/*
  * ScreenPressor decoder
  *
  * Copyright (c) 2017 Paul B Mahol
  *
  * 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 <stdio.h>
 #include <stdlib.h>
 #include <string.h>
 
 #include "avcodec.h"
 #include "bytestream.h"
 #include "internal.h"
 
 #define TOP  0x01000000
 #define BOT    0x010000
 
 typedef struct RangeCoder {
     unsigned   code;
     unsigned   range;

     unsigned   code1;

 } RangeCoder;
 
 typedef struct PixelModel {
     unsigned    freq[256];
     unsigned    lookup[16];
     unsigned    total_freq;
 } PixelModel;
 
 typedef struct SCPRContext {
     AVFrame        *last_frame;
     AVFrame        *current_frame;
     GetByteContext  gb;
     RangeCoder      rc;
     PixelModel      pixel_model[3][4096];
     unsigned        op_model[6][7];
     unsigned        run_model[6][257];
     unsigned        range_model[257];
     unsigned        count_model[257];
     unsigned        fill_model[6];
     unsigned        sxy_model[4][17];
     unsigned        mv_model[2][513];
     unsigned        nbx, nby;
     unsigned        nbcount;
     unsigned       *blocks;

     unsigned        cbits;

     int             cxshift;

 
     int           (*get_freq)(RangeCoder *rc, unsigned total_freq, unsigned *freq);

     int           (*decode)(GetByteContext *gb, RangeCoder *rc, unsigned cumFreq, unsigned freq, unsigned total_freq);

 } SCPRContext;
 
 static void init_rangecoder(RangeCoder *rc, GetByteContext *gb)
 {

     rc->code1 = 0;

     rc->range = 0xFFFFFFFFU;
     rc->code  = bytestream2_get_be32(gb);
 }
 
 static void reinit_tables(SCPRContext *s)
 {
     int comp, i, j;
 
     for (comp = 0; comp < 3; comp++) {
         for (j = 0; j < 4096; j++) {
             if (s->pixel_model[comp][j].total_freq != 256) {
                 for (i = 0; i < 256; i++)
                     s->pixel_model[comp][j].freq[i] = 1;
                 for (i = 0; i < 16; i++)
                     s->pixel_model[comp][j].lookup[i] = 16;
                 s->pixel_model[comp][j].total_freq = 256;
             }
         }
     }
 
     for (j = 0; j < 6; j++) {
         unsigned *p = s->run_model[j];
         for (i = 0; i < 256; i++)
             p[i] = 1;
         p[256] = 256;
     }
 
     for (j = 0; j < 6; j++) {
         unsigned *op = s->op_model[j];
         for (i = 0; i < 6; i++)
             op[i] = 1;
         op[6] = 6;
     }
 
     for (i = 0; i < 256; i++) {
         s->range_model[i] = 1;
         s->count_model[i] = 1;
     }
     s->range_model[256] = 256;
     s->count_model[256] = 256;
 
     for (i = 0; i < 5; i++) {
         s->fill_model[i] = 1;
     }
     s->fill_model[5] = 5;
 
     for (j = 0; j < 4; j++) {
         for (i = 0; i < 16; i++) {
             s->sxy_model[j][i] = 1;
         }
         s->sxy_model[j][16] = 16;
     }
 
     for (i = 0; i < 512; i++) {
         s->mv_model[0][i] = 1;
         s->mv_model[1][i] = 1;
     }
     s->mv_model[0][512] = 512;
     s->mv_model[1][512] = 512;
 }
 

 static int decode(GetByteContext *gb, RangeCoder *rc, unsigned cumFreq, unsigned freq, unsigned total_freq)

 {
     rc->code -= cumFreq * rc->range;
     rc->range *= freq;
 
     while (rc->range < TOP && bytestream2_get_bytes_left(gb) > 0) {
         unsigned byte = bytestream2_get_byte(gb);
         rc->code = (rc->code << 8) | byte;
         rc->range <<= 8;
     }

 
     return 0;

 }
 
 static int get_freq(RangeCoder *rc, unsigned total_freq, unsigned *freq)
 {
     if (total_freq == 0)
         return AVERROR_INVALIDDATA;
 
     rc->range = rc->range / total_freq;
 
     if (rc->range == 0)
         return AVERROR_INVALIDDATA;
 
