/*
  * Interplay MVE Video Decoder
  * Copyright (C) 2003 the ffmpeg project
  *

  * 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

  * Interplay MVE Video Decoder by Mike Melanson (melanson@pcisys.net)

  * For more information about the Interplay MVE format, visit:

  *   http://www.pcisys.net/~melanson/codecs/interplay-mve.txt
  * This code is written in such a way that the identifiers match up
  * with the encoding descriptions in the document.
  *
  * This decoder presently only supports a PAL8 output colorspace.
  *
  * An Interplay video frame consists of 2 parts: The decoding map and
  * the video data. A demuxer must load these 2 parts together in a single
  * buffer before sending it through the stream to this decoder.

  */
 
 #include <stdio.h>
 #include <stdlib.h>
 #include <string.h>
 
 #include "avcodec.h"

 #include "bytestream.h"

 #include "hpeldsp.h"

 #define BITSTREAM_READER_LE

 #include "get_bits.h"

 #include "internal.h"

 #define PALETTE_COUNT 256
 

 typedef struct IpvideoContext {
 
     AVCodecContext *avctx;

     HpelDSPContext hdsp;

     AVFrame *second_last_frame;
     AVFrame *last_frame;

     const unsigned char *decoding_map;

     int decoding_map_size;
 

     int is_16bpp;

     GetByteContext stream_ptr, mv_ptr;

     unsigned char *pixel_ptr;
     int line_inc;
     int stride;
     int upper_motion_limit_offset;
 

     uint32_t pal[256];

 } IpvideoContext;
 

 static int copy_from(IpvideoContext *s, AVFrame *src, AVFrame *dst, int delta_x, int delta_y)

 {

     int current_offset = s->pixel_ptr - dst->data[0];
     int motion_offset = current_offset + delta_y * dst->linesize[0]

                        + delta_x * (1 + s->is_16bpp);

     if (motion_offset < 0) {

         av_log(s->avctx, AV_LOG_ERROR, "motion offset < 0 (%d)\n", motion_offset);

         return AVERROR_INVALIDDATA;

     } else if (motion_offset > s->upper_motion_limit_offset) {

         av_log(s->avctx, AV_LOG_ERROR, "motion offset above limit (%d >= %d)\n",

             motion_offset, s->upper_motion_limit_offset);

         return AVERROR_INVALIDDATA;

     }

     if (src->data[0] == NULL) {
         av_log(s->avctx, AV_LOG_ERROR, "Invalid decode type, corrupted header?\n");
         return AVERROR(EINVAL);
     }

     s->hdsp.put_pixels_tab[!s->is_16bpp][0](s->pixel_ptr, src->data[0] + motion_offset,
                                             dst->linesize[0], 8);

     return 0;
 }
 

 static int ipvideo_decode_block_opcode_0x0(IpvideoContext *s, AVFrame *frame)

 {

     return copy_from(s, s->last_frame, frame, 0, 0);

 }

 static int ipvideo_decode_block_opcode_0x1(IpvideoContext *s, AVFrame *frame)

 {

     return copy_from(s, s->second_last_frame, frame, 0, 0);

 }
 

 static int ipvideo_decode_block_opcode_0x2(IpvideoContext *s, AVFrame *frame)

 {
     unsigned char B;
     int x, y;
 

     /* copy block from 2 frames ago using a motion vector; need 1 more byte */

     if (!s->is_16bpp) {

         B = bytestream2_get_byte(&s->stream_ptr);

     } else {

         B = bytestream2_get_byte(&s->mv_ptr);

     }

 
     if (B < 56) {
         x = 8 + (B % 7);
         y = B / 7;
     } else {
         x = -14 + ((B - 56) % 29);
         y =   8 + ((B - 56) / 29);
     }
 

     av_dlog(s->avctx, "motion byte = %d, (x, y) = (%d, %d)\n", B, x, y);

     return copy_from(s, s->second_last_frame, frame, x, y);

 }
 

 static int ipvideo_decode_block_opcode_0x3(IpvideoContext *s, AVFrame *frame)

 {
     unsigned char B;
     int x, y;
 
     /* copy 8x8 block from current frame from an up/left block */
 
     /* need 1 more byte for motion */

     if (!s->is_16bpp) {

         B = bytestream2_get_byte(&s->stream_ptr);

     } else {

         B = bytestream2_get_byte(&s->mv_ptr);

     }

 
     if (B < 56) {
         x = -(8 + (B % 7));
         y = -(B / 7);
     } else {
         x = -(-14 + ((B - 56) % 29));
         y = -(  8 + ((B - 56) / 29));
     }
 

     av_dlog(s->avctx, "motion byte = %d, (x, y) = (%d, %d)\n", B, x, y);

     return copy_from(s, frame, frame, x, y);

