From: Scott Worley Date: Thu, 23 Feb 2023 20:38:26 +0000 (-0800) Subject: Read & parse voltage & current data X-Git-Url: http://git.scottworley.com/batteryviewer/commitdiff_plain/0f9e308a287e1e6d8cfd73a074d31f06c3e4c937?hp=6f50819eef408d0d7bc691bc1a239e26aae01cf5 Read & parse voltage & current data --- diff --git a/batteryviewer.c b/batteryviewer.c index 65d7009..1c38b3c 100644 --- a/batteryviewer.c +++ b/batteryviewer.c @@ -1,12 +1,50 @@ #include "chart.h" +#include +#include #include +#include +#include +#include + +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; }