static int flic_decode_frame_8BPP(AVCodecContext *avctx,

                                  void *data, int *data_size,

                                  const uint8_t *buf, int buf_size)

{

    FlicDecodeContext *s = avctx->priv_data;



    int stream_ptr = 0;

    int pixel_ptr;

    int palette_ptr;

    unsigned char palette_idx1;

    unsigned char palette_idx2;



    unsigned int frame_size;

    int num_chunks;



    unsigned int chunk_size;

    int chunk_type;



    int i, j;



    int color_packets;

    int color_changes;

    int color_shift;

    unsigned char r, g, b;



    int lines;

    int compressed_lines;

    int starting_line;

    signed short line_packets;

    int y_ptr;

    int byte_run;

    int pixel_skip;

    int pixel_countdown;

    unsigned char *pixels;

    unsigned int pixel_limit;



    s->frame.reference = 3;

    s->frame.buffer_hints = FF_BUFFER_HINTS_VALID | FF_BUFFER_HINTS_PRESERVE | FF_BUFFER_HINTS_REUSABLE;

    if (avctx->reget_buffer(avctx, &s->frame) < 0) {

        av_log(avctx, AV_LOG_ERROR, "reget_buffer() failed\n");

        return -1;

    }



    pixels = s->frame.data[0];

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



    if (buf_size < 16 || buf_size > INT_MAX - (3 * 256 + FF_INPUT_BUFFER_PADDING_SIZE))

        return AVERROR_INVALIDDATA;

    frame_size = AV_RL32(&buf[stream_ptr]);

    if (frame_size > buf_size)

        frame_size = buf_size;

    stream_ptr += 6;  /* skip the magic number */

    num_chunks = AV_RL16(&buf[stream_ptr]);

    stream_ptr += 10;  /* skip padding */



    frame_size -= 16;



    /* iterate through the chunks */

    while ((frame_size >= 6) && (num_chunks > 0)) {

        int stream_ptr_after_chunk;

        chunk_size = AV_RL32(&buf[stream_ptr]);

        if (chunk_size > frame_size) {

            av_log(avctx, AV_LOG_WARNING,

                   "Invalid chunk_size = %u > frame_size = %u\n", chunk_size, frame_size);

            chunk_size = frame_size;

        }

        stream_ptr_after_chunk = stream_ptr + chunk_size;



        stream_ptr += 4;

        chunk_type = AV_RL16(&buf[stream_ptr]);

        stream_ptr += 2;



        switch (chunk_type) {

        case FLI_256_COLOR:

        case FLI_COLOR:

            /* check special case: If this file is from the Magic Carpet

             * game and uses 6-bit colors even though it reports 256-color

             * chunks in a 0xAF12-type file (fli_type is set to 0xAF13 during

             * initialization) */

            if ((chunk_type == FLI_256_COLOR) && (s->fli_type != FLC_MAGIC_CARPET_SYNTHETIC_TYPE_CODE))

                color_shift = 0;

            else

                color_shift = 2;

            /* set up the palette */

            color_packets = AV_RL16(&buf[stream_ptr]);

            stream_ptr += 2;

            palette_ptr = 0;

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

                /* first byte is how many colors to skip */

                palette_ptr += buf[stream_ptr++];



                /* next byte indicates how many entries to change */

                color_changes = buf[stream_ptr++];



                /* if there are 0 color changes, there are actually 256 */

                if (color_changes == 0)

                    color_changes = 256;



                if (stream_ptr + color_changes * 3 > stream_ptr_after_chunk)

                    break;



                for (j = 0; j < color_changes; j++) {

                    unsigned int entry;



                    /* wrap around, for good measure */

                    if ((unsigned)palette_ptr >= 256)

                        palette_ptr = 0;



                    r = buf[stream_ptr++] << color_shift;

                    g = buf[stream_ptr++] << color_shift;

                    b = buf[stream_ptr++] << color_shift;

                    entry = 0xFF << 24 | r << 16 | g << 8 | b;

                    if (color_shift == 2)

                        entry |= entry >> 6 & 0x30303;

                    if (s->palette[palette_ptr] != entry)

