static int jp2_find_codestream(Jpeg2000DecoderContext *s)
{
    uint32_t atom_size, atom, atom_end;
    int search_range = 10;

    while (search_range
           &&
           bytestream2_get_bytes_left(&s->g) >= 8) {
        atom_size = bytestream2_get_be32u(&s->g);
        atom      = bytestream2_get_be32u(&s->g);
        atom_end  = bytestream2_tell(&s->g) + atom_size - 8;

        if (atom == JP2_CODESTREAM)
            return 1;

        if (bytestream2_get_bytes_left(&s->g) < atom_size || atom_end < atom_size)
            return 0;

        if (atom == JP2_HEADER &&
                   atom_size >= 16) {
            uint32_t atom2_size, atom2, atom2_end;
            do {
                atom2_size = bytestream2_get_be32u(&s->g);
                atom2      = bytestream2_get_be32u(&s->g);
                atom2_end  = bytestream2_tell(&s->g) + atom2_size - 8;
                if (atom2_size < 8 || atom2_end > atom_end || atom2_end < atom2_size)
                    break;
                if (atom2 == JP2_CODESTREAM) {
                    return 1;
                } else if (atom2 == MKBETAG('c','o','l','r') && atom2_size >= 7) {
                    int method = bytestream2_get_byteu(&s->g);
                    bytestream2_skipu(&s->g, 2);
                    if (method == 1) {
                        s->colour_space = bytestream2_get_be32u(&s->g);
                    }
                } else if (atom2 == MKBETAG('p','c','l','r') && atom2_size >= 6) {
                    int i, size, colour_count, colour_channels, colour_depth[3];
                    uint32_t r, g, b;
                    colour_count = bytestream2_get_be16u(&s->g);
                    colour_channels = bytestream2_get_byteu(&s->g);
                    // FIXME: Do not ignore channel_sign
                    colour_depth[0] = (bytestream2_get_byteu(&s->g) & 0x7f) + 1;
                    colour_depth[1] = (bytestream2_get_byteu(&s->g) & 0x7f) + 1;
                    colour_depth[2] = (bytestream2_get_byteu(&s->g) & 0x7f) + 1;
                    size = (colour_depth[0] + 7 >> 3) * colour_count +
                           (colour_depth[1] + 7 >> 3) * colour_count +
                           (colour_depth[2] + 7 >> 3) * colour_count;
                    if (colour_count > 256   ||
                        colour_channels != 3 ||
                        colour_depth[0] > 16 ||
                        colour_depth[1] > 16 ||
                        colour_depth[2] > 16 ||
                        atom2_size < size) {
                        avpriv_request_sample(s->avctx, "Unknown palette");
                        bytestream2_seek(&s->g, atom2_end, SEEK_SET);
                        continue;
                    }
                    s->pal8 = 1;
                    for (i = 0; i < colour_count; i++) {
                        if (colour_depth[0] <= 8) {
                            r = bytestream2_get_byteu(&s->g) << 8 - colour_depth[0];
                            r |= r >> colour_depth[0];
                        } else {
                            r = bytestream2_get_be16u(&s->g) >> colour_depth[0] - 8;
                        }
                        if (colour_depth[1] <= 8) {
                            g = bytestream2_get_byteu(&s->g) << 8 - colour_depth[1];
                            r |= r >> colour_depth[1];
                        } else {
                            g = bytestream2_get_be16u(&s->g) >> colour_depth[1] - 8;
                        }
                        if (colour_depth[2] <= 8) {
                            b = bytestream2_get_byteu(&s->g) << 8 - colour_depth[2];
                            r |= r >> colour_depth[2];
                        } else {
                            b = bytestream2_get_be16u(&s->g) >> colour_depth[2] - 8;
                        }
                        s->palette[i] = 0xffu << 24 | r << 16 | g << 8 | b;
                    }
                } else if (atom2 == MKBETAG('c','d','e','f') && atom2_size >= 2) {
                    int n = bytestream2_get_be16u(&s->g);
                    for (; n>0; n--) {
                        int cn   = bytestream2_get_be16(&s->g);
                        int av_unused typ  = bytestream2_get_be16(&s->g);
                        int asoc = bytestream2_get_be16(&s->g);
                        if (cn < 4 || asoc < 4)
                            s->cdef[cn] = asoc;
                    }
                }
                bytestream2_seek(&s->g, atom2_end, SEEK_SET);
            } while (atom_end - atom2_end >= 8);
        } else {
            search_range--;
        }
        bytestream2_seek(&s->g, atom_end, SEEK_SET);
    }

