/*

  * H.264/HEVC common parsing code

  *

  * This file is part of FFmpeg.

  *

  * FFmpeg is free software; you can redistribute it and/or

  * modify it under the terms of the GNU Lesser General Public
  * License as published by the Free Software Foundation; either
  * version 2.1 of the License, or (at your option) any later version.
  *

  * FFmpeg is distributed in the hope that it will be useful,

  * but WITHOUT ANY WARRANTY; without even the implied warranty of
  * MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE.  See the GNU
  * Lesser General Public License for more details.
  *
  * You should have received a copy of the GNU Lesser General Public

  * License along with FFmpeg; if not, write to the Free Software

  * Foundation, Inc., 51 Franklin Street, Fifth Floor, Boston, MA 02110-1301 USA
  */
 
 #include <string.h>
 
 #include "config.h"
 

 #include "libavutil/intmath.h"

 #include "libavutil/intreadwrite.h"
 #include "libavutil/mem.h"
 

 #include "hevc.h"

 #include "h2645_parse.h"

 int ff_h2645_extract_rbsp(const uint8_t *src, int length,

                           H2645NAL *nal, int small_padding)

 {
     int i, si, di;
     uint8_t *dst;

     int64_t padding = small_padding ? 0 : MAX_MBPAIR_SIZE;

     nal->skipped_bytes = 0;

 #define STARTCODE_TEST                                                  \
         if (i + 2 < length && src[i + 1] == 0 && src[i + 2] <= 3) {     \

             if (src[i + 2] != 3 && src[i + 2] != 0) {                   \

                 /* startcode, so we must be past the end */             \
                 length = i;                                             \
             }                                                           \
             break;                                                      \
         }
 #if HAVE_FAST_UNALIGNED
 #define FIND_FIRST_ZERO                                                 \
         if (i > 0 && !src[i])                                           \
             i--;                                                        \
         while (src[i])                                                  \
             i++
 #if HAVE_FAST_64BIT
     for (i = 0; i + 1 < length; i += 9) {
         if (!((~AV_RN64A(src + i) &
                (AV_RN64A(src + i) - 0x0100010001000101ULL)) &
               0x8000800080008080ULL))
             continue;
         FIND_FIRST_ZERO;
         STARTCODE_TEST;
         i -= 7;
     }
 #else
     for (i = 0; i + 1 < length; i += 5) {
         if (!((~AV_RN32A(src + i) &
                (AV_RN32A(src + i) - 0x01000101U)) &
               0x80008080U))
             continue;
         FIND_FIRST_ZERO;
         STARTCODE_TEST;
         i -= 3;
     }
 #endif /* HAVE_FAST_64BIT */
 #else
     for (i = 0; i + 1 < length; i += 2) {
         if (src[i])
             continue;
         if (i > 0 && src[i - 1] == 0)
             i--;
         STARTCODE_TEST;
     }
 #endif /* HAVE_FAST_UNALIGNED */
 

     if (i >= length - 1 && small_padding) { // no escaped 0

         nal->data     =
         nal->raw_data = src;
         nal->size     =
         nal->raw_size = length;
         return length;

     } else if (i > length)
         i = length;

     av_fast_padded_malloc(&nal->rbsp_buffer, &nal->rbsp_buffer_size,
                           length + padding);

     if (!nal->rbsp_buffer)
         return AVERROR(ENOMEM);
 
     dst = nal->rbsp_buffer;
 
     memcpy(dst, src, i);
     si = di = i;
     while (si + 2 < length) {
         // remove escapes (very rare 1:2^22)
         if (src[si + 2] > 3) {
             dst[di++] = src[si++];
             dst[di++] = src[si++];

         } else if (src[si] == 0 && src[si + 1] == 0 && src[si + 2] != 0) {

             if (src[si + 2] == 3) { // escape
                 dst[di++] = 0;
                 dst[di++] = 0;
                 si       += 3;
 

                 if (nal->skipped_bytes_pos) {

                     nal->skipped_bytes++;
                     if (nal->skipped_bytes_pos_size < nal->skipped_bytes) {
                         nal->skipped_bytes_pos_size *= 2;
                         av_assert0(nal->skipped_bytes_pos_size >= nal->skipped_bytes);
                         av_reallocp_array(&nal->skipped_bytes_pos,
                                 nal->skipped_bytes_pos_size,
                                 sizeof(*nal->skipped_bytes_pos));
                         if (!nal->skipped_bytes_pos) {
                             nal->skipped_bytes_pos_size = 0;
                             return AVERROR(ENOMEM);

