static int decompress_p(AVCodecContext *avctx,

                        uint32_t *dst, int linesize,

                        uint32_t *prev, int plinesize)

{

    SCPRContext *s = avctx->priv_data;

    GetByteContext *gb = &s->gb;

    int ret, temp, min, max, x, y, cx = 0, cx1 = 0;

    int backstep = linesize - avctx->width;

    const int cxshift = s->cxshift;



    if (bytestream2_get_byte(gb) == 0)

        return 0;

    bytestream2_skip(gb, 1);

    init_rangecoder(&s->rc, gb);



    ret  = decode_value(s, s->range_model, 256, 1, &min);

    ret |= decode_value(s, s->range_model, 256, 1, &temp);

    min += temp << 8;

    ret |= decode_value(s, s->range_model, 256, 1, &max);

    ret |= decode_value(s, s->range_model, 256, 1, &temp);

    if (ret < 0)

        return ret;



    max += temp << 8;

    memset(s->blocks, 0, sizeof(*s->blocks) * s->nbcount);



    while (min <= max) {

        int fill, count;



        ret  = decode_value(s, s->fill_model,  5,   10, &fill);

        ret |= decode_value(s, s->count_model, 256, 20, &count);

        if (ret < 0)

            return ret;



        while (min < s->nbcount && count-- > 0) {

            s->blocks[min++] = fill;

        }

    }



    for (y = 0; y < s->nby; y++) {

        for (x = 0; x < s->nbx; x++) {

            int sy1 = 0, sy2 = 16, sx1 = 0, sx2 = 16;



            if (s->blocks[y * s->nbx + x] == 0)

                continue;



            if (((s->blocks[y * s->nbx + x] - 1) & 1) > 0) {

                ret  = decode_value(s, s->sxy_model[0], 16, 100, &sx1);

                ret |= decode_value(s, s->sxy_model[1], 16, 100, &sy1);

                ret |= decode_value(s, s->sxy_model[2], 16, 100, &sx2);

                ret |= decode_value(s, s->sxy_model[3], 16, 100, &sy2);

                if (ret < 0)

                    return ret;



                sx2++;

                sy2++;

            }

            if (((s->blocks[y * s->nbx + x] - 1) & 2) > 0) {

                int i, j, by = y * 16, bx = x * 16;

                int mvx, mvy;



                ret  = decode_value(s, s->mv_model[0], 512, 100, &mvx);

                ret |= decode_value(s, s->mv_model[1], 512, 100, &mvy);

                if (ret < 0)

                    return ret;



                mvx -= 256;

                mvy -= 256;



                if (by + mvy + sy1 < 0 || bx + mvx + sx1 < 0)

                    return AVERROR_INVALIDDATA;



                for (i = 0; i < sy2 - sy1 && (by + sy1 + i) < avctx->height; i++) {

                    for (j = 0; j < sx2 - sx1 && (bx + sx1 + j) < avctx->width; j++) {

                        dst[(by + i + sy1) * linesize + bx + sx1 + j] = prev[(by + mvy + sy1 + i) * plinesize + bx + sx1 + mvx + j];

                    }

                }

            } else {

                int run, r, g, b, z, bx = x * 16 + sx1, by = y * 16 + sy1;

                unsigned clr, ptype = 0;



                for (; by < y * 16 + sy2 && by < avctx->height;) {

                    ret = decode_value(s, s->op_model[ptype], 6, 1000, &ptype);

                    if (ptype == 0) {

                        ret = decode_unit(s, &s->pixel_model[0][cx + cx1], 400, &r);

                        if (ret < 0)

                            return ret;



                        cx1 = (cx << 6) & 0xFC0;

                        cx = r >> cxshift;

                        ret = decode_unit(s, &s->pixel_model[1][cx + cx1], 400, &g);

                        if (ret < 0)

                            return ret;



                        cx1 = (cx << 6) & 0xFC0;

                        cx = g >> cxshift;

                        ret = decode_unit(s, &s->pixel_model[2][cx + cx1], 400, &b);

                        if (ret < 0)

                            return ret;



                        cx1 = (cx << 6) & 0xFC0;

                        cx = b >> cxshift;

                        clr = (b << 16) + (g << 8) + r;

                    }

                    if (ptype > 5)

