Portapack应用开发教程（三）开发步骤

我的思路是这样的，既然我开发的应用是仿造replay的，我只要在前面找到的几个代码的地方复制出一个副本，稍加修改（改名），然后把加出来的代码文件加入对应CMakeLists里就行。

我分了几步。

第一步，在portapack主界面上先增加了一个按钮，这个按钮暂时还是连到replay上。

第二步，对这个按钮就行修改，改图标（改图标还需要上网找图片，然后生成数据）。

第三步，开始改动界面上新增按钮背后对应的app界面，但是这个app还对应于原来的那个后台处理程序。

第四步，增加对应的后台处理程序，使得界面上的新增按钮的app有了完全独立的后台处理程序。

第一步：

打开ui_navigation.cpp，找到如下部分，按照注释更改。

SystemMenuView::SystemMenuView(NavigationView& nav) {
	add_items({
		{ "Play dead",				ui::Color::red(),		&bitmap_icon_playdead,	[&nav](){ nav.push<PlayDeadView>(); } },
		{ "Receivers", 	ui::Color::dark_cyan(),		&bitmap_icon_receivers,	[&nav](){ nav.push<ReceiversMenuView>(); } },
		{ "Transmit", 	ui::Color::green(),			&bitmap_icon_transmit,	[&nav](){ nav.push<TransmittersMenuView>(); } },
		{ "Capture",				ui::Color::blue(),		&bitmap_icon_capture,	[&nav](){ nav.push<CaptureAppView>(); } },
		{ "Replay",					ui::Color::purple(),	&bitmap_icon_replay,	[&nav](){ nav.push<ReplayAppView>(); } },
                { "GPS Sim",                              ui::Color::white(),     &bitmap_icon_replay,    [&nav]() { nav.push<ReplayAppView>(); } },
 //这一行是我们自己增加的，只改了名字和颜色
		{ "Calls",		ui::Color::yellow(),	    &bitmap_icon_closecall,	[&nav](){ nav.push<SearchView>(); } },
		{ "Scanner",	ui::Color::orange(),		&bitmap_icon_scanner,	[&nav](){ nav.push<ScannerView>(); } },
		{ "Utilities",				ui::Color::light_grey(),	&bitmap_icon_utilities,	[&nav](){ nav.push<UtilitiesMenuView>(); } },
		{ "Settings", 	ui::Color::cyan(),			&bitmap_icon_setup,	  	[&nav](){ nav.push<SettingsMenuView>(); } },
		//{ "Debug",		ui::Color::cyan(),			nullptr,   				[&nav](){ nav.push<DebugMenuView>(); } },
		{ "HackRF", 	ui::Color::cyan(),			&bitmap_icon_hackrf,	[this, &nav](){ hackrf_mode(nav); } },
		{ "About", 		ui::Color::cyan(),			nullptr,				[&nav](){ nav.push<AboutView>(); } }
	});
	
