/*
  * HEVC Annex B format parser
  *
  * Copyright (C) 2012 - 2013 Guillaume Martres
  *
  * 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 "libavutil/common.h"

 #include "parser.h"
 #include "hevc.h"

 #include "golomb.h"

 
 #define START_CODE 0x000001 ///< start_code_prefix_one_3bytes
 

 typedef struct HEVCParseContext {
     HEVCContext  h;
     ParseContext pc;
 } HEVCParseContext;
 

 /**
  * Find the end of the current frame in the bitstream.
  * @return the position of the first byte of the next frame, or END_NOT_FOUND
  */

 static int hevc_find_frame_end(AVCodecParserContext *s, const uint8_t *buf,
                                int buf_size)

 {
     int i;

     ParseContext *pc = &((HEVCParseContext *)s->priv_data)->pc;

 
     for (i = 0; i < buf_size; i++) {
         int nut;
 
         pc->state64 = (pc->state64 << 8) | buf[i];
 
         if (((pc->state64 >> 3 * 8) & 0xFFFFFF) != START_CODE)
             continue;
 
         nut = (pc->state64 >> 2 * 8 + 1) & 0x3F;
         // Beginning of access unit
         if ((nut >= NAL_VPS && nut <= NAL_AUD) || nut == NAL_SEI_PREFIX ||
             (nut >= 41 && nut <= 44) || (nut >= 48 && nut <= 55)) {
             if (pc->frame_start_found) {
                 pc->frame_start_found = 0;
                 return i - 5;
             }
         } else if (nut <= NAL_RASL_R ||
                    (nut >= NAL_BLA_W_LP && nut <= NAL_CRA_NUT)) {
             int first_slice_segment_in_pic_flag = buf[i] >> 7;
             if (first_slice_segment_in_pic_flag) {
                 if (!pc->frame_start_found) {
                     pc->frame_start_found = 1;
                 } else { // First slice of next frame found
                     pc->frame_start_found = 0;
                     return i - 5;
                 }
             }
         }
     }
 
     return END_NOT_FOUND;
 }
 

 /**
  * Parse NAL units of found picture and decode some basic information.
  *
  * @param s parser context.
  * @param avctx codec context.
  * @param buf buffer with field/frame data.
  * @param buf_size size of the buffer.
  */

 static inline int parse_nal_units(AVCodecParserContext *s, AVCodecContext *avctx,
                       const uint8_t *buf, int buf_size)

 {
     HEVCContext   *h  = &((HEVCParseContext *)s->priv_data)->h;
     GetBitContext *gb = &h->HEVClc->gb;
     SliceHeader   *sh = &h->sh;
     const uint8_t *buf_end = buf + buf_size;
     int state = -1, i;
     HEVCNAL *nal;
 
     /* set some sane default values */
     s->pict_type         = AV_PICTURE_TYPE_I;
     s->key_frame         = 0;
     s->picture_structure = AV_PICTURE_STRUCTURE_UNKNOWN;
 
     h->avctx = avctx;
 
     if (!buf_size)
         return 0;
 
     if (h->nals_allocated < 1) {
         HEVCNAL *tmp = av_realloc_array(h->nals, 1, sizeof(*tmp));
         if (!tmp)
             return AVERROR(ENOMEM);
         h->nals = tmp;
         memset(h->nals, 0, sizeof(*tmp));
         h->nals_allocated = 1;
     }
 
     nal = &h->nals[0];
 
     for (;;) {
         int src_length, consumed;
         buf = avpriv_find_start_code(buf, buf_end, &state);
         if (--buf + 2 >= buf_end)
             break;
         src_length = buf_end - buf;
 
         h->nal_unit_type = (*buf >> 1) & 0x3f;
         h->temporal_id   = (*(buf + 1) & 0x07) - 1;
         if (h->nal_unit_type <= NAL_CRA_NUT) {
             // Do not walk the whole buffer just to decode slice segment header
             if (src_length > 20)
                 src_length = 20;
         }
 
         consumed = ff_hevc_extract_rbsp(h, buf, src_length, nal);
         if (consumed < 0)
             return consumed;
 
