/*
  * Electronic Arts Madcow Video Decoder
  * Copyright (c) 2007-2009 Peter Ross
  *
  * 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 St, Fifth Floor, Boston, MA  02110-1301  USA
  */
 
 /**

  * @file

  * Electronic Arts Madcow Video Decoder
  * by Peter Ross <pross@xvid.org>
  *
  * Technical details here:
  * http://wiki.multimedia.cx/index.php?title=Electronic_Arts_MAD
  */
 
 #include "avcodec.h"
 #include "get_bits.h"
 #include "dsputil.h"
 #include "aandcttab.h"
 #include "mpeg12.h"
 #include "mpeg12data.h"

 #include "libavutil/imgutils.h"

 
 #define EA_PREAMBLE_SIZE    8
 #define MADk_TAG MKTAG('M', 'A', 'D', 'k')    /* MAD i-frame */
 #define MADm_TAG MKTAG('M', 'A', 'D', 'm')    /* MAD p-frame */
 #define MADe_TAG MKTAG('M', 'A', 'D', 'e')    /* MAD lqp-frame */
 
 typedef struct MadContext {
     MpegEncContext s;
     AVFrame frame;
     AVFrame last_frame;
     void *bitstream_buf;
     unsigned int bitstream_buf_size;

     DECLARE_ALIGNED(16, DCTELEM, block)[64];

 } MadContext;
 
 static void bswap16_buf(uint16_t *dst, const uint16_t *src, int count)
 {
     int i;
     for (i=0; i<count; i++)

         dst[i] = av_bswap16(src[i]);

 }
 
 static av_cold int decode_init(AVCodecContext *avctx)
 {
     MadContext *t = avctx->priv_data;
     MpegEncContext *s = &t->s;
     s->avctx = avctx;
     avctx->pix_fmt = PIX_FMT_YUV420P;
     if (avctx->idct_algo == FF_IDCT_AUTO)
         avctx->idct_algo = FF_IDCT_EA;
     dsputil_init(&s->dsp, avctx);
     ff_init_scantable(s->dsp.idct_permutation, &s->intra_scantable, ff_zigzag_direct);
     ff_mpeg12_init_vlcs();
     return 0;
 }
 
 static inline void comp(unsigned char *dst, int dst_stride,
                         unsigned char *src, int src_stride, int add)
 {
     int j, i;
     for (j=0; j<8; j++)
         for (i=0; i<8; i++)
             dst[j*dst_stride + i] = av_clip_uint8(src[j*src_stride + i] + add);
 }
 
 static inline void comp_block(MadContext *t, int mb_x, int mb_y,
                               int j, int mv_x, int mv_y, int add)
 {
     MpegEncContext *s = &t->s;
     if (j < 4) {

         unsigned offset = (mb_y*16 + ((j&2)<<2) + mv_y)*t->last_frame.linesize[0] + mb_x*16 + ((j&1)<<3) + mv_x;
         if (offset >= (s->height - 7) * t->last_frame.linesize[0] - 7)
             return;

         comp(t->frame.data[0] + (mb_y*16 + ((j&2)<<2))*t->frame.linesize[0] + mb_x*16 + ((j&1)<<3),
              t->frame.linesize[0],

              t->last_frame.data[0] + offset,

              t->last_frame.linesize[0], add);
     } else if (!(s->avctx->flags & CODEC_FLAG_GRAY)) {
         int index = j - 3;

         unsigned offset = (mb_y * 8 + (mv_y/2))*t->last_frame.linesize[index] + mb_x * 8 + (mv_x/2);
         if (offset >= (s->height/2 - 7) * t->last_frame.linesize[index] - 7)
             return;

         comp(t->frame.data[index] + (mb_y*8)*t->frame.linesize[index] + mb_x * 8,
              t->frame.linesize[index],

