switch to alsalib

Makefile

@@ -6,11 +6,11 @@ OBJS = $(addsuffix .o, $(basename $(notdir $(SOURCES))))
 
 CXXFLAGS = -std=c++14 -I$(IMGUI_DIR) -I$(IMGUI_DIR)/backends
 CXXFLAGS += -g -Wall -Wformat -O2
-LIBS =
+LIBS = -L$(TINYALSA_DIR)/lib
 
-LIBS += -lGL `pkg-config --static --libs glfw3`
+LIBS += -lGL `pkg-config --static --libs glfw3 alsa`
 
-CXXFLAGS += `pkg-config --cflags glfw3`
+CXXFLAGS += `pkg-config --cflags glfw3 alsa`
 CFLAGS = $(CXXFLAGS)
 
 ##---------------------------------------------------------------------

flake.nix

@@ -12,7 +12,7 @@
         name = "microsa";
         src = self;
         nativeBuildInputs = [ pkgs.pkg-config ];
-        propagatedBuildInputs = [ pkgs.wayland pkgs.glfw-wayland pkgs.libffi ];
+        propagatedBuildInputs = [ pkgs.wayland pkgs.glfw-wayland pkgs.libffi pkgs.alsa-lib ];
         preBuild = ''
           export IMGUI_DIR=${imgui_dir}
         '';

main.cpp

@@ -1,8 +1,10 @@
+#include <iostream>
 #include <cstdlib>
+#include <cstring>
 #include <thread>
-#include <chrono>
 #include <atomic>
 #include <mutex>
+#include <vector>
 
 #include <GLFW/glfw3.h>
 
@@ -10,37 +12,54 @@
 #include <imgui_impl_glfw.h>
 #include <imgui_impl_opengl3.h>
 
+#include <alsa/asoundlib.h>
+
 static std::atomic<bool> terminate_dsp;
+
+static snd_pcm_t* 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_literals;
-
-    int t = 0;
+    std::vector<short int> frames(6400);
     while(!terminate_dsp) {
-        t++;
+        int read_count = snd_pcm_readi(pcm, frames.data(), 6400);
+        if(read_count < 0) {
+            std::cerr << "read from audio interface failed: " << snd_strerror(read_count) << std::endl;
+            break;
+        }
         {
             std::lock_guard<std::mutex> guard(waterfall_data_mutex);
-            for(int y=0;y<waterfall_height;y++)
-                for(int x=0;x<waterfall_width;x++)
-                    waterfall_data[y*waterfall_width+x] = (x+y+t) | 0xff000000;
+            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 | 0x010101*(frames[i*read_count/waterfall_width]/256 + 128);
+            }
         }
-        std::this_thread::sleep_for(20ms);
     };
 }
 
-int main(int, char**)
+int main(int argc, char* argv[])
 {
-    if (!glfwInit())
+    if(argc != 2) {
+        std::cerr << "please specify ALSA device on the command line" << std::endl;
+        std::cerr << "use arecord -L to list, and select raw device without pulseaudio" << std::endl;
         return 1;
+    }
+    char* alsa_device = argv[1];
+
+    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 = []() {
@@ -72,6 +91,56 @@ int main(int, char**)
     glTexParameteri(GL_TEXTURE_2D, GL_TEXTURE_WRAP_S, GL_CLAMP_TO_EDGE);
     glTexParameteri(GL_TEXTURE_2D, GL_TEXTURE_WRAP_T, GL_CLAMP_TO_EDGE);
 
+    int err;
+    if ((err = snd_pcm_open(&pcm, alsa_device, SND_PCM_STREAM_CAPTURE, 0)) < 0) {
+        std::cerr << "cannot open ALSA device: " << snd_strerror(err) << std::endl;
+        return 1;
+    }
+    static auto PCMClose = []() {
+        snd_pcm_close(pcm);
+    };
+    std::atexit(PCMClose);
+    snd_pcm_hw_params_t* pcm_hw_params;
+    if((err = snd_pcm_hw_params_malloc(&pcm_hw_params)) < 0) {
+        std::cerr << "cannot allocate ALSA hardware parameter structure: " << snd_strerror(err) << std::endl;
+        return 1;
+    }
+    if((err = snd_pcm_hw_params_any(pcm, pcm_hw_params)) < 0) {
+        std::cerr << "cannot initialize ALSA hardware parameter structure: " << snd_strerror (err) << std::endl;
+        snd_pcm_hw_params_free(pcm_hw_params);
+        return 1;
+    }
+    if((err = snd_pcm_hw_params_set_access(pcm, pcm_hw_params, SND_PCM_ACCESS_RW_INTERLEAVED)) < 0) {
+        std::cerr << "cannot set ALSA access type: " << snd_strerror (err) << std::endl;
+        snd_pcm_hw_params_free(pcm_hw_params);
+        return 1;
+    }
+    if((err = snd_pcm_hw_params_set_format(pcm, pcm_hw_params, SND_PCM_FORMAT_S16_LE)) < 0) {
+        std::cerr << "cannot set sample format: " << snd_strerror (err) << std::endl;
+        snd_pcm_hw_params_free(pcm_hw_params);
+        return 1;
+    }
+    if((err = snd_pcm_hw_params_set_rate(pcm, pcm_hw_params, 192000, 0)) < 0) {
+        std::cerr << "cannot set ALSA sample rate: " << snd_strerror (err) << std::endl;
+        snd_pcm_hw_params_free(pcm_hw_params);
+        return 1;
+    }
+    if((err = snd_pcm_hw_params_set_channels(pcm, pcm_hw_params, 1)) < 0) {
+        std::cerr << "cannot set ALSA channel count: " << snd_strerror (err) << std::endl;
+        snd_pcm_hw_params_free(pcm_hw_params);
+        return 1;
+    }
+    if((err = snd_pcm_hw_params(pcm, pcm_hw_params)) < 0) {
+        std::cerr << "cannot set ALSA parameters: " << snd_strerror (err) << std::endl;
+        snd_pcm_hw_params_free(pcm_hw_params);
+        return 1;
+    }
+    snd_pcm_hw_params_free(pcm_hw_params);
+    if((err = snd_pcm_prepare(pcm)) < 0) {
+        std::cerr << "cannot prepare ALSA interface: " << snd_strerror (err) << std::endl;
+        return 1;
+    }
+
     terminate_dsp = false;
     static std::thread dsp_thread_h = std::thread(dsp_thread);
     static auto TerminateDSP = []() {