/*
 * Copyright (c) 2021, Alliance for Open Media. All rights reserved
 *
 * This source code is subject to the terms of the BSD 3-Clause Clear License
 * and the Alliance for Open Media Patent License 1.0. If the BSD 3-Clause Clear
 * License was not distributed with this source code in the LICENSE file, you
 * can obtain it at aomedia.org/license/software-license/bsd-3-c-c/.  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
 * aomedia.org/license/patent-license/.
 */
#include <stdbool.h>
#include <stdio.h>
#include <string.h>

#include "aom/aom_image.h"
#include "aom/aom_integer.h"
#include "aom_dsp/bitreader_buffer.h"
#include "aom_dsp/bitwriter_buffer.h"
#include "av1/common/obu_util.h"
#include "common/av1_config.h"
#include "config/aom_config.h"
#if CONFIG_EXTENDED_WARP_PREDICTION
#include "av1/common/enums.h"
#endif

// Helper macros to reduce verbosity required to check for read errors.
//
// Note that when using these macros, even single line if statements should use
// curly braces to avoid unexpected behavior because all but the
// AV1C_POP_ERROR_HANDLER_DATA() macro consist of multiple statements.
#define AV1C_READ_BIT_OR_RETURN_ERROR(field)                                   \
  int field = 0;                                                               \
  do {                                                                         \
    field = aom_rb_read_bit(reader);                                           \
    if (result == -1) {                                                        \
      fprintf(stderr,                                                          \
              "av1c: Error reading bit for " #field ", value=%d result=%d.\n", \
              field, result);                                                  \
      return -1;                                                               \
    }                                                                          \
  } while (0)

#define AV1C_READ_BITS_OR_RETURN_ERROR(field, length) \
  int field = 0;                                      \
  do {                                                \
    field = aom_rb_read_literal(reader, (length));    \
    if (result == -1) {                               \
      fprintf(stderr,                                 \
              "av1c: Could not read bits for " #field \
              ", value=%d result=%d.\n",              \
              field, result);                         \
      return -1;                                      \
    }                                                 \
  } while (0)

// Helper macros for setting/restoring the error handler data in
// aom_read_bit_buffer.
#define AV1C_PUSH_ERROR_HANDLER_DATA(new_data)                \
  void *original_error_handler_data = NULL;                   \
  do {                                                        \
    original_error_handler_data = reader->error_handler_data; \
    reader->error_handler_data = &new_data;                   \
  } while (0)

#define AV1C_POP_ERROR_HANDLER_DATA()                         \
  do {                                                        \
    reader->error_handler_data = original_error_handler_data; \
  } while (0)

static const size_t kAv1cSize = 4;

static void bitreader_error_handler(void *data) {
  int *error_val = (int *)data;
  *error_val = -1;
}

// Parse the AV1 timing_info() structure:
// timing_info( ) {
//   num_units_in_display_tick       f(32)
//   time_scale                      f(32)
//   equal_picture_interval          f(1)
//   if (equal_picture_interval)
//     num_ticks_per_picture_minus_1 uvlc()
//   }
static int parse_timing_info(struct aom_read_bit_buffer *reader) {
  int result = 0;
  AV1C_PUSH_ERROR_HANDLER_DATA(result);

  AV1C_READ_BITS_OR_RETURN_ERROR(num_units_in_display_tick, 32);
  AV1C_READ_BITS_OR_RETURN_ERROR(time_scale, 32);

  AV1C_READ_BIT_OR_RETURN_ERROR(equal_picture_interval);
  if (equal_picture_interval) {
    uint32_t num_ticks_per_picture_minus_1 = aom_rb_read_uvlc(reader);
    if (result == -1) {
      fprintf(stderr,
              "av1c: Could not read bits for "
              "num_ticks_per_picture_minus_1, value=%u.\n",
              num_ticks_per_picture_minus_1);
      return result;
    }
  }

