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// WTFPL
#include <stdio.h>
#include <stdlib.h>
#include <unistd.h>
#include <stdint.h>
#include <sys/time.h>
#include <sys/mman.h>
#include <sys/param.h>
#define MS * 1000
#define SEC * 1000000
#define DEBOUNCE (10 MS)
#define THREAD_WAIT (100 MS)
#define BACKLIGHT_TIME (10 SEC)
#define BACKLIGHT_FADE_FRAMETIME (50 MS)
#define BACKLIGHT_FADE_TIME (1000 MS)
#define BACKLIGHT_FADE_STEPS (BACKLIGHT_FADE_TIME / BACKLIGHT_FADE_FRAMETIME)
#define KEYPRESS_SIZE 72
#define KEYBOARD_FILE "/dev/input/event1"
#define BACKLIGHT_FILE "/sys/class/leds/keyboard_light/brightness"
//#define BACKLIGHT_FILE stdout
#define MAX_BRIGHTNESS 255
static struct timeval* last_press;
static uint32_t curr_brightness;
static FILE* backlight_fp;
void write_to_backlight(int n) {
fprintf(backlight_fp, "%d", n);
fflush(backlight_fp);
curr_brightness = n;
}
#if 0
void backlight_fade(void) {
short brightness_step = MAX_BRIGHTNESS / BACKLIGHT_FADE_STEPS;
short* brightness = malloc(sizeof(short));
*brightness = MAX_BRIGHTNESS;
fprintf(stderr, "ha, gay\n");
do {
fprintf(stderr, "%d %d %d\n", *brightness, brightness_step, 0);
write_to_backlight(*brightness);
*brightness -= brightness_step;
usleep(BACKLIGHT_FADE_FRAMETIME);
} while (*brightness >= brightness_step);
}
#endif
void backlight_off(void) {
if (curr_brightness == 0) return;
write_to_backlight(0);
// backlight_fade();
}
void backlight_on(void) {
curr_brightness = MAX_BRIGHTNESS;
write_to_backlight(MAX_BRIGHTNESS);
usleep(BACKLIGHT_TIME);
}
void light_thread(void) {
// check last_press vs time, do the thing
backlight_fp = fopen(BACKLIGHT_FILE, "w");
// FILE* backlight_fp = BACKLIGHT_FILE;
struct timeval now;
uint64_t now_usec;
uint64_t press_usec;
uint64_t diff;
while (1) {
gettimeofday(&now, NULL);
now_usec = now.tv_sec * 1000000L;
now_usec += now.tv_usec;
press_usec = last_press->tv_sec * 1000000L;
press_usec += last_press->tv_usec;
diff = now_usec - press_usec;
if (diff > BACKLIGHT_TIME) backlight_off();
else backlight_on();
usleep(THREAD_WAIT);
fflush(stdout);
}
}
void on_press(void) {
gettimeofday(last_press, NULL);
}
void daemonize(void) {
daemon(0, 0);
}
int main(int argc, const char* argv[]) {
FILE* fp = fopen(KEYBOARD_FILE, "r");
fseek(fp, 0, SEEK_END);
void* discard = malloc(KEYPRESS_SIZE);
// shared mem b/c new proc doesn't share mem space
last_press = mmap(NULL, sizeof(last_press), PROT_READ | PROT_WRITE, MAP_SHARED | MAP_ANONYMOUS, -1, 0);
if (fork() == 0) {
daemonize();
light_thread();
} else daemonize();
while (1) {
fseek(fp, 0, SEEK_END);
fread(discard, 1, KEYPRESS_SIZE, fp);
on_press();
usleep(DEBOUNCE);
}
return 0;
}
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