/*
  * 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

  * 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 "libavutil/intreadwrite.h"

 #include "libavutil/mem.h"

 
 #define BITSTREAM_READER_LE

 #include "avcodec.h"

 #include "bytestream.h"

 #include "get_bits.h"

 #include "internal.h"

 #define RUNTIME_GAMMA 0
 

 #define VGA__TAG MKTAG('V', 'G', 'A', ' ')
 #define PALT_TAG MKTAG('P', 'A', 'L', 'T')
 #define SHOT_TAG MKTAG('S', 'H', 'O', 'T')
 #define PALETTE_COUNT 256
 #define PALETTE_SIZE (PALETTE_COUNT * 3)
 #define PALETTES_MAX 256
 

 typedef struct XanContext {
 
     AVCodecContext *avctx;

     AVFrame *last_frame;

     const uint8_t *buf;

     int size;
 
     /* scratch space */

     uint8_t *buffer1;

     int buffer1_size;

     uint8_t *buffer2;

     int buffer2_size;

     unsigned *palettes;
     int palettes_count;
     int cur_palette;
 

     int frame_size;

 } XanContext;

 static av_cold int xan_decode_end(AVCodecContext *avctx)
 {
     XanContext *s = avctx->priv_data;
 
     av_frame_free(&s->last_frame);
 
     av_freep(&s->buffer1);
     av_freep(&s->buffer2);
     av_freep(&s->palettes);
 
     return 0;
 }

 static av_cold int xan_decode_init(AVCodecContext *avctx)

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

     s->frame_size = 0;

     avctx->pix_fmt = AV_PIX_FMT_PAL8;

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

     if (!s->buffer1)

         return AVERROR(ENOMEM);

     s->buffer2_size = avctx->width * avctx->height;

     s->buffer2 = av_malloc(s->buffer2_size + 130);

     if (!s->buffer2) {
         av_freep(&s->buffer1);

         return AVERROR(ENOMEM);

     }

     s->last_frame = av_frame_alloc();
     if (!s->last_frame) {
         xan_decode_end(avctx);
         return AVERROR(ENOMEM);
     }

 
     return 0;
 }
 

 static int xan_huffman_decode(uint8_t *dest, int dest_len,
                               const uint8_t *src, int src_len)

 {

     uint8_t byte = *src++;
     uint8_t ival = byte + 0x16;
     const uint8_t * ptr = src + byte*2;

     int ptr_len = src_len - 1 - byte*2;

     uint8_t val = ival;
     uint8_t *dest_end = dest + dest_len;

     uint8_t *dest_start = dest;

     int ret;

     GetBitContext gb;

     if ((ret = init_get_bits8(&gb, ptr, ptr_len)) < 0)
         return ret;

     while (val != 0x16) {

         unsigned idx;
         if (get_bits_left(&gb) < 1)
             return AVERROR_INVALIDDATA;
         idx = val - 0x17 + get_bits1(&gb) * byte;

         if (idx >= 2 * byte)

             return AVERROR_INVALIDDATA;

         val = src[idx];

         if (val < 0x16) {

             if (dest >= dest_end)

                 return dest_len;

             *dest++ = val;
             val = ival;
         }
     }
 

     return dest - dest_start;

 }
 

 /**
  * unpack simple compression
  *

  * @param dest destination buffer of dest_len, must be padded with at least 130 bytes

  */

 static void xan_unpack(uint8_t *dest, int dest_len,
                        const uint8_t *src, int src_len)

 {

     uint8_t opcode;

     int size;

     uint8_t *dest_org = dest;
     uint8_t *dest_end = dest + dest_len;

     GetByteContext ctx;

     bytestream2_init(&ctx, src, src_len);
     while (dest < dest_end && bytestream2_get_bytes_left(&ctx)) {
         opcode = bytestream2_get_byte(&ctx);

         if (opcode < 0xe0) {

             int size2, back;

             if ((opcode & 0x80) == 0) {

                 size = opcode & 3;

                 back  = ((opcode & 0x60) << 3) + bytestream2_get_byte(&ctx) + 1;

                 size2 = ((opcode & 0x1c) >> 2) + 3;

