/*
  * CD Graphics Video Decoder
  * Copyright (c) 2009 Michael Tison
  *
  * 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"
 
 /**

  * @file

  * @brief CD Graphics Video Decoder
  * @author Michael Tison
  * @sa http://wiki.multimedia.cx/index.php?title=CD_Graphics
  * @sa http://www.ccs.neu.edu/home/bchafy/cdb/info/cdg
  */
 
 /// default screen sizes
 #define CDG_FULL_WIDTH           300
 #define CDG_FULL_HEIGHT          216
 #define CDG_DISPLAY_WIDTH        294
 #define CDG_DISPLAY_HEIGHT       204
 #define CDG_BORDER_WIDTH           6
 #define CDG_BORDER_HEIGHT         12
 
 /// masks
 #define CDG_COMMAND             0x09
 #define CDG_MASK                0x3F
 
 /// instruction codes
 #define CDG_INST_MEMORY_PRESET     1
 #define CDG_INST_BORDER_PRESET     2
 #define CDG_INST_TILE_BLOCK        6
 #define CDG_INST_SCROLL_PRESET    20
 #define CDG_INST_SCROLL_COPY      24
 #define CDG_INST_LOAD_PAL_LO      30
 #define CDG_INST_LOAD_PAL_HIGH    31
 #define CDG_INST_TILE_BLOCK_XOR   38
 
 /// data sizes
 #define CDG_PACKET_SIZE           24
 #define CDG_DATA_SIZE             16
 #define CDG_TILE_HEIGHT           12
 #define CDG_TILE_WIDTH             6
 #define CDG_MINIMUM_PKT_SIZE       6
 #define CDG_MINIMUM_SCROLL_SIZE    3
 #define CDG_HEADER_SIZE            8
 #define CDG_PALETTE_SIZE          16
 
 typedef struct CDGraphicsContext {
     AVFrame frame;
     int hscroll;
     int vscroll;
 } CDGraphicsContext;
 
 static void cdg_init_frame(AVFrame *frame)
 {
     avcodec_get_frame_defaults(frame);

     frame->reference = 3;

     frame->buffer_hints = FF_BUFFER_HINTS_VALID    |

                           FF_BUFFER_HINTS_READABLE |

                           FF_BUFFER_HINTS_PRESERVE |
                           FF_BUFFER_HINTS_REUSABLE;
 }
 
 static av_cold int cdg_decode_init(AVCodecContext *avctx)
 {
     CDGraphicsContext *cc = avctx->priv_data;
 
     cdg_init_frame(&cc->frame);
 
     avctx->width   = CDG_FULL_WIDTH;
     avctx->height  = CDG_FULL_HEIGHT;
     avctx->pix_fmt = PIX_FMT_PAL8;
 
     return 0;
 }
 
 static void cdg_border_preset(CDGraphicsContext *cc, uint8_t *data)
 {
     int y;
     int lsize    = cc->frame.linesize[0];
     uint8_t *buf = cc->frame.data[0];
     int color    = data[0] & 0x0F;
 
     if (!(data[1] & 0x0F)) {
         /// fill the top and bottom borders
         memset(buf, color, CDG_BORDER_HEIGHT * lsize);
         memset(buf + (CDG_FULL_HEIGHT - CDG_BORDER_HEIGHT) * lsize,
                color, CDG_BORDER_HEIGHT * lsize);
 
         /// fill the side borders
         for (y = CDG_BORDER_HEIGHT; y < CDG_FULL_HEIGHT - CDG_BORDER_HEIGHT; y++) {
             memset(buf + y * lsize, color, CDG_BORDER_WIDTH);
             memset(buf + CDG_FULL_WIDTH - CDG_BORDER_WIDTH + y * lsize,
                    color, CDG_BORDER_WIDTH);
         }
     }
 }
 
 static void cdg_load_palette(CDGraphicsContext *cc, uint8_t *data, int low)
 {
     uint8_t r, g, b;
     uint16_t color;
     int i;
     int array_offset  = low ? 0 : 8;
     uint32_t *palette = (uint32_t *) cc->frame.data[1];
 
     for (i = 0; i < 8; i++) {
         color = (data[2 * i] << 6) + (data[2 * i + 1] & 0x3F);
         r = ((color >> 8) & 0x000F) * 17;
         g = ((color >> 4) & 0x000F) * 17;
         b = ((color     ) & 0x000F) * 17;
         palette[i + array_offset] = r << 16 | g << 8 | b;
     }
     cc->frame.palette_has_changed = 1;
 }
 
 static int cdg_tile_block(CDGraphicsContext *cc, uint8_t *data, int b)
 {
     unsigned ci, ri;
     int color;
     int x, y;
     int ai;
     int stride   = cc->frame.linesize[0];
     uint8_t *buf = cc->frame.data[0];
 