	set_highlighted(1);		// Startup selection is "Receivers"
}

原来的主界面： 

改完了以后可以看到主界面是这样的：

第二步：

还是打开ui_navigation.cpp，根据注释找到对应位置更改。

SystemMenuView::SystemMenuView(NavigationView& nav) {
	add_items({
		{ "Play dead",				ui::Color::red(),		&bitmap_icon_playdead,	[&nav](){ nav.push<PlayDeadView>(); } },
		{ "Receivers", 	ui::Color::dark_cyan(),		&bitmap_icon_receivers,	[&nav](){ nav.push<ReceiversMenuView>(); } },
		{ "Transmit", 	ui::Color::green(),			&bitmap_icon_transmit,	[&nav](){ nav.push<TransmittersMenuView>(); } },
		{ "Capture",				ui::Color::blue(),		&bitmap_icon_capture,	[&nav](){ nav.push<CaptureAppView>(); } },
		{ "Replay",					ui::Color::purple(),	&bitmap_icon_replay,	[&nav](){ nav.push<ReplayAppView>(); } },
                { "GPS Sim",                              ui::Color::white(),     &bitmap_gps_sim,    [&nav]()
{ nav.push< ReplayAppView >(); } },
//我们现在把图标从bitmap_icon_replay改为bitmap_gps_sim
		{ "Calls",		ui::Color::yellow(),	    &bitmap_icon_closecall,	[&nav](){ nav.push<SearchView>(); } },
		{ "Scanner",	ui::Color::orange(),		&bitmap_icon_scanner,	[&nav](){ nav.push<ScannerView>(); } },
		{ "Utilities",				ui::Color::light_grey(),	&bitmap_icon_utilities,	[&nav](){ nav.push<UtilitiesMenuView>(); } },
		{ "Settings", 	ui::Color::cyan(),			&bitmap_icon_setup,	  	[&nav](){ nav.push<SettingsMenuView>(); } },
		//{ "Debug",		ui::Color::cyan(),			nullptr,   				[&nav](){ nav.push<DebugMenuView>(); } },
		{ "HackRF", 	ui::Color::cyan(),			&bitmap_icon_hackrf,	[this, &nav](){ hackrf_mode(nav); } },
		{ "About", 		ui::Color::cyan(),			nullptr,				[&nav](){ nav.push<AboutView>(); } }
	});
	
	set_highlighted(1);		// Startup selection is "Receivers"
}

但是现在bitmap_gps_sim是没有的，我们如果现在编译会报错。我搜索了一下，被它替换的bitmap_icon_replay在bitmap.hpp中出现过，片段如下：

static constexpr uint8_t bitmap_icon_replay_data[] = {
	0x00, 0x00, 
	0xC0, 0x07, 
	0xF0, 0x1F, 
	0x79, 0x3C, 
	0x1D, 0x70, 
	0x0F, 0x60, 
	0x07, 0xE0, 
	0x1F, 0xC0, 
	0x00, 0xC0, 
	0x00, 0xE0, 
	0x00, 0x60, 
	0x00, 0x70, 
	0x30, 0x3C, 
	0xE0, 0x0F, 
	0x80, 0x03, 
	0x00, 0x00, 
};
static constexpr Bitmap bitmap_icon_replay {
	{ 16, 16 }, bitmap_icon_replay_data
};

也就是说，我们要想办法把图标生成出这样的数据，然后仿照这样的格式填进去就行。

我找到了firmware/tools/make_bitmap.py，根据代码的要求，只要找到宽高能被8整除的png图片，放到一个文件夹里，然后运行：

python make_bitmap.py 文件夹名

就能够生成对应的bitmap.hpp文件了，然后把需要的部分代码复制出来到原来的bitmap.hpp里去就行。

我找到如下图标

然后生成了数据：

static constexpr uint8_t bitmap_gps_sim_data[] = {
	0x00, 0x00, 
	0x00, 0x00, 
	0x40, 0x06, 
	0x20, 0x00, 
	0x10, 0x10, 
	0x08, 0x10, 
	0x00, 0x20, 
	0x00, 0x00, 
	0x08, 0x00, 
	0x08, 0x00, 
	0x08, 0x10, 
	0x10, 0x00, 
	0x40, 0x0C, 
	0xC0, 0x02, 
	0x00, 0x00, 
	0x00, 0x00, 
};
static constexpr Bitmap bitmap_gps_sim {
	{ 16, 16 }, bitmap_gps_sim_data
};

 注意图标的文件名和生成的代码的变量名是对应的，这个名字后面也要用到ui_navigation的代码里，要保持一致，否则找不到这段数据。

这样改完了编译烧录后主界面会变为这样：

但是点GPS Sim进去后出来的界面和点replay的界面是一样的。

第三步：

首先要仿照replay_app.cpp和replay_app.hpp，生成gps_sim_app.cpp和gps_sim_app.hpp，放到firmware/applicaition/app下。

gps_sim_app.cpp

#include "gps_sim_app.hpp"
#include "string_format.hpp"

#include "ui_fileman.hpp"
#include "io_file.hpp"

#include "baseband_api.hpp"
#include "portapack.hpp"
#include "portapack_persistent_memory.hpp"

using namespace portapack;

namespace ui {

void GpsSimAppView::set_ready() {
	ready_signal = true;
}

void GpsSimAppView::on_file_changed(std::filesystem::path new_file_path) {
	File data_file, info_file;
	char file_data[257];
	