              t->last_frame.data[index] + offset,

              t->last_frame.linesize[index], add);
     }
 }
 
 static inline void idct_put(MadContext *t, DCTELEM *block, int mb_x, int mb_y, int j)
 {
     MpegEncContext *s = &t->s;
     if (j < 4) {
         s->dsp.idct_put(
             t->frame.data[0] + (mb_y*16 + ((j&2)<<2))*t->frame.linesize[0] + mb_x*16 + ((j&1)<<3),
             t->frame.linesize[0], block);
     } else if (!(s->avctx->flags & CODEC_FLAG_GRAY)) {
         int index = j - 3;
         s->dsp.idct_put(
             t->frame.data[index] + (mb_y*8)*t->frame.linesize[index] + mb_x*8,
             t->frame.linesize[index], block);
     }
 }
 
 static inline void decode_block_intra(MadContext * t, DCTELEM * block)
 {
     MpegEncContext *s = &t->s;
     int level, i, j, run;
     RLTable *rl = &ff_rl_mpeg1;
     const uint8_t *scantable = s->intra_scantable.permutated;
     int16_t *quant_matrix = s->intra_matrix;
 
     block[0] = (128 + get_sbits(&s->gb, 8)) * quant_matrix[0];
 
     /* The RL decoder is derived from mpeg1_decode_block_intra;
        Escaped level and run values a decoded differently */

     i = 0;

     {
         OPEN_READER(re, &s->gb);
         /* now quantify & encode AC coefficients */
         for (;;) {
             UPDATE_CACHE(re, &s->gb);
             GET_RL_VLC(level, run, re, &s->gb, rl->rl_vlc[0], TEX_VLC_BITS, 2, 0);
 
             if (level == 127) {
                 break;
             } else if (level != 0) {
                 i += run;
                 j = scantable[i];
                 level = (level*quant_matrix[j]) >> 4;
                 level = (level-1)|1;
                 level = (level ^ SHOW_SBITS(re, &s->gb, 1)) - SHOW_SBITS(re, &s->gb, 1);
                 LAST_SKIP_BITS(re, &s->gb, 1);
             } else {
                 /* escape */
                 UPDATE_CACHE(re, &s->gb);
                 level = SHOW_SBITS(re, &s->gb, 10); SKIP_BITS(re, &s->gb, 10);
 
                 UPDATE_CACHE(re, &s->gb);
                 run = SHOW_UBITS(re, &s->gb, 6)+1; LAST_SKIP_BITS(re, &s->gb, 6);
 
                 i += run;
                 j = scantable[i];
                 if (level < 0) {
                     level = -level;
                     level = (level*quant_matrix[j]) >> 4;
                     level = (level-1)|1;
                     level = -level;
                 } else {
                     level = (level*quant_matrix[j]) >> 4;
                     level = (level-1)|1;
                 }
             }
             if (i > 63) {
                 av_log(s->avctx, AV_LOG_ERROR, "ac-tex damaged at %d %d\n", s->mb_x, s->mb_y);
                 return;
             }
 
             block[j] = level;
         }
         CLOSE_READER(re, &s->gb);
     }
 }
 
 static int decode_motion(GetBitContext *gb)
 {
     int value = 0;
     if (get_bits1(gb)) {
         if (get_bits1(gb))
             value = -17;
         value += get_bits(gb, 4) + 1;
     }
     return value;
 }
 
 static void decode_mb(MadContext *t, int inter)
 {
     MpegEncContext *s = &t->s;
     int mv_map = 0;
     int mv_x, mv_y;
     int j;
 
     if (inter) {
         int v = decode210(&s->gb);
         if (v < 2) {
             mv_map = v ? get_bits(&s->gb, 6) : 63;
             mv_x = decode_motion(&s->gb);
             mv_y = decode_motion(&s->gb);
         } else {
             mv_map = 0;
         }
     }
 
     for (j=0; j<6; j++) {
         if (mv_map & (1<<j)) {  // mv_x and mv_y are guarded by mv_map
             int add = 2*decode_motion(&s->gb);

             if (t->last_frame.data[0])
                 comp_block(t, s->mb_x, s->mb_y, j, mv_x, mv_y, add);