 }
 

 static int ipvideo_decode_block_opcode_0x4(IpvideoContext *s, AVFrame *frame)

 {
     int x, y;
     unsigned char B, BL, BH;
 
     /* copy a block from the previous frame; need 1 more byte */

     if (!s->is_16bpp) {

         B = bytestream2_get_byte(&s->stream_ptr);

     } else {

         B = bytestream2_get_byte(&s->mv_ptr);

     }

 
     BL = B & 0x0F;
     BH = (B >> 4) & 0x0F;
     x = -8 + BL;
     y = -8 + BH;
 

     av_dlog(s->avctx, "motion byte = %d, (x, y) = (%d, %d)\n", B, x, y);

     return copy_from(s, s->last_frame, frame, x, y);

 }
 

 static int ipvideo_decode_block_opcode_0x5(IpvideoContext *s, AVFrame *frame)

 {
     signed char x, y;
 
     /* copy a block from the previous frame using an expanded range;
      * need 2 more bytes */

     x = bytestream2_get_byte(&s->stream_ptr);
     y = bytestream2_get_byte(&s->stream_ptr);

     av_dlog(s->avctx, "motion bytes = %d, %d\n", x, y);

     return copy_from(s, s->last_frame, frame, x, y);

 }
 

 static int ipvideo_decode_block_opcode_0x6(IpvideoContext *s, AVFrame *frame)

 {
     /* mystery opcode? skip multiple blocks? */

     av_log(s->avctx, AV_LOG_ERROR, "Help! Mystery opcode 0x6 seen\n");

 
     /* report success */
     return 0;
 }
 

 static int ipvideo_decode_block_opcode_0x7(IpvideoContext *s, AVFrame *frame)

 {
     int x, y;

     unsigned char P[2];

     unsigned int flags;
 
     /* 2-color encoding */

     P[0] = bytestream2_get_byte(&s->stream_ptr);
     P[1] = bytestream2_get_byte(&s->stream_ptr);

     if (P[0] <= P[1]) {

 
         /* need 8 more bytes from the stream */
         for (y = 0; y < 8; y++) {

             flags = bytestream2_get_byte(&s->stream_ptr) | 0x100;

             for (; flags != 1; flags >>= 1)

                 *s->pixel_ptr++ = P[flags & 1];

             s->pixel_ptr += s->line_inc;

         }
 
     } else {
 
         /* need 2 more bytes from the stream */

         flags = bytestream2_get_le16(&s->stream_ptr);

         for (y = 0; y < 8; y += 2) {

             for (x = 0; x < 8; x += 2, flags >>= 1) {

                 s->pixel_ptr[x                ] =
                 s->pixel_ptr[x + 1            ] =
                 s->pixel_ptr[x +     s->stride] =
                 s->pixel_ptr[x + 1 + s->stride] = P[flags & 1];

             }

             s->pixel_ptr += s->stride * 2;

         }
     }
 
     /* report success */
     return 0;
 }
 

 static int ipvideo_decode_block_opcode_0x8(IpvideoContext *s, AVFrame *frame)

 {
     int x, y;

     unsigned char P[4];

     unsigned int flags = 0;
 
     /* 2-color encoding for each 4x4 quadrant, or 2-color encoding on
      * either top and bottom or left and right halves */

     P[0] = bytestream2_get_byte(&s->stream_ptr);
     P[1] = bytestream2_get_byte(&s->stream_ptr);

 
     if (P[0] <= P[1]) {

         for (y = 0; y < 16; y++) {
             // new values for each 4x4 block
             if (!(y & 3)) {

                 if (y) {
                     P[0]  = bytestream2_get_byte(&s->stream_ptr);
                     P[1]  = bytestream2_get_byte(&s->stream_ptr);
                 }
                 flags = bytestream2_get_le16(&s->stream_ptr);

             }
 

             for (x = 0; x < 4; x++, flags >>= 1)

                 *s->pixel_ptr++ = P[flags & 1];
             s->pixel_ptr += s->stride - 4;
             // switch to right half
             if (y == 7) s->pixel_ptr -= 8 * s->stride - 4;

         }
 
     } else {

         flags = bytestream2_get_le32(&s->stream_ptr);
         P[2] = bytestream2_get_byte(&s->stream_ptr);
         P[3] = bytestream2_get_byte(&s->stream_ptr);

         if (P[2] <= P[3]) {

             /* vertical split; left & right halves are 2-color encoded */
 

             for (y = 0; y < 16; y++) {

                 for (x = 0; x < 4; x++, flags >>= 1)