         init_get_bits8(gb, nal->data + 2, nal->size);
         switch (h->nal_unit_type) {
         case NAL_VPS:
             ff_hevc_decode_nal_vps(h);
             break;
         case NAL_SPS:
             ff_hevc_decode_nal_sps(h);
             break;
         case NAL_PPS:
             ff_hevc_decode_nal_pps(h);
             break;
         case NAL_SEI_PREFIX:
         case NAL_SEI_SUFFIX:
             ff_hevc_decode_nal_sei(h);
             break;
         case NAL_TRAIL_N:
         case NAL_TRAIL_R:
         case NAL_TSA_N:
         case NAL_TSA_R:
         case NAL_STSA_N:
         case NAL_STSA_R:
         case NAL_RADL_N:
         case NAL_RADL_R:
         case NAL_RASL_N:
         case NAL_RASL_R:
         case NAL_BLA_W_LP:
         case NAL_BLA_W_RADL:
         case NAL_BLA_N_LP:
         case NAL_IDR_W_RADL:
         case NAL_IDR_N_LP:
         case NAL_CRA_NUT:
             sh->first_slice_in_pic_flag = get_bits1(gb);

             s->picture_structure = h->picture_struct;
             s->field_order = h->picture_struct;

             if (IS_IRAP(h)) {

                 s->key_frame = 1;
                 sh->no_output_of_prior_pics_flag = get_bits1(gb);
             }
 
             sh->pps_id = get_ue_golomb(gb);
             if (sh->pps_id >= MAX_PPS_COUNT || !h->pps_list[sh->pps_id]) {
                 av_log(h->avctx, AV_LOG_ERROR, "PPS id out of range: %d\n", sh->pps_id);
                 return AVERROR_INVALIDDATA;
             }
             h->pps = (HEVCPPS*)h->pps_list[sh->pps_id]->data;
 
             if (h->pps->sps_id >= MAX_SPS_COUNT || !h->sps_list[h->pps->sps_id]) {
                 av_log(h->avctx, AV_LOG_ERROR, "SPS id out of range: %d\n", h->pps->sps_id);
                 return AVERROR_INVALIDDATA;
             }
             if (h->sps != (HEVCSPS*)h->sps_list[h->pps->sps_id]->data) {
                 h->sps = (HEVCSPS*)h->sps_list[h->pps->sps_id]->data;

                 h->vps = (HEVCVPS*)h->vps_list[h->sps->vps_id]->data;

             }
 
             if (!sh->first_slice_in_pic_flag) {
                 int slice_address_length;
 
                 if (h->pps->dependent_slice_segments_enabled_flag)
                     sh->dependent_slice_segment_flag = get_bits1(gb);
                 else
                     sh->dependent_slice_segment_flag = 0;
 
                 slice_address_length = av_ceil_log2_c(h->sps->ctb_width *
                                                       h->sps->ctb_height);
                 sh->slice_segment_addr = get_bits(gb, slice_address_length);
                 if (sh->slice_segment_addr >= h->sps->ctb_width * h->sps->ctb_height) {
                     av_log(h->avctx, AV_LOG_ERROR, "Invalid slice segment address: %u.\n",
                            sh->slice_segment_addr);
                     return AVERROR_INVALIDDATA;
                 }
             } else
                 sh->dependent_slice_segment_flag = 0;
 
             if (sh->dependent_slice_segment_flag)
                 break;
 
             for (i = 0; i < h->pps->num_extra_slice_header_bits; i++)
                 skip_bits(gb, 1); // slice_reserved_undetermined_flag[]
 
             sh->slice_type = get_ue_golomb(gb);
             if (!(sh->slice_type == I_SLICE || sh->slice_type == P_SLICE ||
                   sh->slice_type == B_SLICE)) {
                 av_log(h->avctx, AV_LOG_ERROR, "Unknown slice type: %d.\n",
                        sh->slice_type);
                 return AVERROR_INVALIDDATA;
             }
             s->pict_type = sh->slice_type == B_SLICE ? AV_PICTURE_TYPE_B :
                            sh->slice_type == P_SLICE ? AV_PICTURE_TYPE_P :
                                                        AV_PICTURE_TYPE_I;
 
             if (h->pps->output_flag_present_flag)
                 sh->pic_output_flag = get_bits1(gb);
 
             if (h->sps->separate_colour_plane_flag)
                 sh->colour_plane_id = get_bits(gb, 2);
 
