/* -*- c++ -*- */
/*
 * Copyright 2013 Free Software Foundation, Inc.
 *
 * This file is part of GNU Radio
 *
 * GNU Radio is free software; you can redistribute it and/or modify
 * it under the terms of the GNU General Public License as published by
 * the Free Software Foundation; either version 3, or (at your option)
 * any later version.
 *
 * GNU Radio 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 General Public License for more details.
 *
 * You should have received a copy of the GNU General Public License
 * along with GNU Radio; see the file COPYING.  If not, write to
 * the Free Software Foundation, Inc., 51 Franklin Street,
 * Boston, MA 02110-1301, USA.
 */

#ifdef HAVE_CONFIG_H
#include "config.h"
#endif

#include "crc32_bb_impl.h"
#include <gnuradio/io_signature.h>

namespace gr {
namespace digital {

crc32_bb::sptr crc32_bb::make(bool check, const std::string& lengthtagname, bool packed)
{
    return gnuradio::get_initial_sptr(new crc32_bb_impl(check, lengthtagname, packed));
}

crc32_bb_impl::crc32_bb_impl(bool check, const std::string& lengthtagname, bool packed)
    : tagged_stream_block("crc32_bb",
                          io_signature::make(1, 1, sizeof(char)),
                          io_signature::make(1, 1, sizeof(char)),
                          lengthtagname),
      d_check(check),
      d_packed(packed)
{
    d_crc_length = 4;
    if (!d_packed) {
        d_crc_length = 32;
        d_buffer = std::vector<char>(d_crc_length);
    } else {
        d_buffer = std::vector<char>(4096);
    }
    set_tag_propagation_policy(TPP_DONT);
}

crc32_bb_impl::~crc32_bb_impl() {}

int crc32_bb_impl::calculate_output_stream_length(const gr_vector_int& ninput_items)
{
    if (d_check) {
        return ninput_items[0] - d_crc_length;
    } else {
        return ninput_items[0] + d_crc_length;
    }
}

unsigned int crc32_bb_impl::calculate_crc32(const unsigned char* in, size_t packet_length)
{
    unsigned int crc = 0;
    d_crc_impl.reset();
    if (!d_packed) {
        const size_t n_packed_length = 1 + ((packet_length - 1) / 8);
        if (n_packed_length > d_buffer.size()) {
            d_buffer.resize(n_packed_length);
        }
        std::fill(d_buffer.begin(), d_buffer.begin() + n_packed_length, 0);
        for (size_t bit = 0; bit < packet_length; bit++) {
            d_buffer[bit / 8] |= (in[bit] << (bit % 8));
        }
        d_crc_impl.process_bytes(&d_buffer[0], n_packed_length);
        crc = d_crc_impl();
    } else {
        d_crc_impl.process_bytes(in, packet_length);
        crc = d_crc_impl();
    }
    return crc;
}

int crc32_bb_impl::work(int noutput_items,
                        gr_vector_int& ninput_items,
                        gr_vector_const_void_star& input_items,
                        gr_vector_void_star& output_items)
{
    const unsigned char* in = (const unsigned char*)input_items[0];
    unsigned char* out = (unsigned char*)output_items[0];
    size_t packet_length = ninput_items[0];
    int packet_size_diff = d_check ? -d_crc_length : d_crc_length;
    unsigned int crc;

    if (d_check) {
        if (packet_length <= d_crc_length) {
            return 0;
        }
        d_crc_impl.process_bytes(in, packet_length - d_crc_length);
        crc = calculate_crc32(in, packet_length - d_crc_length);
        if (d_packed) {
            if (crc !=
                *(unsigned int*)(in + packet_length - d_crc_length)) { // Drop package
                return 0;
            }
        } else {
            for (unsigned int i = 0; i < d_crc_length; i++) {
                if (((crc >> i) & 0x1) !=
                    *(in + packet_length - d_crc_length + i)) { // Drop package
                    return 0;
                }
            }
        }
        memcpy((void*)out, (const void*)in, packet_length - d_crc_length);
    } else {
        crc = calculate_crc32(in, packet_length);
        memcpy((void*)out, (const void*)in, packet_length);
        if (d_packed) {
            memcpy((void*)(out + packet_length),
                   &crc,
                   d_crc_length); // FIXME big-endian/little-endian, this might be wrong
        } else {
            for (unsigned int i = 0; i < d_crc_length;
                 i++) { // unpack CRC and store in buffer
                d_buffer[i] = (crc >> i) & 0x1;
            }
            memcpy((void*)(out + packet_length), (void*)&d_buffer[0], d_crc_length);
        }
    }

    std::vector<tag_t> tags;
    get_tags_in_range(tags, 0, nitems_read(0), nitems_read(0) + packet_length);
    for (size_t i = 0; i < tags.size(); i++) {
        tags[i].offset -= nitems_read(0);
        if (d_check &&
            tags[i].offset > (unsigned int)(packet_length + packet_size_diff)) {
            tags[i].offset = packet_length - d_crc_length - 1;
        }
        add_item_tag(0, nitems_written(0) + tags[i].offset, tags[i].key, tags[i].value);
    }

    return packet_length + packet_size_diff;
}

} /* namespace digital */
} /* namespace gr */