	// Get file size
	auto data_open_error = data_file.open("/" + new_file_path.string());
	if (data_open_error.is_valid()) {
		file_error();
		return;
	}
	
	file_path = new_file_path;
	
	// Get original record frequency if available
	std::filesystem::path info_file_path = file_path;
	info_file_path.replace_extension(u".TXT");
	
	sample_rate = 500000;
	
	auto info_open_error = info_file.open("/" + info_file_path.string());
	if (!info_open_error.is_valid()) {
		memset(file_data, 0, 257);
		auto read_size = info_file.read(file_data, 256);
		if (!read_size.is_error()) {
			auto pos1 = strstr(file_data, "center_frequency=");
			if (pos1) {
				pos1 += 17;
				field_frequency.set_value(strtoll(pos1, nullptr, 10));
			}
			
			auto pos2 = strstr(file_data, "sample_rate=");
			if (pos2) {
				pos2 += 12;
				sample_rate = strtoll(pos2, nullptr, 10);
			}
		}
	}
	
	text_sample_rate.set(unit_auto_scale(sample_rate, 3, 1) + "Hz");
	
	auto file_size = data_file.size();
	auto duration = (file_size * 1000) / (1 * 2 * sample_rate);
	
	progressbar.set_max(file_size);
	text_filename.set(file_path.filename().string().substr(0, 12));
	text_duration.set(to_string_time_ms(duration));
	
	button_play.focus();
}

void GpsSimAppView::on_tx_progress(const uint32_t progress) {
	progressbar.set_value(progress);
}

void GpsSimAppView::focus() {
	button_open.focus();
}

void GpsSimAppView::file_error() {
	nav_.display_modal("Error", "File read error.");
}

bool GpsSimAppView::is_active() const {
	return (bool)replay_thread;
}

void GpsSimAppView::toggle() {
	if( is_active() ) {
		stop(false);
	} else {
		start();
	}
}

void GpsSimAppView::start() {
	stop(false);

	std::unique_ptr<stream::Reader> reader;
	
	auto p = std::make_unique<FileReader>();
	auto open_error = p->open(file_path);
	if( open_error.is_valid() ) {
		file_error();
	} else {
		reader = std::move(p);
	}

	if( reader ) {
		button_play.set_bitmap(&bitmap_stop);
		baseband::set_sample_rate(sample_rate * 4);
		
		replay_thread = std::make_unique<ReplayThread>(
			std::move(reader),
			read_size, buffer_count,
			&ready_signal,
			[](uint32_t return_code) {
				ReplayThreadDoneMessage message { return_code };
				EventDispatcher::send_message(message);
			}
		);
	}
	
	radio::enable({
		receiver_model.tuning_frequency(),
		sample_rate * 4,
		baseband_bandwidth,
		rf::Direction::Transmit,
		receiver_model.rf_amp(),
		static_cast<int8_t>(receiver_model.lna()),
		static_cast<int8_t>(receiver_model.vga())
	});
}

void GpsSimAppView::stop(const bool do_loop) {
	if( is_active() )
		replay_thread.reset();
	
	if (do_loop && check_loop.value()) {
		start();
	} else {
		radio::disable();
		button_play.set_bitmap(&bitmap_play);
	}
	
	ready_signal = false;
}

void GpsSimAppView::handle_replay_thread_done(const uint32_t return_code) {
	if (return_code == ReplayThread::END_OF_FILE) {
		stop(true);
	} else if (return_code == ReplayThread::READ_ERROR) {
		stop(false);
		file_error();
	}
	
	progressbar.set_value(0);
}

GpsSimAppView::GpsSimAppView(
	NavigationView& nav
) : nav_ (nav)
{
	baseband::run_image(portapack::spi_flash::image_tag_replay);

	add_children({
		&labels,
		&button_open,
		&text_filename,
		&text_sample_rate,
		&text_duration,
		&progressbar,
		&field_frequency,
		&field_lna,
		&field_rf_amp,
		&check_loop,
		&button_play,
		&waterfall,
	});
	