                     *s->pixel_ptr++ = P[flags & 1];
                 s->pixel_ptr += s->stride - 4;
                 // switch to right half
                 if (y == 7) {
                     s->pixel_ptr -= 8 * s->stride - 4;

                     P[0]  = P[2];
                     P[1]  = P[3];
                     flags = bytestream2_get_le32(&s->stream_ptr);

                 }
             }
 
         } else {
 
             /* horizontal split; top & bottom halves are 2-color encoded */
 
             for (y = 0; y < 8; y++) {

                 if (y == 4) {

                     P[0]  = P[2];
                     P[1]  = P[3];
                     flags = bytestream2_get_le32(&s->stream_ptr);

                 }
 

                 for (x = 0; x < 8; x++, flags >>= 1)

                     *s->pixel_ptr++ = P[flags & 1];

                 s->pixel_ptr += s->line_inc;

             }
         }
     }
 
     /* report success */
     return 0;
 }
 

 static int ipvideo_decode_block_opcode_0x9(IpvideoContext *s, AVFrame *frame)

 {
     int x, y;
     unsigned char P[4];
 
     /* 4-color encoding */

     bytestream2_get_buffer(&s->stream_ptr, P, 4);

     if (P[0] <= P[1]) {
         if (P[2] <= P[3]) {

             /* 1 of 4 colors for each pixel, need 16 more bytes */
             for (y = 0; y < 8; y++) {
                 /* get the next set of 8 2-bit flags */

                 int flags = bytestream2_get_le16(&s->stream_ptr);

                 for (x = 0; x < 8; x++, flags >>= 2)

                     *s->pixel_ptr++ = P[flags & 0x03];
                 s->pixel_ptr += s->line_inc;

             }
 

         } else {

             uint32_t flags;

             /* 1 of 4 colors for each 2x2 block, need 4 more bytes */

             flags = bytestream2_get_le32(&s->stream_ptr);

             for (y = 0; y < 8; y += 2) {
                 for (x = 0; x < 8; x += 2, flags >>= 2) {
                     s->pixel_ptr[x                ] =
                     s->pixel_ptr[x + 1            ] =
                     s->pixel_ptr[x +     s->stride] =
                     s->pixel_ptr[x + 1 + s->stride] = P[flags & 0x03];
                 }
                 s->pixel_ptr += s->stride * 2;

             }
 

         }
     } else {

         uint64_t flags;

         /* 1 of 4 colors for each 2x1 or 1x2 block, need 8 more bytes */

         flags = bytestream2_get_le64(&s->stream_ptr);

         if (P[2] <= P[3]) {

             for (y = 0; y < 8; y++) {
                 for (x = 0; x < 8; x += 2, flags >>= 2) {
                     s->pixel_ptr[x    ] =
                     s->pixel_ptr[x + 1] = P[flags & 0x03];
                 }
                 s->pixel_ptr += s->stride;

             }

         } else {

             for (y = 0; y < 8; y += 2) {
                 for (x = 0; x < 8; x++, flags >>= 2) {
                     s->pixel_ptr[x            ] =
                     s->pixel_ptr[x + s->stride] = P[flags & 0x03];
                 }
                 s->pixel_ptr += s->stride * 2;

             }

         }

     }
 
     /* report success */
     return 0;
 }
 

 static int ipvideo_decode_block_opcode_0xA(IpvideoContext *s, AVFrame *frame)

 {
     int x, y;

     unsigned char P[8];

     int flags = 0;
 

     bytestream2_get_buffer(&s->stream_ptr, P, 4);
 

     /* 4-color encoding for each 4x4 quadrant, or 4-color encoding on
      * either top and bottom or left and right halves */

     if (P[0] <= P[1]) {

         /* 4-color encoding for each quadrant; need 32 bytes */

         for (y = 0; y < 16; y++) {
             // new values for each 4x4 block
             if (!(y & 3)) {

                 if (y) bytestream2_get_buffer(&s->stream_ptr, P, 4);
                 flags = bytestream2_get_le32(&s->stream_ptr);

             }

             for (x = 0; x < 4; x++, flags >>= 2)

                 *s->pixel_ptr++ = P[flags & 0x03];

             s->pixel_ptr += s->stride - 4;
             // switch to right half
             if (y == 7) s->pixel_ptr -= 8 * s->stride - 4;

         }
 
     } else {

         // vertical split?

         int vert;
         uint64_t flags = bytestream2_get_le64(&s->stream_ptr);
 
         bytestream2_get_buffer(&s->stream_ptr, P + 4, 4);
         vert = P[4] <= P[5];

