/*
  * 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

  * @brief IntraX8 (J-Frame) subdecoder, used by WMV2 and VC-1

  */
 

 #include "libavutil/avassert.h"

 #include "avcodec.h"

 #include "get_bits.h"

 #include "idctdsp.h"

 #include "msmpeg4data.h"
 #include "intrax8huf.h"
 #include "intrax8.h"

 #include "intrax8dsp.h"

 #include "mpegutils.h"

 #define MAX_TABLE_DEPTH(table_bits, max_bits) \
     ((max_bits + table_bits - 1) / table_bits)

 
 #define DC_VLC_BITS 9
 #define AC_VLC_BITS 9
 #define OR_VLC_BITS 7
 
 #define DC_VLC_MTD MAX_TABLE_DEPTH(DC_VLC_BITS, MAX_DC_VLC_BITS)
 #define AC_VLC_MTD MAX_TABLE_DEPTH(AC_VLC_BITS, MAX_AC_VLC_BITS)
 #define OR_VLC_MTD MAX_TABLE_DEPTH(OR_VLC_BITS, MAX_OR_VLC_BITS)
 

 static VLC j_ac_vlc[2][2][8];  // [quant < 13], [intra / inter], [select]
 static VLC j_dc_vlc[2][8];     // [quant], [select]
 static VLC j_orient_vlc[2][4]; // [quant], [select]

 static av_cold int x8_vlc_init(void)

 {

     int i;

     int offset = 0;
     int sizeidx = 0;

     static const uint16_t sizes[8 * 4 + 8 * 2 + 2 + 4] = {

         576, 548, 582, 618, 546, 616, 560, 642,
         584, 582, 704, 664, 512, 544, 656, 640,
         512, 648, 582, 566, 532, 614, 596, 648,
         586, 552, 584, 590, 544, 578, 584, 624,
 
         528, 528, 526, 528, 536, 528, 526, 544,
         544, 512, 512, 528, 528, 544, 512, 544,
 

         128, 128, 128, 128, 128, 128,
     };

 
     static VLC_TYPE table[28150][2];

 // set ac tables
 #define init_ac_vlc(dst, src)                                                 \
     do {                                                                      \
         dst.table           = &table[offset];                                 \
         dst.table_allocated = sizes[sizeidx];                                 \
         offset             += sizes[sizeidx++];                               \
         init_vlc(&dst, AC_VLC_BITS, 77, &src[1], 4, 2, &src[0], 4, 2,         \
                  INIT_VLC_USE_NEW_STATIC);                                    \

     } while(0)

 
     for (i = 0; i < 8; i++) {
         init_ac_vlc(j_ac_vlc[0][0][i], x8_ac0_highquant_table[i][0]);
         init_ac_vlc(j_ac_vlc[0][1][i], x8_ac1_highquant_table[i][0]);
         init_ac_vlc(j_ac_vlc[1][0][i], x8_ac0_lowquant_table[i][0]);
         init_ac_vlc(j_ac_vlc[1][1][i], x8_ac1_lowquant_table[i][0]);

     }
 #undef init_ac_vlc
 

 // set dc tables
 #define init_dc_vlc(dst, src)                                                 \
     do {                                                                      \
         dst.table           = &table[offset];                                 \
         dst.table_allocated = sizes[sizeidx];                                 \
         offset             += sizes[sizeidx++];                               \
         init_vlc(&dst, DC_VLC_BITS, 34, &src[1], 4, 2, &src[0], 4, 2,         \
                  INIT_VLC_USE_NEW_STATIC);                                    \

     } while(0)

 
     for (i = 0; i < 8; i++) {
         init_dc_vlc(j_dc_vlc[0][i], x8_dc_highquant_table[i][0]);
         init_dc_vlc(j_dc_vlc[1][i], x8_dc_lowquant_table[i][0]);

     }
 #undef init_dc_vlc
 

 // set orient tables
 #define init_or_vlc(dst, src)                                                 \
     do {                                                                      \
         dst.table           = &table[offset];                                 \
         dst.table_allocated = sizes[sizeidx];                                 \
         offset             += sizes[sizeidx++];                               \
         init_vlc(&dst, OR_VLC_BITS, 12, &src[1], 4, 2, &src[0], 4, 2,         \
                  INIT_VLC_USE_NEW_STATIC);                                    \

