/*
  * H.26L/H.264/AVC/JVT/14496-10/... parser
  * Copyright (c) 2003 Michael Niedermayer <michaelni@gmx.at>
  *
  * 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
  */
 
 /**

  * @file

  * H.264 / AVC / MPEG4 part10 parser.
  * @author Michael Niedermayer <michaelni@gmx.at>
  */
 

 #define UNCHECKED_BITSTREAM_READER 1
 

 #include "parser.h"

 #include "h264data.h"
 #include "golomb.h"

 
 #include <assert.h>
 
 

 static int ff_h264_find_frame_end(H264Context *h, const uint8_t *buf, int buf_size)

 {

     int i, j;

     uint32_t state;
     ParseContext *pc = &(h->s.parse_context);

     int next_avc= h->is_avc ? 0 : buf_size;
 

 //printf("first %02X%02X%02X%02X\n", buf[0], buf[1],buf[2],buf[3]);
 //    mb_addr= pc->mb_addr - 1;
     state= pc->state;
     if(state>13)
         state= 7;
 

     if(h->is_avc && !h->nal_length_size)
         av_log(h->s.avctx, AV_LOG_ERROR, "AVC-parser: nal length size invalid\n");
 

     for(i=0; i<buf_size; i++){

         if(i >= next_avc) {
             int nalsize = 0;
             i = next_avc;
             for(j = 0; j < h->nal_length_size; j++)
                 nalsize = (nalsize << 8) | buf[i++];
             if(nalsize <= 0 || nalsize > buf_size - i){
                 av_log(h->s.avctx, AV_LOG_ERROR, "AVC-parser: nal size %d remaining %d\n", nalsize, buf_size - i);
                 return buf_size;
             }
             next_avc= i + nalsize;
             state= 5;
         }
 

         if(state==7){

 #if HAVE_FAST_UNALIGNED

         /* we check i<buf_size instead of i+3/7 because its simpler
          * and there should be FF_INPUT_BUFFER_PADDING_SIZE bytes at the end
          */

 #    if HAVE_FAST_64BIT

             while(i<next_avc && !((~*(const uint64_t*)(buf+i) & (*(const uint64_t*)(buf+i) - 0x0101010101010101ULL)) & 0x8080808080808080ULL))

                 i+=8;
 #    else

             while(i<next_avc && !((~*(const uint32_t*)(buf+i) & (*(const uint32_t*)(buf+i) - 0x01010101U)) & 0x80808080U))

                 i+=4;
 #    endif
 #endif

             for(; i<next_avc; i++){

                 if(!buf[i]){
                     state=2;
                     break;
                 }
             }
         }else if(state<=2){
             if(buf[i]==1)   state^= 5; //2->7, 1->4, 0->5
             else if(buf[i]) state = 7;
             else            state>>=1; //2->1, 1->0, 0->0
         }else if(state<=5){
             int v= buf[i] & 0x1F;

             if(v==6 || v==7 || v==8 || v==9){

                 if(pc->frame_start_found){
                     i++;

                     goto found;

                 }
             }else if(v==1 || v==2 || v==5){

                 state+=8;
                 continue;
             }
             state= 7;
         }else{
             h->parse_history[h->parse_history_count++]= buf[i];
             if(h->parse_history_count>3){
                 unsigned int mb, last_mb= h->parse_last_mb;
                 GetBitContext gb;
 
                 init_get_bits(&gb, h->parse_history, 8*h->parse_history_count);
                 h->parse_history_count=0;
                 mb= get_ue_golomb_long(&gb);
                 last_mb= h->parse_last_mb;
                 h->parse_last_mb= mb;

                 if(pc->frame_start_found){

                     if(mb <= last_mb)
                         goto found;

                 }else
                     pc->frame_start_found = 1;

                 state= 7;

             }
         }
     }
     pc->state= state;

     if(h->is_avc)
         return next_avc;

     return END_NOT_FOUND;

 
 found:
     pc->state=7;
     pc->frame_start_found= 0;

     if(h->is_avc)
         return next_avc;

     return i-(state&5) - 3*(state>7);

 }
 

 /**

  * 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)
 {
     H264Context *h = s->priv_data;
     const uint8_t *buf_end = buf + buf_size;

     unsigned int pps_id;

     unsigned int slice_type;

     int state = -1;

     const uint8_t *ptr;

     int q264 = buf_size >=4 && !memcmp("Q264", buf, 4);