     *freq = rc->code / rc->range;
 
     return 0;
 }
 

 static int decode0(GetByteContext *gb, RangeCoder *rc, unsigned cumFreq, unsigned freq, unsigned total_freq)

 {

     unsigned t;

 
     if (total_freq == 0)
         return AVERROR_INVALIDDATA;
 
     t = rc->range * (uint64_t)cumFreq / total_freq;

 
     rc->code1 += t + 1;
     rc->range = rc->range * (uint64_t)(freq + cumFreq) / total_freq - (t + 1);
 
     while (rc->range < TOP && bytestream2_get_bytes_left(gb) > 0) {
         unsigned byte = bytestream2_get_byte(gb);
         rc->code = (rc->code << 8) | byte;
         rc->code1 <<= 8;
         rc->range <<= 8;
     }

 
     return 0;

 }
 
 static int get_freq0(RangeCoder *rc, unsigned total_freq, unsigned *freq)
 {
     if (rc->range == 0)
         return AVERROR_INVALIDDATA;
 
     *freq = total_freq * (uint64_t)(rc->code - rc->code1) / rc->range;
 
     return 0;
 }
 

 static int decode_value(SCPRContext *s, unsigned *cnt, unsigned maxc, unsigned step, unsigned *rval)
 {
     GetByteContext *gb = &s->gb;
     RangeCoder *rc = &s->rc;
     unsigned totfr = cnt[maxc];
     unsigned value;
     unsigned c = 0, cumfr = 0, cnt_c = 0;
     int i, ret;
 

     if ((ret = s->get_freq(rc, totfr, &value)) < 0)

         return ret;
 
     while (c < maxc) {
         cnt_c = cnt[c];
         if (value >= cumfr + cnt_c)
             cumfr += cnt_c;
         else
             break;
         c++;
     }

 
     if (c >= maxc)
         return AVERROR_INVALIDDATA;
 

     if ((ret = s->decode(gb, rc, cumfr, cnt_c, totfr)) < 0)
         return ret;

 
     cnt[c] = cnt_c + step;
     totfr += step;
     if (totfr > BOT) {
         totfr = 0;
         for (i = 0; i < maxc; i++) {
             unsigned nc = (cnt[i] >> 1) + 1;
             cnt[i] = nc;
             totfr += nc;
         }
     }
 
     cnt[maxc] = totfr;
     *rval = c;
 
     return 0;
 }
 
 static int decode_unit(SCPRContext *s, PixelModel *pixel, unsigned step, unsigned *rval)
 {
     GetByteContext *gb = &s->gb;
     RangeCoder *rc = &s->rc;
     unsigned totfr = pixel->total_freq;
     unsigned value, x = 0, cumfr = 0, cnt_x = 0;
     int i, j, ret, c, cnt_c;
 

     if ((ret = s->get_freq(rc, totfr, &value)) < 0)

         return ret;
 
     while (x < 16) {
         cnt_x = pixel->lookup[x];
         if (value >= cumfr + cnt_x)
             cumfr += cnt_x;
         else
             break;
         x++;
     }
 
     c = x * 16;
     cnt_c = 0;
     while (c < 256) {
         cnt_c = pixel->freq[c];
         if (value >= cumfr + cnt_c)
             cumfr += cnt_c;
         else
             break;
         c++;
     }

     if (x >= 16 || c >= 256) {
         return AVERROR_INVALIDDATA;
     }

 
     if ((ret = s->decode(gb, rc, cumfr, cnt_c, totfr)) < 0)
         return ret;
 

     pixel->freq[c] = cnt_c + step;
     pixel->lookup[x] = cnt_x + step;
     totfr += step;
     if (totfr > BOT) {
         totfr = 0;
         for (i = 0; i < 256; i++) {
             unsigned nc = (pixel->freq[i] >> 1) + 1;
             pixel->freq[i] = nc;
             totfr += nc;
         }
         for (i = 0; i < 16; i++) {
             unsigned sum = 0;
             unsigned i16_17 = i << 4;
             for (j = 0; j < 16; j++)
                 sum += pixel->freq[i16_17 + j];
             pixel->lookup[i] = sum;
         }
     }
     pixel->total_freq = totfr;
 