     } while(0)

 
     for (i = 0; i < 2; i++)
         init_or_vlc(j_orient_vlc[0][i], x8_orient_highquant_table[i][0]);
     for (i = 0; i < 4; i++)
         init_or_vlc(j_orient_vlc[1][i], x8_orient_lowquant_table[i][0]);
 #undef init_or_vlc
 

     if (offset != sizeof(table) / sizeof(VLC_TYPE) / 2) {

         av_log(NULL, AV_LOG_ERROR, "table size %"SIZE_SPECIFIER" does not match needed %i\n",

                sizeof(table) / sizeof(VLC_TYPE) / 2, offset);

         return AVERROR_INVALIDDATA;
     }
 
     return 0;

 }
 

 static void x8_reset_vlc_tables(IntraX8Context *w)
 {
     memset(w->j_dc_vlc, 0, sizeof(w->j_dc_vlc));
     memset(w->j_ac_vlc, 0, sizeof(w->j_ac_vlc));
     w->j_orient_vlc = NULL;

 }
 

 static inline void x8_select_ac_table(IntraX8Context *const w, int mode)
 {

     int table_index;
 

     av_assert2(mode < 4);

     if (w->j_ac_vlc[mode])
         return;
 

     table_index       = get_bits(w->gb, 3);

     // 2 modes use same tables
     w->j_ac_vlc[mode] = &j_ac_vlc[w->quant < 13][mode >> 1][table_index];

     av_assert2(w->j_ac_vlc[mode]);

 }
 

 static inline int x8_get_orient_vlc(IntraX8Context *w)
 {
     if (!w->j_orient_vlc) {

         int table_index = get_bits(w->gb, 1 + (w->quant < 13));

         w->j_orient_vlc = &j_orient_vlc[w->quant < 13][table_index];

     }
 

     return get_vlc2(w->gb, w->j_orient_vlc->table, OR_VLC_BITS, OR_VLC_MTD);

 }
 

 #define extra_bits(eb)  (eb)        // 3 bits
 #define extra_run       (0xFF << 8) // 1 bit
 #define extra_level     (0x00 << 8) // 1 bit
 #define run_offset(r)   ((r) << 16) // 6 bits
 #define level_offset(l) ((l) << 24) // 5 bits

 static const uint32_t ac_decode_table[] = {
     /* 46 */ extra_bits(3) | extra_run   | run_offset(16) | level_offset(0),
     /* 47 */ extra_bits(3) | extra_run   | run_offset(24) | level_offset(0),
     /* 48 */ extra_bits(2) | extra_run   | run_offset(4)  | level_offset(1),
     /* 49 */ extra_bits(3) | extra_run   | run_offset(8)  | level_offset(1),
 
     /* 50 */ extra_bits(5) | extra_run   | run_offset(32) | level_offset(0),
     /* 51 */ extra_bits(4) | extra_run   | run_offset(16) | level_offset(1),
 
     /* 52 */ extra_bits(2) | extra_level | run_offset(0)  | level_offset(4),
     /* 53 */ extra_bits(2) | extra_level | run_offset(0)  | level_offset(8),
     /* 54 */ extra_bits(2) | extra_level | run_offset(0)  | level_offset(12),
     /* 55 */ extra_bits(3) | extra_level | run_offset(0)  | level_offset(16),
     /* 56 */ extra_bits(3) | extra_level | run_offset(0)  | level_offset(24),
 
     /* 57 */ extra_bits(2) | extra_level | run_offset(1)  | level_offset(3),
     /* 58 */ extra_bits(3) | extra_level | run_offset(1)  | level_offset(7),
 