	field_frequency.set_value(target_frequency());
	field_frequency.set_step(receiver_model.frequency_step());
	field_frequency.on_change = [this](rf::Frequency f) {
		this->on_target_frequency_changed(f);
	};
	field_frequency.on_edit = [this, &nav]() {
		// TODO: Provide separate modal method/scheme?
		auto new_view = nav.push<FrequencyKeypadView>(this->target_frequency());
		new_view->on_changed = [this](rf::Frequency f) {
			this->on_target_frequency_changed(f);
			this->field_frequency.set_value(f);
		};
	};

	field_frequency.set_step(5000);
	
	button_play.on_select = [this](ImageButton&) {
		this->toggle();
	};
	
	button_open.on_select = [this, &nav](Button&) {
		auto open_view = nav.push<FileLoadView>(".C8");
		open_view->on_changed = [this](std::filesystem::path new_file_path) {
			on_file_changed(new_file_path);
		};
	};
}

GpsSimAppView::~GpsSimAppView() {
	radio::disable();
	baseband::shutdown();
}

void GpsSimAppView::on_hide() {
	// TODO: Terrible kludge because widget system doesn't notify Waterfall that
	// it's being shown or hidden.
	waterfall.on_hide();
	View::on_hide();
}

void GpsSimAppView::set_parent_rect(const Rect new_parent_rect) {
	View::set_parent_rect(new_parent_rect);

	const ui::Rect waterfall_rect { 0, header_height, new_parent_rect.width(), new_parent_rect.height() - header_height };
	waterfall.set_parent_rect(waterfall_rect);
}

void GpsSimAppView::on_target_frequency_changed(rf::Frequency f) {
	set_target_frequency(f);
}

void GpsSimAppView::set_target_frequency(const rf::Frequency new_value) {
	persistent_memory::set_tuned_frequency(new_value);;
}

rf::Frequency GpsSimAppView::target_frequency() const {
	return persistent_memory::tuned_frequency();
}

} /* namespace ui */

gps_sim_app.hpp

#ifndef __GPS_SIM_APP_HPP__
#define __GPS_SIM_APP_HPP__

#include "ui_widget.hpp"
#include "ui_navigation.hpp"
#include "ui_receiver.hpp"
#include "replay_thread.hpp"
#include "ui_spectrum.hpp"

#include <string>
#include <memory>

namespace ui {

class GpsSimAppView : public View {
public:
	GpsSimAppView(NavigationView& nav);
	~GpsSimAppView();

	void on_hide() override;
	void set_parent_rect(const Rect new_parent_rect) override;
	void focus() override;

	std::string title() const override { return "GPS Simulator"; };
	
private:
	NavigationView& nav_;
	
	static constexpr ui::Dim header_height = 3 * 16;
	
	uint32_t sample_rate = 0;
	static constexpr uint32_t baseband_bandwidth = 2000000;
	const size_t read_size { 16384 };
	const size_t buffer_count { 3 };

	void on_file_changed(std::filesystem::path new_file_path);
	void on_target_frequency_changed(rf::Frequency f);
	void on_tx_progress(const uint32_t progress);
	
	void set_target_frequency(const rf::Frequency new_value);
	rf::Frequency target_frequency() const;

	void toggle();
	void start();
	void stop(const bool do_loop);
	bool is_active() const;
	void set_ready();
	void handle_replay_thread_done(const uint32_t return_code);
	void file_error();

	std::filesystem::path file_path { };
	std::unique_ptr<ReplayThread> replay_thread { };
	bool ready_signal { false };

	Labels labels {
		{ { 10 * 8, 2 * 16 }, "LNA:   A:", Color::light_grey() }
	};
	
	Button button_open {
		{ 0 * 8, 0 * 16, 10 * 8, 2 * 16 },
		"Open file"
	};
	
	Text text_filename {
		{ 11 * 8, 0 * 16, 12 * 8, 16 },
		"-"
	};
	Text text_sample_rate {
		{ 24 * 8, 0 * 16, 6 * 8, 16 },
		"-"
	};
	
	Text text_duration {
		{ 11 * 8, 1 * 16, 6 * 8, 16 },
		"-"
	};
	ProgressBar progressbar {
		{ 18 * 8, 1 * 16, 12 * 8, 16 }
	};
	