             } else if ((opcode & 0x40) == 0) {

                 size = bytestream2_peek_byte(&ctx) >> 6;

                 back  = (bytestream2_get_be16(&ctx) & 0x3fff) + 1;

                 size2 = (opcode & 0x3f) + 4;
             } else {
                 size = opcode & 3;

                 back  = ((opcode & 0x10) << 12) + bytestream2_get_be16(&ctx) + 1;
                 size2 = ((opcode & 0x0c) <<  6) + bytestream2_get_byte(&ctx) + 5;

             }

             if (dest_end - dest < size + size2 ||
                 dest + size - dest_org < back ||

                 bytestream2_get_bytes_left(&ctx) < size)

                 return;

             bytestream2_get_buffer(&ctx, dest, size);
             dest += size;

             av_memcpy_backptr(dest, back, size2);
             dest += size2;

         } else {

             int finish = opcode >= 0xfc;
             size = finish ? opcode & 3 : ((opcode & 0x1f) << 2) + 4;

             if (dest_end - dest < size || bytestream2_get_bytes_left(&ctx) < size)

                 return;

             bytestream2_get_buffer(&ctx, dest, size);
             dest += size;

             if (finish)
                 return;

         }
     }
 }
 

 static inline void xan_wc3_output_pixel_run(XanContext *s, AVFrame *frame,

     const uint8_t *pixel_buffer, int x, int y, int pixel_count)

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

     uint8_t *palette_plane;

     palette_plane = frame->data[0];
     stride = frame->linesize[0];

     line_inc = stride - width;
     index = y * stride + x;
     current_x = x;

     while (pixel_count && index < s->frame_size) {

         int count = FFMIN(pixel_count, width - current_x);
         memcpy(palette_plane + index, pixel_buffer, count);
         pixel_count  -= count;
         index        += count;
         pixel_buffer += count;
         current_x    += count;

 
         if (current_x >= width) {
             index += line_inc;
             current_x = 0;

         }

     }
 }
 

 static inline void xan_wc3_copy_pixel_run(XanContext *s, AVFrame *frame,
                                           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;

     uint8_t *palette_plane, *prev_palette_plane;

     if (y + motion_y < 0 || y + motion_y >= s->avctx->height ||
         x + motion_x < 0 || x + motion_x >= s->avctx->width)

         return;
 

     palette_plane = frame->data[0];

     prev_palette_plane = s->last_frame->data[0];

     if (!prev_palette_plane)
         prev_palette_plane = palette_plane;

     stride = 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;

     if (prev_palette_plane == palette_plane && FFABS(motion_x + width*motion_y) < pixel_count) {

          avpriv_request_sample(s->avctx, "Overlapping copy");

          return ;
     }
 

     while (pixel_count &&
            curframe_index  < s->frame_size &&
            prevframe_index < s->frame_size) {
         int count = FFMIN3(pixel_count, width - curframe_x,
                            width - prevframe_x);
 
         memcpy(palette_plane + curframe_index,
                prev_palette_plane + prevframe_index, count);

         pixel_count     -= count;
         curframe_index  += count;
         prevframe_index += count;
         curframe_x      += count;
         prevframe_x     += count;

 
         if (curframe_x >= width) {
             curframe_index += line_inc;
             curframe_x = 0;

         }
 

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

     }
 }
 

 static int xan_wc3_decode_frame(XanContext *s, AVFrame *frame)
 {

     int width  = s->avctx->width;

     int height = s->avctx->height;
     int total_pixels = width * height;

     uint8_t opcode;
     uint8_t flag = 0;

     int size = 0;
     int motion_x, motion_y;

     int x, y, ret;

     uint8_t *opcode_buffer = s->buffer1;
     uint8_t *opcode_buffer_end = s->buffer1 + s->buffer1_size;

     int opcode_buffer_size = s->buffer1_size;

     const uint8_t *imagedata_buffer = s->buffer2;

 
     /* pointers to segments inside the compressed chunk */

     const uint8_t *huffman_segment;