                         }

                     }
                     if (nal->skipped_bytes_pos)
                         nal->skipped_bytes_pos[nal->skipped_bytes-1] = di - 1;

                 }

                 continue;
             } else // next start code
                 goto nsc;
         }
 
         dst[di++] = src[si++];
     }
     while (si < length)
         dst[di++] = src[si++];
 
 nsc:

     memset(dst + di, 0, AV_INPUT_BUFFER_PADDING_SIZE);

 
     nal->data = dst;
     nal->size = di;
     nal->raw_data = src;
     nal->raw_size = si;
     return si;
 }

 static const char *nal_unit_name(int nal_type)
 {
     switch(nal_type) {

     case HEVC_NAL_TRAIL_N    : return "TRAIL_N";
     case HEVC_NAL_TRAIL_R    : return "TRAIL_R";
     case HEVC_NAL_TSA_N      : return "TSA_N";
     case HEVC_NAL_TSA_R      : return "TSA_R";
     case HEVC_NAL_STSA_N     : return "STSA_N";
     case HEVC_NAL_STSA_R     : return "STSA_R";
     case HEVC_NAL_RADL_N     : return "RADL_N";
     case HEVC_NAL_RADL_R     : return "RADL_R";
     case HEVC_NAL_RASL_N     : return "RASL_N";
     case HEVC_NAL_RASL_R     : return "RASL_R";
     case HEVC_NAL_BLA_W_LP   : return "BLA_W_LP";
     case HEVC_NAL_BLA_W_RADL : return "BLA_W_RADL";
     case HEVC_NAL_BLA_N_LP   : return "BLA_N_LP";
     case HEVC_NAL_IDR_W_RADL : return "IDR_W_RADL";
     case HEVC_NAL_IDR_N_LP   : return "IDR_N_LP";
     case HEVC_NAL_CRA_NUT    : return "CRA_NUT";
     case HEVC_NAL_VPS        : return "VPS";
     case HEVC_NAL_SPS        : return "SPS";
     case HEVC_NAL_PPS        : return "PPS";
     case HEVC_NAL_AUD        : return "AUD";
     case HEVC_NAL_EOS_NUT    : return "EOS_NUT";
     case HEVC_NAL_EOB_NUT    : return "EOB_NUT";
     case HEVC_NAL_FD_NUT     : return "FD_NUT";
     case HEVC_NAL_SEI_PREFIX : return "SEI_PREFIX";
     case HEVC_NAL_SEI_SUFFIX : return "SEI_SUFFIX";

     default : return "?";
     }
 }
 

 static int get_bit_length(H2645NAL *nal, int skip_trailing_zeros)
 {
     int size = nal->size;
     int v;
 
     while (skip_trailing_zeros && size > 0 && nal->data[size - 1] == 0)
         size--;
 
     if (!size)
         return 0;
 
     v = nal->data[size - 1];
 
     if (size > INT_MAX / 8)
         return AVERROR(ERANGE);
     size *= 8;
 
     /* remove the stop bit and following trailing zeros,
      * or nothing for damaged bitstreams */
     if (v)

         size -= ff_ctz(v) + 1;

 
     return size;
 }
 

 /**
  * @return AVERROR_INVALIDDATA if the packet is not a valid NAL unit,
  * 0 if the unit should be skipped, 1 otherwise
  */

 static int hevc_parse_nal_header(H2645NAL *nal, void *logctx)

 {
     GetBitContext *gb = &nal->gb;
     int nuh_layer_id;
 
     if (get_bits1(gb) != 0)
         return AVERROR_INVALIDDATA;
 
     nal->type = get_bits(gb, 6);
 
     nuh_layer_id   = get_bits(gb, 6);
     nal->temporal_id = get_bits(gb, 3) - 1;
     if (nal->temporal_id < 0)
         return AVERROR_INVALIDDATA;
 

     av_log(logctx, AV_LOG_DEBUG,

            "nal_unit_type: %d(%s), nuh_layer_id: %d, temporal_id: %d\n",
            nal->type, nal_unit_name(nal->type), nuh_layer_id, nal->temporal_id);

 
     return nuh_layer_id == 0;
 }
 

 static int h264_parse_nal_header(H2645NAL *nal, void *logctx)
 {
     GetBitContext *gb = &nal->gb;
 
     if (get_bits1(gb) != 0)
         return AVERROR_INVALIDDATA;
 
     nal->ref_idc = get_bits(gb, 2);
     nal->type    = get_bits(gb, 5);
 
     av_log(logctx, AV_LOG_DEBUG,
            "nal_unit_type: %d, nal_ref_idc: %d\n",
            nal->type, nal->ref_idc);
 
     return 1;
 }

 int ff_h2645_packet_split(H2645Packet *pkt, const uint8_t *buf, int length,

                           void *logctx, int is_nalff, int nal_length_size,

                           enum AVCodecID codec_id, int small_padding)