     /* 59 */ extra_bits(2) | extra_run   | run_offset(16) | level_offset(0),
     /* 60 */ extra_bits(2) | extra_run   | run_offset(20) | level_offset(0),
     /* 61 */ extra_bits(2) | extra_run   | run_offset(24) | level_offset(0),
     /* 62 */ extra_bits(2) | extra_run   | run_offset(28) | level_offset(0),
     /* 63 */ extra_bits(4) | extra_run   | run_offset(32) | level_offset(0),
     /* 64 */ extra_bits(4) | extra_run   | run_offset(48) | level_offset(0),
 
     /* 65 */ extra_bits(2) | extra_run   | run_offset(4)  | level_offset(1),
     /* 66 */ extra_bits(3) | extra_run   | run_offset(8)  | level_offset(1),
     /* 67 */ extra_bits(4) | extra_run   | run_offset(16) | level_offset(1),
 
     /* 68 */ extra_bits(2) | extra_level | run_offset(0)  | level_offset(4),
     /* 69 */ extra_bits(3) | extra_level | run_offset(0)  | level_offset(8),
     /* 70 */ extra_bits(4) | extra_level | run_offset(0)  | level_offset(16),
 
     /* 71 */ extra_bits(2) | extra_level | run_offset(1)  | level_offset(3),
     /* 72 */ extra_bits(3) | extra_level | run_offset(1)  | level_offset(7),

 };
 #undef extra_bits
 #undef extra_run
 #undef extra_level
 #undef run_offset
 #undef level_offset
 

 static void x8_get_ac_rlf(IntraX8Context *const w, const int mode,
                           int *const run, int *const level, int *const final)
 {
     int i, e;

 //    x8_select_ac_table(w, mode);

     i = get_vlc2(w->gb, w->j_ac_vlc[mode]->table, AC_VLC_BITS, AC_VLC_MTD);

     if (i < 46) { // [0-45]
         int t, l;
         if (i < 0) {

             *level =

             *final =      // prevent 'may be used uninitialized'

             *run   = 64;  // this would cause error exit in the ac loop

             return;
         }
 

         /*
          * i == 0-15  r = 0-15 l = 0; r = i & %01111
          * i == 16-19 r = 0-3  l = 1; r = i & %00011
          * i == 20-21 r = 0-1  l = 2; r = i & %00001
          * i == 22    r = 0    l = 3; r = i & %00000
          */
 

         *final =
         t      = i > 22;
         i     -= 23 * t;

 
         /* l = lut_l[i / 2] = { 0, 0, 0, 0, 0, 0, 0, 0, 1, 1, 2, 3 }[i >> 1];
          *     11 10'01 01'00 00'00 00'00 00'00 00 => 0xE50000 */

         l = (0xE50000 >> (i & 0x1E)) & 3; // 0x1E or ~1 or (i >> 1 << 1)

 
         /* t = lut_mask[l] = { 0x0f, 0x03, 0x01, 0x00 }[l];
          *     as i < 256 the higher bits do not matter */

         t = 0x01030F >> (l << 3);

         *run   = i & t;
         *level = l;

     } else if (i < 73) { // [46-72]

         uint32_t sm;
         uint32_t mask;
 

         i -= 46;
         sm = ac_decode_table[i];
 

         e    = get_bits(w->gb, sm & 0xF);

         sm >>= 8;                               // 3 bits

         mask = sm & 0xff;

         sm >>= 8;                               // 1 bit

         *run   = (sm &  0xff) + (e &  mask);    // 6 bits
         *level = (sm >>    8) + (e & ~mask);    // 5 bits

         *final = i > (58 - 46);

     } else if (i < 75) { // [73-74]
         static const uint8_t crazy_mix_runlevel[32] = {
             0x22, 0x32, 0x33, 0x53, 0x23, 0x42, 0x43, 0x63,
             0x24, 0x52, 0x34, 0x73, 0x25, 0x62, 0x44, 0x83,
             0x26, 0x72, 0x35, 0x54, 0x27, 0x82, 0x45, 0x64,
             0x28, 0x92, 0x36, 0x74, 0x29, 0xa2, 0x46, 0x84,
         };
 

         *final = !(i & 1);
         e      = get_bits(w->gb, 5); // get the extra bits
         *run   = crazy_mix_runlevel[e] >> 4;
         *level = crazy_mix_runlevel[e] & 0x0F;