     *rval = c & s->cbits;

 
     return 0;
 }
 
 static int decompress_i(AVCodecContext *avctx, uint32_t *dst, int linesize)
 {
     SCPRContext *s = avctx->priv_data;
     GetByteContext *gb = &s->gb;
     int cx = 0, cx1 = 0, k = 0, clr = 0;

     int run, r, g, b, off, y = 0, x = 0, z, ret;
     unsigned backstep = linesize - avctx->width;

     const int cxshift = s->cxshift;
     unsigned lx, ly, ptype;
 
     reinit_tables(s);
     bytestream2_skip(gb, 2);
     init_rangecoder(&s->rc, gb);
 
     while (k < avctx->width + 1) {
         ret = decode_unit(s, &s->pixel_model[0][cx + cx1], 400, &r);
         if (ret < 0)
             return ret;
 
         cx1 = (cx << 6) & 0xFC0;
         cx = r >> cxshift;
         ret = decode_unit(s, &s->pixel_model[1][cx + cx1], 400, &g);
         if (ret < 0)
             return ret;
 
         cx1 = (cx << 6) & 0xFC0;
         cx = g >> cxshift;
         ret = decode_unit(s, &s->pixel_model[2][cx + cx1], 400, &b);
         if (ret < 0)
             return ret;
 
         cx1 = (cx << 6) & 0xFC0;
         cx = b >> cxshift;
 
         ret = decode_value(s, s->run_model[0], 256, 400, &run);
         if (ret < 0)
             return ret;
 
         clr = (b << 16) + (g << 8) + r;
         k += run;
         while (run-- > 0) {

             if (y >= avctx->height)
                 return AVERROR_INVALIDDATA;
 

             dst[y * linesize + x] = clr;
             lx = x;
             ly = y;
             x++;
             if (x >= avctx->width) {
                 x = 0;
                 y++;
             }
         }
     }
     off = -linesize - 1;
     ptype = 0;
 
     while (x < avctx->width && y < avctx->height) {
         ret = decode_value(s, s->op_model[ptype], 6, 1000, &ptype);
         if (ret < 0)
             return ret;
         if (ptype == 0) {
             ret = decode_unit(s, &s->pixel_model[0][cx + cx1], 400, &r);
             if (ret < 0)
                 return ret;
 
             cx1 = (cx << 6) & 0xFC0;
             cx = r >> cxshift;
             ret = decode_unit(s, &s->pixel_model[1][cx + cx1], 400, &g);
             if (ret < 0)
                 return ret;
 
             cx1 = (cx << 6) & 0xFC0;
             cx = g >> cxshift;
             ret = decode_unit(s, &s->pixel_model[2][cx + cx1], 400, &b);
             if (ret < 0)
                 return ret;
 
             clr = (b << 16) + (g << 8) + r;
         }
         if (ptype > 5)
             return AVERROR_INVALIDDATA;
         ret = decode_value(s, s->run_model[ptype], 256, 400, &run);
         if (ret < 0)
             return ret;
 
         switch (ptype) {
         case 0:
             while (run-- > 0) {

                 if (y >= avctx->height)
                     return AVERROR_INVALIDDATA;
 

                 dst[y * linesize + x] = clr;
                 lx = x;
                 ly = y;
                 x++;
                 if (x >= avctx->width) {
                     x = 0;
                     y++;
                 }
             }
             break;
         case 1:
             while (run-- > 0) {

                 if (y >= avctx->height)
                     return AVERROR_INVALIDDATA;
 

                 dst[y * linesize + x] = dst[ly * linesize + lx];
                 lx = x;
                 ly = y;
                 x++;
                 if (x >= avctx->width) {
                     x = 0;
                     y++;
                 }
             }
             clr = dst[ly * linesize + lx];
             break;
         case 2:
             while (run-- > 0) {

                 if (y < 1 || y >= avctx->height)
                     return AVERROR_INVALIDDATA;
 

                 clr = dst[y * linesize + x + off + 1];
                 dst[y * linesize + x] = clr;
                 lx = x;
                 ly = y;
                 x++;
                 if (x >= avctx->width) {
                     x = 0;
                     y++;
                 }
             }
             break;
         case 4:
             while (run-- > 0) {
                 uint8_t *odst = (uint8_t *)dst;

                 if (y < 1 || y >= avctx->height ||
                     (y == 1 && x == 0))

                     return AVERROR_INVALIDDATA;
 

                 if (x == 0) {
                     z = backstep;
                 } else {
                     z = 0;
                 }
 