  AV1C_POP_ERROR_HANDLER_DATA();
  return result;
}

// Parse the AV1 decoder_model_info() structure:
// decoder_model_info( ) {
//   buffer_delay_length_minus_1            f(5)
//   num_units_in_decoding_tick             f(32)
//   buffer_removal_time_length_minus_1     f(5)
//   frame_presentation_time_length_minus_1 f(5)
// }
//
// Returns -1 upon failure, or the value of buffer_delay_length_minus_1 + 1.
static int parse_decoder_model_info(struct aom_read_bit_buffer *reader) {
  int result = 0;
  AV1C_PUSH_ERROR_HANDLER_DATA(result);

  AV1C_READ_BITS_OR_RETURN_ERROR(buffer_delay_length_minus_1, 5);
  AV1C_READ_BITS_OR_RETURN_ERROR(num_units_in_decoding_tick, 32);
  AV1C_READ_BITS_OR_RETURN_ERROR(buffer_removal_time_length_minus_1, 5);
  AV1C_READ_BITS_OR_RETURN_ERROR(frame_presentation_time_length_minus_1, 5);

  AV1C_POP_ERROR_HANDLER_DATA();
  return buffer_delay_length_minus_1 + 1;
}

// Parse the AV1 operating_parameters_info() structure:
// operating_parameters_info( op ) {
//   n = buffer_delay_length_minus_1 + 1
//   decoder_buffer_delay[ op ] f(n)
//   encoder_buffer_delay[ op ] f(n)
//   low_delay_mode_flag[ op ] f(1)
// }
static int parse_operating_parameters_info(struct aom_read_bit_buffer *reader,
                                           int buffer_delay_length_minus_1) {
  int result = 0;
  AV1C_PUSH_ERROR_HANDLER_DATA(result);

  const int buffer_delay_length = buffer_delay_length_minus_1 + 1;
  AV1C_READ_BITS_OR_RETURN_ERROR(decoder_buffer_delay, buffer_delay_length);
  AV1C_READ_BITS_OR_RETURN_ERROR(encoder_buffer_delay, buffer_delay_length);
  AV1C_READ_BIT_OR_RETURN_ERROR(low_delay_mode_flag);

  AV1C_POP_ERROR_HANDLER_DATA();
  return result;
}

// Parse the AV1 color_config() structure..See:
// https://aomediacodec.github.io/av1-spec/av1-spec.pdf#page=44
static int parse_color_config(struct aom_read_bit_buffer *reader,
                              Av1Config *config) {
  int result = 0;
  AV1C_PUSH_ERROR_HANDLER_DATA(result);

  AV1C_READ_BIT_OR_RETURN_ERROR(high_bitdepth);
  config->high_bitdepth = high_bitdepth;

  int bit_depth = 0;
  if (config->seq_profile == 2 && config->high_bitdepth) {
    AV1C_READ_BIT_OR_RETURN_ERROR(twelve_bit);
    config->twelve_bit = twelve_bit;
    bit_depth = config->twelve_bit ? 12 : 10;
  } else {
    bit_depth = config->high_bitdepth ? 10 : 8;
  }

  if (config->seq_profile != 1) {
    AV1C_READ_BIT_OR_RETURN_ERROR(mono_chrome);
    config->monochrome = mono_chrome;
  }

  int color_primaries = AOM_CICP_CP_UNSPECIFIED;
  int transfer_characteristics = AOM_CICP_TC_UNSPECIFIED;
  int matrix_coefficients = AOM_CICP_MC_UNSPECIFIED;

