/*
  * Wing Commander/Xan 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 libavcodec/xan.c

  * Xan video decoder for Wing Commander III computer game

  * by Mario Brito (mbrito@student.dei.uc.pt)
  * and Mike Melanson (melanson@pcisys.net)

  *

  * The xan_wc3 decoder outputs PAL8 data.

  */
 
 #include <stdio.h>
 #include <stdlib.h>
 #include <string.h>
 #include <unistd.h>
 

 #include "libavutil/intreadwrite.h"

 #include "avcodec.h"
 
 typedef struct XanContext {
 
     AVCodecContext *avctx;
     AVFrame last_frame;
     AVFrame current_frame;
 

     const unsigned char *buf;

     int size;
 
     /* scratch space */
     unsigned char *buffer1;

     int buffer1_size;

     unsigned char *buffer2;

     int buffer2_size;

     int frame_size;

 } XanContext;

 static av_cold int xan_decode_init(AVCodecContext *avctx)

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

     s->frame_size = 0;

     if ((avctx->codec->id == CODEC_ID_XAN_WC3) &&

         (s->avctx->palctrl == NULL)) {

         av_log(avctx, AV_LOG_ERROR, " WC3 Xan video: palette expected.\n");

         return -1;
     }
 

     avctx->pix_fmt = PIX_FMT_PAL8;

     if(avcodec_check_dimensions(avctx, avctx->width, avctx->height))
         return -1;

     s->buffer1_size = avctx->width * avctx->height;
     s->buffer1 = av_malloc(s->buffer1_size);
     s->buffer2_size = avctx->width * avctx->height;
     s->buffer2 = av_malloc(s->buffer2_size);

     if (!s->buffer1 || !s->buffer2)
         return -1;
 
     return 0;
 }
 

 /* This function is used in lieu of memcpy(). This decoder cannot use

  * memcpy because the memory locations often overlap and
  * memcpy doesn't like that; it's not uncommon, for example, for
  * dest = src+1, to turn byte A into  pattern AAAAAAAA.
  * This was originally repz movsb in Intel x86 ASM. */

 static inline void bytecopy(unsigned char *dest, const unsigned char *src, int count)

 {
     int i;
 
     for (i = 0; i < count; i++)
         dest[i] = src[i];
 }
 

 static int xan_huffman_decode(unsigned char *dest, const unsigned char *src,

     int dest_len)

 {
     unsigned char byte = *src++;
     unsigned char ival = byte + 0x16;

     const unsigned char * ptr = src + byte*2;

     unsigned char val = ival;
     int counter = 0;

     unsigned char *dest_end = dest + dest_len;

 
     unsigned char bits = *ptr++;
 
     while ( val != 0x16 ) {
         if ( (1 << counter) & bits )
             val = src[byte + val - 0x17];
         else
             val = src[val - 0x17];
 
         if ( val < 0x16 ) {

             if (dest + 1 > dest_end)
                 return 0;

             *dest++ = val;
             val = ival;
         }
 
         if (counter++ == 7) {
             counter = 0;
             bits = *ptr++;
         }
     }
 
     return 0;
 }
 

 static void xan_unpack(unsigned char *dest, const unsigned char *src, int dest_len)

 {
     unsigned char opcode;
     int size;
     int offset;
     int byte1, byte2, byte3;

     unsigned char *dest_end = dest + dest_len;

 
     for (;;) {
         opcode = *src++;
 
         if ( (opcode & 0x80) == 0 ) {
 
             offset = *src++;
 
             size = opcode & 3;

             if (dest + size > dest_end)
                 return;

             bytecopy(dest, src, size);  dest += size;  src += size;
 
             size = ((opcode & 0x1c) >> 2) + 3;

             if (dest + size > dest_end)
                 return;

             bytecopy (dest, dest - (((opcode & 0x60) << 3) + offset + 1), size);
             dest += size;
 
         } else if ( (opcode & 0x40) == 0 ) {
 
             byte1 = *src++;
             byte2 = *src++;
 
             size = byte1 >> 6;

             if (dest + size > dest_end)
                 return;

             bytecopy (dest, src, size);  dest += size;  src += size;
 
             size = (opcode & 0x3f) + 4;

             if (dest + size > dest_end)
                 return;

             bytecopy (dest, dest - (((byte1 & 0x3f) << 8) + byte2 + 1), size);
             dest += size;
 
