fastsa/main.cpp

#include <iostream>
#include <cstdlib>
#include <cstring>
#include <thread>
#include <chrono>
#include <atomic>
#include <mutex>
#include <vector>

#include <GLFW/glfw3.h>

#include <imgui.h>
#include <imgui_impl_glfw.h>
#include <imgui_impl_opengl3.h>

#include <tinyalsa/pcm.h>

static std::atomic<bool> terminate_dsp;

static struct pcm* pcm;

static std::mutex waterfall_data_mutex;
static int waterfall_width = 1600;
static int waterfall_height = 700;
static unsigned int waterfall_data[1600*700];

static void dsp_thread() {
    using namespace std::chrono;

    int frame_count = pcm_get_rate(pcm);
    std::vector<int> frames(pcm_frames_to_bytes(pcm, frame_count)/4);
    int total_read_count = 0;
    std::chrono::steady_clock::time_point begin = std::chrono::steady_clock::now();
    while(!terminate_dsp) {
        int read_count = pcm_readi(pcm, frames.data(), frame_count);
        total_read_count += read_count;
        std::cout << read_count << std::endl;
        {
            std::lock_guard<std::mutex> guard(waterfall_data_mutex);
            std::memmove(&waterfall_data[waterfall_width], &waterfall_data[0], 4*waterfall_width*(waterfall_height - 1));
            for(int i=0;i<waterfall_width;i++) {
                waterfall_data[i] = 0xff000000 | frames[2*i*read_count/waterfall_width];
            }
        }
    };
    std::chrono::steady_clock::time_point end = std::chrono::steady_clock::now();
    std::cout << "measured sample rate: " << total_read_count/((end - begin)/1s) << std::endl;
}

int main(int, char**)
{
    if (!glfwInit()) {
        std::cerr << "failed to initialize GLFW" << std::endl;
        return 1;
    }
    std::atexit(glfwTerminate);
    glfwWindowHint(GLFW_CONTEXT_VERSION_MAJOR, 3);
    glfwWindowHint(GLFW_CONTEXT_VERSION_MINOR, 0);
    static GLFWwindow* window = glfwCreateWindow(1900, 720, "microsa", nullptr, nullptr);
    if (window == nullptr) {
        std::cerr << "failed to create GLFW window" << std::endl;
        return 1;
    }
    static auto DestroyWindow = []() {
        glfwDestroyWindow(window);
    };
    std::atexit(DestroyWindow);
    glfwMakeContextCurrent(window);
    glfwSwapInterval(1);

    IMGUI_CHECKVERSION();
    ImGui::CreateContext();
    static auto ImGuiDestroyContext = []() {
        ImGui::DestroyContext();
    };
    std::atexit(ImGuiDestroyContext);
    ImGuiIO& io = ImGui::GetIO();
    io.ConfigFlags |= ImGuiConfigFlags_NavEnableKeyboard;
    ImGui::StyleColorsDark();
    ImGui_ImplGlfw_InitForOpenGL(window, true);
    std::atexit(ImGui_ImplGlfw_Shutdown);
    ImGui_ImplOpenGL3_Init("#version 130");
    std::atexit(ImGui_ImplOpenGL3_Shutdown);

    GLuint waterfall;
    glGenTextures(1, &waterfall);
    glBindTexture(GL_TEXTURE_2D, waterfall);
    glTexParameteri(GL_TEXTURE_2D, GL_TEXTURE_MIN_FILTER, GL_LINEAR);
    glTexParameteri(GL_TEXTURE_2D, GL_TEXTURE_MAG_FILTER, GL_LINEAR);
    glTexParameteri(GL_TEXTURE_2D, GL_TEXTURE_WRAP_S, GL_CLAMP_TO_EDGE);
    glTexParameteri(GL_TEXTURE_2D, GL_TEXTURE_WRAP_T, GL_CLAMP_TO_EDGE);

    const struct pcm_config config = {
        .channels = 2,
        .rate = 192000,
        .period_size = 1024,
        .period_count = 2,
        .format = PCM_FORMAT_S32_LE,
        .start_threshold = 1024,
        .stop_threshold = 1024 * 2,
        .silence_threshold = 1024 * 2,
    };
    pcm = pcm_open(0, 0, PCM_IN, &config);
    if(pcm == nullptr) {
        std::cerr << "failed to allocate memory for PCM" << std::endl;
        return 1;
    }
    static auto PCMClose = []() {
        pcm_close(pcm);
    };
    std::atexit(PCMClose);
    if (!pcm_is_ready(pcm)){
        std::cerr << "failed to open PCM" << std::endl;
        return 1;
    }

    terminate_dsp = false;
    static std::thread dsp_thread_h = std::thread(dsp_thread);
    static auto TerminateDSP = []() {
        terminate_dsp = true;
        dsp_thread_h.join();
    };
    std::atexit(TerminateDSP);

    bool exit = false;
    while(!exit && !glfwWindowShouldClose(window)) {
        glfwPollEvents();
        glClearColor(0.0f, 0.0f, 0.0f, 1.0f);
        glClear(GL_COLOR_BUFFER_BIT);

        glBindTexture(GL_TEXTURE_2D, waterfall);
        #if defined(GL_UNPACK_ROW_LENGTH) && !defined(__EMSCRIPTEN__)
        glPixelStorei(GL_UNPACK_ROW_LENGTH, 0);
        #endif
        {
            std::lock_guard<std::mutex> guard(waterfall_data_mutex);
            glTexImage2D(GL_TEXTURE_2D, 0, GL_RGBA, waterfall_width, waterfall_height, 0, GL_RGBA, GL_UNSIGNED_BYTE, waterfall_data);
        }

        ImGui_ImplOpenGL3_NewFrame();
        ImGui_ImplGlfw_NewFrame();
        ImGui::NewFrame();

        ImGui::SetNextWindowPos(ImVec2(0.0f, 0.0f));
        ImGui::SetNextWindowSize(io.DisplaySize);
        ImGui::PushStyleVar(ImGuiStyleVar_WindowRounding, 0.0f);
        ImGui::Begin("microsa", nullptr, ImGuiWindowFlags_NoDecoration | ImGuiWindowFlags_NoResize);

        ImGui::BeginTable("microsa", 2, ImGuiTableFlags_SizingStretchSame | ImGuiTableFlags_Resizable);
        ImGui::TableSetupColumn("", 0, 280.0);
        ImGui::TableSetupColumn("", 0, 1600.0);
        ImGui::TableNextColumn();
        if(ImGui::Button("Exit"))
            exit = true;
        ImGui::TableNextColumn();
        ImGui::Image((void*)(intptr_t)waterfall, ImVec2(waterfall_width, waterfall_height));
        ImGui::EndTable();

        ImGui::End();
        ImGui::PopStyleVar(1);

        // Rendering
        ImGui::Render();
        ImGui_ImplOpenGL3_RenderDrawData(ImGui::GetDrawData());
        int display_w, display_h;
        glfwGetFramebufferSize(window, &display_w, &display_h);
        glViewport(0, 0, display_w, display_h);
        glfwSwapBuffers(window);
    }

    return 0;
}