the first symbol such that it brings the state to the smallest normal
+  // state from an initial state that would have been a subnormal/refill state.
+  if (c->buf[offset].method == ANS_METHOD_RANS) {
+    c->ans.state += c->buf[offset].val_start;
+  } else {
+    c->ans.state += c->buf[offset].val_start ? c->buf[offset].prob : 0;
+  }
+  for (offset = offset - 1; offset >= 0; --offset) {
+    if (c->buf[offset].method == ANS_METHOD_RANS) {
+      rans_write(&c->ans, c->buf[offset].val_start, c->buf[offset].prob);
+    } else {
+      rabs_write(&c->ans, (uint8_t)c->buf[offset].val_start,
+                 (AnsP8)c->buf[offset].prob);
+    }
+  }
+  c->offset = 0;
+  c->output_bytes += ans_write_end(&c->ans);
+}