         } else if ( (opcode & 0x20) == 0 ) {
 
             byte1 = *src++;
             byte2 = *src++;
             byte3 = *src++;
 
             size = opcode & 3;

             if (dest + size > dest_end)
                 return;

             bytecopy (dest, src, size);  dest += size;  src += size;
 
             size = byte3 + 5 + ((opcode & 0xc) << 6);

             if (dest + size > dest_end)
                 return;

             bytecopy (dest,
                 dest - ((((opcode & 0x10) >> 4) << 0x10) + 1 + (byte1 << 8) + byte2),
                 size);
             dest += size;
         } else {
             size = ((opcode & 0x1f) << 2) + 4;
 
             if (size > 0x70)
                 break;
 

             if (dest + size > dest_end)
                 return;

             bytecopy (dest, src, size);  dest += size;  src += size;
         }
     }
 
     size = opcode & 3;
     bytecopy(dest, src, size);  dest += size;  src += size;
 }
 

 static inline void xan_wc3_output_pixel_run(XanContext *s,

     const unsigned char *pixel_buffer, int x, int y, int pixel_count)

 {
     int stride;
     int line_inc;
     int index;
     int current_x;
     int width = s->avctx->width;

     unsigned char *palette_plane;
 

     palette_plane = s->current_frame.data[0];
     stride = s->current_frame.linesize[0];
     line_inc = stride - width;
     index = y * stride + x;
     current_x = x;
     while((pixel_count--) && (index < s->frame_size)) {
 
         /* don't do a memcpy() here; keyframes generally copy an entire
          * frame of data and the stride needs to be accounted for */
         palette_plane[index++] = *pixel_buffer++;
 
         current_x++;
         if (current_x >= width) {
             index += line_inc;
             current_x = 0;

         }

     }
 }
 

 static inline void xan_wc3_copy_pixel_run(XanContext *s,

     int x, int y, int pixel_count, int motion_x, int motion_y)
 {
     int stride;
     int line_inc;
     int curframe_index, prevframe_index;
     int curframe_x, prevframe_x;
     int width = s->avctx->width;

     unsigned char *palette_plane, *prev_palette_plane;

 
     palette_plane = s->current_frame.data[0];
     prev_palette_plane = s->last_frame.data[0];
     stride = s->current_frame.linesize[0];
     line_inc = stride - width;
     curframe_index = y * stride + x;
     curframe_x = x;
     prevframe_index = (y + motion_y) * stride + x + motion_x;
     prevframe_x = x + motion_x;
     while((pixel_count--) && (curframe_index < s->frame_size)) {
 

         palette_plane[curframe_index++] =

             prev_palette_plane[prevframe_index++];
 
         curframe_x++;
         if (curframe_x >= width) {
             curframe_index += line_inc;
             curframe_x = 0;

         }
 

         prevframe_x++;
         if (prevframe_x >= width) {
             prevframe_index += line_inc;
             prevframe_x = 0;
         }

     }
 }
 
 static void xan_wc3_decode_frame(XanContext *s) {
 
     int width = s->avctx->width;
     int height = s->avctx->height;
     int total_pixels = width * height;
     unsigned char opcode;
     unsigned char flag = 0;
     int size = 0;
     int motion_x, motion_y;
     int x, y;
 

     unsigned char *opcode_buffer = s->buffer1;

     int opcode_buffer_size = s->buffer1_size;

     const unsigned char *imagedata_buffer = s->buffer2;

 
     /* pointers to segments inside the compressed chunk */

     const unsigned char *huffman_segment;
     const unsigned char *size_segment;
     const unsigned char *vector_segment;
     const unsigned char *imagedata_segment;

     huffman_segment =   s->buf + AV_RL16(&s->buf[0]);
     size_segment =      s->buf + AV_RL16(&s->buf[2]);
     vector_segment =    s->buf + AV_RL16(&s->buf[4]);
     imagedata_segment = s->buf + AV_RL16(&s->buf[6]);

     xan_huffman_decode(opcode_buffer, huffman_segment, opcode_buffer_size);

     if (imagedata_segment[0] == 2)

         xan_unpack(s->buffer2, &imagedata_segment[1], s->buffer2_size);

     else

         imagedata_buffer = &imagedata_segment[1];

