Read & parse voltage & current data

[batteryviewer] / batteryviewer.c

diff --git a/batteryviewer.c b/batteryviewer.c
index 535ef74fed43f609417199bb7e644d70a2bc845a..1c38b3cca8527a36052023be1d85a54c5863c453 100644 (file)
--- a/batteryviewer.c
+++ b/batteryviewer.c
@@ -1,8 +1,54 @@
 #include "chart.h"
+#include <ctype.h>
+#include <errno.h>
 #include <gtk/gtk.h>
+#include <math.h>
+#include <stdio.h>
+#include <stdlib.h>
 
-static void activate(GtkApplication *app,
-                     gpointer user_data __attribute__((unused))) {
+const char voltage_filename[] = "/sys/class/power_supply/BAT0/voltage_now";
+const char current_filename[] = "/sys/class/power_supply/BAT0/current_now";
+
+struct State {
+  BVChart *voltage;
+  BVChart *current;
+};
+
+static float fatof(const char *filename) {
+  FILE *f = fopen(filename, "r");
+  if (f == NULL) {
+    return NAN;
+  }
+
+  const int bufsize = 1024;
+  char buf[bufsize];
+  const int read = fread(buf, sizeof(char), bufsize, f);
+  if (read == 0 || read == bufsize || ferror(f)) {
+    fclose(f);
+    return NAN;
+  }
+  fclose(f);
+
+  char *end;
+  errno = 0;
+  float val = strtof(buf, &end);
+  int parsed = end - buf;
+  gboolean parsed_all = parsed == read;
+  gboolean parsed_all_but_space = parsed == read - 1 && isspace(*end);
+  gboolean parse_ok = parsed_all || parsed_all_but_space;
+  if (errno != 0 || parsed == 0 || !parse_ok) {
+    return NAN;
+  }
+  return val;
+}
+
+static gboolean collect_data(struct State *state __attribute__((unused))) {
+  fprintf(stderr, "Voltage: %f, current: %f\n", fatof(voltage_filename),
+          fatof(current_filename));
+  return TRUE;
+}
+
+static void activate(GtkApplication *app, gpointer user_data) {
 
   GtkWidget *window = gtk_application_window_new(app);
   gtk_window_set_title(GTK_WINDOW(window), "BatteryViewer");
@@ -11,28 +57,34 @@ static void activate(GtkApplication *app,
   GtkWidget *box = gtk_box_new(GTK_ORIENTATION_VERTICAL, 1);
   gtk_container_add(GTK_CONTAINER(window), box);
 
-  GtkWidget *chart = bv_chart_new();
-  bv_chart_add_point(BV_CHART(chart), 0.0, 0.0);
-  bv_chart_add_point(BV_CHART(chart), 1.0, 1.0);
-  bv_chart_add_point(BV_CHART(chart), 3.0, 2.0);
+  struct State *state = (struct State *)user_data;
+  state->voltage = BV_CHART(bv_chart_new());
+  bv_chart_add_point(state->voltage, 0.0, 0.0);
+  bv_chart_add_point(state->voltage, 1.0, 1.0);
+  bv_chart_add_point(state->voltage, 3.0, 2.0);
   gboolean expand = TRUE;
   gboolean fill = TRUE;
   guint padding = 0;
-  gtk_box_pack_start(GTK_BOX(box), chart, expand, fill, padding);
+  gtk_box_pack_start(GTK_BOX(box), GTK_WIDGET(state->voltage), expand, fill,
+                     padding);
 
-  GtkWidget *chart2 = bv_chart_new();
-  bv_chart_add_point(BV_CHART(chart2), 0.0, 1.0);
-  bv_chart_add_point(BV_CHART(chart2), 1.0, 0.0);
-  gtk_box_pack_end(GTK_BOX(box), chart2, expand, fill, padding);
+  state->current = BV_CHART(bv_chart_new());
+  bv_chart_add_point(state->current, 0.0, 1.0);
+  bv_chart_add_point(state->current, 1.0, 0.0);
+  gtk_box_pack_end(GTK_BOX(box), GTK_WIDGET(state->current), expand, fill,
+                   padding);
 
   gtk_widget_show_all(window);
+
+  g_timeout_add_seconds(1, (GSourceFunc)collect_data, user_data);
 }
 
 int main(int argc, char **argv) {
+  struct State state;
 
   GtkApplication *app = gtk_application_new("com.scottworley.batteryviewer",
                                             G_APPLICATION_DEFAULT_FLAGS);
-  g_signal_connect(app, "activate", G_CALLBACK(activate), NULL);
+  g_signal_connect(app, "activate", G_CALLBACK(activate), &state);
   int status = g_application_run(G_APPLICATION(app), argc, argv);
   g_object_unref(app);