/*
  * Interplay C93 video decoder
  * Copyright (c) 2007 Anssi Hannula <anssi.hannula@gmail.com>
  *
  * 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 "avcodec.h"
 #include "bytestream.h"

 #include "internal.h"

 
 typedef struct {

     AVFrame *pictures[2];

     int currentpic;
 } C93DecoderContext;
 
 typedef enum {
     C93_8X8_FROM_PREV  = 0x02,
     C93_4X4_FROM_PREV  = 0x06,
     C93_4X4_FROM_CURR  = 0x07,
     C93_8X8_2COLOR     = 0x08,
     C93_4X4_2COLOR     = 0x0A,
     C93_4X4_4COLOR_GRP = 0x0B,
     C93_4X4_4COLOR     = 0x0D,
     C93_NOOP           = 0x0E,
     C93_8X8_INTRA      = 0x0F,
 } C93BlockType;
 
 #define WIDTH   320
 #define HEIGHT  192
 
 #define C93_HAS_PALETTE 0x01
 #define C93_FIRST_FRAME 0x02
 

 static av_cold int decode_end(AVCodecContext *avctx)

 {

     C93DecoderContext * const c93 = avctx->priv_data;
 
     av_frame_free(&c93->pictures[0]);
     av_frame_free(&c93->pictures[1]);
 

     return 0;
 }
 

 static av_cold int decode_init(AVCodecContext *avctx)

 {

     C93DecoderContext *s = avctx->priv_data;
     avctx->pix_fmt = AV_PIX_FMT_PAL8;

     s->pictures[0] = av_frame_alloc();
     s->pictures[1] = av_frame_alloc();
     if (!s->pictures[0] || !s->pictures[1]) {
         decode_end(avctx);
         return AVERROR(ENOMEM);
     }

     return 0;
 }
 

 static inline int copy_block(AVCodecContext *avctx, uint8_t *to,

         uint8_t *from, int offset, int height, int stride)
 {
     int i;
     int width = height;
     int from_x = offset % WIDTH;
     int from_y = offset / WIDTH;
     int overflow = from_x + width - WIDTH;
 
     if (!from) {
         /* silently ignoring predictive blocks in first frame */
         return 0;
     }
 
     if (from_y + height > HEIGHT) {
         av_log(avctx, AV_LOG_ERROR, "invalid offset %d during C93 decoding\n",
                offset);

         return AVERROR_INVALIDDATA;

     }
 
     if (overflow > 0) {
         width -= overflow;
         for (i = 0; i < height; i++) {
             memcpy(&to[i*stride+width], &from[(from_y+i)*stride], overflow);
         }
     }
 
     for (i = 0; i < height; i++) {
         memcpy(&to[i*stride], &from[(from_y+i)*stride+from_x], width);
     }
 
     return 0;
 }
 

 static inline void draw_n_color(uint8_t *out, int stride, int width,

          int height, int bpp, uint8_t cols[4], uint8_t grps[4], uint32_t col)
 {
     int x, y;
     for (y = 0; y < height; y++) {
         if (grps)
             cols[0] = grps[3 * (y >> 1)];
         for (x = 0; x < width; x++) {
             if (grps)
                 cols[1]= grps[(x >> 1) + 1];
             out[x + y*stride] = cols[col & ((1 << bpp) - 1)];
             col >>= bpp;
         }
     }
 }
 

 static int decode_frame(AVCodecContext *avctx, void *data,

                         int *got_frame, AVPacket *avpkt)

 {

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

     C93DecoderContext * const c93 = avctx->priv_data;

     AVFrame * const newpic = c93->pictures[c93->currentpic];
     AVFrame * const oldpic = c93->pictures[c93->currentpic^1];

     GetByteContext gb;

     uint8_t *out;

     int stride, ret, i, x, y, b, bt = 0;

     if ((ret = ff_set_dimensions(avctx, WIDTH, HEIGHT)) < 0)
         return ret;

     c93->currentpic ^= 1;
 

     if ((ret = ff_reget_buffer(avctx, newpic)) < 0)

         return ret;

 
     stride = newpic->linesize[0];
 

     bytestream2_init(&gb, buf, buf_size);
     b = bytestream2_get_byte(&gb);
     if (b & C93_FIRST_FRAME) {

         newpic->pict_type = AV_PICTURE_TYPE_I;

         newpic->key_frame = 1;
     } else {

         newpic->pict_type = AV_PICTURE_TYPE_P;

         newpic->key_frame = 0;
     }
 
     for (y = 0; y < HEIGHT; y += 8) {
         out = newpic->data[0] + y * stride;
         for (x = 0; x < WIDTH; x += 8) {
             uint8_t *copy_from = oldpic->data[0];
             unsigned int offset, j;
             uint8_t cols[4], grps[4];