 
     /* use the decoded data segments to build the frame */
     x = y = 0;
     while (total_pixels) {
 

         opcode = *opcode_buffer++;

         size = 0;
 
         switch (opcode) {
 
         case 0:
             flag ^= 1;
             continue;
 
         case 1:
         case 2:
         case 3:
         case 4:
         case 5:
         case 6:
         case 7:
         case 8:
             size = opcode;
             break;
 
         case 12:
         case 13:
         case 14:
         case 15:
         case 16:
         case 17:
         case 18:
             size += (opcode - 10);
             break;
 
         case 9:
         case 19:
             size = *size_segment++;
             break;
 
         case 10:
         case 20:

             size = AV_RB16(&size_segment[0]);

             size_segment += 2;
             break;
 
         case 11:
         case 21:

             size = AV_RB24(size_segment);

             size_segment += 3;
             break;
         }
 
         if (opcode < 12) {
             flag ^= 1;
             if (flag) {
                 /* run of (size) pixels is unchanged from last frame */
                 xan_wc3_copy_pixel_run(s, x, y, size, 0, 0);
             } else {

                 /* output a run of pixels from imagedata_buffer */
                 xan_wc3_output_pixel_run(s, imagedata_buffer, x, y, size);
                 imagedata_buffer += size;

             }
         } else {
             /* run-based motion compensation from last frame */
             motion_x = (*vector_segment >> 4) & 0xF;
             motion_y = *vector_segment & 0xF;
             vector_segment++;
 
             /* sign extension */
             if (motion_x & 0x8)
                 motion_x |= 0xFFFFFFF0;
             if (motion_y & 0x8)
                 motion_y |= 0xFFFFFFF0;
 
             /* copy a run of pixels from the previous frame */
             xan_wc3_copy_pixel_run(s, x, y, size, motion_x, motion_y);
 
             flag = 0;
         }
 
         /* coordinate accounting */
         total_pixels -= size;
         while (size) {
             if (x + size >= width) {
                 y++;
                 size -= (width - x);
                 x = 0;
             } else {
                 x += size;
                 size = 0;
             }
         }
     }
 }
 
 static void xan_wc4_decode_frame(XanContext *s) {
 }
 
 static int xan_decode_frame(AVCodecContext *avctx,
                             void *data, int *data_size,

                             const uint8_t *buf, int buf_size)

 {
     XanContext *s = avctx->priv_data;

     AVPaletteControl *palette_control = avctx->palctrl;

 
     if (avctx->get_buffer(avctx, &s->current_frame)) {

         av_log(s->avctx, AV_LOG_ERROR, "  Xan Video: get_buffer() failed\n");

         return -1;
     }

     s->current_frame.reference = 3;

     if (!s->frame_size)
         s->frame_size = s->current_frame.linesize[0] * s->avctx->height;
 
     palette_control->palette_changed = 0;

     memcpy(s->current_frame.data[1], palette_control->palette,

         AVPALETTE_SIZE);
     s->current_frame.palette_has_changed = 1;
 

     s->buf = buf;
     s->size = buf_size;
 

     if (avctx->codec->id == CODEC_ID_XAN_WC3)
         xan_wc3_decode_frame(s);
     else if (avctx->codec->id == CODEC_ID_XAN_WC4)

         xan_wc4_decode_frame(s);

     /* release the last frame if it is allocated */
     if (s->last_frame.data[0])
         avctx->release_buffer(avctx, &s->last_frame);
 
     *data_size = sizeof(AVFrame);
     *(AVFrame*)data = s->current_frame;
 

     /* shuffle frames */
     FFSWAP(AVFrame, s->current_frame, s->last_frame);
 

     /* always report that the buffer was completely consumed */
     return buf_size;
 }
 

 static av_cold int xan_decode_end(AVCodecContext *avctx)

 {
     XanContext *s = avctx->priv_data;
 

     /* release the frames */

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

     if (s->current_frame.data[0])
         avctx->release_buffer(avctx, &s->current_frame);

 
     av_free(s->buffer1);
     av_free(s->buffer2);
 
     return 0;
 }
 
 AVCodec xan_wc3_decoder = {
     "xan_wc3",
     CODEC_TYPE_VIDEO,
     CODEC_ID_XAN_WC3,
     sizeof(XanContext),
     xan_decode_init,
     NULL,
     xan_decode_end,
     xan_decode_frame,
     CODEC_CAP_DR1,

     .long_name = NULL_IF_CONFIG_SMALL("Wing Commander III / Xan"),

 };
 
 /*
 AVCodec xan_wc4_decoder = {
     "xan_wc4",
     CODEC_TYPE_VIDEO,
     CODEC_ID_XAN_WC4,
     sizeof(XanContext),
     xan_decode_init,
     NULL,
     xan_decode_end,
     xan_decode_frame,
     CODEC_CAP_DR1,
 };
 */