	FrequencyField field_frequency {
		{ 0 * 8, 2 * 16 },
	};
	LNAGainField field_lna {
		{ 14 * 8, 2 * 16 }
	};
	RFAmpField field_rf_amp {
		{ 19 * 8, 2 * 16 }
	};
	Checkbox check_loop {
		{ 21 * 8, 2 * 16 },
		4,
		"Loop",
		true
	};
	ImageButton button_play {
		{ 28 * 8, 2 * 16, 2 * 8, 1 * 16 },
		&bitmap_play,
		Color::green(),
		Color::black()
	};

	spectrum::WaterfallWidget waterfall { };

	MessageHandlerRegistration message_handler_replay_thread_error {
		Message::ID::ReplayThreadDone,
		[this](const Message* const p) {
			const auto message = *reinterpret_cast<const ReplayThreadDoneMessage*>(p);
			this->handle_replay_thread_done(message.return_code);
		}
	};
	
	MessageHandlerRegistration message_handler_fifo_signal {
		Message::ID::RequestSignal,
		[this](const Message* const p) {
			const auto message = static_cast<const RequestSignalMessage*>(p);
			if (message->signal == RequestSignalMessage::Signal::FillRequest) {
				this->set_ready();
			}
		}
	};
	
	MessageHandlerRegistration message_handler_tx_progress {
		Message::ID::TXProgress,
		[this](const Message* const p) {
			const auto message = *reinterpret_cast<const TXProgressMessage*>(p);
			this->on_tx_progress(message.progress);
		}
	};
};

} /* namespace ui */

#endif/*__GPS_SIM_APP_HPP__*/

然后在firmware/application/CMakeLists.txt中找到apps/replay_app.cpp，在它下方插入apps/gps_sim_app.cpp。如下：

	apps/replay_app.cpp
        apps/gps_sim_app.cpp

然后打开ui_navigation.cpp，开头加上#include "gps_sim_app.hpp"

然后也是ui_navigation.cpp里下面要改GPS Sim的nav.push调用的窗口

SystemMenuView::SystemMenuView(NavigationView& nav) {
	add_items({
		{ "Play dead",				ui::Color::red(),		&bitmap_icon_playdead,	[&nav](){ nav.push<PlayDeadView>(); } },
		{ "Receivers", 	ui::Color::dark_cyan(),		&bitmap_icon_receivers,	[&nav](){ nav.push<ReceiversMenuView>(); } },
		{ "Transmit", 	ui::Color::green(),			&bitmap_icon_transmit,	[&nav](){ nav.push<TransmittersMenuView>(); } },
		{ "Capture",				ui::Color::blue(),		&bitmap_icon_capture,	[&nav](){ nav.push<CaptureAppView>(); } },
		{ "Replay",					ui::Color::purple(),	&bitmap_icon_replay,	[&nav](){ nav.push<ReplayAppView>(); } },
                { "GPS Sim",                              ui::Color::white(),     &bitmap_gps_sim,    [&nav]()
{ nav.push<GpsSimAppView>(); } }, //注意nav.push这改为另一个界面了
		{ "Calls",		ui::Color::yellow(),	    &bitmap_icon_closecall,	[&nav](){ nav.push<SearchView>(); } },
		{ "Scanner",	ui::Color::orange(),		&bitmap_icon_scanner,	[&nav](){ nav.push<ScannerView>(); } },
		{ "Utilities",				ui::Color::light_grey(),	&bitmap_icon_utilities,	[&nav](){ nav.push<UtilitiesMenuView>(); } },
		{ "Settings", 	ui::Color::cyan(),			&bitmap_icon_setup,	  	[&nav](){ nav.push<SettingsMenuView>(); } },
		//{ "Debug",		ui::Color::cyan(),			nullptr,   				[&nav](){ nav.push<DebugMenuView>(); } },
		{ "HackRF", 	ui::Color::cyan(),			&bitmap_icon_hackrf,	[this, &nav](){ hackrf_mode(nav); } },
		{ "About", 		ui::Color::cyan(),			nullptr,				[&nav](){ nav.push<AboutView>(); } }
	});
	
	set_highlighted(1);		// Startup selection is "Receivers"
}

第三步做完了以后点GPS Sim会看到类似下面的界面，可以看到标题已经变了，我还打开了之前准备好的一个GPS数据文件，区别会更明显。

第四步：

第三步的gps_sim_app.cpp里的第183行，image_tag_replay改为image_tag_gps。

	baseband::run_image(portapack::spi_flash::image_tag_gps);