             C93BlockType block_type;

 
             if (!bt)

                 bt = bytestream2_get_byte(&gb);

             block_type= bt & 0x0F;
             switch (block_type) {

             case C93_8X8_FROM_PREV:

                 offset = bytestream2_get_le16(&gb);

                 if ((ret = copy_block(avctx, out, copy_from, offset, 8, stride)) < 0)
                     return ret;

                 break;
 
             case C93_4X4_FROM_CURR:
                 copy_from = newpic->data[0];
             case C93_4X4_FROM_PREV:
                 for (j = 0; j < 8; j += 4) {
                     for (i = 0; i < 8; i += 4) {

                         int offset = bytestream2_get_le16(&gb);
                         int from_x = offset % WIDTH;
                         int from_y = offset / WIDTH;
                         if (block_type == C93_4X4_FROM_CURR && from_y == y+j &&
                             (FFABS(from_x - x-i) < 4 || FFABS(from_x - x-i) > WIDTH-4)) {
                             avpriv_request_sample(avctx, "block overlap %d %d %d %d\n", from_x, x+i, from_y, y+j);
                             return AVERROR_INVALIDDATA;
                         }

                         if ((ret = copy_block(avctx, &out[j*stride+i],
                                               copy_from, offset, 4, stride)) < 0)
                             return ret;

                     }
                 }
                 break;
 
             case C93_8X8_2COLOR:

                 bytestream2_get_buffer(&gb, cols, 2);

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

                     draw_n_color(out + i*stride, stride, 8, 1, 1, cols,

                                      NULL, bytestream2_get_byte(&gb));

                 }
 
                 break;
 
             case C93_4X4_2COLOR:
             case C93_4X4_4COLOR:
             case C93_4X4_4COLOR_GRP:
                 for (j = 0; j < 8; j += 4) {
                     for (i = 0; i < 8; i += 4) {

                         if (block_type == C93_4X4_2COLOR) {

                             bytestream2_get_buffer(&gb, cols, 2);

                             draw_n_color(out + i + j*stride, stride, 4, 4,

                                     1, cols, NULL, bytestream2_get_le16(&gb));

                         } else if (block_type == C93_4X4_4COLOR) {

                             bytestream2_get_buffer(&gb, cols, 4);

                             draw_n_color(out + i + j*stride, stride, 4, 4,

                                     2, cols, NULL, bytestream2_get_le32(&gb));

                         } else {

                             bytestream2_get_buffer(&gb, grps, 4);

                             draw_n_color(out + i + j*stride, stride, 4, 4,

                                     1, cols, grps, bytestream2_get_le16(&gb));

                         }
                     }
                 }
                 break;
 
             case C93_NOOP:
                 break;
 
             case C93_8X8_INTRA:
                 for (j = 0; j < 8; j++)

                     bytestream2_get_buffer(&gb, out + j*stride, 8);

                 break;
 
             default:
                 av_log(avctx, AV_LOG_ERROR, "unexpected type %x at %dx%d\n",

                        block_type, x, y);

                 return AVERROR_INVALIDDATA;

             }
             bt >>= 4;
             out += 8;
         }
     }
 

     if (b & C93_HAS_PALETTE) {
         uint32_t *palette = (uint32_t *) newpic->data[1];
         for (i = 0; i < 256; i++) {

             palette[i] = 0xFFU << 24 | bytestream2_get_be24(&gb);

         }

         newpic->palette_has_changed = 1;

     } else {
         if (oldpic->data[1])
             memcpy(newpic->data[1], oldpic->data[1], 256 * 4);
     }
 

     if ((ret = av_frame_ref(data, newpic)) < 0)
         return ret;

     *got_frame = 1;

 
     return buf_size;
 }
 

 AVCodec ff_c93_decoder = {

     .name           = "c93",

     .long_name      = NULL_IF_CONFIG_SMALL("Interplay C93"),

     .type           = AVMEDIA_TYPE_VIDEO,

     .id             = AV_CODEC_ID_C93,

     .priv_data_size = sizeof(C93DecoderContext),
     .init           = decode_init,
     .close          = decode_end,
     .decode         = decode_frame,
     .capabilities   = CODEC_CAP_DR1,

 };