    return 0;
}
static int jp2_find_codestream(Jpeg2000DecoderContext *s)
{
    uint32_t atom_size, atom, atom_end;
    int search_range = 10;

    while (search_range
           &&
           bytestream2_get_bytes_left(&s->g) >= 8) {
        atom_size = bytestream2_get_be32u(&s->g);
        atom      = bytestream2_get_be32u(&s->g);
        atom_end  = bytestream2_tell(&s->g) + atom_size - 8;

        if (atom == JP2_CODESTREAM)
            return 1;

        if (bytestream2_get_bytes_left(&s->g) < atom_size || atom_end < atom_size)
            return 0;

        if (atom == JP2_HEADER &&
                   atom_size >= 16) {
            uint32_t atom2_size, atom2, atom2_end;
            do {
                atom2_size = bytestream2_get_be32u(&s->g);
                atom2      = bytestream2_get_be32u(&s->g);
                atom2_end  = bytestream2_tell(&s->g) + atom2_size - 8;
                if (atom2_size < 8 || atom2_end > atom_end || atom2_end < atom2_size)
                    break;
                if (atom2 == JP2_CODESTREAM) {
                    return 1;
                } else if (atom2 == MKBETAG('c','o','l','r') && atom2_size >= 7) {
                    int method = bytestream2_get_byteu(&s->g);
                    bytestream2_skipu(&s->g, 2);
                    if (method == 1) {
                        s->colour_space = bytestream2_get_be32u(&s->g);
                    }
                } else if (atom2 == MKBETAG('p','c','l','r') && atom2_size >= 6) {
                    int i, size, colour_count, colour_channels, colour_depth[3];
                    uint32_t r, g, b;
                    colour_count = bytestream2_get_be16u(&s->g);
                    colour_channels = bytestream2_get_byteu(&s->g);
                     
                    colour_depth[0] = (bytestream2_get_byteu(&s->g) & 0x7f) + 1;
                    colour_depth[1] = (bytestream2_get_byteu(&s->g) & 0x7f) + 1;
                    colour_depth[2] = (bytestream2_get_byteu(&s->g) & 0x7f) + 1;
                    size = (colour_depth[0] + 7 >> 3) * colour_count +
                           (colour_depth[1] + 7 >> 3) * colour_count +
                           (colour_depth[2] + 7 >> 3) * colour_count;
                    if (colour_count > 256   ||
                        colour_channels != 3 ||
                        colour_depth[0] > 16 ||
                        colour_depth[1] > 16 ||
                        colour_depth[2] > 16 ||
                        atom2_size < size) {
                        avpriv_request_sample(s->avctx, "Unknown palette");
                        bytestream2_seek(&s->g, atom2_end, SEEK_SET);
                        continue;
                    }
                    s->pal8 = 1;
                    for (i = 0; i < colour_count; i++) {
                        if (colour_depth[0] <= 8) {
                            r = bytestream2_get_byteu(&s->g) << 8 - colour_depth[0];
                            r |= r >> colour_depth[0];
                        } else {
                            r = bytestream2_get_be16u(&s->g) >> colour_depth[0] - 8;
                        }
                        if (colour_depth[1] <= 8) {
                            g = bytestream2_get_byteu(&s->g) << 8 - colour_depth[1];
                            r |= r >> colour_depth[1];
                        } else {
                            g = bytestream2_get_be16u(&s->g) >> colour_depth[1] - 8;
                        }
                        if (colour_depth[2] <= 8) {
                            b = bytestream2_get_byteu(&s->g) << 8 - colour_depth[2];
                            r |= r >> colour_depth[2];
                        } else {
                            b = bytestream2_get_be16u(&s->g) >> colour_depth[2] - 8;
                        }
                        s->palette[i] = 0xffu << 24 | r << 16 | g << 8 | b;
                    }
                } else if (atom2 == MKBETAG('c','d','e','f') && atom2_size >= 2) {
                    int n = bytestream2_get_be16u(&s->g);
                    for (; n>0; n--) {
                        int cn   = bytestream2_get_be16(&s->g);
                        int av_unused typ  = bytestream2_get_be16(&s->g);
                        int asoc = bytestream2_get_be16(&s->g);
                        if (cn < 4 || asoc < 4)
                            s->cdef[cn] = asoc;
                    }
                }
                bytestream2_seek(&s->g, atom2_end, SEEK_SET);
            } while (atom_end - atom2_end >= 8);
        } else {
            search_range--;
        }
        bytestream2_seek(&s->g, atom_end, SEEK_SET);
    }

    return 0;
}