  AV1C_READ_BIT_OR_RETURN_ERROR(color_description_present_flag);
  if (color_description_present_flag) {
    AV1C_READ_BITS_OR_RETURN_ERROR(color_primaries_val, 8);
    color_primaries = color_primaries_val;
    AV1C_READ_BITS_OR_RETURN_ERROR(transfer_characteristics_val, 8);
    transfer_characteristics = transfer_characteristics_val;
    AV1C_READ_BITS_OR_RETURN_ERROR(matrix_coefficients_val, 8);
    matrix_coefficients = matrix_coefficients_val;
  }

  if (config->monochrome) {
    AV1C_READ_BIT_OR_RETURN_ERROR(color_range);
    config->chroma_subsampling_x = 1;
    config->chroma_subsampling_y = 1;
  } else if (color_primaries == AOM_CICP_CP_BT_709 &&
             transfer_characteristics == AOM_CICP_TC_SRGB &&
             matrix_coefficients == AOM_CICP_MC_IDENTITY) {
    config->chroma_subsampling_x = 0;
    config->chroma_subsampling_y = 0;
  } else {
    AV1C_READ_BIT_OR_RETURN_ERROR(color_range);
    if (config->seq_profile == 0) {
      config->chroma_subsampling_x = 1;
      config->chroma_subsampling_y = 1;
    } else if (config->seq_profile == 1) {
      config->chroma_subsampling_x = 0;
      config->chroma_subsampling_y = 0;
    } else {
      if (bit_depth == 12) {
        AV1C_READ_BIT_OR_RETURN_ERROR(subsampling_x);
        config->chroma_subsampling_x = subsampling_x;
        if (subsampling_x) {
          AV1C_READ_BIT_OR_RETURN_ERROR(subsampling_y);
          config->chroma_subsampling_y = subsampling_y;
        } else {
          config->chroma_subsampling_y = 0;
        }
      } else {
        config->chroma_subsampling_x = 1;
        config->chroma_subsampling_y = 0;
      }
    }

    if (config->chroma_subsampling_x && config->chroma_subsampling_y) {
      AV1C_READ_BITS_OR_RETURN_ERROR(chroma_sample_position, 2);
      config->chroma_sample_position = chroma_sample_position;
    }
  }

  if (!config->monochrome) {
    AV1C_READ_BIT_OR_RETURN_ERROR(separate_uv_delta_q);
  }

  AV1C_POP_ERROR_HANDLER_DATA();
  return result;
}

// Parse Sequence Header OBU for coding tools beyond AV1
int parse_sequence_header_beyond_av1(struct aom_read_bit_buffer *reader,
                                     bool reduced_still_picture_header) {
  (void)reduced_still_picture_header;

  int result = 0;
  AV1C_READ_BIT_OR_RETURN_ERROR(enable_refmvbank);
  AV1C_READ_BIT_OR_RETURN_ERROR(reduced_ref_frame_set);
  if (reduced_ref_frame_set) {
    AV1C_READ_BITS_OR_RETURN_ERROR(max_reference_frames, 2);
  }
  AV1C_READ_BIT_OR_RETURN_ERROR(explicit_ref_frame_map);
#if CONFIG_OUTPUT_FRAME_BASED_ON_ORDER_HINT
  // 0: show_existing_frame, 1: implicit derivation
  AV1C_READ_BIT_OR_RETURN_ERROR(enable_frame_output_order);
#endif  // CONFIG_OUTPUT_FRAME_BASED_ON_ORDER_HINT
  AV1C_READ_BIT_OR_RETURN_ERROR(enable_sdp);
  AV1C_READ_BIT_OR_RETURN_ERROR(enable_ist);
  AV1C_READ_BIT_OR_RETURN_ERROR(enable_cctx);
  AV1C_READ_BIT_OR_RETURN_ERROR(enable_mrls);
  AV1C_READ_BIT_OR_RETURN_ERROR(enable_tip);
  if (enable_tip) {
    AV1C_READ_BIT_OR_RETURN_ERROR(enable_tip_hole_fill);
  }
#if CONFIG_BAWP
  AV1C_READ_BIT_OR_RETURN_ERROR(enable_bawp);
#endif  // CONFIG_BAWP
  AV1C_READ_BIT_OR_RETURN_ERROR(enable_cwp);
#if CONFIG_D071_IMP_MSK_BLD
  AV1C_READ_BIT_OR_RETURN_ERROR(enable_imp_msk_bld);
#endif  // CONFIG_D071_IMP_MSK_BLD
  AV1C_READ_BIT_OR_RETURN_ERROR(enable_fsc);
#if CONFIG_CCSO
  AV1C_READ_BIT_OR_RETURN_ERROR(enable_ccso);
#endif
  AV1C_READ_BIT_OR_RETURN_ERROR(enable_pef);
  AV1C_READ_BIT_OR_RETURN_ERROR(enable_orip);
#if CONFIG_IDIF
  AV1C_READ_BIT_OR_RETURN_ERROR(enable_idif);
#endif  // CONFIG_IDIF
  AV1C_READ_BIT_OR_RETURN_ERROR(enable_ibp);
  AV1C_READ_BIT_OR_RETURN_ERROR(enable_adaptive_mvd);
#if CONFIG_REFINEMV
  AV1C_READ_BIT_OR_RETURN_ERROR(enable_refinemv);
#endif  // CONFIG_REFINEMV