     } else {

         *level = get_bits(w->gb, 7 - 3 * (i & 1));
         *run   = get_bits(w->gb, 6);
         *final = get_bits1(w->gb);

     }
     return;
 }
 

 /* static const uint8_t dc_extra_sbits[] = {
  *     0, 1, 1, 1, 1, 2, 2, 3, 3, 4, 4, 5, 5, 6, 6, 7, 7,
  * }; */
 static const uint8_t dc_index_offset[] = {
     0, 1, 2, 3, 4, 5, 7, 9, 13, 17, 25, 33, 49, 65, 97, 129, 193,
 };

 static int x8_get_dc_rlf(IntraX8Context *const w, const int mode,
                          int *const level, int *const final)

 {
     int i, e, c;
 

     av_assert2(mode < 3);

     if (!w->j_dc_vlc[mode]) {

         int table_index = get_bits(w->gb, 3);

         // 4 modes, same table
         w->j_dc_vlc[mode] = &j_dc_vlc[w->quant < 13][table_index];

     }
 

     i = get_vlc2(w->gb, w->j_dc_vlc[mode]->table, DC_VLC_BITS, DC_VLC_MTD);

     /* (i >= 17) { i -= 17; final =1; } */

     c      = i > 16;
     *final = c;
     i      -= 17 * c;

     if (i <= 0) {

         *level = 0;

         return -i;
     }

     c  = (i + 1) >> 1; // hackish way to calculate dc_extra_sbits[]
     c -= c > 1;

     e = get_bits(w->gb, c); // get the extra bits

     i = dc_index_offset[i] + (e >> 1);

     e      = -(e & 1);     // 0, 0xffffff
     *level =  (i ^ e) - e; // (i ^ 0) - 0, (i ^ 0xff) - (-1)

     return 0;
 }
 

 // end of huffman
 
 static int x8_setup_spatial_predictor(IntraX8Context *const w, const int chroma)
 {

     int range;
     int sum;
     int quant;
 

     w->dsp.setup_spatial_compensation(w->dest[chroma], w->scratchpad,

                                       w->frame->linesize[chroma > 0],

                                       &range, &sum, w->edges);

     if (chroma) {
         w->orient = w->chroma_orient;
         quant     = w->quant_dc_chroma;
     } else {
         quant = w->quant;

     }
 

     w->flat_dc = 0;
     if (range < quant || range < 3) {
         w->orient = 0;
 
         // yep you read right, a +-1 idct error may break decoding!
         if (range < 3) {
             w->flat_dc      = 1;
             sum            += 9;
             // ((1 << 17) + 9) / (8 + 8 + 1 + 2) = 6899

             w->predicted_dc = sum * 6899 >> 17;

         }
     }

     if (chroma)

         return 0;
 

     av_assert2(w->orient < 3);

     if (range < 2 * w->quant) {
         if ((w->edges & 3) == 0) {
             if (w->orient == 1)
                 w->orient = 11;
             if (w->orient == 2)
                 w->orient = 10;
         } else {
             w->orient = 0;

         }

         w->raw_orient = 0;
     } else {
         static const uint8_t prediction_table[3][12] = {
             { 0, 8, 4, 10, 11, 2, 6, 9, 1, 3, 5, 7 },
             { 4, 0, 8, 11, 10, 3, 5, 2, 6, 9, 1, 7 },
             { 8, 0, 4, 10, 11, 1, 7, 2, 6, 9, 3, 5 },

         };

         w->raw_orient = x8_get_orient_vlc(w);
         if (w->raw_orient < 0)
             return -1;

         av_assert2(w->raw_orient < 12);
         av_assert2(w->orient < 3);

         w->orient=prediction_table[w->orient][w->raw_orient];
     }
     return 0;
 }
 

 static void x8_update_predictions(IntraX8Context *const w, const int orient,
                                   const int est_run)
 {

     w->prediction_table[w->mb_x * 2 + (w->mb_y & 1)] = (est_run << 2) + 1 * (orient == 4) + 2 * (orient == 8);

