/* -*- c++ -*- */
/* Copyright 2012 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 <gnuradio/digital/packet_header_default.h>
#include <string.h>

namespace gr {
namespace digital {

packet_header_default::sptr packet_header_default::make(long header_len,
                                                        const std::string& len_tag_key,
                                                        const std::string& num_tag_key,
                                                        int bits_per_byte)
{
    return packet_header_default::sptr(
        new packet_header_default(header_len, len_tag_key, num_tag_key, bits_per_byte));
}

const unsigned MASK_LUT[9] = { 0x00, 0x01, 0x03, 0x07, 0x0F, 0x1F, 0x2F, 0x7F, 0xFF };
packet_header_default::packet_header_default(long header_len,
                                             const std::string& len_tag_key,
                                             const std::string& num_tag_key,
                                             int bits_per_byte)
    : d_header_len(header_len),
      d_len_tag_key(pmt::string_to_symbol(len_tag_key)),
      d_num_tag_key(num_tag_key.empty() ? pmt::PMT_NIL
                                        : pmt::string_to_symbol(num_tag_key)),
      d_bits_per_byte(bits_per_byte),
      d_header_number(0)
{
    if (d_bits_per_byte < 1 || d_bits_per_byte > 8) {
        throw std::invalid_argument("bits_per_byte must be in [1, 8]");
    }
    d_mask = MASK_LUT[d_bits_per_byte];
}

packet_header_default::~packet_header_default() {}

bool packet_header_default::header_formatter(long packet_len,
                                             unsigned char* out,
                                             const std::vector<tag_t>& tags)
{
    packet_len &= 0x0FFF;
    d_crc_impl.reset();
    d_crc_impl.process_bytes((void const*)&packet_len, 2);
    d_crc_impl.process_bytes((void const*)&d_header_number, 2);
    unsigned char crc = d_crc_impl();

    memset(out, 0x00, d_header_len);
    int k = 0; // Position in out
    for (int i = 0; i < 12 && k < d_header_len; i += d_bits_per_byte, k++) {
        out[k] = (unsigned char)((packet_len >> i) & d_mask);
    }
    for (int i = 0; i < 12 && k < d_header_len; i += d_bits_per_byte, k++) {
        out[k] = (unsigned char)((d_header_number >> i) & d_mask);
    }
    for (int i = 0; i < 8 && k < d_header_len; i += d_bits_per_byte, k++) {
        out[k] = (unsigned char)((crc >> i) & d_mask);
    }
    d_header_number++;
    d_header_number &= 0x0FFF;

    return true;
}

bool packet_header_default::header_parser(const unsigned char* in,
                                          std::vector<tag_t>& tags)
{
    unsigned header_len = 0;
    unsigned header_num = 0;
    tag_t tag;

    int k = 0; // Position in "in"
    for (int i = 0; i < 12 && k < d_header_len; i += d_bits_per_byte, k++) {
        header_len |= (((int)in[k]) & d_mask) << i;
    }
    tag.key = d_len_tag_key;
    tag.value = pmt::from_long(header_len);
    tags.push_back(tag);
    if (k >= d_header_len) {
        return true;
    }
    if (d_num_tag_key == pmt::PMT_NIL) {
        k += 12;
    } else {
        for (int i = 0; i < 12 && k < d_header_len; i += d_bits_per_byte, k++) {
            header_num |= (((int)in[k]) & d_mask) << i;
        }
        tag.key = d_num_tag_key;
        tag.value = pmt::from_long(header_num);
        tags.push_back(tag);
    }
    if (k >= d_header_len) {
        return true;
    }

    d_crc_impl.reset();
    d_crc_impl.process_bytes((void const*)&header_len, 2);
    d_crc_impl.process_bytes((void const*)&header_num, 2);
    unsigned char crc_calcd = d_crc_impl();
    for (int i = 0; i < 8 && k < d_header_len; i += d_bits_per_byte, k++) {
        if ((((int)in[k]) & d_mask) != (((int)crc_calcd >> i) & d_mask)) {
            return false;
        }
    }

    return true;
}

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