 
         /* 4-color encoding for either left and right or top and bottom

          * halves */

         for (y = 0; y < 16; y++) {
             for (x = 0; x < 4; x++, flags >>= 2)
                 *s->pixel_ptr++ = P[flags & 0x03];

             if (vert) {
                 s->pixel_ptr += s->stride - 4;
                 // switch to right half
                 if (y == 7) s->pixel_ptr -= 8 * s->stride - 4;
             } else if (y & 1) s->pixel_ptr += s->line_inc;

 
             // load values for second half
             if (y == 7) {
                 memcpy(P, P + 4, 4);
                 flags = bytestream2_get_le64(&s->stream_ptr);
             }

         }
     }
 
     /* report success */
     return 0;
 }
 

 static int ipvideo_decode_block_opcode_0xB(IpvideoContext *s, AVFrame *frame)

 {

     int y;

 
     /* 64-color encoding (each pixel in block is a different color) */
     for (y = 0; y < 8; y++) {

         bytestream2_get_buffer(&s->stream_ptr, s->pixel_ptr, 8);

         s->pixel_ptr  += s->stride;

     }
 
     /* report success */
     return 0;
 }
 

 static int ipvideo_decode_block_opcode_0xC(IpvideoContext *s, AVFrame *frame)

 {
     int x, y;
 
     /* 16-color block encoding: each 2x2 block is a different color */
     for (y = 0; y < 8; y += 2) {
         for (x = 0; x < 8; x += 2) {

             s->pixel_ptr[x                ] =
             s->pixel_ptr[x + 1            ] =
             s->pixel_ptr[x +     s->stride] =

             s->pixel_ptr[x + 1 + s->stride] = bytestream2_get_byte(&s->stream_ptr);

         }

         s->pixel_ptr += s->stride * 2;

     }
 
     /* report success */
     return 0;
 }
 

 static int ipvideo_decode_block_opcode_0xD(IpvideoContext *s, AVFrame *frame)

 {

     int y;

     unsigned char P[2];

 
     /* 4-color block encoding: each 4x4 block is a different color */

     for (y = 0; y < 8; y++) {
         if (!(y & 3)) {

             P[0] = bytestream2_get_byte(&s->stream_ptr);
             P[1] = bytestream2_get_byte(&s->stream_ptr);

         }
         memset(s->pixel_ptr,     P[0], 4);
         memset(s->pixel_ptr + 4, P[1], 4);

         s->pixel_ptr += s->stride;

     }
 
     /* report success */
     return 0;
 }
 

 static int ipvideo_decode_block_opcode_0xE(IpvideoContext *s, AVFrame *frame)

 {

     int y;

     unsigned char pix;
 
     /* 1-color encoding: the whole block is 1 solid color */

     pix = bytestream2_get_byte(&s->stream_ptr);

 
     for (y = 0; y < 8; y++) {

         memset(s->pixel_ptr, pix, 8);
         s->pixel_ptr += s->stride;

     }
 
     /* report success */
     return 0;
 }
 

 static int ipvideo_decode_block_opcode_0xF(IpvideoContext *s, AVFrame *frame)

 {
     int x, y;

     unsigned char sample[2];

 
     /* dithered encoding */

     sample[0] = bytestream2_get_byte(&s->stream_ptr);
     sample[1] = bytestream2_get_byte(&s->stream_ptr);

 
     for (y = 0; y < 8; y++) {
         for (x = 0; x < 8; x += 2) {

             *s->pixel_ptr++ = sample[  y & 1 ];
             *s->pixel_ptr++ = sample[!(y & 1)];

         }

         s->pixel_ptr += s->line_inc;

     }
 
     /* report success */
     return 0;
 }
 

 static int ipvideo_decode_block_opcode_0x6_16(IpvideoContext *s, AVFrame *frame)

 {
     signed char x, y;
 
     /* copy a block from the second last frame using an expanded range */

     x = bytestream2_get_byte(&s->stream_ptr);
     y = bytestream2_get_byte(&s->stream_ptr);

     av_dlog(s->avctx, "motion bytes = %d, %d\n", x, y);

     return copy_from(s, s->second_last_frame, frame, x, y);

 }
 

 static int ipvideo_decode_block_opcode_0x7_16(IpvideoContext *s, AVFrame *frame)

 {
     int x, y;
     uint16_t P[2];
     unsigned int flags;
     uint16_t *pixel_ptr = (uint16_t*)s->pixel_ptr;
 