  AV1C_READ_BIT_OR_RETURN_ERROR(enable_flex_mvres);
#if CONFIG_IMPROVED_CFL
  AV1C_READ_BIT_OR_RETURN_ERROR(enable_cfl_ds_filter);
#endif  // CONFIG_IMPROVED_CFL
  AV1C_READ_BIT_OR_RETURN_ERROR(enable_parity_hiding);
#if CONFIG_IMPROVED_GLOBAL_MOTION
  if (!reduced_still_picture_header) {
    AV1C_READ_BIT_OR_RETURN_ERROR(enable_global_motion);
  }
#endif  // CONFIG_IMPROVED_GLOBAL_MOTION
#if CONFIG_REFRESH_FLAG
  AV1C_READ_BIT_OR_RETURN_ERROR(enable_short_refresh_frame_flags);
#endif  // CONFIG_REFRESH_FLAG

  return 0;
}

// Parse AV1 Sequence Header OBU. See:
// https://aomediacodec.github.io/av1-spec/av1-spec.pdf#page=41
static int parse_sequence_header(const uint8_t *const buffer, size_t length,
                                 Av1Config *config) {
  int result = 0;
  // The reader instance is local to this function, but a pointer to the
  // reader instance is used within this function and throughout this file to
  // allow use of the helper macros that reduce parse error checking verbosity.
  struct aom_read_bit_buffer reader_instance = { buffer, buffer + length, 0,
                                                 &result,
                                                 bitreader_error_handler };
  struct aom_read_bit_buffer *reader = &reader_instance;

  AV1C_READ_BITS_OR_RETURN_ERROR(seq_profile, 3);
  config->seq_profile = seq_profile;
  AV1C_READ_BIT_OR_RETURN_ERROR(still_picture);
  AV1C_READ_BIT_OR_RETURN_ERROR(reduced_still_picture_header);
  if (reduced_still_picture_header) {
    config->initial_presentation_delay_present = 0;
    AV1C_READ_BITS_OR_RETURN_ERROR(seq_level_idx_0, 5);
    config->seq_level_idx_0 = seq_level_idx_0;
    config->seq_tier_0 = 0;
  } else {
    int has_decoder_model = 0;
    int buffer_delay_length = 0;

    AV1C_READ_BIT_OR_RETURN_ERROR(timing_info_present_flag);
    if (timing_info_present_flag) {
      if (parse_timing_info(reader) != 0) return -1;

      AV1C_READ_BIT_OR_RETURN_ERROR(decoder_model_info_present_flag);
      if (decoder_model_info_present_flag &&
          (buffer_delay_length = parse_decoder_model_info(reader)) == -1) {
        return -1;
      }
      has_decoder_model = 1;
    }