                 r = odst[(ly * linesize + lx) * 4] +

                     odst[((y * linesize + x) + off) * 4 + 4] -

                     odst[((y * linesize + x) + off - z) * 4];

                 g = odst[(ly * linesize + lx) * 4 + 1] +

                     odst[((y * linesize + x) + off) * 4 + 5] -

                     odst[((y * linesize + x) + off - z) * 4 + 1];

                 b = odst[(ly * linesize + lx) * 4 + 2] +

                     odst[((y * linesize + x) + off) * 4 + 6] -

                     odst[((y * linesize + x) + off - z) * 4 + 2];

                 clr = ((b & 0xFF) << 16) + ((g & 0xFF) << 8) + (r & 0xFF);
                 dst[y * linesize + x] = clr;
                 lx = x;
                 ly = y;
                 x++;
                 if (x >= avctx->width) {
                     x = 0;
                     y++;
                 }
             }
             break;
         case 5:
             while (run-- > 0) {

                 if (y < 1 || y >= avctx->height ||
                     (y == 1 && x == 0))

                     return AVERROR_INVALIDDATA;
 

                 if (x == 0) {
                     z = backstep;
                 } else {
                     z = 0;
                 }
 
                 clr = dst[y * linesize + x + off - z];

                 dst[y * linesize + x] = clr;
                 lx = x;
                 ly = y;
                 x++;
                 if (x >= avctx->width) {
                     x = 0;
                     y++;
                 }
             }
             break;
         }
 
         if (avctx->bits_per_coded_sample == 16) {

             cx1 = (clr & 0x3F00) >> 2;

             cx = (clr & 0x3FFFFF) >> 16;

         } else {
             cx1 = (clr & 0xFC00) >> 4;
             cx = (clr & 0xFFFFFF) >> 18;
         }
     }
 
     return 0;
 }
 
 static int decompress_p(AVCodecContext *avctx,
                         uint32_t *dst, int linesize,
                         uint32_t *prev, int plinesize)
 {
     SCPRContext *s = avctx->priv_data;
     GetByteContext *gb = &s->gb;

     int ret, temp = 0, min, max, x, y, cx = 0, cx1 = 0;

     int backstep = linesize - avctx->width;
     const int cxshift = s->cxshift;
 
     if (bytestream2_get_byte(gb) == 0)
         return 0;
     bytestream2_skip(gb, 1);
     init_rangecoder(&s->rc, gb);
 
     ret  = decode_value(s, s->range_model, 256, 1, &min);
     ret |= decode_value(s, s->range_model, 256, 1, &temp);
     min += temp << 8;
     ret |= decode_value(s, s->range_model, 256, 1, &max);
     ret |= decode_value(s, s->range_model, 256, 1, &temp);
     if (ret < 0)
         return ret;
 
     max += temp << 8;

     if (min > max)
         return AVERROR_INVALIDDATA;
 

     memset(s->blocks, 0, sizeof(*s->blocks) * s->nbcount);
 
     while (min <= max) {
         int fill, count;
 
         ret  = decode_value(s, s->fill_model,  5,   10, &fill);
         ret |= decode_value(s, s->count_model, 256, 20, &count);
         if (ret < 0)
             return ret;
 
         while (min < s->nbcount && count-- > 0) {
             s->blocks[min++] = fill;
         }
     }
 
     for (y = 0; y < s->nby; y++) {
         for (x = 0; x < s->nbx; x++) {
             int sy1 = 0, sy2 = 16, sx1 = 0, sx2 = 16;
 
             if (s->blocks[y * s->nbx + x] == 0)
                 continue;
 
             if (((s->blocks[y * s->nbx + x] - 1) & 1) > 0) {
                 ret  = decode_value(s, s->sxy_model[0], 16, 100, &sx1);
                 ret |= decode_value(s, s->sxy_model[1], 16, 100, &sy1);
                 ret |= decode_value(s, s->sxy_model[2], 16, 100, &sx2);
                 ret |= decode_value(s, s->sxy_model[3], 16, 100, &sy2);
                 if (ret < 0)
                     return ret;
 
                 sx2++;
                 sy2++;
             }
             if (((s->blocks[y * s->nbx + x] - 1) & 2) > 0) {
                 int i, j, by = y * 16, bx = x * 16;
                 int mvx, mvy;
 
