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/entdec.h

@@ -0,0 +1,91 @@
+/*
+ * Copyright (c) 2001-2016, 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.
+ */
+
+#if !defined(_entdec_H)
+#define _entdec_H (1)
+#include <limits.h>
+#include "aom_dsp/entcode.h"
+
+#ifdef __cplusplus
+extern "C" {
+#endif
+
+typedef struct od_ec_dec od_ec_dec;
+
+#if defined(OD_ACCOUNTING) && OD_ACCOUNTING
+#define OD_ACC_STR , char *acc_str
+#define od_ec_dec_bits(dec, ftb, str) od_ec_dec_bits_(dec, ftb, str)
+#else
+#define OD_ACC_STR
+#define od_ec_dec_bits(dec, ftb, str) od_ec_dec_bits_(dec, ftb)
+#endif
+
+/*The entropy decoder context.*/
+struct od_ec_dec {
+  /*The start of the current input buffer.*/
+  const unsigned char *buf;
+  /*The read pointer for the raw bits.*/
+  const unsigned char *eptr;
+  /*Bits that will be read from/written at the end.*/
+  od_ec_window end_window;
+  /*Number of valid bits in end_window.*/
+  int nend_bits;
+  /*An offset used to keep track of tell after reaching the end of the stream.
+    This is constant throughout most of the decoding process, but becomes
+     important once we hit the end of the buffer and stop incrementing pointers
+     (and instead pretend cnt/nend_bits have lots of bits).*/
+  int32_t tell_offs;
+  /*The end of the current input buffer.*/
+  const unsigned char *end;
+  /*The read pointer for the entropy-coded bits.*/
+  const unsigned char *bptr;
+  /*The difference between the coded value and the low end of the current
+     range.
+    {EC_SMALLMUL} The difference between the high end of the current range,
+     (low + rng), and the coded value, minus 1.
+    This stores up to OD_EC_WINDOW_SIZE bits of that difference, but the
+     decoder only uses the top 16 bits of the window to decode the next symbol.
+    As we shift up during renormalization, if we don't have enough bits left in
+     the window to fill the top 16, we'll read in more bits of the coded
+     value.*/
+  od_ec_window dif;
+  /*The number of values in the current range.*/
+  uint16_t rng;
+  /*The number of bits of data in the current value.*/
+  int16_t cnt;
+  /*Nonzero if an error occurred.*/
+  int error;
+};
+
+/*See entdec.c for further documentation.*/
+
+void od_ec_dec_init(od_ec_dec *dec, const unsigned char *buf, uint32_t storage)
+    OD_ARG_NONNULL(1) OD_ARG_NONNULL(2);
+
+OD_WARN_UNUSED_RESULT int od_ec_decode_bool_q15(od_ec_dec *dec, unsigned f)
+    OD_ARG_NONNULL(1);
+OD_WARN_UNUSED_RESULT int od_ec_decode_cdf_q15(od_ec_dec *dec,
+                                               const uint16_t *cdf, int nsyms)
+    OD_ARG_NONNULL(1) OD_ARG_NONNULL(2);
+
+OD_WARN_UNUSED_RESULT uint32_t od_ec_dec_bits_(od_ec_dec *dec, unsigned ftb)
+    OD_ARG_NONNULL(1);
+
+OD_WARN_UNUSED_RESULT int od_ec_dec_tell(const od_ec_dec *dec)
+    OD_ARG_NONNULL(1);
+OD_WARN_UNUSED_RESULT uint32_t od_ec_dec_tell_frac(const od_ec_dec *dec)
+    OD_ARG_NONNULL(1);
+
+#ifdef __cplusplus
+}  // extern "C"
+#endif
+
+#endif