VILLASnode/lib/hooks/decimate.cpp

/* Decimate hook.
 *
 * Author: Steffen Vogel <post@steffenvogel.de>
 * SPDX-FileCopyrightText: 2014-2023 Institute for Automation of Complex Power Systems, RWTH Aachen University
 * SPDX-License-Identifier: Apache-2.0
 */

#include <villas/hooks/decimate.hpp>
#include <villas/sample.hpp>

namespace villas {
namespace node {

void DecimateHook::start() {
  assert(state == State::PREPARED);

  counter = 0;

  state = State::STARTED;
}

void DecimateHook::parse(json_t *json) {
  int ret;
  json_error_t err;

  assert(state != State::STARTED);

  Hook::parse(json);

  ret = json_unpack_ex(json, &err, 0, "{ s: i, s?: b }", "ratio", &ratio,
                       "renumber", &renumber);
  if (ret)
    throw ConfigError(json, err, "node-config-hook-decimate");

  state = State::PARSED;
}

Hook::Reason DecimateHook::process(struct Sample *smp) {
  assert(state == State::STARTED);

  if (renumber)
    smp->sequence /= ratio;

  if (ratio && counter++ % ratio != 0)
    return Hook::Reason::SKIP_SAMPLE;

  return Reason::OK;
}

// Register hook
static char n[] = "decimate";
static char d[] = "Downsamping by integer factor";
static HookPlugin<DecimateHook, n, d,
                  (int)Hook::Flags::NODE_READ | (int)Hook::Flags::NODE_WRITE |
                      (int)Hook::Flags::PATH>
    p;

} // namespace node
} // namespace villas