             if (!IS_IDR(h)) {
                 sh->pic_order_cnt_lsb = get_bits(gb, h->sps->log2_max_poc_lsb);
                 s->output_picture_number = h->poc = ff_hevc_compute_poc(h, sh->pic_order_cnt_lsb);
             } else
                 s->output_picture_number = h->poc = 0;
 
             if (h->temporal_id == 0 &&
                 h->nal_unit_type != NAL_TRAIL_N &&
                 h->nal_unit_type != NAL_TSA_N &&
                 h->nal_unit_type != NAL_STSA_N &&
                 h->nal_unit_type != NAL_RADL_N &&
                 h->nal_unit_type != NAL_RASL_N &&
                 h->nal_unit_type != NAL_RADL_R &&
                 h->nal_unit_type != NAL_RASL_R)
                 h->pocTid0 = h->poc;
 
             return 0; /* no need to evaluate the rest */
         }
         buf += consumed;
     }
     /* didn't find a picture! */
     av_log(h->avctx, AV_LOG_ERROR, "missing picture in access unit\n");
     return -1;
 }
 

 static int hevc_parse(AVCodecParserContext *s,
                       AVCodecContext *avctx,
                       const uint8_t **poutbuf, int *poutbuf_size,
                       const uint8_t *buf, int buf_size)
 {
     int next;

     ParseContext *pc = &((HEVCParseContext *)s->priv_data)->pc;

 
     if (s->flags & PARSER_FLAG_COMPLETE_FRAMES) {
         next = buf_size;
     } else {
         next = hevc_find_frame_end(s, buf, buf_size);
         if (ff_combine_frame(pc, next, &buf, &buf_size) < 0) {

             *poutbuf      = NULL;

             *poutbuf_size = 0;
             return buf_size;
         }
     }
 

     parse_nal_units(s, avctx, buf, buf_size);
 

     *poutbuf      = buf;

     *poutbuf_size = buf_size;
     return next;
 }
 
 // Split after the parameter sets at the beginning of the stream if they exist.
 static int hevc_split(AVCodecContext *avctx, const uint8_t *buf, int buf_size)
 {

     const uint8_t *ptr = buf, *end = buf + buf_size;

     uint32_t state = -1;

     int has_ps = 0, nut;

     while (ptr < end) {
         ptr = avpriv_find_start_code(ptr, end, &state);
         if ((state >> 8) != START_CODE)
             break;
         nut = (state >> 1) & 0x3F;
         if (nut >= NAL_VPS && nut <= NAL_PPS)
             has_ps = 1;
         else if (has_ps)
             return ptr - 4 - buf;
         else // no parameter set at the beginning of the stream
             return 0;

     }
     return 0;
 }
 

 static int hevc_init(AVCodecParserContext *s)
 {
     HEVCContext  *h  = &((HEVCParseContext *)s->priv_data)->h;
     h->HEVClc = av_mallocz(sizeof(HEVCLocalContext));

     if (!h->HEVClc)
         return AVERROR(ENOMEM);

     h->skipped_bytes_pos_size = INT_MAX;
 
     return 0;
 }
 
 static void hevc_close(AVCodecParserContext *s)
 {
     int i;
     HEVCContext  *h  = &((HEVCParseContext *)s->priv_data)->h;
     ParseContext *pc = &((HEVCParseContext *)s->priv_data)->pc;
 
     av_freep(&h->skipped_bytes_pos);
     av_freep(&h->HEVClc);
     av_freep(&pc->buffer);
 
     for (i = 0; i < FF_ARRAY_ELEMS(h->vps_list); i++)

         av_buffer_unref(&h->vps_list[i]);

     for (i = 0; i < FF_ARRAY_ELEMS(h->sps_list); i++)
         av_buffer_unref(&h->sps_list[i]);
     for (i = 0; i < FF_ARRAY_ELEMS(h->pps_list); i++)
         av_buffer_unref(&h->pps_list[i]);
 

     h->sps = NULL;
 

     for (i = 0; i < h->nals_allocated; i++)
         av_freep(&h->nals[i].rbsp_buffer);
     av_freep(&h->nals);
     h->nals_allocated = 0;
 }
 

 AVCodecParser ff_hevc_parser = {
     .codec_ids      = { AV_CODEC_ID_HEVC },

     .priv_data_size = sizeof(HEVCParseContext),
     .parser_init    = hevc_init,

     .parser_parse   = hevc_parse,

     .parser_close   = hevc_close,

     .split          = hevc_split,
 };