    AV1C_READ_BIT_OR_RETURN_ERROR(initial_presentation_delay_present);
    config->initial_presentation_delay_present =
        initial_presentation_delay_present;

    AV1C_READ_BITS_OR_RETURN_ERROR(operating_points_cnt_minus_1, 5);
    const int num_operating_points = operating_points_cnt_minus_1 + 1;

    for (int op_index = 0; op_index < num_operating_points; ++op_index) {
      AV1C_READ_BITS_OR_RETURN_ERROR(operating_point_idc, 12);
      AV1C_READ_BITS_OR_RETURN_ERROR(seq_level_idx, 5);

      int seq_tier = 0;
      if (seq_level_idx > 7) {
        AV1C_READ_BIT_OR_RETURN_ERROR(seq_tier_this_op);
        seq_tier = seq_tier_this_op;
      }

      if (has_decoder_model) {
        AV1C_READ_BIT_OR_RETURN_ERROR(decoder_model_present_for_op);
        if (decoder_model_present_for_op) {
          if (parse_operating_parameters_info(reader, buffer_delay_length) ==
              -1) {
            return -1;
          }
        }
      }

      if (config->initial_presentation_delay_present) {
        // Skip the initial presentation delay bits if present since this
        // function has no access to the data required to properly set the
        // field.
        AV1C_READ_BIT_OR_RETURN_ERROR(
            initial_presentation_delay_present_for_this_op);
        if (initial_presentation_delay_present_for_this_op) {
          AV1C_READ_BITS_OR_RETURN_ERROR(initial_presentation_delay_minus_1, 4);
        }
      }

      if (op_index == 0) {
        // Av1Config needs only the values from the first operating point.
        config->seq_level_idx_0 = seq_level_idx;
        config->seq_tier_0 = seq_tier;
        config->initial_presentation_delay_present = 0;
        config->initial_presentation_delay_minus_one = 0;
      }
    }
  }

  AV1C_READ_BITS_OR_RETURN_ERROR(frame_width_bits_minus_1, 4);
  AV1C_READ_BITS_OR_RETURN_ERROR(frame_height_bits_minus_1, 4);
  AV1C_READ_BITS_OR_RETURN_ERROR(max_frame_width_minus_1,
                                 frame_width_bits_minus_1 + 1);
  AV1C_READ_BITS_OR_RETURN_ERROR(max_frame_height_minus_1,
                                 frame_height_bits_minus_1 + 1);

  uint8_t frame_id_numbers_present = 0;
  if (!reduced_still_picture_header) {
    AV1C_READ_BIT_OR_RETURN_ERROR(frame_id_numbers_present_flag);
    frame_id_numbers_present = frame_id_numbers_present_flag;
  }

  if (frame_id_numbers_present) {
    AV1C_READ_BITS_OR_RETURN_ERROR(delta_frame_id_length_minus_2, 4);
    AV1C_READ_BITS_OR_RETURN_ERROR(additional_frame_id_length_minus_1, 3);
  }

  AV1C_READ_BIT_OR_RETURN_ERROR(use_128x128_superblock);
  AV1C_READ_BIT_OR_RETURN_ERROR(enable_filter_intra);
  AV1C_READ_BIT_OR_RETURN_ERROR(enable_intra_edge_filter);
  if (!reduced_still_picture_header) {
#if CONFIG_EXTENDED_WARP_PREDICTION
    for (int motion_mode = INTERINTRA; motion_mode < MOTION_MODES;
         motion_mode++) {
      AV1C_READ_BIT_OR_RETURN_ERROR(seq_enabled_motion_modes);
    }
#else
    AV1C_READ_BIT_OR_RETURN_ERROR(enable_interintra_compound);
#endif  // CONFIG_EXTENDED_WARP_PREDICTION
    AV1C_READ_BIT_OR_RETURN_ERROR(enable_masked_compound);
#if !CONFIG_EXTENDED_WARP_PREDICTION
    AV1C_READ_BIT_OR_RETURN_ERROR(enable_warped_motion);
#endif  // !CONFIG_EXTENDED_WARP_PREDICTION
    AV1C_READ_BIT_OR_RETURN_ERROR(enable_order_hint);
    if (enable_order_hint) {
      AV1C_READ_BIT_OR_RETURN_ERROR(enable_ref_frame_mvs);
#if CONFIG_OPTFLOW_REFINEMENT
      AV1C_READ_BIT_OR_RETURN_ERROR(enable_opfl_refine);
#endif  // CONFIG_OPTFLOW_REFINEMENT
#if CONFIG_AFFINE_REFINEMENT
      AV1C_READ_BIT_OR_RETURN_ERROR(enable_affine_refine);
#endif  // CONFIG_AFFINE_REFINEMENT
    }