                 ret  = decode_value(s, s->mv_model[0], 512, 100, &mvx);
                 ret |= decode_value(s, s->mv_model[1], 512, 100, &mvy);
                 if (ret < 0)
                     return ret;
 
                 mvx -= 256;
                 mvy -= 256;
 

                 if (by + mvy + sy1 < 0 || bx + mvx + sx1 < 0 ||
                     by + mvy + sy1 >= avctx->height || bx + mvx + sx1 >= avctx->width)

                     return AVERROR_INVALIDDATA;
 

                 for (i = 0; i < sy2 - sy1 && (by + sy1 + i) < avctx->height && (by + mvy + sy1 + i) < avctx->height; i++) {
                     for (j = 0; j < sx2 - sx1 && (bx + sx1 + j) < avctx->width && (bx + mvx + sx1 + j) < avctx->width; j++) {

                         dst[(by + i + sy1) * linesize + bx + sx1 + j] = prev[(by + mvy + sy1 + i) * plinesize + bx + sx1 + mvx + j];
                     }
                 }
             } else {
                 int run, r, g, b, z, bx = x * 16 + sx1, by = y * 16 + sy1;
                 unsigned clr, ptype = 0;
 
                 for (; by < y * 16 + sy2 && by < avctx->height;) {
                     ret = decode_value(s, s->op_model[ptype], 6, 1000, &ptype);

                     if (ret < 0)
                         return ret;

                     if (ptype == 0) {
                         ret = decode_unit(s, &s->pixel_model[0][cx + cx1], 400, &r);
                         if (ret < 0)
                             return ret;
 
                         cx1 = (cx << 6) & 0xFC0;
                         cx = r >> cxshift;
                         ret = decode_unit(s, &s->pixel_model[1][cx + cx1], 400, &g);
                         if (ret < 0)
                             return ret;
 
                         cx1 = (cx << 6) & 0xFC0;
                         cx = g >> cxshift;
                         ret = decode_unit(s, &s->pixel_model[2][cx + cx1], 400, &b);
                         if (ret < 0)
                             return ret;
 
                         clr = (b << 16) + (g << 8) + r;
                     }
                     if (ptype > 5)
                         return AVERROR_INVALIDDATA;
                     ret = decode_value(s, s->run_model[ptype], 256, 400, &run);
                     if (ret < 0)
                         return ret;
 
                     switch (ptype) {
                     case 0:
                         while (run-- > 0) {
                             if (by >= avctx->height)
                                 return AVERROR_INVALIDDATA;
 
                             dst[by * linesize + bx] = clr;
                             bx++;
                             if (bx >= x * 16 + sx2 || bx >= avctx->width) {
                                 bx = x * 16 + sx1;
                                 by++;
                             }
                         }
                         break;
                     case 1:
                         while (run-- > 0) {
                             if (bx == 0) {
                                 if (by < 1)
                                     return AVERROR_INVALIDDATA;
                                 z = backstep;
                             } else {
                                 z = 0;
                             }
 
                             if (by >= avctx->height)
                                 return AVERROR_INVALIDDATA;
 
                             clr = dst[by * linesize + bx - 1 - z];
                             dst[by * linesize + bx] = clr;
                             bx++;
                             if (bx >= x * 16 + sx2 || bx >= avctx->width) {
                                 bx = x * 16 + sx1;
                                 by++;
                             }
                         }
                         break;
                     case 2:
                         while (run-- > 0) {
                             if (by < 1 || by >= avctx->height)
                                 return AVERROR_INVALIDDATA;
 
                             clr = dst[(by - 1) * linesize + bx];
                             dst[by * linesize + bx] = clr;
                             bx++;
                             if (bx >= x * 16 + sx2 || bx >= avctx->width) {
                                 bx = x * 16 + sx1;
                                 by++;
                             }
                         }
                         break;
                     case 3:
                         while (run-- > 0) {
                             if (by >= avctx->height)
                                 return AVERROR_INVALIDDATA;
 

                             clr = prev[by * plinesize + bx];

                             dst[by * linesize + bx] = clr;
                             bx++;
                             if (bx >= x * 16 + sx2 || bx >= avctx->width) {
                                 bx = x * 16 + sx1;
                                 by++;
                             }
                         }
                         break;
                     case 4:
                         while (run-- > 0) {
                             uint8_t *odst = (uint8_t *)dst;
 