这样这个界面程序在执行的时候就会去寻找另一个后台处理程序了，但是暂时它是找不到的。我们需要在firmware/baseband里仿照proc_replay.app和proc_replay.hpp增加proc_gps_sim.cpp和proc_gps_sim.hpp两个文件。然后在firmware/common/里找到spi_image.hpp里，找到。image_tag_replay，仿照它增加image_tag_gps。

constexpr image_tag_t image_tag_replay				{ 'P', 'R', 'E', 'P' };
constexpr image_tag_t image_tag_gps                             { 'P', 'G', 'P', 'S' };

这样每次界面程序去找image_tag_gps就会去找PGPS了，这个PGPS如何对应到proc_gps_sim.cpp呢？这也是我们接下去要做的。

打开firmware/baseband/CMakeLists.txt 找到###Replay

### Replay

set(MODE_CPPSRC
	proc_replay.cpp
)
DeclareTargets(PREP replay)

### GPS Simulator

set(MODE_CPPSRC
	proc_gps_sim.cpp
)
DeclareTargets(PGPS gps_sim)

然后仿照它写下### GPS Simulator后面的内容，看到最下面的DeclareTargets里有PGPS，也就是说每次调用PGPS，都会去找proc_gps_sim.cpp编译出的程序。

最后附上我目前的proc_gps_sim.cpp和proc_gps_sim.hpp

proc_gps_sim.cpp

#include "proc_gps_sim.hpp"
#include "sine_table_int8.hpp"
#include "portapack_shared_memory.hpp"

#include "event_m4.hpp"

#include "utility.hpp"

ReplayProcessor::ReplayProcessor() {
	channel_filter_pass_f = taps_200k_decim_1.pass_frequency_normalized * 1000000;	// 162760.416666667
	channel_filter_stop_f = taps_200k_decim_1.stop_frequency_normalized * 1000000;	// 337239.583333333
	
	spectrum_samples = 0;

	channel_spectrum.set_decimation_factor(1);
	
	configured = false;
}

void ReplayProcessor::execute(const buffer_c8_t& buffer) {
	/* 4MHz, 2048 samples */
	
	if (!configured) return;
	
	// File data is in C16 format, we need C8
	// File samplerate is 500kHz, we're at 4MHz
	// iq_buffer can only be 512 C16 samples (RAM limitation)
	// To fill up the 2048-sample C8 buffer, we need:
	// 2048 samples * 2 bytes per sample = 4096 bytes
	// Since we're oversampling by 4M/500k = 8, we only need 2048/8 = 256 samples from the file and duplicate them 8 times each
	// So 256 * 4 bytes per sample (C16) = 1024 bytes from the file
	if( stream ) {                             //sizeof(*buffer.p) = sizeof(C8) = 2*int8 = 2 bytes //buffer.count = 2048
		const size_t bytes_to_read = sizeof(*buffer.p) * 1 * (buffer.count / 8);	// *2 (C16), /8 (oversampling) should be == 1024
		bytes_read += stream->read(iq_buffer.p, bytes_to_read);
	}
	
	// Fill and "stretch"
	for (size_t i = 0; i < buffer.count; i++) {
		/*if (i & 3) {
			buffer.p[i] = buffer.p[i - 1];
		} else {
			auto re_out = iq_buffer.p[i >> 3].real() ;
			auto im_out = iq_buffer.p[i >> 3].imag() ;
			buffer.p[i] = { (int8_t)re_out, (int8_t)im_out };
		}*/
                if (i % 8 != 0) {
			buffer.p[i] = buffer.p[i - 1];
		} else {
			auto re_out = iq_buffer.p[i/8].real() ;
			auto im_out = iq_buffer.p[i/8].imag() ;
			buffer.p[i] = { (int8_t)re_out, (int8_t)im_out };
		}
                /*
                auto re_out = iq_buffer.p[i].real() ;
	        auto im_out = iq_buffer.p[i].imag() ;
		buffer.p[i] = { (int8_t)re_out, (int8_t)im_out };*/
	}
	