 /*

  * y = 2n + 0 -> // 0 2 4
  * y = 2n + 1 -> // 1 3 5
  */

 }
 

 static void x8_get_prediction_chroma(IntraX8Context *const w)
 {

     w->edges  = 1 * !(w->mb_x >> 1);
     w->edges |= 2 * !(w->mb_y >> 1);

     w->edges |= 4 * (w->mb_x >= (2 * w->mb_width - 1)); // mb_x for chroma would always be odd

 
     w->raw_orient = 0;
     // lut_co[8] = {inv,4,8,8, inv,4,8,8} <- => {1,1,0,0;1,1,0,0} => 0xCC
     if (w->edges & 3) {
         w->chroma_orient = 4 << ((0xCC >> w->edges) & 1);

         return;
     }

     // block[x - 1][y | 1 - 1)]

     w->chroma_orient = (w->prediction_table[2 * w->mb_x - 2] & 0x03) << 2;

 }
 

 static void x8_get_prediction(IntraX8Context *const w)
 {
     int a, b, c, i;
 

     w->edges  = 1 * !w->mb_x;
     w->edges |= 2 * !w->mb_y;

     w->edges |= 4 * (w->mb_x >= (2 * w->mb_width - 1));

 
     switch (w->edges & 3) {
     case 0:
         break;
     case 1:
         // take the one from the above block[0][y - 1]

         w->est_run = w->prediction_table[!(w->mb_y & 1)] >> 2;

         w->orient  = 1;
         return;
     case 2:
         // take the one from the previous block[x - 1][0]

         w->est_run = w->prediction_table[2 * w->mb_x - 2] >> 2;

         w->orient  = 2;
         return;
     case 3:
         w->est_run = 16;
         w->orient  = 0;
         return;

     }

     // no edge cases

     b = w->prediction_table[2 * w->mb_x     + !(w->mb_y & 1)]; // block[x    ][y - 1]
     a = w->prediction_table[2 * w->mb_x - 2 +  (w->mb_y & 1)]; // block[x - 1][y    ]
     c = w->prediction_table[2 * w->mb_x - 2 + !(w->mb_y & 1)]; // block[x - 1][y - 1]

     w->est_run = FFMIN(b, a);

     /* This condition has nothing to do with w->edges, even if it looks

      * similar it would trigger if e.g. x = 3; y = 2;
      * I guess somebody wrote something wrong and it became standard. */

     if ((w->mb_x & w->mb_y) != 0)

         w->est_run = FFMIN(c, w->est_run);
     w->est_run >>= 2;
 
     a &= 3;
     b &= 3;
     c &= 3;
 
     i = (0xFFEAF4C4 >> (2 * b + 8 * a)) & 3;
     if (i != 3)
         w->orient = i;
     else
         w->orient = (0xFFEAD8 >> (2 * c + 8 * (w->quant > 12))) & 3;

 /*

  * lut1[b][a] = {
  * ->{ 0, 1, 0, pad },
  *   { 0, 1, X, pad },
  *   { 2, 2, 2, pad }
  * }
  * pad 2  2  2;
  * pad X  1  0;
  * pad 0  1  0 <-
  * -> 11 10 '10 10 '11 11'01 00 '11 00'01 00 => 0xEAF4C4
  *
  * lut2[q>12][c] = {
  * ->{ 0, 2, 1, pad},
  *   { 2, 2, 2, pad}
  * }
  * pad 2  2  2;
  * pad 1  2  0 <-
  * -> 11 10'10 10 '11 01'10 00 => 0xEAD8
  */

 }
 

 static void x8_ac_compensation(IntraX8Context *const w, const int direction,
                                const int dc_level)

 {

     int t;

 #define B(x,y)  w->block[0][w->idct_permutation[(x) + (y) * 8]]