                        s->new_palette = 1;

                    s->palette[palette_ptr++] = entry;

                }

            }

            break;



        case FLI_DELTA:

            y_ptr = 0;

            compressed_lines = AV_RL16(&buf[stream_ptr]);

            stream_ptr += 2;

            while (compressed_lines > 0) {

                if (stream_ptr + 2 > stream_ptr_after_chunk)

                    break;

                line_packets = AV_RL16(&buf[stream_ptr]);

                stream_ptr += 2;

                if ((line_packets & 0xC000) == 0xC000) {

                    // line skip opcode

                    line_packets = -line_packets;

                    y_ptr += line_packets * s->frame.linesize[0];

                } else if ((line_packets & 0xC000) == 0x4000) {

                    av_log(avctx, AV_LOG_ERROR, "Undefined opcode (%x) in DELTA_FLI\n", line_packets);

                } else if ((line_packets & 0xC000) == 0x8000) {

                    // "last byte" opcode

                    pixel_ptr= y_ptr + s->frame.linesize[0] - 1;

                    CHECK_PIXEL_PTR(0);

                    pixels[pixel_ptr] = line_packets & 0xff;

                } else {

                    compressed_lines--;

                    pixel_ptr = y_ptr;

                    CHECK_PIXEL_PTR(0);

                    pixel_countdown = s->avctx->width;

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

                        if (stream_ptr + 2 > stream_ptr_after_chunk)

                            break;

                        /* account for the skip bytes */

                        pixel_skip = buf[stream_ptr++];

                        pixel_ptr += pixel_skip;

                        pixel_countdown -= pixel_skip;

                        byte_run = (signed char)(buf[stream_ptr++]);

                        if (byte_run < 0) {

                            byte_run = -byte_run;

                            palette_idx1 = buf[stream_ptr++];

                            palette_idx2 = buf[stream_ptr++];

                            CHECK_PIXEL_PTR(byte_run * 2);

                            for (j = 0; j < byte_run; j++, pixel_countdown -= 2) {

                                pixels[pixel_ptr++] = palette_idx1;

                                pixels[pixel_ptr++] = palette_idx2;

                            }

                        } else {

                            CHECK_PIXEL_PTR(byte_run * 2);

                            if (stream_ptr + byte_run * 2 > stream_ptr_after_chunk)

                                break;

                            for (j = 0; j < byte_run * 2; j++, pixel_countdown--) {

                                palette_idx1 = buf[stream_ptr++];

                                pixels[pixel_ptr++] = palette_idx1;

                            }

                        }

                    }



                    y_ptr += s->frame.linesize[0];

                }

            }

            break;



        case FLI_LC:

            /* line compressed */

            starting_line = AV_RL16(&buf[stream_ptr]);

            stream_ptr += 2;

            y_ptr = 0;

            y_ptr += starting_line * s->frame.linesize[0];



            compressed_lines = AV_RL16(&buf[stream_ptr]);

            stream_ptr += 2;

            while (compressed_lines > 0) {

                pixel_ptr = y_ptr;

                CHECK_PIXEL_PTR(0);

                pixel_countdown = s->avctx->width;

                line_packets = buf[stream_ptr++];

                if (stream_ptr + 2 * line_packets > stream_ptr_after_chunk)

                    break;

                if (line_packets > 0) {

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

                        /* account for the skip bytes */

                        pixel_skip = buf[stream_ptr++];

                        pixel_ptr += pixel_skip;

                        pixel_countdown -= pixel_skip;

                        byte_run = (signed char)(buf[stream_ptr++]);

                        if (byte_run > 0) {

                            CHECK_PIXEL_PTR(byte_run);

                            if (stream_ptr + byte_run > stream_ptr_after_chunk)

                                break;

                            for (j = 0; j < byte_run; j++, pixel_countdown--) {

                                palette_idx1 = buf[stream_ptr++];

                                pixels[pixel_ptr++] = palette_idx1;

                            }

                        } else if (byte_run < 0) {

                            byte_run = -byte_run;

                            palette_idx1 = buf[stream_ptr++];