 {
     int consumed, ret = 0;

     const uint8_t *next_avc = is_nalff ? buf : buf + length;

 
     pkt->nb_nals = 0;
     while (length >= 4) {

         H2645NAL *nal;

         int extract_length = 0;

         int skip_trailing_zeros = 1;

         if (buf == next_avc) {

             int i = 0;
             extract_length = get_nalsize(nal_length_size,
                                          buf, length, &i, logctx);
             if (extract_length < 0)
                 return extract_length;
 

             buf    += nal_length_size;
             length -= nal_length_size;
 

             next_avc = buf + extract_length;

         } else {

             if (buf > next_avc)
                 av_log(logctx, AV_LOG_WARNING, "Exceeded next NALFF position, re-syncing.\n");
 

             /* search start code */
             while (buf[0] != 0 || buf[1] != 0 || buf[2] != 1) {
                 ++buf;
                 --length;
                 if (length < 4) {

                     if (pkt->nb_nals > 0) {
                         // No more start codes: we discarded some irrelevant
                         // bytes at the end of the packet.
                         return 0;
                     } else {

                         av_log(logctx, AV_LOG_ERROR, "No start code is found.\n");

                         return AVERROR_INVALIDDATA;
                     }

                 } else if (buf >= (next_avc - 3))
                     break;

             }
 
             buf           += 3;
             length        -= 3;

             extract_length = FFMIN(length, next_avc - buf);

 
             if (buf >= next_avc) {
                 /* skip to the start of the next NAL */
                 int offset = next_avc - buf;
                 buf    += offset;
                 length -= offset;
                 continue;
             }

         }
 
         if (pkt->nals_allocated < pkt->nb_nals + 1) {
             int new_size = pkt->nals_allocated + 1;

             void *tmp = av_realloc_array(pkt->nals, new_size, sizeof(*pkt->nals));
 

             if (!tmp)
                 return AVERROR(ENOMEM);
 
             pkt->nals = tmp;
             memset(pkt->nals + pkt->nals_allocated, 0,

                    (new_size - pkt->nals_allocated) * sizeof(*pkt->nals));
 

             nal = &pkt->nals[pkt->nb_nals];

             nal->skipped_bytes_pos_size = 1024; // initial buffer size
             nal->skipped_bytes_pos = av_malloc_array(nal->skipped_bytes_pos_size, sizeof(*nal->skipped_bytes_pos));
             if (!nal->skipped_bytes_pos)

                 return AVERROR(ENOMEM);
 

             pkt->nals_allocated = new_size;
         }

         nal = &pkt->nals[pkt->nb_nals];

         consumed = ff_h2645_extract_rbsp(buf, extract_length, nal, small_padding);

         if (consumed < 0)
             return consumed;
 

         if (is_nalff && (extract_length != consumed) && extract_length)
             av_log(logctx, AV_LOG_DEBUG,
                    "NALFF: Consumed only %d bytes instead of %d\n",
                    consumed, extract_length);
 

         pkt->nb_nals++;

         /* see commit 3566042a0 */
         if (consumed < length - 3 &&
             buf[consumed]     == 0x00 && buf[consumed + 1] == 0x00 &&
             buf[consumed + 2] == 0x01 && buf[consumed + 3] == 0xE0)
             skip_trailing_zeros = 0;
 
         nal->size_bits = get_bit_length(nal, skip_trailing_zeros);
 

         ret = init_get_bits(&nal->gb, nal->data, nal->size_bits);

         if (ret < 0)
             return ret;
 

         if (codec_id == AV_CODEC_ID_HEVC)
             ret = hevc_parse_nal_header(nal, logctx);
         else
             ret = h264_parse_nal_header(nal, logctx);

         if (ret <= 0 || nal->size <= 0) {

             if (ret < 0) {

                 av_log(logctx, AV_LOG_ERROR, "Invalid NAL unit %d, skipping.\n",

                        nal->type);
             }
             pkt->nb_nals--;
         }
 
         buf    += consumed;
         length -= consumed;
     }
 
     return 0;
 }

 void ff_h2645_packet_uninit(H2645Packet *pkt)
 {
     int i;

     for (i = 0; i < pkt->nals_allocated; i++) {

         av_freep(&pkt->nals[i].rbsp_buffer);

         av_freep(&pkt->nals[i].skipped_bytes_pos);
     }

     av_freep(&pkt->nals);
     pkt->nals_allocated = 0;
 }