 #define T(x)  ((x) * dc_level + 0x8000) >> 16;

     switch (direction) {

     case 0:

         t        = T(3811); // h
         B(1, 0) -= t;
         B(0, 1) -= t;
 
         t        = T(487); // e
         B(2, 0) -= t;
         B(0, 2) -= t;
 
         t        = T(506); // f
         B(3, 0) -= t;
         B(0, 3) -= t;
 
         t        = T(135); // c
         B(4, 0) -= t;
         B(0, 4) -= t;
         B(2, 1) += t;
         B(1, 2) += t;
         B(3, 1) += t;
         B(1, 3) += t;
 
         t        = T(173); // d
         B(5, 0) -= t;
         B(0, 5) -= t;
 
         t        = T(61); // b
         B(6, 0) -= t;
         B(0, 6) -= t;
         B(5, 1) += t;
         B(1, 5) += t;
 
         t        = T(42); // a
         B(7, 0) -= t;
         B(0, 7) -= t;
         B(4, 1) += t;
         B(1, 4) += t;
         B(4, 4) += t;
 
         t        = T(1084); // g
         B(1, 1) += t;
 

         w->block_last_index[0] = FFMAX(w->block_last_index[0], 7 * 8);

         break;
     case 1:

         B(0, 1) -= T(6269);
         B(0, 3) -= T(708);
         B(0, 5) -= T(172);
         B(0, 7) -= T(73);

         w->block_last_index[0] = FFMAX(w->block_last_index[0], 7 * 8);

         break;
     case 2:

         B(1, 0) -= T(6269);
         B(3, 0) -= T(708);
         B(5, 0) -= T(172);
         B(7, 0) -= T(73);

         w->block_last_index[0] = FFMAX(w->block_last_index[0], 7);

         break;
     }
 #undef B
 #undef T
 }
 

 static void dsp_x8_put_solidcolor(const uint8_t pix, uint8_t *dst,
                                   const int linesize)

 {

     int k;

     for (k = 0; k < 8; k++) {
         memset(dst, pix, 8);
         dst += linesize;

     }
 }
 
 static const int16_t quant_table[64] = {

     256, 256, 256, 256, 256, 256, 259, 262,
     265, 269, 272, 275, 278, 282, 285, 288,
     292, 295, 299, 303, 306, 310, 314, 317,
     321, 325, 329, 333, 337, 341, 345, 349,
     353, 358, 362, 366, 371, 375, 379, 384,
     389, 393, 398, 403, 408, 413, 417, 422,
     428, 433, 438, 443, 448, 454, 459, 465,
     470, 476, 482, 488, 493, 499, 505, 511,

 };
 

 static int x8_decode_intra_mb(IntraX8Context *const w, const int chroma)
 {
     uint8_t *scantable;
     int final, run, level;
     int ac_mode, dc_mode, est_run, dc_level;
     int pos, n;

     int zeros_only;
     int use_quant_matrix;
     int sign;
 

     av_assert2(w->orient < 12);

     w->bdsp.clear_block(w->block[0]);

     if (chroma)
         dc_mode = 2;
     else
         dc_mode = !!w->est_run; // 0, 1
 
     if (x8_get_dc_rlf(w, dc_mode, &dc_level, &final))
         return -1;
     n          = 0;
     zeros_only = 0;
     if (!final) { // decode ac
         use_quant_matrix = w->use_quant_matrix;
         if (chroma) {

             ac_mode = 1;

             est_run = 64; // not used
         } else {
             if (w->raw_orient < 3)

                 use_quant_matrix = 0;

 
             if (w->raw_orient > 4) {

                 ac_mode = 0;
                 est_run = 64;

             } else {
                 if (w->est_run > 1) {

                     ac_mode = 2;

                     est_run = w->est_run;
                 } else {

                     ac_mode = 3;
                     est_run = 64;
                 }
             }
         }

         x8_select_ac_table(w, ac_mode);
         /* scantable_selector[12] = { 0, 2, 0, 1, 1, 1, 0, 2, 2, 0, 1, 2 }; <-
          * -> 10'01' 00'10' 10'00' 01'01' 01'00' 10'00 => 0x928548 */
         scantable = w->scantable[(0x928548 >> (2 * w->orient)) & 3].permutated;
         pos       = 0;

         do {
             n++;

             if (n >= est_run) {
                 ac_mode = 3;
                 x8_select_ac_table(w, 3);