     /* 2-color encoding */

     P[0] = bytestream2_get_le16(&s->stream_ptr);
     P[1] = bytestream2_get_le16(&s->stream_ptr);

 
     if (!(P[0] & 0x8000)) {
 
         for (y = 0; y < 8; y++) {

             flags = bytestream2_get_byte(&s->stream_ptr) | 0x100;

             for (; flags != 1; flags >>= 1)
                 *pixel_ptr++ = P[flags & 1];
             pixel_ptr += s->line_inc;
         }
 
     } else {
 

         flags = bytestream2_get_le16(&s->stream_ptr);

         for (y = 0; y < 8; y += 2) {
             for (x = 0; x < 8; x += 2, flags >>= 1) {
                 pixel_ptr[x                ] =
                 pixel_ptr[x + 1            ] =
                 pixel_ptr[x +     s->stride] =
                 pixel_ptr[x + 1 + s->stride] = P[flags & 1];
             }
             pixel_ptr += s->stride * 2;
         }
     }
 
     return 0;
 }
 

 static int ipvideo_decode_block_opcode_0x8_16(IpvideoContext *s, AVFrame *frame)

 {
     int x, y;

     uint16_t P[4];

     unsigned int flags = 0;
     uint16_t *pixel_ptr = (uint16_t*)s->pixel_ptr;
 
     /* 2-color encoding for each 4x4 quadrant, or 2-color encoding on
      * either top and bottom or left and right halves */

     P[0] = bytestream2_get_le16(&s->stream_ptr);
     P[1] = bytestream2_get_le16(&s->stream_ptr);

 
     if (!(P[0] & 0x8000)) {
 
         for (y = 0; y < 16; y++) {
             // new values for each 4x4 block
             if (!(y & 3)) {

                 if (y) {
                     P[0] = bytestream2_get_le16(&s->stream_ptr);
                     P[1] = bytestream2_get_le16(&s->stream_ptr);
                 }
                 flags = bytestream2_get_le16(&s->stream_ptr);

             }
 
             for (x = 0; x < 4; x++, flags >>= 1)
                 *pixel_ptr++ = P[flags & 1];
             pixel_ptr += s->stride - 4;
             // switch to right half
             if (y == 7) pixel_ptr -= 8 * s->stride - 4;
         }
 
     } else {
 

         flags = bytestream2_get_le32(&s->stream_ptr);
         P[2]  = bytestream2_get_le16(&s->stream_ptr);
         P[3]  = bytestream2_get_le16(&s->stream_ptr);

         if (!(P[2] & 0x8000)) {

 
             /* vertical split; left & right halves are 2-color encoded */
 
             for (y = 0; y < 16; y++) {
                 for (x = 0; x < 4; x++, flags >>= 1)
                     *pixel_ptr++ = P[flags & 1];
                 pixel_ptr += s->stride - 4;
                 // switch to right half
                 if (y == 7) {
                     pixel_ptr -= 8 * s->stride - 4;

                     P[0]  = P[2];
                     P[1]  = P[3];
                     flags = bytestream2_get_le32(&s->stream_ptr);

                 }
             }
 
         } else {
 
             /* horizontal split; top & bottom halves are 2-color encoded */
 
             for (y = 0; y < 8; y++) {
                 if (y == 4) {

                     P[0]  = P[2];
                     P[1]  = P[3];
                     flags = bytestream2_get_le32(&s->stream_ptr);

                 }
 

                 for (x = 0; x < 8; x++, flags >>= 1)

                     *pixel_ptr++ = P[flags & 1];
                 pixel_ptr += s->line_inc;
             }
         }
     }
 
     /* report success */
     return 0;
 }
 

 static int ipvideo_decode_block_opcode_0x9_16(IpvideoContext *s, AVFrame *frame)

 {
     int x, y;
     uint16_t P[4];
     uint16_t *pixel_ptr = (uint16_t*)s->pixel_ptr;
 
     /* 4-color encoding */
     for (x = 0; x < 4; x++)

         P[x] = bytestream2_get_le16(&s->stream_ptr);

 
     if (!(P[0] & 0x8000)) {
         if (!(P[2] & 0x8000)) {
 
             /* 1 of 4 colors for each pixel */
             for (y = 0; y < 8; y++) {
                 /* get the next set of 8 2-bit flags */

                 int flags = bytestream2_get_le16(&s->stream_ptr);

                 for (x = 0; x < 8; x++, flags >>= 2)
                     *pixel_ptr++ = P[flags & 0x03];
                 pixel_ptr += s->line_inc;
             }
 
         } else {
             uint32_t flags;
 
