sdr_ifile.c

// Part of readsb, a Mode-S/ADSB/TIS message decoder.
//
// sdr_ifile.c: "file" SDR support
//
// Copyright (c) 2020 Michael Wolf <michael@mictronics.de>
//
// This code is based on a detached fork of dump1090-fa.
//
// Copyright (c) 2014-2017 Oliver Jowett <oliver@mutability.co.uk>
// Copyright (c) 2017 FlightAware LLC
//
// This file 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 of the License, or
// any later version.
//
// This file 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 this program.  If not, see <http://www.gnu.org/licenses/>.
//
// This file incorporates work covered by the following copyright and
// license:
//
// Copyright (C) 2012 by Salvatore Sanfilippo <antirez@gmail.com>
//
// All rights reserved.
//
// Redistribution and use in source and binary forms, with or without
// modification, are permitted provided that the following conditions are
// met:
//
//  *  Redistributions of source code must retain the above copyright
//     notice, this list of conditions and the following disclaimer.
//
//  *  Redistributions in binary form must reproduce the above copyright
//     notice, this list of conditions and the following disclaimer in the
//     documentation and/or other materials provided with the distribution.
//
// THIS SOFTWARE IS PROVIDED BY THE COPYRIGHT HOLDERS AND CONTRIBUTORS
// "AS IS" AND ANY EXPRESS OR IMPLIED WARRANTIES, INCLUDING, BUT NOT
// LIMITED TO, THE IMPLIED WARRANTIES OF MERCHANTABILITY AND FITNESS FOR
// A PARTICULAR PURPOSE ARE DISCLAIMED. IN NO EVENT SHALL THE COPYRIGHT
// HOLDER OR CONTRIBUTORS BE LIABLE FOR ANY DIRECT, INDIRECT, INCIDENTAL,
// SPECIAL, EXEMPLARY, OR CONSEQUENTIAL DAMAGES (INCLUDING, BUT NOT
// LIMITED TO, PROCUREMENT OF SUBSTITUTE GOODS OR SERVICES; LOSS OF USE,
// DATA, OR PROFITS; OR BUSINESS INTERRUPTION) HOWEVER CAUSED AND ON ANY
// THEORY OF LIABILITY, WHETHER IN CONTRACT, STRICT LIABILITY, OR TORT
// (INCLUDING NEGLIGENCE OR OTHERWISE) ARISING IN ANY WAY OUT OF THE USE
// OF THIS SOFTWARE, EVEN IF ADVISED OF THE POSSIBILITY OF SUCH DAMAGE.

#include "readsb.h"
#include "sdr_ifile.h"

static struct {
    input_format_t input_format;
    int fd;
    unsigned bytes_per_sample;
    bool throttle;
    unsigned bufsize;
    char *readbuf;
    iq_convert_fn converter;
    struct converter_state *converter_state;
    const char *filename;
} ifile;

void ifileInitConfig(void) {
    ifile.filename = NULL;
    ifile.input_format = INPUT_UC8;
    ifile.throttle = false;
    ifile.fd = -1;
    ifile.bytes_per_sample = 0;
    ifile.bufsize = 0;
    ifile.readbuf = NULL;
    ifile.converter = NULL;
    ifile.converter_state = NULL;
}

bool ifileHandleOption(int argc, char *argv) {
    switch (argc) {
        case OptIfileName:
            ifile.filename = strdup(argv);
            Modes.sdr_type = SDR_IFILE;
            break;
        case OptIfileFormat:
            if (!strcasecmp(argv, "uc8")) {
                ifile.input_format = INPUT_UC8;
            } else if (!strcasecmp(argv, "sc16")) {
                ifile.input_format = INPUT_SC16;
            } else if (!strcasecmp(argv, "sc16q11")) {
                ifile.input_format = INPUT_SC16Q11;
            } else {
                fprintf(stderr, "Input format '%s' not understood (supported values: UC8, SC16, SC16Q11)\n",
                        argv);
                return false;
            }
            break;
        case OptIfileThrottle:
            ifile.throttle = true;
            break;
    }
    return true;
}