     ri = (data[2] & 0x1F) * CDG_TILE_HEIGHT + cc->vscroll;
     ci = (data[3] & 0x3F) * CDG_TILE_WIDTH  + cc->hscroll;
 
     if (ri > (CDG_FULL_HEIGHT - CDG_TILE_HEIGHT))
         return AVERROR(EINVAL);
     if (ci > (CDG_FULL_WIDTH - CDG_TILE_WIDTH))
         return AVERROR(EINVAL);
 
     for (y = 0; y < CDG_TILE_HEIGHT; y++) {
         for (x = 0; x < CDG_TILE_WIDTH; x++) {
             if (!((data[4 + y] >> (5 - x)) & 0x01))
                 color = data[0] & 0x0F;
             else
                 color = data[1] & 0x0F;
 
             ai = ci + x + (stride * (ri + y));
             if (b)
                 color ^= buf[ai];
             buf[ai] = color;
         }
     }
 
     return 0;
 }
 
 #define UP    2
 #define DOWN  1
 #define LEFT  2
 #define RIGHT 1
 
 static void cdg_copy_rect_buf(int out_tl_x, int out_tl_y, uint8_t *out,
                               int in_tl_x, int in_tl_y, uint8_t *in,
                               int w, int h, int stride)
 {
     int y;
 
     in  += in_tl_x  + in_tl_y  * stride;
     out += out_tl_x + out_tl_y * stride;
     for (y = 0; y < h; y++)
         memcpy(out + y * stride, in + y * stride, w);
 }
 
 static void cdg_fill_rect_preset(int tl_x, int tl_y, uint8_t *out,
                                  int color, int w, int h, int stride)
 {
     int y;
 
     for (y = tl_y; y < tl_y + h; y++)
         memset(out + tl_x + y * stride, color, w);
 }
 
 static void cdg_fill_wrapper(int out_tl_x, int out_tl_y, uint8_t *out,
                              int in_tl_x, int in_tl_y, uint8_t *in,
                              int color, int w, int h, int stride, int roll)
 {
     if (roll) {
         cdg_copy_rect_buf(out_tl_x, out_tl_y, out, in_tl_x, in_tl_y,
                           in, w, h, stride);
     } else {
         cdg_fill_rect_preset(out_tl_x, out_tl_y, out, color, w, h, stride);
     }
 }
 
 static void cdg_scroll(CDGraphicsContext *cc, uint8_t *data,
                        AVFrame *new_frame, int roll_over)
 {
     int color;
     int hscmd, h_off, hinc, vscmd, v_off, vinc;
     int y;
     int stride   = cc->frame.linesize[0];
     uint8_t *in  = cc->frame.data[0];
     uint8_t *out = new_frame->data[0];
 
     color =  data[0] & 0x0F;
     hscmd = (data[1] & 0x30) >> 4;
     vscmd = (data[2] & 0x30) >> 4;
 
     h_off =  FFMIN(data[1] & 0x07, CDG_BORDER_WIDTH  - 1);
     v_off =  FFMIN(data[2] & 0x07, CDG_BORDER_HEIGHT - 1);
 
     /// find the difference and save the offset for cdg_tile_block usage
     hinc = h_off - cc->hscroll;
     vinc = v_off - cc->vscroll;
     cc->hscroll = h_off;
     cc->vscroll = v_off;
 
     if (vscmd == UP)
         vinc -= 12;
     if (vscmd == DOWN)
         vinc += 12;
     if (hscmd == LEFT)
         hinc -= 6;
     if (hscmd == RIGHT)
         hinc += 6;
 
     if (!hinc && !vinc)
         return;
 
     memcpy(new_frame->data[1], cc->frame.data[1], CDG_PALETTE_SIZE * 4);
 
     for (y = FFMAX(0, vinc); y < FFMIN(CDG_FULL_HEIGHT + vinc, CDG_FULL_HEIGHT); y++)
         memcpy(out + FFMAX(0, hinc) + stride * y,
                in + FFMAX(0, hinc) - hinc + (y - vinc) * stride,
                FFMIN(stride + hinc, stride));
 
     if (vinc > 0)
         cdg_fill_wrapper(0, 0, out,
                          0, CDG_FULL_HEIGHT - vinc, in, color,
                          stride, vinc, stride, roll_over);
     else if (vinc < 0)
         cdg_fill_wrapper(0, CDG_FULL_HEIGHT + vinc, out,
                          0, 0, in, color,
                          stride, -1 * vinc, stride, roll_over);
 
     if (hinc > 0)
         cdg_fill_wrapper(0, 0, out,
                          CDG_FULL_WIDTH - hinc, 0, in, color,
                          hinc, CDG_FULL_HEIGHT, stride, roll_over);
     else if (hinc < 0)
         cdg_fill_wrapper(CDG_FULL_WIDTH + hinc, 0, out,
                          0, 0, in, color,
                          -1 * hinc, CDG_FULL_HEIGHT, stride, roll_over);
 