             /* 1 of 4 colors for each 2x2 block */

             flags = bytestream2_get_le32(&s->stream_ptr);

 
             for (y = 0; y < 8; y += 2) {
                 for (x = 0; x < 8; x += 2, flags >>= 2) {
                     pixel_ptr[x                ] =
                     pixel_ptr[x + 1            ] =
                     pixel_ptr[x +     s->stride] =
                     pixel_ptr[x + 1 + s->stride] = P[flags & 0x03];
                 }
                 pixel_ptr += s->stride * 2;
             }
 
         }
     } else {
         uint64_t flags;
 
         /* 1 of 4 colors for each 2x1 or 1x2 block */

         flags = bytestream2_get_le64(&s->stream_ptr);

         if (!(P[2] & 0x8000)) {
             for (y = 0; y < 8; y++) {
                 for (x = 0; x < 8; x += 2, flags >>= 2) {
                     pixel_ptr[x    ] =
                     pixel_ptr[x + 1] = P[flags & 0x03];
                 }
                 pixel_ptr += s->stride;
             }
         } else {
             for (y = 0; y < 8; y += 2) {
                 for (x = 0; x < 8; x++, flags >>= 2) {
                     pixel_ptr[x            ] =
                     pixel_ptr[x + s->stride] = P[flags & 0x03];
                 }
                 pixel_ptr += s->stride * 2;
             }
         }
     }
 
     /* report success */
     return 0;
 }
 

 static int ipvideo_decode_block_opcode_0xA_16(IpvideoContext *s, AVFrame *frame)

 {
     int x, y;

     uint16_t P[8];

     int flags = 0;
     uint16_t *pixel_ptr = (uint16_t*)s->pixel_ptr;
 

     for (x = 0; x < 4; x++)
         P[x] = bytestream2_get_le16(&s->stream_ptr);
 

     /* 4-color encoding for each 4x4 quadrant, or 4-color encoding on
      * either top and bottom or left and right halves */

     if (!(P[0] & 0x8000)) {

 
         /* 4-color encoding for each quadrant */
         for (y = 0; y < 16; y++) {
             // new values for each 4x4 block
             if (!(y & 3)) {

                 if (y)
                     for (x = 0; x < 4; x++)
                         P[x] = bytestream2_get_le16(&s->stream_ptr);
                 flags = bytestream2_get_le32(&s->stream_ptr);

             }
 
             for (x = 0; x < 4; x++, flags >>= 2)
                 *pixel_ptr++ = P[flags & 0x03];
 
             pixel_ptr += s->stride - 4;
             // switch to right half
             if (y == 7) pixel_ptr -= 8 * s->stride - 4;
         }
 
     } else {
         // vertical split?

         int vert;
         uint64_t flags = bytestream2_get_le64(&s->stream_ptr);
 
         for (x = 4; x < 8; x++)
             P[x] = bytestream2_get_le16(&s->stream_ptr);
         vert = !(P[4] & 0x8000);

 
         /* 4-color encoding for either left and right or top and bottom
          * halves */
 
         for (y = 0; y < 16; y++) {
             for (x = 0; x < 4; x++, flags >>= 2)
                 *pixel_ptr++ = P[flags & 0x03];
 
             if (vert) {
                 pixel_ptr += s->stride - 4;
                 // switch to right half
                 if (y == 7) pixel_ptr -= 8 * s->stride - 4;
             } else if (y & 1) pixel_ptr += s->line_inc;

 
             // load values for second half
             if (y == 7) {
                 memcpy(P, P + 4, 8);
                 flags = bytestream2_get_le64(&s->stream_ptr);
             }

         }
     }
 
     /* report success */
     return 0;
 }
 

 static int ipvideo_decode_block_opcode_0xB_16(IpvideoContext *s, AVFrame *frame)

 {
     int x, y;
     uint16_t *pixel_ptr = (uint16_t*)s->pixel_ptr;
 
     /* 64-color encoding (each pixel in block is a different color) */
     for (y = 0; y < 8; y++) {
         for (x = 0; x < 8; x++)

             pixel_ptr[x] = bytestream2_get_le16(&s->stream_ptr);

         pixel_ptr  += s->stride;
     }
 
     /* report success */
     return 0;
 }
 

 static int ipvideo_decode_block_opcode_0xC_16(IpvideoContext *s, AVFrame *frame)

 {
     int x, y;
     uint16_t *pixel_ptr = (uint16_t*)s->pixel_ptr;
 
     /* 16-color block encoding: each 2x2 block is a different color */
     for (y = 0; y < 8; y += 2) {
         for (x = 0; x < 8; x += 2) {
             pixel_ptr[x                ] =
             pixel_ptr[x + 1            ] =
             pixel_ptr[x +     s->stride] =

             pixel_ptr[x + 1 + s->stride] = bytestream2_get_le16(&s->stream_ptr);