	spectrum_samples += buffer.count;
	if( spectrum_samples >= spectrum_interval_samples ) {
		spectrum_samples -= spectrum_interval_samples;
		//channel_spectrum.feed(iq_buffer, channel_filter_pass_f, channel_filter_stop_f);
		
		txprogress_message.progress = bytes_read;	// Inform UI about progress
		txprogress_message.done = false;
		shared_memory.application_queue.push(txprogress_message);
	}
}

void ReplayProcessor::on_message(const Message* const message) {
	switch(message->id) {
	case Message::ID::UpdateSpectrum:
	case Message::ID::SpectrumStreamingConfig:
		channel_spectrum.on_message(message);
		break;

	case Message::ID::SamplerateConfig:
		samplerate_config(*reinterpret_cast<const SamplerateConfigMessage*>(message));
		break;
	
	case Message::ID::ReplayConfig:
		configured = false;
		bytes_read = 0;
		replay_config(*reinterpret_cast<const ReplayConfigMessage*>(message));
		break;
		
	// App has prefilled the buffers, we're ready to go now
	case Message::ID::FIFOData:
		configured = true;
		break;

	default:
		break;
	}
}

void ReplayProcessor::samplerate_config(const SamplerateConfigMessage& message) {
	baseband_fs = message.sample_rate;
	baseband_thread.set_sampling_rate(baseband_fs);
	spectrum_interval_samples = baseband_fs / spectrum_rate_hz;
}

void ReplayProcessor::replay_config(const ReplayConfigMessage& message) {
	if( message.config ) {
		
		stream = std::make_unique<StreamOutput>(message.config);
		
		// Tell application that the buffers and FIFO pointers are ready, prefill
		shared_memory.application_queue.push(sig_message);
	} else {
		stream.reset();
	}
}

int main() {
	EventDispatcher event_dispatcher { std::make_unique<ReplayProcessor>() };
	event_dispatcher.run();
	return 0;
}

proc_gps_sim.hpp

#ifndef __PROC_GPS_SIM_HPP__
#define __PROC_GPS_SIM_HPP__

#include "baseband_processor.hpp"
#include "baseband_thread.hpp"

#include "spectrum_collector.hpp"

#include "stream_output.hpp"

#include <array>
#include <memory>

class ReplayProcessor : public BasebandProcessor {
public:
	ReplayProcessor();

	void execute(const buffer_c8_t& buffer) override;

	void on_message(const Message* const message) override;

private:
	size_t baseband_fs = 0;
	static constexpr auto spectrum_rate_hz = 50.0f;

	BasebandThread baseband_thread { baseband_fs, this, NORMALPRIO + 20, baseband::Direction::Transmit };

	std::array<complex8_t, 256> iq { };
	const buffer_c8_t iq_buffer {
		iq.data(),
		iq.size(),
		baseband_fs /4
	};
	
	uint32_t channel_filter_pass_f = 0;
	uint32_t channel_filter_stop_f = 0;

	std::unique_ptr<StreamOutput> stream { };

	SpectrumCollector channel_spectrum { };
	size_t spectrum_interval_samples = 0;
	size_t spectrum_samples = 0;
	
	bool configured { false };
	uint32_t bytes_read { 0 };

	void samplerate_config(const SamplerateConfigMessage& message);
	void replay_config(const ReplayConfigMessage& message);
	
	TXProgressMessage txprogress_message { };
	RequestSignalMessage sig_message { RequestSignalMessage::Signal::FillRequest };
};

#endif/*__PROC_GPS_SIM_HPP__*/

下一篇文章会仔细分析我写的gps_sim_app.cpp，gps_sim_app.hpp，proc_gps_sim.cpp，proc_gps_sim.hpp这4个文件，以及我碰到的问题。

这些问题和GPS信号与iq数据处理有关。

但是以上做的这几个步骤已经可以看作是写一个新的应用的流程了。