 }
 
 static int cdg_decode_frame(AVCodecContext *avctx,
                             void *data, int *data_size, AVPacket *avpkt)
 {
     const uint8_t *buf = avpkt->data;
     int buf_size       = avpkt->size;
     int ret;
     uint8_t command, inst;
     uint8_t cdg_data[CDG_DATA_SIZE];
     AVFrame new_frame;
     CDGraphicsContext *cc = avctx->priv_data;
 
     if (buf_size < CDG_MINIMUM_PKT_SIZE) {
         av_log(avctx, AV_LOG_ERROR, "buffer too small for decoder\n");
         return AVERROR(EINVAL);
     }
 
     ret = avctx->reget_buffer(avctx, &cc->frame);
     if (ret) {
         av_log(avctx, AV_LOG_ERROR, "reget_buffer() failed\n");
         return ret;
     }
 
     command = bytestream_get_byte(&buf);
     inst    = bytestream_get_byte(&buf);
     inst    &= CDG_MASK;
     buf += 2;  /// skipping 2 unneeded bytes
     bytestream_get_buffer(&buf, cdg_data, buf_size - CDG_HEADER_SIZE);
 
     if ((command & CDG_MASK) == CDG_COMMAND) {
         switch (inst) {
         case CDG_INST_MEMORY_PRESET:
             if (!(cdg_data[1] & 0x0F))
                 memset(cc->frame.data[0], cdg_data[0] & 0x0F,
                        cc->frame.linesize[0] * CDG_FULL_HEIGHT);
             break;
         case CDG_INST_LOAD_PAL_LO:
         case CDG_INST_LOAD_PAL_HIGH:
             if (buf_size - CDG_HEADER_SIZE < CDG_DATA_SIZE) {
                 av_log(avctx, AV_LOG_ERROR, "buffer too small for loading palette\n");
                 return AVERROR(EINVAL);
             }
 
             cdg_load_palette(cc, cdg_data, inst == CDG_INST_LOAD_PAL_LO);
             break;
         case CDG_INST_BORDER_PRESET:
             cdg_border_preset(cc, cdg_data);
             break;
         case CDG_INST_TILE_BLOCK_XOR:
         case CDG_INST_TILE_BLOCK:
             if (buf_size - CDG_HEADER_SIZE < CDG_DATA_SIZE) {
                 av_log(avctx, AV_LOG_ERROR, "buffer too small for drawing tile\n");
                 return AVERROR(EINVAL);
             }
 
             ret = cdg_tile_block(cc, cdg_data, inst == CDG_INST_TILE_BLOCK_XOR);
             if (ret) {
                 av_log(avctx, AV_LOG_ERROR, "tile is out of range\n");
                 return ret;
             }
             break;
         case CDG_INST_SCROLL_PRESET:
         case CDG_INST_SCROLL_COPY:
             if (buf_size - CDG_HEADER_SIZE < CDG_MINIMUM_SCROLL_SIZE) {
                 av_log(avctx, AV_LOG_ERROR, "buffer too small for scrolling\n");
                 return AVERROR(EINVAL);
             }
 
             cdg_init_frame(&new_frame);
             ret = avctx->get_buffer(avctx, &new_frame);
             if (ret) {
                 av_log(avctx, AV_LOG_ERROR, "get_buffer() failed\n");
                 return ret;
             }
 
             cdg_scroll(cc, cdg_data, &new_frame, inst == CDG_INST_SCROLL_COPY);
             avctx->release_buffer(avctx, &cc->frame);
             cc->frame = new_frame;
             break;
         default:
             break;
         }
 
         *data_size = sizeof(AVFrame);
     } else {
         *data_size = 0;
         buf_size   = 0;
     }
 
     *(AVFrame *) data = cc->frame;
     return buf_size;
 }
 
 static av_cold int cdg_decode_end(AVCodecContext *avctx)
 {
     CDGraphicsContext *cc = avctx->priv_data;
 
     if (cc->frame.data[0])
         avctx->release_buffer(avctx, &cc->frame);
 
     return 0;
 }
 

 AVCodec ff_cdgraphics_decoder = {

     "cdgraphics",

     AVMEDIA_TYPE_VIDEO,

     CODEC_ID_CDGRAPHICS,
     sizeof(CDGraphicsContext),
     cdg_decode_init,
     NULL,
     cdg_decode_end,
     cdg_decode_frame,
     CODEC_CAP_DR1,
     .long_name = NULL_IF_CONFIG_SMALL("CD Graphics video"),
 };