             }
 

             x8_get_ac_rlf(w, ac_mode, &run, &level, &final);

             pos += run + 1;
             if (pos > 63) {
                 // this also handles vlc error in x8_get_ac_rlf

                 return -1;
             }

             level  = (level + 1) * w->dquant;
             level += w->qsum;

             sign  = -get_bits1(w->gb);

             level = (level ^ sign) - sign;
 

             if (use_quant_matrix)
                 level = (level * quant_table[pos]) >> 8;

             w->block[0][scantable[pos]] = level;

         } while (!final);

         w->block_last_index[0] = pos;

     } else { // DC only

         w->block_last_index[0] = 0;

         if (w->flat_dc && ((unsigned) (dc_level + 1)) < 3) { // [-1; 1]
             int32_t divide_quant = !chroma ? w->divide_quant_dc_luma
                                            : w->divide_quant_dc_chroma;
             int32_t dc_quant     = !chroma ? w->quant
                                            : w->quant_dc_chroma;

             // original intent dc_level += predicted_dc/quant;
             // but it got lost somewhere in the rounding
             dc_level += (w->predicted_dc * divide_quant + (1 << 12)) >> 13;
 
             dsp_x8_put_solidcolor(av_clip_uint8((dc_level * dc_quant + 4) >> 3),

                                   w->dest[chroma],

                                   w->frame->linesize[!!chroma]);

 
             goto block_placed;
         }

         zeros_only = dc_level == 0;

     }

     if (!chroma)

         w->block[0][0] = dc_level * w->quant;

     else

         w->block[0][0] = dc_level * w->quant_dc_chroma;

     // there is !zero_only check in the original, but dc_level check is enough
     if ((unsigned int) (dc_level + 1) >= 3 && (w->edges & 3) != 3) {

         int direction;

         /* ac_comp_direction[orient] = { 0, 3, 3, 1, 1, 0, 0, 0, 2, 2, 2, 1 }; <-
          * -> 01'10' 10'10' 00'00' 00'01' 01'11' 11'00 => 0x6A017C */
         direction = (0x6A017C >> (w->orient * 2)) & 3;
         if (direction != 3) {
             // modify block_last[]

             x8_ac_compensation(w, direction, w->block[0][0]);

         }
     }
 

     if (w->flat_dc) {

         dsp_x8_put_solidcolor(w->predicted_dc, w->dest[chroma],

                               w->frame->linesize[!!chroma]);

     } else {

         w->dsp.spatial_compensation[w->orient](w->scratchpad,

                                                w->dest[chroma],

                                                w->frame->linesize[!!chroma]);

     }

     if (!zeros_only)

         w->wdsp.idct_add(w->dest[chroma],

                          w->frame->linesize[!!chroma],

                          w->block[0]);

 
 block_placed:

     if (!chroma)
         x8_update_predictions(w, w->orient, n);

     if (w->loopfilter) {

         uint8_t *ptr = w->dest[chroma];

         int linesize = w->frame->linesize[!!chroma];

         if (!((w->edges & 2) || (zeros_only && (w->orient | 4) == 4)))

             w->dsp.h_loop_filter(ptr, linesize, w->quant);

 
         if (!((w->edges & 1) || (zeros_only && (w->orient | 8) == 8)))

             w->dsp.v_loop_filter(ptr, linesize, w->quant);

     }
     return 0;
 }
 

 // FIXME maybe merge with ff_*

 static void x8_init_block_index(IntraX8Context *w, AVFrame *frame)

 {

     // not parent codec linesize as this would be wrong for field pics

     // not that IntraX8 has interlacing support ;)

     const int linesize   = frame->linesize[0];
     const int uvlinesize = frame->linesize[1];

     w->dest[0] = frame->data[0];
     w->dest[1] = frame->data[1];
     w->dest[2] = frame->data[2];

     w->dest[0] +=  w->mb_y       * linesize   << 3;

     // chroma blocks are on add rows

     w->dest[1] += (w->mb_y & ~1) * uvlinesize << 2;
     w->dest[2] += (w->mb_y & ~1) * uvlinesize << 2;

 }
 

 av_cold int ff_intrax8_common_init(AVCodecContext *avctx,
                                    IntraX8Context *w, IDCTDSPContext *idsp,