                             if (by < 1 || by >= avctx->height)
                                 return AVERROR_INVALIDDATA;
 
                             if (bx == 0) {

                                 if (by < 2)
                                     return AVERROR_INVALIDDATA;

                                 z = backstep;
                             } else {
                                 z = 0;
                             }
 
                             r = odst[((by - 1) * linesize + bx) * 4] +
                                 odst[(by * linesize + bx - 1 - z) * 4] -
                                 odst[((by - 1) * linesize + bx - 1 - z) * 4];
                             g = odst[((by - 1) * linesize + bx) * 4 + 1] +
                                 odst[(by * linesize + bx - 1 - z) * 4 + 1] -
                                 odst[((by - 1) * linesize + bx - 1 - z) * 4 + 1];
                             b = odst[((by - 1) * linesize + bx) * 4 + 2] +
                                 odst[(by * linesize + bx - 1 - z) * 4 + 2] -
                                 odst[((by - 1) * linesize + bx - 1 - z) * 4 + 2];
                             clr = ((b & 0xFF) << 16) + ((g & 0xFF) << 8) + (r & 0xFF);
                             dst[by * linesize + bx] = clr;
                             bx++;
                             if (bx >= x * 16 + sx2 || bx >= avctx->width) {
                                 bx = x * 16 + sx1;
                                 by++;
                             }
                         }
                         break;
                     case 5:
                         while (run-- > 0) {
                             if (by < 1 || by >= avctx->height)
                                 return AVERROR_INVALIDDATA;
 
                             if (bx == 0) {

                                 if (by < 2)
                                     return AVERROR_INVALIDDATA;

                                 z = backstep;
                             } else {
                                 z = 0;
                             }
 
                             clr = dst[(by - 1) * linesize + bx - 1 - z];
                             dst[by * linesize + bx] = clr;
                             bx++;
                             if (bx >= x * 16 + sx2 || bx >= avctx->width) {
                                 bx = x * 16 + sx1;
                                 by++;
                             }
                         }
                         break;
                     }
 
                     if (avctx->bits_per_coded_sample == 16) {

                         cx1 = (clr & 0x3F00) >> 2;

                         cx = (clr & 0x3FFFFF) >> 16;

                     } else {
                         cx1 = (clr & 0xFC00) >> 4;
                         cx = (clr & 0xFFFFFF) >> 18;
                     }
                 }
             }
         }
     }
 
     return 0;
 }
 
 static int decode_frame(AVCodecContext *avctx, void *data, int *got_frame,
                         AVPacket *avpkt)
 {
     SCPRContext *s = avctx->priv_data;
     GetByteContext *gb = &s->gb;
     AVFrame *frame = data;
     int ret, type;
 
     if (avctx->bits_per_coded_sample == 16) {
         if ((ret = ff_get_buffer(avctx, frame, 0)) < 0)
             return ret;
     }
 
     if ((ret = ff_reget_buffer(avctx, s->current_frame)) < 0)
         return ret;
 
     bytestream2_init(gb, avpkt->data, avpkt->size);
 
     type = bytestream2_peek_byte(gb);
 

     if (type == 2) {
         s->get_freq = get_freq0;
         s->decode = decode0;
         frame->key_frame = 1;
         ret = decompress_i(avctx, (uint32_t *)s->current_frame->data[0],
                            s->current_frame->linesize[0] / 4);
     } else if (type == 18) {
         s->get_freq = get_freq;
         s->decode = decode;

         frame->key_frame = 1;
         ret = decompress_i(avctx, (uint32_t *)s->current_frame->data[0],
                            s->current_frame->linesize[0] / 4);
     } else if (type == 17) {
         uint32_t clr, *dst = (uint32_t *)s->current_frame->data[0];

         int y;

 
         frame->key_frame = 1;
         bytestream2_skip(gb, 1);
         if (avctx->bits_per_coded_sample == 16) {
             uint16_t value = bytestream2_get_le16(gb);
             int r, g, b;
 
             r = (value      ) & 31;
             g = (value >>  5) & 31;
             b = (value >> 10) & 31;
             clr = (r << 16) + (g << 8) + b;
         } else {
             clr = bytestream2_get_le24(gb);
         }
         for (y = 0; y < avctx->height; y++) {

             dst[0] = clr;
             av_memcpy_backptr((uint8_t*)(dst+1), 4, 4*avctx->width - 4);

