inputfile: Increase chunk size from 16KB to 4MB.

[pulseview.git] / pv / devices / inputfile.cpp

/*
 * This file is part of the PulseView project.
 *
 * Copyright (C) 2015 Joel Holdsworth <joel@airwebreathe.org.uk>
 *
 * This program 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 2 of the License, or
 * (at your option) any later version.
 *
 * This program 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/>.
 */

#include <cassert>
#include <fstream>
#include <vector>

#include <QString>

#include "inputfile.hpp"

using std::map;
using std::shared_ptr;
using std::streamsize;
using std::string;
using std::ifstream;
using std::ios;
using std::vector;

namespace pv {
namespace devices {

// Use a 4MB chunk size for reading a file into memory. Larger values don't
// seem to provide any substancial performance improvements, but can cause
// UI lag and a visually "stuttering" display of the data currently loading.
const streamsize InputFile::BufferSize = (4 * 1024 * 1024);

InputFile::InputFile(const shared_ptr<sigrok::Context> &context,
	const string &file_name,
	shared_ptr<sigrok::InputFormat> format,
	const map<string, Glib::VariantBase> &options) :
	File(file_name),
	context_(context),
	format_(format),
	options_(options),
	interrupt_(false)
{
}

void InputFile::open()
{
	if (session_)
		close();
	else
		session_ = context_->create_session();

	input_ = format_->create_input(options_);

	if (!input_)
		throw QString("Failed to create input");

	// open() should add the input device to the session but
	// we can't open the device without sending some data first
	f = new ifstream(file_name_, ios::binary);

	vector<char> buffer(BufferSize);

	f->read(buffer.data(), BufferSize);
	const streamsize size = f->gcount();
	if (size == 0)
		return;

	input_->send(buffer.data(), size);

	try {
		device_ = input_->device();
	} catch (sigrok::Error&) {
		return;
	}

	session_->add_device(device_);
}

void InputFile::close()
{
	if (session_)
		session_->remove_devices();
}

void InputFile::start()
{
}

void InputFile::run()
{
	if (!f) {
		// Previous call to run() processed the entire file already
		f = new ifstream(file_name_, ios::binary);
		input_->reset();
	}

	vector<char> buffer(BufferSize);

	interrupt_ = false;
	while (!interrupt_ && !f->eof()) {
		f->read(buffer.data(), BufferSize);
		const streamsize size = f->gcount();
		if (size == 0)
			break;

		input_->send(buffer.data(), size);

		if (size != BufferSize)
			break;
	}

	input_->end();

	delete f;
	f = nullptr;
}

void InputFile::stop()
{
	interrupt_ = true;
}

} // namespace devices
} // namespace pv