                                    int16_t (*block)[64],
                                    int block_last_index[12],

                                    int mb_width, int mb_height)

 {

     int ret = x8_vlc_init();
     if (ret < 0)
         return ret;
 

     w->avctx = avctx;

     w->idsp = *idsp;

     w->mb_width  = mb_width;
     w->mb_height = mb_height;

     w->block = block;
     w->block_last_index = block_last_index;

     // two rows, 2 blocks per cannon mb

     w->prediction_table = av_mallocz(w->mb_width * 2 * 2);

     if (!w->prediction_table)
         return AVERROR(ENOMEM);

     ff_wmv2dsp_init(&w->wdsp);

     ff_init_scantable_permutation(w->idct_permutation,
                                   w->wdsp.idct_perm);
 

     ff_init_scantable(w->idct_permutation, &w->scantable[0],

                       ff_wmv1_scantable[0]);

     ff_init_scantable(w->idct_permutation, &w->scantable[1],

                       ff_wmv1_scantable[2]);

     ff_init_scantable(w->idct_permutation, &w->scantable[2],

                       ff_wmv1_scantable[3]);

 
     ff_intrax8dsp_init(&w->dsp);

     ff_blockdsp_init(&w->bdsp, avctx);

 
     return 0;

 }
 

 av_cold void ff_intrax8_common_end(IntraX8Context *w)

 {
     av_freep(&w->prediction_table);
 }
 

 int ff_intrax8_decode_picture(IntraX8Context *const w, Picture *pict,

                               GetBitContext *gb, int *mb_x, int *mb_y,

                               int dquant, int quant_offset,
                               int loopfilter, int lowdelay)

 {

     int mb_xy;
 

     w->gb     = gb;

     w->dquant = dquant;
     w->quant  = dquant >> 1;
     w->qsum   = quant_offset;

     w->frame  = pict->f;

     w->loopfilter = loopfilter;

     w->use_quant_matrix = get_bits1(w->gb);

     w->mb_x = *mb_x;
     w->mb_y = *mb_y;
 

     w->divide_quant_dc_luma = ((1 << 16) + (w->quant >> 1)) / w->quant;
     if (w->quant < 5) {
         w->quant_dc_chroma        = w->quant;

         w->divide_quant_dc_chroma = w->divide_quant_dc_luma;

     } else {
         w->quant_dc_chroma        = w->quant + ((w->quant + 3) >> 3);
         w->divide_quant_dc_chroma = ((1 << 16) + (w->quant_dc_chroma >> 1)) / w->quant_dc_chroma;

     }
     x8_reset_vlc_tables(w);
 

     for (w->mb_y = 0; w->mb_y < w->mb_height * 2; w->mb_y++) {
         x8_init_block_index(w, w->frame);
         mb_xy = (w->mb_y >> 1) * (w->mb_width + 1);
         for (w->mb_x = 0; w->mb_x < w->mb_width * 2; w->mb_x++) {

             x8_get_prediction(w);

             if (x8_setup_spatial_predictor(w, 0))
                 goto error;
             if (x8_decode_intra_mb(w, 0))
                 goto error;

             if (w->mb_x & w->mb_y & 1) {

                 x8_get_prediction_chroma(w);
 

                 /* when setting up chroma, no vlc is read,
                  * so no error condition can be reached */
                 x8_setup_spatial_predictor(w, 1);
                 if (x8_decode_intra_mb(w, 1))
                     goto error;

                 x8_setup_spatial_predictor(w, 2);
                 if (x8_decode_intra_mb(w, 2))
                     goto error;

                 w->dest[1] += 8;
                 w->dest[2] += 8;

                 pict->qscale_table[mb_xy] = w->quant;

                 mb_xy++;
             }

             w->dest[0] += 8;

         }

         if (w->mb_y & 1)

             ff_draw_horiz_band(w->avctx, w->frame, w->frame,
                                (w->mb_y - 1) * 8, 16,
                                PICT_FRAME, 0, lowdelay);

     }
 
 error:

     *mb_x = w->mb_x;
     *mb_y = w->mb_y;
 

     return 0;
 }