         }
         pixel_ptr += s->stride * 2;
     }
 
     /* report success */
     return 0;
 }
 

 static int ipvideo_decode_block_opcode_0xD_16(IpvideoContext *s, AVFrame *frame)

 {
     int x, y;
     uint16_t P[2];
     uint16_t *pixel_ptr = (uint16_t*)s->pixel_ptr;
 
     /* 4-color block encoding: each 4x4 block is a different color */
     for (y = 0; y < 8; y++) {
         if (!(y & 3)) {

             P[0] = bytestream2_get_le16(&s->stream_ptr);
             P[1] = bytestream2_get_le16(&s->stream_ptr);

         }
         for (x = 0; x < 8; x++)
             pixel_ptr[x] = P[x >> 2];
         pixel_ptr += s->stride;
     }
 
     /* report success */
     return 0;
 }
 

 static int ipvideo_decode_block_opcode_0xE_16(IpvideoContext *s, AVFrame *frame)

 {
     int x, y;
     uint16_t pix;
     uint16_t *pixel_ptr = (uint16_t*)s->pixel_ptr;
 
     /* 1-color encoding: the whole block is 1 solid color */

     pix = bytestream2_get_le16(&s->stream_ptr);

 
     for (y = 0; y < 8; y++) {
         for (x = 0; x < 8; x++)
             pixel_ptr[x] = pix;
         pixel_ptr += s->stride;
     }
 
     /* report success */
     return 0;
 }
 

 static int (* const ipvideo_decode_block[])(IpvideoContext *s, AVFrame *frame) = {

     ipvideo_decode_block_opcode_0x0, ipvideo_decode_block_opcode_0x1,
     ipvideo_decode_block_opcode_0x2, ipvideo_decode_block_opcode_0x3,
     ipvideo_decode_block_opcode_0x4, ipvideo_decode_block_opcode_0x5,
     ipvideo_decode_block_opcode_0x6, ipvideo_decode_block_opcode_0x7,
     ipvideo_decode_block_opcode_0x8, ipvideo_decode_block_opcode_0x9,
     ipvideo_decode_block_opcode_0xA, ipvideo_decode_block_opcode_0xB,
     ipvideo_decode_block_opcode_0xC, ipvideo_decode_block_opcode_0xD,
     ipvideo_decode_block_opcode_0xE, ipvideo_decode_block_opcode_0xF,
 };

 static int (* const ipvideo_decode_block16[])(IpvideoContext *s, AVFrame *frame) = {

     ipvideo_decode_block_opcode_0x0,    ipvideo_decode_block_opcode_0x1,
     ipvideo_decode_block_opcode_0x2,    ipvideo_decode_block_opcode_0x3,
     ipvideo_decode_block_opcode_0x4,    ipvideo_decode_block_opcode_0x5,
     ipvideo_decode_block_opcode_0x6_16, ipvideo_decode_block_opcode_0x7_16,
     ipvideo_decode_block_opcode_0x8_16, ipvideo_decode_block_opcode_0x9_16,
     ipvideo_decode_block_opcode_0xA_16, ipvideo_decode_block_opcode_0xB_16,
     ipvideo_decode_block_opcode_0xC_16, ipvideo_decode_block_opcode_0xD_16,
     ipvideo_decode_block_opcode_0xE_16, ipvideo_decode_block_opcode_0x1,
 };
 

 static void ipvideo_decode_opcodes(IpvideoContext *s, AVFrame *frame)

 {
     int x, y;
     unsigned char opcode;
     int ret;

     GetBitContext gb;

     bytestream2_skip(&s->stream_ptr, 14); /* data starts 14 bytes in */

     if (!s->is_16bpp) {

         /* this is PAL8, so make the palette available */

         memcpy(frame->data[1], s->pal, AVPALETTE_SIZE);

         s->stride = frame->linesize[0];

     } else {

         s->stride = frame->linesize[0] >> 1;

         s->mv_ptr = s->stream_ptr;
         bytestream2_skip(&s->mv_ptr, bytestream2_get_le16(&s->stream_ptr));

     }

     s->line_inc = s->stride - 8;

     s->upper_motion_limit_offset = (s->avctx->height - 8) * frame->linesize[0]

                                   + (s->avctx->width - 8) * (1 + s->is_16bpp);

     init_get_bits(&gb, s->decoding_map, s->decoding_map_size * 8);

     for (y = 0; y < s->avctx->height; y += 8) {
         for (x = 0; x < s->avctx->width; x += 8) {

             opcode = get_bits(&gb, 4);

             av_dlog(s->avctx,
                     "  block @ (%3d, %3d): encoding 0x%X, data ptr offset %d\n",
                     x, y, opcode, bytestream2_tell(&s->stream_ptr));

             if (!s->is_16bpp) {

                 s->pixel_ptr = frame->data[0] + x
                               + y*frame->linesize[0];
                 ret = ipvideo_decode_block[opcode](s, frame);