                        return AVERROR_INVALIDDATA;

                    ret = decode_value(s, s->run_model[ptype], 256, 400, &run);

                    if (ret < 0)

                        return ret;



                    switch (ptype) {

                    case 0:

                        while (run-- > 0) {

                            if (by >= avctx->height)

                                return AVERROR_INVALIDDATA;



                            dst[by * linesize + bx] = clr;

                            bx++;

                            if (bx >= x * 16 + sx2 || bx >= avctx->width) {

                                bx = x * 16 + sx1;

                                by++;

                            }

                        }

                        break;

                    case 1:

                        while (run-- > 0) {

                            if (bx == 0) {

                                if (by < 1)

                                    return AVERROR_INVALIDDATA;

                                z = backstep;

                            } else {

                                z = 0;

                            }



                            if (by >= avctx->height)

                                return AVERROR_INVALIDDATA;



                            clr = dst[by * linesize + bx - 1 - z];

                            dst[by * linesize + bx] = clr;

                            bx++;

                            if (bx >= x * 16 + sx2 || bx >= avctx->width) {

                                bx = x * 16 + sx1;

                                by++;

                            }

                        }

                        break;

                    case 2:

                        while (run-- > 0) {

                            if (by < 1 || by >= avctx->height)

                                return AVERROR_INVALIDDATA;



                            clr = dst[(by - 1) * linesize + bx];

                            dst[by * linesize + bx] = clr;

                            bx++;

                            if (bx >= x * 16 + sx2 || bx >= avctx->width) {

                                bx = x * 16 + sx1;

                                by++;

                            }

                        }

                        break;

                    case 3:

                        while (run-- > 0) {

                            if (by >= avctx->height)

                                return AVERROR_INVALIDDATA;



                            clr = prev[by * linesize + bx];

                            dst[by * linesize + bx] = clr;

                            bx++;

                            if (bx >= x * 16 + sx2 || bx >= avctx->width) {

                                bx = x * 16 + sx1;

                                by++;

                            }

                        }

                        break;

                    case 4:

                        while (run-- > 0) {

                            uint8_t *odst = (uint8_t *)dst;



                            if (by < 1 || by >= avctx->height)

                                return AVERROR_INVALIDDATA;



                            if (bx == 0) {

                                z = backstep;

                            } else {

                                z = 0;

                            }



                            r = odst[((by - 1) * linesize + bx) * 4] +

                                odst[(by * linesize + bx - 1 - z) * 4] -

                                odst[((by - 1) * linesize + bx - 1 - z) * 4];

                            g = odst[((by - 1) * linesize + bx) * 4 + 1] +

                                odst[(by * linesize + bx - 1 - z) * 4 + 1] -

                                odst[((by - 1) * linesize + bx - 1 - z) * 4 + 1];

                            b = odst[((by - 1) * linesize + bx) * 4 + 2] +

                                odst[(by * linesize + bx - 1 - z) * 4 + 2] -

                                odst[((by - 1) * linesize + bx - 1 - z) * 4 + 2];

                            clr = ((b & 0xFF) << 16) + ((g & 0xFF) << 8) + (r & 0xFF);

                            dst[by * linesize + bx] = clr;

                            bx++;

                            if (bx >= x * 16 + sx2 || bx >= avctx->width) {

                                bx = x * 16 + sx1;

                                by++;

                            }

                        }

                        break;

                    case 5:

                        while (run-- > 0) {

                            if (by < 1 || by >= avctx->height)

                                return AVERROR_INVALIDDATA;



                            if (bx == 0) {

                                z = backstep;

                            } else {

                                z = 0;

                            }



                            clr = dst[(by - 1) * linesize + bx - 1 - z];

                            dst[by * linesize + bx] = clr;

                            bx++;

                            if (bx >= x * 16 + sx2 || bx >= avctx->width) {

                                bx = x * 16 + sx1;

                                by++;

                            }

                        }

                        break;

                    }



                    if (avctx->bits_per_coded_sample == 16) {

                        cx1 = (clr & 0xFF00) >> 2;

                        cx = (clr & 0xFFFFFF) >> 16;

                    } else {

                        cx1 = (clr & 0xFC00) >> 4;

                        cx = (clr & 0xFFFFFF) >> 18;

                    }

                }

            }

        }

    }



    return 0;

}