                            CHECK_PIXEL_PTR(byte_run);

                            for (j = 0; j < byte_run; j++, pixel_countdown--) {

                                pixels[pixel_ptr++] = palette_idx1;

                            }

                        }

                    }

                }



                y_ptr += s->frame.linesize[0];

                compressed_lines--;

            }

            break;



        case FLI_BLACK:

            /* set the whole frame to color 0 (which is usually black) */

            memset(pixels, 0,

                s->frame.linesize[0] * s->avctx->height);

            break;



        case FLI_BRUN:

            /* Byte run compression: This chunk type only occurs in the first

             * FLI frame and it will update the entire frame. */

            y_ptr = 0;

            for (lines = 0; lines < s->avctx->height; lines++) {

                pixel_ptr = y_ptr;

                /* disregard the line packets; instead, iterate through all

                 * pixels on a row */

                stream_ptr++;

                pixel_countdown = s->avctx->width;

                while (pixel_countdown > 0) {

                    if (stream_ptr + 1 > stream_ptr_after_chunk)

                        break;

                    byte_run = (signed char)(buf[stream_ptr++]);

                    if (byte_run > 0) {

                        palette_idx1 = buf[stream_ptr++];

                        CHECK_PIXEL_PTR(byte_run);

                        for (j = 0; j < byte_run; j++) {

                            pixels[pixel_ptr++] = palette_idx1;

                            pixel_countdown--;

                            if (pixel_countdown < 0)

                                av_log(avctx, AV_LOG_ERROR, "pixel_countdown < 0 (%d) at line %d\n",

                                       pixel_countdown, lines);

                        }

                    } else {  /* copy bytes if byte_run < 0 */

                        byte_run = -byte_run;

                        CHECK_PIXEL_PTR(byte_run);

                        if (stream_ptr + byte_run > stream_ptr_after_chunk)

                            break;

                        for (j = 0; j < byte_run; j++) {

                            palette_idx1 = buf[stream_ptr++];

                            pixels[pixel_ptr++] = palette_idx1;

                            pixel_countdown--;

                            if (pixel_countdown < 0)

                                av_log(avctx, AV_LOG_ERROR, "pixel_countdown < 0 (%d) at line %d\n",

                                       pixel_countdown, lines);

                        }

                    }

                }



                y_ptr += s->frame.linesize[0];

            }

            break;



        case FLI_COPY:

            /* copy the chunk (uncompressed frame) */

            if (chunk_size - 6 != s->avctx->width * s->avctx->height) {

                av_log(avctx, AV_LOG_ERROR, "In chunk FLI_COPY : source data (%d bytes) " \

                       "has incorrect size, skipping chunk\n", chunk_size - 6);

            } else {

                for (y_ptr = 0; y_ptr < s->frame.linesize[0] * s->avctx->height;

                     y_ptr += s->frame.linesize[0]) {

                    memcpy(&pixels[y_ptr], &buf[stream_ptr],

                        s->avctx->width);

                    stream_ptr += s->avctx->width;

                }

            }

            break;



        case FLI_MINI:

            /* some sort of a thumbnail? disregard this chunk... */

            break;



        default:

            av_log(avctx, AV_LOG_ERROR, "Unrecognized chunk type: %d\n", chunk_type);

            break;

        }



        stream_ptr = stream_ptr_after_chunk;



        frame_size -= chunk_size;

        num_chunks--;

    }



    /* by the end of the chunk, the stream ptr should equal the frame

     * size (minus 1, possibly); if it doesn't, issue a warning */

    if ((stream_ptr != buf_size) && (stream_ptr != buf_size - 1))

        av_log(avctx, AV_LOG_ERROR, "Processed FLI chunk where chunk size = %d " \

               "and final chunk ptr = %d\n", buf_size, stream_ptr);



    /* make the palette available on the way out */

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

    if (s->new_palette) {

        s->frame.palette_has_changed = 1;

        s->new_palette = 0;

    }



    *data_size=sizeof(AVFrame);

    *(AVFrame*)data = s->frame;



    return buf_size;

}