             } else {

                 s->pixel_ptr = frame->data[0] + x*2
                               + y*frame->linesize[0];
                 ret = ipvideo_decode_block16[opcode](s, frame);

             }

             if (ret != 0) {

                 av_log(s->avctx, AV_LOG_ERROR, "decode problem on frame %d, @ block (%d, %d)\n",

                        s->avctx->frame_number, x, y);

                 return;

             }
         }
     }

     if (bytestream2_get_bytes_left(&s->stream_ptr) > 1) {
         av_log(s->avctx, AV_LOG_ERROR,

                "decode finished with %d bytes left over\n",

                bytestream2_get_bytes_left(&s->stream_ptr));

     }

 }
 

 static av_cold int ipvideo_decode_init(AVCodecContext *avctx)

 {
     IpvideoContext *s = avctx->priv_data;
 
     s->avctx = avctx;

     s->is_16bpp = avctx->bits_per_coded_sample == 16;

     avctx->pix_fmt = s->is_16bpp ? AV_PIX_FMT_RGB555 : AV_PIX_FMT_PAL8;

     ff_hpeldsp_init(&s->hdsp, avctx->flags);

     s->last_frame        = av_frame_alloc();
     s->second_last_frame = av_frame_alloc();
     if (!s->last_frame || !s->second_last_frame) {
         av_frame_free(&s->last_frame);
         av_frame_free(&s->second_last_frame);
         return AVERROR(ENOMEM);
     }

     return 0;
 }
 
 static int ipvideo_decode_frame(AVCodecContext *avctx,

                                 void *data, int *got_frame,

                                 AVPacket *avpkt)

 {

     const uint8_t *buf = avpkt->data;
     int buf_size = avpkt->size;

     IpvideoContext *s = avctx->priv_data;

     AVFrame *frame = data;

     int ret;

     /* decoding map contains 4 bits of information per 8x8 block */
     s->decoding_map_size = avctx->width * avctx->height / (8 * 8 * 2);
 

     /* compressed buffer needs to be large enough to at least hold an entire
      * decoding map */
     if (buf_size < s->decoding_map_size)
         return buf_size;
 

     if (av_packet_get_side_data(avpkt, AV_PKT_DATA_PARAM_CHANGE, NULL)) {
         av_frame_unref(s->last_frame);
         av_frame_unref(s->second_last_frame);

     }
 

     s->decoding_map = buf;

     bytestream2_init(&s->stream_ptr, buf + s->decoding_map_size,
                      buf_size - s->decoding_map_size);

     if ((ret = ff_get_buffer(avctx, frame, AV_GET_BUFFER_FLAG_REF)) < 0)

         return ret;

     if (!s->is_16bpp) {
         const uint8_t *pal = av_packet_get_side_data(avpkt, AV_PKT_DATA_PALETTE, NULL);
         if (pal) {

             frame->palette_has_changed = 1;

             memcpy(s->pal, pal, AVPALETTE_SIZE);
         }

     }
 

     ipvideo_decode_opcodes(s, frame);

     *got_frame = 1;

     /* shuffle frames */

     av_frame_unref(s->second_last_frame);
     FFSWAP(AVFrame*, s->second_last_frame, s->last_frame);
     if ((ret = av_frame_ref(s->last_frame, frame)) < 0)
         return ret;

     /* report that the buffer was completely consumed */

     return buf_size;
 }
 

 static av_cold int ipvideo_decode_end(AVCodecContext *avctx)

 {
     IpvideoContext *s = avctx->priv_data;
 

     av_frame_free(&s->last_frame);
     av_frame_free(&s->second_last_frame);

 
     return 0;
 }
 

 AVCodec ff_interplay_video_decoder = {

     .name           = "interplayvideo",

     .long_name      = NULL_IF_CONFIG_SMALL("Interplay MVE video"),

     .type           = AVMEDIA_TYPE_VIDEO,

     .id             = AV_CODEC_ID_INTERPLAY_VIDEO,

     .priv_data_size = sizeof(IpvideoContext),
     .init           = ipvideo_decode_init,
     .close          = ipvideo_decode_end,
     .decode         = ipvideo_decode_frame,

     .capabilities   = CODEC_CAP_DR1 | CODEC_CAP_PARAM_CHANGE,

 };