/* -*- c++ -*- */
/*
 * Copyright 2005,2012 Free Software Foundation, Inc.
 *
 * This file is part of GNU Radio
 *
 * SPDX-License-Identifier: GPL-3.0-or-later
 *
 */

#ifndef INCLUDED_GR_PACKET_SINK_IMPL_H
#define INCLUDED_GR_PACKET_SINK_IMPL_H

#include <gnuradio/digital/packet_sink.h>

namespace gr {
namespace digital {

class packet_sink_impl : public packet_sink
{
private:
    enum state_t { STATE_SYNC_SEARCH, STATE_HAVE_SYNC, STATE_HAVE_HEADER };

    static constexpr int MAX_PKT_LEN = 4096;
    static constexpr int HEADERBITLEN = 32;

    msg_queue::sptr d_target_queue;   // where to send the packet when received
    unsigned long long d_sync_vector; // access code to locate start of packet
    unsigned int d_threshold;         // how many bits may be wrong in sync vector

    state_t d_state;

    unsigned long long d_shift_reg; // used to look for sync_vector

    unsigned int d_header;  // header bits
    int d_headerbitlen_cnt; // how many so far

    unsigned char d_packet[MAX_PKT_LEN]; // assembled payload
    unsigned char d_packet_byte;         // byte being assembled
    int d_packet_byte_index;             // which bit of d_packet_byte we're working on
    int d_packetlen;                     // length of packet
    int d_packetlen_cnt;                 // how many so far

protected:
    void enter_search();
    void enter_have_sync();
    void enter_have_header(int payload_len);

    int slice(float x) { return x > 0 ? 1 : 0; }

    bool header_ok()
    {
        // confirm that two copies of header info are identical
        return ((d_header >> 16) ^ (d_header & 0xffff)) == 0;
    }

    int header_payload_len()
    {
        // header consists of two 16-bit shorts in network byte order
        int t = (d_header >> 16) & 0xffff;
        return t;
    }

public:
    packet_sink_impl(const std::vector<unsigned char>& sync_vector,
                     msg_queue::sptr target_queue,
                     int threshold = -1);
    ~packet_sink_impl();

    int work(int noutput_items,
             gr_vector_const_void_star& input_items,
             gr_vector_void_star& output_items) override;

    //! return true if we detect carrier
    bool carrier_sensed() const { return d_state != STATE_SYNC_SEARCH; }
};

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

#endif /* INCLUDED_GR_PACKET_SINK_IMPL_H */