             dst += s->current_frame->linesize[0] / 4;
         }
     } else if (type == 0 || type == 1) {
         frame->key_frame = 0;
 
         ret = av_frame_copy(s->current_frame, s->last_frame);
         if (ret < 0)
             return ret;
 
         ret = decompress_p(avctx, (uint32_t *)s->current_frame->data[0],
                            s->current_frame->linesize[0] / 4,
                            (uint32_t *)s->last_frame->data[0],
                            s->last_frame->linesize[0] / 4);
     } else {
         return AVERROR_PATCHWELCOME;
     }
 
     if (ret < 0)
         return ret;
 
     if (avctx->bits_per_coded_sample != 16) {
         ret = av_frame_ref(data, s->current_frame);
         if (ret < 0)
             return ret;
     } else {
         uint8_t *dst = frame->data[0];
         int x, y;
 
         ret = av_frame_copy(frame, s->current_frame);
         if (ret < 0)
             return ret;
 

         // scale up each sample by 8

         for (y = 0; y < avctx->height; y++) {

             // If the image is sufficiently aligned, compute 8 samples at once
             if (!(((uintptr_t)dst) & 7)) {
                 uint64_t *dst64 = (uint64_t *)dst;
                 int w = avctx->width>>1;
                 for (x = 0; x < w; x++) {
                     dst64[x] = (dst64[x] << 3) & 0xFCFCFCFCFCFCFCFCULL;
                 }
                 x *= 8;
             } else
                 x = 0;
             for (; x < avctx->width * 4; x++) {

                 dst[x] = dst[x] << 3;
             }
             dst += frame->linesize[0];
         }
     }
 
     frame->pict_type = frame->key_frame ? AV_PICTURE_TYPE_I : AV_PICTURE_TYPE_P;
 
     FFSWAP(AVFrame *, s->current_frame, s->last_frame);
 
     frame->data[0]     += frame->linesize[0] * (avctx->height - 1);
     frame->linesize[0] *= -1;
 
     *got_frame = 1;
 
     return avpkt->size;
 }
 
 static av_cold int decode_init(AVCodecContext *avctx)
 {
     SCPRContext *s = avctx->priv_data;
 
     switch (avctx->bits_per_coded_sample) {
     case 16: avctx->pix_fmt = AV_PIX_FMT_RGB0; break;
     case 24:
     case 32: avctx->pix_fmt = AV_PIX_FMT_BGR0; break;
     default:
         av_log(avctx, AV_LOG_ERROR, "Unsupported bitdepth %i\n", avctx->bits_per_coded_sample);
         return AVERROR_INVALIDDATA;
     }
 

     s->get_freq = get_freq0;
     s->decode = decode0;
 

     s->cxshift = avctx->bits_per_coded_sample == 16 ? 0 : 2;

     s->cbits = avctx->bits_per_coded_sample == 16 ? 0x1F : 0xFF;

     s->nbx = (avctx->width + 15) / 16;
     s->nby = (avctx->height + 15) / 16;
     s->nbcount = s->nbx * s->nby;
     s->blocks = av_malloc_array(s->nbcount, sizeof(*s->blocks));
     if (!s->blocks)
         return AVERROR(ENOMEM);
 
     s->last_frame = av_frame_alloc();
     s->current_frame = av_frame_alloc();
     if (!s->last_frame || !s->current_frame)
         return AVERROR(ENOMEM);
 
     return 0;
 }
 
 static av_cold int decode_close(AVCodecContext *avctx)
 {
     SCPRContext *s = avctx->priv_data;
 
     av_freep(&s->blocks);
     av_frame_free(&s->last_frame);
     av_frame_free(&s->current_frame);
 
     return 0;
 }
 
 AVCodec ff_scpr_decoder = {
     .name             = "scpr",
     .long_name        = NULL_IF_CONFIG_SMALL("ScreenPressor"),
     .type             = AVMEDIA_TYPE_VIDEO,
     .id               = AV_CODEC_ID_SCPR,
     .priv_data_size   = sizeof(SCPRContext),
     .init             = decode_init,
     .close            = decode_close,
     .decode           = decode_frame,
     .capabilities     = AV_CODEC_CAP_DR1,
     .caps_internal    = FF_CODEC_CAP_INIT_THREADSAFE |
                         FF_CODEC_CAP_INIT_CLEANUP,
 };