    const int SELECT_SCREEN_CONTENT_TOOLS = 2;
    int seq_force_screen_content_tools = SELECT_SCREEN_CONTENT_TOOLS;
    AV1C_READ_BIT_OR_RETURN_ERROR(seq_choose_screen_content_tools);
    if (!seq_choose_screen_content_tools) {
      AV1C_READ_BIT_OR_RETURN_ERROR(seq_force_screen_content_tools_val);
      seq_force_screen_content_tools = seq_force_screen_content_tools_val;
    }

    if (seq_force_screen_content_tools > 0) {
      AV1C_READ_BIT_OR_RETURN_ERROR(seq_choose_integer_mv);

      if (!seq_choose_integer_mv) {
        AV1C_READ_BIT_OR_RETURN_ERROR(seq_force_integer_mv);
      }
    }

    if (enable_order_hint) {
      AV1C_READ_BITS_OR_RETURN_ERROR(order_hint_bits_minus_1, 3);
    }
  }

  AV1C_READ_BIT_OR_RETURN_ERROR(enable_superres);
  AV1C_READ_BIT_OR_RETURN_ERROR(enable_cdef);
  AV1C_READ_BIT_OR_RETURN_ERROR(enable_restoration);

  if (parse_color_config(reader, config) != 0) {
    fprintf(stderr, "av1c: color_config() parse failed.\n");
    return -1;
  }

  AV1C_READ_BIT_OR_RETURN_ERROR(film_grain_params_present);

  // Sequence header for coding tools beyond AV1
  parse_sequence_header_beyond_av1(reader, reduced_still_picture_header);

  return 0;
}

int get_av1config_from_obu(const uint8_t *buffer, size_t length, int is_annexb,
                           Av1Config *config) {
  if (!buffer || length == 0 || !config) {
    return -1;
  }

  ObuHeader obu_header;
  memset(&obu_header, 0, sizeof(obu_header));

  size_t sequence_header_length = 0;
  size_t obu_header_length = 0;
  if (aom_read_obu_header_and_size(buffer, length, is_annexb, &obu_header,
                                   &sequence_header_length,
                                   &obu_header_length) != AOM_CODEC_OK ||
      obu_header.type != OBU_SEQUENCE_HEADER ||
      sequence_header_length + obu_header_length > length) {
    return -1;
  }

  memset(config, 0, sizeof(*config));
  config->marker = 1;
  config->version = 1;
  return parse_sequence_header(buffer + obu_header_length,
                               sequence_header_length, config);
}

int read_av1config(const uint8_t *buffer, size_t buffer_length,
                   size_t *bytes_read, Av1Config *config) {
  if (!buffer || buffer_length < kAv1cSize || !bytes_read || !config) return -1;

  *bytes_read = 0;

  int result = 0;
  struct aom_read_bit_buffer reader_instance = { buffer, buffer + buffer_length,
                                                 0, &result,
                                                 bitreader_error_handler };
  struct aom_read_bit_buffer *reader = &reader_instance;

  memset(config, 0, sizeof(*config));