         } else {
             s->dsp.clear_block(t->block);
             decode_block_intra(t, t->block);
             idct_put(t, t->block, s->mb_x, s->mb_y, j);
         }
     }
 }
 
 static void calc_intra_matrix(MadContext *t, int qscale)
 {
     MpegEncContext *s = &t->s;
     int i;
 
     if (s->avctx->idct_algo == FF_IDCT_EA) {
         s->intra_matrix[0] = (ff_inv_aanscales[0]*ff_mpeg1_default_intra_matrix[0]) >> 11;
         for (i=1; i<64; i++)
             s->intra_matrix[i] = (ff_inv_aanscales[i]*ff_mpeg1_default_intra_matrix[i]*qscale + 32) >> 10;
     } else {
         s->intra_matrix[0] = ff_mpeg1_default_intra_matrix[0];
         for (i=1; i<64; i++)
             s->intra_matrix[i] = (ff_mpeg1_default_intra_matrix[i]*qscale) << 1;
     }
 }
 
 static int decode_frame(AVCodecContext *avctx,
                         void *data, int *data_size,
                         AVPacket *avpkt)
 {
     const uint8_t *buf = avpkt->data;
     int buf_size       = avpkt->size;
     const uint8_t *buf_end = buf+buf_size;
     MadContext *t     = avctx->priv_data;
     MpegEncContext *s = &t->s;
     int chunk_type;
     int inter;
 
     if (buf_size < 17) {
         av_log(avctx, AV_LOG_ERROR, "Input buffer too small\n");
         *data_size = 0;
         return -1;
     }
 
     chunk_type = AV_RL32(&buf[0]);
     inter = (chunk_type == MADm_TAG || chunk_type == MADe_TAG);
     buf += 8;
 
     av_reduce(&avctx->time_base.num, &avctx->time_base.den,
               AV_RL16(&buf[6]), 1000, 1<<30);
 
     s->width  = AV_RL16(&buf[8]);
     s->height = AV_RL16(&buf[10]);
     calc_intra_matrix(t, buf[13]);
     buf += 16;
 
     if (avctx->width != s->width || avctx->height != s->height) {

         if (av_image_check_size(s->width, s->height, 0, avctx) < 0)

             return -1;
         avcodec_set_dimensions(avctx, s->width, s->height);
         if (t->frame.data[0])
             avctx->release_buffer(avctx, &t->frame);

         if (t->last_frame.data[0])
             avctx->release_buffer(avctx, &t->last_frame);

     }
 
     t->frame.reference = 1;
     if (!t->frame.data[0]) {
         if (avctx->get_buffer(avctx, &t->frame) < 0) {
             av_log(avctx, AV_LOG_ERROR, "get_buffer() failed\n");
             return -1;
         }
     }
 
     av_fast_malloc(&t->bitstream_buf, &t->bitstream_buf_size, (buf_end-buf) + FF_INPUT_BUFFER_PADDING_SIZE);
     if (!t->bitstream_buf)
         return AVERROR(ENOMEM);
     bswap16_buf(t->bitstream_buf, (const uint16_t*)buf, (buf_end-buf)/2);

     memset((uint8_t*)t->bitstream_buf + (buf_end-buf), 0, FF_INPUT_BUFFER_PADDING_SIZE);

     init_get_bits(&s->gb, t->bitstream_buf, 8*(buf_end-buf));
 
     for (s->mb_y=0; s->mb_y < (avctx->height+15)/16; s->mb_y++)
         for (s->mb_x=0; s->mb_x < (avctx->width +15)/16; s->mb_x++)
             decode_mb(t, inter);
 
     *data_size = sizeof(AVFrame);
     *(AVFrame*)data = t->frame;
 
     if (chunk_type != MADe_TAG)
         FFSWAP(AVFrame, t->frame, t->last_frame);
 
     return buf_size;
 }
 
 static av_cold int decode_end(AVCodecContext *avctx)
 {
     MadContext *t = avctx->priv_data;
     if (t->frame.data[0])
         avctx->release_buffer(avctx, &t->frame);
     if (t->last_frame.data[0])
         avctx->release_buffer(avctx, &t->last_frame);
     av_free(t->bitstream_buf);
     return 0;
 }
 

 AVCodec ff_eamad_decoder = {

     "eamad",

     AVMEDIA_TYPE_VIDEO,

     CODEC_ID_MAD,
     sizeof(MadContext),
     decode_init,
     NULL,
     decode_end,
     decode_frame,
     CODEC_CAP_DR1,
     .long_name = NULL_IF_CONFIG_SMALL("Electronic Arts Madcow Video")
 };