     GetByteContext       size_segment;
     GetByteContext       vector_segment;

     const uint8_t *imagedata_segment;

     int huffman_offset, size_offset, vector_offset, imagedata_offset,
         imagedata_size;

 
     if (s->size < 8)
         return AVERROR_INVALIDDATA;
 
     huffman_offset    = AV_RL16(&s->buf[0]);
     size_offset       = AV_RL16(&s->buf[2]);
     vector_offset     = AV_RL16(&s->buf[4]);
     imagedata_offset  = AV_RL16(&s->buf[6]);

     if (huffman_offset   >= s->size ||
         size_offset      >= s->size ||
         vector_offset    >= s->size ||
         imagedata_offset >= s->size)
         return AVERROR_INVALIDDATA;

     huffman_segment   = s->buf + huffman_offset;

     bytestream2_init(&size_segment,   s->buf + size_offset,   s->size - size_offset);
     bytestream2_init(&vector_segment, s->buf + vector_offset, s->size - vector_offset);

     imagedata_segment = s->buf + imagedata_offset;
 

     if ((ret = xan_huffman_decode(opcode_buffer, opcode_buffer_size,
                                   huffman_segment, s->size - huffman_offset)) < 0)

         return AVERROR_INVALIDDATA;

     opcode_buffer_end = opcode_buffer + ret;

     if (imagedata_segment[0] == 2) {

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

         imagedata_size = s->buffer2_size;
     } else {
         imagedata_size = s->size - imagedata_offset - 1;

         imagedata_buffer = &imagedata_segment[1];

     }

 
     /* use the decoded data segments to build the frame */
     x = y = 0;

     while (total_pixels && opcode_buffer < opcode_buffer_end) {

         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:

             if (bytestream2_get_bytes_left(&size_segment) < 1) {

                 av_log(s->avctx, AV_LOG_ERROR, "size_segment overread\n");
                 return AVERROR_INVALIDDATA;
             }

             size = bytestream2_get_byte(&size_segment);

             break;
 
         case 10:
         case 20:

             if (bytestream2_get_bytes_left(&size_segment) < 2) {

                 av_log(s->avctx, AV_LOG_ERROR, "size_segment overread\n");
                 return AVERROR_INVALIDDATA;
             }

             size = bytestream2_get_be16(&size_segment);

             break;
 
         case 11:
         case 21:

             if (bytestream2_get_bytes_left(&size_segment) < 3) {

                 av_log(s->avctx, AV_LOG_ERROR, "size_segment overread\n");
                 return AVERROR_INVALIDDATA;
             }

             size = bytestream2_get_be24(&size_segment);

             break;
         }

         if (size > total_pixels)
             break;

 
         if (opcode < 12) {
             flag ^= 1;
             if (flag) {
                 /* run of (size) pixels is unchanged from last frame */

                 xan_wc3_copy_pixel_run(s, frame, x, y, size, 0, 0);

             } else {

                 /* output a run of pixels from imagedata_buffer */

                 if (imagedata_size < size)
                     break;

                 xan_wc3_output_pixel_run(s, frame, imagedata_buffer, x, y, size);

                 imagedata_buffer += size;

                 imagedata_size -= size;

             }
         } else {

             uint8_t vector;
             if (bytestream2_get_bytes_left(&vector_segment) <= 0) {

                 av_log(s->avctx, AV_LOG_ERROR, "vector_segment overread\n");
                 return AVERROR_INVALIDDATA;
             }

             /* run-based motion compensation from last frame */

             vector = bytestream2_get_byte(&vector_segment);

             motion_x = sign_extend(vector >> 4,  4);
             motion_y = sign_extend(vector & 0xF, 4);

 
             /* copy a run of pixels from the previous frame */

             xan_wc3_copy_pixel_run(s, frame, x, y, size, motion_x, motion_y);

 
             flag = 0;
         }
 
         /* coordinate accounting */
         total_pixels -= size;

         y += (x + size) / width;
         x  = (x + size) % width;

     }

     return 0;

 }
 

 #if RUNTIME_GAMMA
 static inline unsigned mul(unsigned a, unsigned b)
 {
     return (a * b) >> 16;
 }
 
 static inline unsigned pow4(unsigned a)
 {
     unsigned square = mul(a, a);
     return mul(square, square);
 }
 