  AV1C_READ_BIT_OR_RETURN_ERROR(marker);
  config->marker = marker;

  AV1C_READ_BITS_OR_RETURN_ERROR(version, 7);
  config->version = version;

  AV1C_READ_BITS_OR_RETURN_ERROR(seq_profile, 3);
  config->seq_profile = seq_profile;

  AV1C_READ_BITS_OR_RETURN_ERROR(seq_level_idx_0, 5);
  config->seq_level_idx_0 = seq_level_idx_0;

  AV1C_READ_BIT_OR_RETURN_ERROR(seq_tier_0);
  config->seq_tier_0 = seq_tier_0;

  AV1C_READ_BIT_OR_RETURN_ERROR(high_bitdepth);
  config->high_bitdepth = high_bitdepth;

  AV1C_READ_BIT_OR_RETURN_ERROR(twelve_bit);
  config->twelve_bit = twelve_bit;

  AV1C_READ_BIT_OR_RETURN_ERROR(monochrome);
  config->monochrome = monochrome;

  AV1C_READ_BIT_OR_RETURN_ERROR(chroma_subsampling_x);
  config->chroma_subsampling_x = chroma_subsampling_x;

  AV1C_READ_BIT_OR_RETURN_ERROR(chroma_subsampling_y);
  config->chroma_subsampling_y = chroma_subsampling_y;

  AV1C_READ_BITS_OR_RETURN_ERROR(chroma_sample_position, 2);
  config->chroma_sample_position = chroma_sample_position;

  AV1C_READ_BITS_OR_RETURN_ERROR(reserved, 3);

  AV1C_READ_BIT_OR_RETURN_ERROR(initial_presentation_delay_present);
  config->initial_presentation_delay_present =
      initial_presentation_delay_present;

  AV1C_READ_BITS_OR_RETURN_ERROR(initial_presentation_delay_minus_one, 4);
  config->initial_presentation_delay_minus_one =
      initial_presentation_delay_minus_one;

  *bytes_read = aom_rb_bytes_read(reader);

  return 0;
}

int write_av1config(const Av1Config *config, size_t capacity,
                    size_t *bytes_written, uint8_t *buffer) {
  if (!config || !buffer || capacity < kAv1cSize || !bytes_written) return -1;

  *bytes_written = 0;
  memset(buffer, 0, kAv1cSize);

  struct aom_write_bit_buffer writer = { buffer, 0 };

  aom_wb_write_bit(&writer, config->marker);
  aom_wb_write_literal(&writer, config->version, 7);
  aom_wb_write_literal(&writer, config->seq_profile, 3);
  aom_wb_write_literal(&writer, config->seq_level_idx_0, 5);
  aom_wb_write_bit(&writer, config->seq_tier_0);
  aom_wb_write_bit(&writer, config->high_bitdepth);
  aom_wb_write_bit(&writer, config->twelve_bit);
  aom_wb_write_bit(&writer, config->monochrome);
  aom_wb_write_bit(&writer, config->chroma_subsampling_x);
  aom_wb_write_bit(&writer, config->chroma_subsampling_y);
  aom_wb_write_literal(&writer, config->chroma_sample_position, 2);
  aom_wb_write_literal(&writer, 0, 3);  // reserved
  aom_wb_write_bit(&writer, config->initial_presentation_delay_present);

  if (config->initial_presentation_delay_present) {
    aom_wb_write_literal(&writer, config->initial_presentation_delay_minus_one,
                         4);
  } else {
    aom_wb_write_literal(&writer, 0, 4);  // reserved
  }

  *bytes_written = aom_wb_bytes_written(&writer);
  return 0;
}

#undef AV1C_READ_BIT_OR_RETURN_ERROR
#undef AV1C_READ_BITS_OR_RETURN_ERROR
#undef AV1C_PUSH_ERROR_HANDLER_DATA
#undef AV1C_POP_ERROR_HANDLER_DATA