 
     /* set some sane default values */

     s->pict_type = AV_PICTURE_TYPE_I;

     s->key_frame = 0;

 
     h->s.avctx= avctx;

     h->sei_recovery_frame_cnt = -1;

     h->sei_dpb_output_delay         =  0;
     h->sei_cpb_removal_delay        = -1;
     h->sei_buffering_period_present =  0;

     if (!buf_size)
         return 0;
 

     for(;;) {
         int src_length, dst_length, consumed;

         buf = avpriv_mpv_find_start_code(buf, buf_end, &state);

         if(buf >= buf_end)
             break;
         --buf;
         src_length = buf_end - buf;
         switch (state & 0x1f) {
         case NAL_SLICE:
         case NAL_IDR_SLICE:
             // Do not walk the whole buffer just to decode slice header
             if (src_length > 20)
                 src_length = 20;
             break;
         }
         ptr= ff_h264_decode_nal(h, buf, &dst_length, &consumed, src_length);
         if (ptr==NULL || dst_length < 0)
             break;
 
         init_get_bits(&h->s.gb, ptr, 8*dst_length);
         switch(h->nal_unit_type) {
         case NAL_SPS:
             ff_h264_decode_seq_parameter_set(h);
             break;
         case NAL_PPS:
             ff_h264_decode_picture_parameter_set(h, h->s.gb.size_in_bits);
             break;
         case NAL_SEI:
             ff_h264_decode_sei(h);
             break;
         case NAL_IDR_SLICE:

             s->key_frame = 1;
             /* fall through */

         case NAL_SLICE:

             get_ue_golomb_long(&h->s.gb);  // skip first_mb_in_slice

             slice_type = get_ue_golomb_31(&h->s.gb);
             s->pict_type = golomb_to_pict_type[slice_type % 5];

             if (h->sei_recovery_frame_cnt >= 0) {
                 /* key frame, since recovery_frame_cnt is set */
                 s->key_frame = 1;
             }

             pps_id= get_ue_golomb(&h->s.gb);
             if(pps_id>=MAX_PPS_COUNT) {
                 av_log(h->s.avctx, AV_LOG_ERROR, "pps_id out of range\n");
                 return -1;
             }
             if(!h->pps_buffers[pps_id]) {
                 av_log(h->s.avctx, AV_LOG_ERROR, "non-existing PPS referenced\n");
                 return -1;
             }
             h->pps= *h->pps_buffers[pps_id];
             if(!h->sps_buffers[h->pps.sps_id]) {
                 av_log(h->s.avctx, AV_LOG_ERROR, "non-existing SPS referenced\n");
                 return -1;
             }
             h->sps = *h->sps_buffers[h->pps.sps_id];
             h->frame_num = get_bits(&h->s.gb, h->sps.log2_max_frame_num);
 

             avctx->profile = ff_h264_get_profile(&h->sps);

             avctx->level   = h->sps.level_idc;
 

             if(h->sps.frame_mbs_only_flag){
                 h->s.picture_structure= PICT_FRAME;
             }else{
                 if(get_bits1(&h->s.gb)) { //field_pic_flag
                     h->s.picture_structure= PICT_TOP_FIELD + get_bits1(&h->s.gb); //bottom_field_flag
                 } else {
                     h->s.picture_structure= PICT_FRAME;
                 }
             }
 

             if(h->sps.pic_struct_present_flag) {
                 switch (h->sei_pic_struct) {
                     case SEI_PIC_STRUCT_TOP_FIELD:
                     case SEI_PIC_STRUCT_BOTTOM_FIELD:

                         s->repeat_pict = 0;

                         break;
                     case SEI_PIC_STRUCT_FRAME:
                     case SEI_PIC_STRUCT_TOP_BOTTOM:
                     case SEI_PIC_STRUCT_BOTTOM_TOP:

                         s->repeat_pict = 1;

                         break;
                     case SEI_PIC_STRUCT_TOP_BOTTOM_TOP:
                     case SEI_PIC_STRUCT_BOTTOM_TOP_BOTTOM:

                         s->repeat_pict = 2;

                         break;
                     case SEI_PIC_STRUCT_FRAME_DOUBLING:

                         s->repeat_pict = 3;

                         break;
                     case SEI_PIC_STRUCT_FRAME_TRIPLING:

                         s->repeat_pict = 5;

                         break;
                     default:

                         s->repeat_pict = h->s.picture_structure == PICT_FRAME ? 1 : 0;

                         break;
                 }
             } else {

                 s->repeat_pict = h->s.picture_structure == PICT_FRAME ? 1 : 0;

             }
 

             return 0; /* no need to evaluate the rest */
         }
         buf += consumed;
     }

     if (q264)
         return 0;

     /* didn't find a picture! */

     av_log(h->s.avctx, AV_LOG_ERROR, "missing picture in access unit with size %d\n", buf_size);

     return -1;
 }
 

 static int h264_parse(AVCodecParserContext *s,
                       AVCodecContext *avctx,
                       const uint8_t **poutbuf, int *poutbuf_size,
                       const uint8_t *buf, int buf_size)
 {
     H264Context *h = s->priv_data;
     ParseContext *pc = &h->s.parse_context;
     int next;
 

     if (!h->got_first) {
         h->got_first = 1;

         if (avctx->extradata_size) {
             h->s.avctx = avctx;

             // must be done like in decoder, otherwise opening the parser,
             // letting it create extradata and then closing and opening again
             // will cause has_b_frames to be always set.
             // Note that estimate_timings_from_pts does exactly this.
             if (!avctx->has_b_frames)
                 h->s.low_delay = 1;

             ff_h264_decode_extradata(h, avctx->extradata, avctx->extradata_size);

         }
     }
 

     if(s->flags & PARSER_FLAG_COMPLETE_FRAMES){
         next= buf_size;
     }else{
         next= ff_h264_find_frame_end(h, buf, buf_size);
 
         if (ff_combine_frame(pc, next, &buf, &buf_size) < 0) {
             *poutbuf = NULL;
             *poutbuf_size = 0;
             return buf_size;
         }
 
         if(next<0 && next != END_NOT_FOUND){
             assert(pc->last_index + next >= 0 );
             ff_h264_find_frame_end(h, &pc->buffer[pc->last_index + next], -next); //update state
         }

     }

     if(!h->is_avc){

     parse_nal_units(s, avctx, buf, buf_size);

     if (h->sei_cpb_removal_delay >= 0) {
         s->dts_sync_point    = h->sei_buffering_period_present;
         s->dts_ref_dts_delta = h->sei_cpb_removal_delay;
         s->pts_dts_delta     = h->sei_dpb_output_delay;
     } else {
         s->dts_sync_point    = INT_MIN;
         s->dts_ref_dts_delta = INT_MIN;
         s->pts_dts_delta     = INT_MIN;
     }

     if (s->flags & PARSER_FLAG_ONCE) {
         s->flags &= PARSER_FLAG_COMPLETE_FRAMES;
     }

     }

 
     *poutbuf = buf;
     *poutbuf_size = buf_size;
     return next;
 }
 
 static int h264_split(AVCodecContext *avctx,
                       const uint8_t *buf, int buf_size)
 {
     int i;
     uint32_t state = -1;
     int has_sps= 0;
 
     for(i=0; i<=buf_size; i++){
         if((state&0xFFFFFF1F) == 0x107)
             has_sps=1;
 /*        if((state&0xFFFFFF1F) == 0x101 || (state&0xFFFFFF1F) == 0x102 || (state&0xFFFFFF1F) == 0x105){
         }*/
         if((state&0xFFFFFF00) == 0x100 && (state&0xFFFFFF1F) != 0x107 && (state&0xFFFFFF1F) != 0x108 && (state&0xFFFFFF1F) != 0x109){
             if(has_sps){
                 while(i>4 && buf[i-5]==0) i--;
                 return i-4;
             }
         }
         if (i<buf_size)
             state= (state<<8) | buf[i];
     }
     return 0;
 }
 

 static void close(AVCodecParserContext *s)

 {
     H264Context *h = s->priv_data;
     ParseContext *pc = &h->s.parse_context;
 
     av_free(pc->buffer);

     ff_h264_free_context(h);

 }
 

 static int init(AVCodecParserContext *s)
 {
     H264Context *h = s->priv_data;
     h->thread_context[0] = h;
     return 0;
 }

 AVCodecParser ff_h264_parser = {

     .codec_ids      = { CODEC_ID_H264 },
     .priv_data_size = sizeof(H264Context),
     .parser_init    = init,
     .parser_parse   = h264_parse,
     .parser_close   = close,
     .split          = h264_split,

 };