 static inline unsigned pow5(unsigned a)
 {
     return mul(pow4(a), a);
 }
 
 static uint8_t gamma_corr(uint8_t in) {
     unsigned lo, hi = 0xff40, target;
     int i = 15;
     in = (in << 2) | (in >> 6);
     /*  equivalent float code:
     if (in >= 252)
         return 253;
     return round(pow(in / 256.0, 0.8) * 256);
     */
     lo = target = in << 8;
     do {
         unsigned mid = (lo + hi) >> 1;
         unsigned pow = pow5(mid);
         if (pow > target) hi = mid;
         else lo = mid;
     } while (--i);
     return (pow4((lo + hi) >> 1) + 0x80) >> 8;
 }
 #else
 /**
  * This is a gamma correction that xan3 applies to all palette entries.
  *
  * There is a peculiarity, namely that the values are clamped to 253 -
  * it seems likely that this table was calculated by a buggy fixed-point
  * implementation, the one above under RUNTIME_GAMMA behaves like this for
  * example.
  * The exponent value of 0.8 can be explained by this as well, since 0.8 = 4/5
  * and thus pow(x, 0.8) is still easy to calculate.
  * Also, the input values are first rotated to the left by 2.
  */

 static const uint8_t gamma_lookup[256] = {
     0x00, 0x09, 0x10, 0x16, 0x1C, 0x21, 0x27, 0x2C,
     0x31, 0x35, 0x3A, 0x3F, 0x43, 0x48, 0x4C, 0x50,
     0x54, 0x59, 0x5D, 0x61, 0x65, 0x69, 0x6D, 0x71,
     0x75, 0x79, 0x7D, 0x80, 0x84, 0x88, 0x8C, 0x8F,
     0x93, 0x97, 0x9A, 0x9E, 0xA2, 0xA5, 0xA9, 0xAC,
     0xB0, 0xB3, 0xB7, 0xBA, 0xBE, 0xC1, 0xC5, 0xC8,
     0xCB, 0xCF, 0xD2, 0xD5, 0xD9, 0xDC, 0xDF, 0xE3,
     0xE6, 0xE9, 0xED, 0xF0, 0xF3, 0xF6, 0xFA, 0xFD,
     0x03, 0x0B, 0x12, 0x18, 0x1D, 0x23, 0x28, 0x2D,
     0x32, 0x36, 0x3B, 0x40, 0x44, 0x49, 0x4D, 0x51,
     0x56, 0x5A, 0x5E, 0x62, 0x66, 0x6A, 0x6E, 0x72,
     0x76, 0x7A, 0x7D, 0x81, 0x85, 0x89, 0x8D, 0x90,
     0x94, 0x98, 0x9B, 0x9F, 0xA2, 0xA6, 0xAA, 0xAD,
     0xB1, 0xB4, 0xB8, 0xBB, 0xBF, 0xC2, 0xC5, 0xC9,
     0xCC, 0xD0, 0xD3, 0xD6, 0xDA, 0xDD, 0xE0, 0xE4,
     0xE7, 0xEA, 0xED, 0xF1, 0xF4, 0xF7, 0xFA, 0xFD,
     0x05, 0x0D, 0x13, 0x19, 0x1F, 0x24, 0x29, 0x2E,
     0x33, 0x38, 0x3C, 0x41, 0x45, 0x4A, 0x4E, 0x52,
     0x57, 0x5B, 0x5F, 0x63, 0x67, 0x6B, 0x6F, 0x73,
     0x77, 0x7B, 0x7E, 0x82, 0x86, 0x8A, 0x8D, 0x91,
     0x95, 0x99, 0x9C, 0xA0, 0xA3, 0xA7, 0xAA, 0xAE,
     0xB2, 0xB5, 0xB9, 0xBC, 0xBF, 0xC3, 0xC6, 0xCA,
     0xCD, 0xD0, 0xD4, 0xD7, 0xDA, 0xDE, 0xE1, 0xE4,
     0xE8, 0xEB, 0xEE, 0xF1, 0xF5, 0xF8, 0xFB, 0xFD,
     0x07, 0x0E, 0x15, 0x1A, 0x20, 0x25, 0x2A, 0x2F,
     0x34, 0x39, 0x3D, 0x42, 0x46, 0x4B, 0x4F, 0x53,
     0x58, 0x5C, 0x60, 0x64, 0x68, 0x6C, 0x70, 0x74,
     0x78, 0x7C, 0x7F, 0x83, 0x87, 0x8B, 0x8E, 0x92,
     0x96, 0x99, 0x9D, 0xA1, 0xA4, 0xA8, 0xAB, 0xAF,
     0xB2, 0xB6, 0xB9, 0xBD, 0xC0, 0xC4, 0xC7, 0xCB,
     0xCE, 0xD1, 0xD5, 0xD8, 0xDB, 0xDF, 0xE2, 0xE5,
     0xE9, 0xEC, 0xEF, 0xF2, 0xF6, 0xF9, 0xFC, 0xFD
 };