//
//=========================================================================
//
// This is used when --ifile is specified in order to read data from file
// instead of using an RTLSDR device
//

bool ifileOpen(void) {
    if (!ifile.filename) {
        fprintf(stderr, "SDR type 'ifile' requires an --ifile argument\n");
        return false;
    }

    if (!strcmp(ifile.filename, "-")) {
        ifile.fd = STDIN_FILENO;
    } else if ((ifile.fd = open(ifile.filename, O_RDONLY)) < 0) {
        fprintf(stderr, "ifile: could not open %s: %s\n",
                ifile.filename, strerror(errno));
        return false;
    }

    switch (ifile.input_format) {
        case INPUT_UC8:
            ifile.bytes_per_sample = 2;
            break;
        case INPUT_SC16:
        case INPUT_SC16Q11:
            ifile.bytes_per_sample = 4;
            break;
        default:
            fprintf(stderr, "ifile: unhandled input format\n");
            ifileClose();
            return false;
    }

    ifile.bufsize = ifile.bytes_per_sample * MODES_MAG_BUF_SAMPLES; /* ~1M samples, about half a second's worth */

    if (!(ifile.readbuf = malloc(ifile.bufsize))) {
        fprintf(stderr, "ifile: failed to allocate read buffer\n");
        ifileClose();
        return false;
    }

    ifile.converter = init_converter(ifile.input_format,
            Modes.sample_rate,
            Modes.dc_filter,
            &ifile.converter_state);
    if (!ifile.converter) {
        fprintf(stderr, "ifile: can't initialize sample converter\n");
        ifileClose();
        return false;
    }

    return true;
}

void ifileRun() {
    if (ifile.fd < 0)
        return;

    struct timespec next_buffer_delivery;
    clock_gettime(CLOCK_MONOTONIC, &next_buffer_delivery);

    bool eof = false;

    uint64_t sampleCounter = 0;

    while (!Modes.exit && !eof) {

        /* wait for up to 1000ms for a buffer */
        struct mag_buf *outbuf = fifo_acquire(100 /* milliseconds */);
        if (!outbuf) {
            // maybe we're slow, maybe we halted
            continue;
        }

        sdrMonitor();
        
        // Compute the sample timestamp for the start of the block
        outbuf->sampleTimestamp = sampleCounter * 12e6 / Modes.sample_rate;
        
        // Get the system time for the start of this block
        outbuf->sysTimestamp = outbuf->sampleTimestamp / 12000U + Modes.startup_time;

        unsigned bytes_wanted = (outbuf->totalLength - outbuf->overlap) * ifile.bytes_per_sample;
        if (bytes_wanted > ifile.bufsize) {
            bytes_wanted = ifile.bufsize;
        }

        unsigned bytes_read = 0;
        while (bytes_read < bytes_wanted) {
            ssize_t nread = read(ifile.fd, ifile.readbuf + bytes_read, bytes_wanted - bytes_read);
            if (nread <= 0) {
                if (nread < 0) {
                    fprintf(stderr, "ifile: error reading input file: %s\n", strerror(errno));
                }
                // Done.
                eof = true;
                break;
            }
            bytes_read += nread;
        }

        unsigned samples_read = bytes_read / ifile.bytes_per_sample;

        // Convert the new data
        ifile.converter(ifile.readbuf, &outbuf->data[outbuf->overlap], samples_read, ifile.converter_state, &outbuf->mean_level, &outbuf->mean_power);
        outbuf->validLength = outbuf->overlap + samples_read;
        outbuf->flags = 0;

        if (ifile.throttle || Modes.interactive) {
            // Wait until we are allowed to release this buffer to the FIFO
            while (clock_nanosleep(CLOCK_MONOTONIC, TIMER_ABSTIME, &next_buffer_delivery, NULL) == EINTR)
                ;

            // compute the time we can deliver the next buffer.
            next_buffer_delivery.tv_nsec += samples_read * 1e9 / Modes.sample_rate;
            normalize_timespec(&next_buffer_delivery);
        }

        // Push the new data to the FIFO
        fifo_enqueue(outbuf);
        sampleCounter += samples_read;
    }

    // Wait for the FIFO to drain so we don't throw away trailing data
    fifo_drain();
    
    Modes.exit = 1;
}

void ifileClose() {
    if (ifile.converter) {
        cleanup_converter(ifile.converter_state);
        ifile.converter = NULL;
        ifile.converter_state = NULL;
    }

    if (ifile.readbuf) {
        free(ifile.readbuf);
        ifile.readbuf = NULL;
    }

    if (ifile.fd >= 0 && ifile.fd != STDIN_FILENO) {
        close(ifile.fd);
        ifile.fd = -1;
    }
}