 #endif

 static int xan_decode_frame(AVCodecContext *avctx,

                             void *data, int *got_frame,

                             AVPacket *avpkt)

 {

     AVFrame *frame = data;

     const uint8_t *buf = avpkt->data;

     int ret, buf_size = avpkt->size;

     XanContext *s = avctx->priv_data;

     GetByteContext ctx;

     int tag = 0;
 

     bytestream2_init(&ctx, buf, buf_size);
     while (bytestream2_get_bytes_left(&ctx) > 8 && tag != VGA__TAG) {

         unsigned *tmpptr;
         uint32_t new_pal;
         int size;
         int i;

         tag  = bytestream2_get_le32(&ctx);
         size = bytestream2_get_be32(&ctx);

         if (size < 0) {

             av_log(avctx, AV_LOG_ERROR, "Invalid tag size %d\n", size);
             return AVERROR_INVALIDDATA;
         }

         size = FFMIN(size, bytestream2_get_bytes_left(&ctx));

         switch (tag) {
         case PALT_TAG:
             if (size < PALETTE_SIZE)

                 return AVERROR_INVALIDDATA;

             if (s->palettes_count >= PALETTES_MAX)
                 return AVERROR_INVALIDDATA;

             tmpptr = av_realloc_array(s->palettes,
                                       s->palettes_count + 1, AVPALETTE_SIZE);

             if (!tmpptr)
                 return AVERROR(ENOMEM);
             s->palettes = tmpptr;
             tmpptr += s->palettes_count * AVPALETTE_COUNT;
             for (i = 0; i < PALETTE_COUNT; i++) {

 #if RUNTIME_GAMMA

                 int r = gamma_corr(bytestream2_get_byteu(&ctx));
                 int g = gamma_corr(bytestream2_get_byteu(&ctx));
                 int b = gamma_corr(bytestream2_get_byteu(&ctx));

 #else

                 int r = gamma_lookup[bytestream2_get_byteu(&ctx)];
                 int g = gamma_lookup[bytestream2_get_byteu(&ctx)];
                 int b = gamma_lookup[bytestream2_get_byteu(&ctx)];

 #endif

                 *tmpptr++ = (0xFFU << 24) | (r << 16) | (g << 8) | b;

             }

             s->palettes_count++;
             break;
         case SHOT_TAG:
             if (size < 4)
                 return AVERROR_INVALIDDATA;

             new_pal = bytestream2_get_le32(&ctx);

             if (new_pal < s->palettes_count) {
                 s->cur_palette = new_pal;
             } else
                 av_log(avctx, AV_LOG_ERROR, "Invalid palette selected\n");
             break;
         case VGA__TAG:
             break;
         default:

             bytestream2_skip(&ctx, size);

             break;

         }
     }

     buf_size = bytestream2_get_bytes_left(&ctx);

     if (s->palettes_count <= 0) {
         av_log(s->avctx, AV_LOG_ERROR, "No palette found\n");

         return AVERROR_INVALIDDATA;

     }

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

         return ret;

     if (!s->frame_size)

         s->frame_size = frame->linesize[0] * s->avctx->height;

     memcpy(frame->data[1],

            s->palettes + s->cur_palette * AVPALETTE_COUNT, AVPALETTE_SIZE);

     s->buf = ctx.buffer;

     s->size = buf_size;
 

     if (xan_wc3_decode_frame(s, frame) < 0)

         return AVERROR_INVALIDDATA;

     av_frame_unref(s->last_frame);
     if ((ret = av_frame_ref(s->last_frame, frame)) < 0)

         return ret;

     *got_frame = 1;

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

 AVCodec ff_xan_wc3_decoder = {

     .name           = "xan_wc3",

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

     .type           = AVMEDIA_TYPE_VIDEO,

     .id             = AV_CODEC_ID_XAN_WC3,

     .priv_data_size = sizeof(XanContext),
     .init           = xan_decode_init,
     .close          = xan_decode_end,
     .decode         = xan_decode_frame,

     .capabilities   = AV_CODEC_CAP_DR1,

 };