verbose and retry on file read

.gitignore

@@ -1,3 +1,4 @@
 ambientd
 !sv/**
 .ccls-cache
+.zed

Makefile

@@ -1,8 +1,7 @@
-CC = gcc
-CFLAGS = -Wall -Wextra -pedantic -std=c99 -O2
 PREFIX = /usr/local
 
-ambientd: ambientd.c
+ambientd: ambientd.c3
+	c3c compile -O1 -g0 --optsize=small --fp-math=fast --x86cpu=native ambientd.c3
 
 install:
 	cp ambientd ${PREFIX}/bin/

TODO

@@ -1,10 +0,0 @@
-[ ] Add a config file
-[ ] Use a better filter than a simple median, maybe a kalman filter
-[ ] Add a way to customise the brightness curve
-	Percieved brightness is not linear, on low light you need a slightly higher
-	brightness and on high light you can get away with a lower brightness
-	than the max, the goal is to find the right curve for the screen
-[ ] Automatically detect backlight device, or at least make it configurable
-[ ] Add signal handlers
-	[ ] SIGUSR1 to reset the user offset
-	[ ] Handle kill by closing all file descriptors

ambientd.c

@@ -1,178 +0,0 @@
-#include <stdlib.h>
-#include <stdio.h>
-#include <errno.h>
-#include <string.h>
-#include <unistd.h>
-#include <limits.h>
-
-#define MAX(x, y) ((x) > (y) ? (x) : (y))
-#define MIN(x, y) ((x) < (y) ? (x) : (y))
-#define ABS(x)    ((x) < 0 ? -(x) : (x))
-#define MEDIAN_SAMPLES 4
-
-const char *LUMINANCE_DEV = "/sys/bus/iio/devices/iio:device0/in_illuminance_raw";
-const char *MAX_BRIGHTNESS_DEV = "/sys/class/backlight/intel_backlight/max_brightness";
-const char *BRIGHTNESS_DEV = "/sys/class/backlight/intel_backlight/brightness";
-const char *ACTUAL_BRIGHTNESS_DEV = "/sys/class/backlight/intel_backlight/actual_brightness";
-
-char STR_BUFFER[128] = {0};
-
-// file pointer to the luminance device
-FILE *luminance_fp = NULL;
-
-// max luminance that the display can output
-int max_luminance = 550;
-
-// minimum display brightness in percent
-float min_brightness_percent = 0.05;
-
-// returns the luminance value in percentage between 0 and 1
-int get_luminance_raw (void)
-{
-	freopen(NULL, "r", luminance_fp);
-	const char *x = fgets(STR_BUFFER, sizeof(STR_BUFFER), luminance_fp);
-	if (x == NULL) {
-		return -1;
-	}
-	int luminance = strtol(STR_BUFFER, NULL, 10);
-
-	return luminance;
-}
-
-// read a string from a file and convert it to int, should only be used for
-// positive numbers since negative numbers mean an error
-int read_int(FILE *fp)
-{
-	freopen(NULL, "r", fp);
-	const char *p = fgets(STR_BUFFER, sizeof(STR_BUFFER), fp);
-	if (p == NULL) {
-		return -1;
-	}
-	long r = strtol(STR_BUFFER, NULL, 10);
-	if (r == LONG_MIN || r == LONG_MAX) {
-		return -1;
-	}
-	return r;
-}
-
-float bezier(float t)
-{
-	const float B = 0.66;
-	const float D = 0.28; 
-	return 3*B*t+(3*D-6*B)*t*t+(1+3*B-3*D)*t*t*t;
-}
-
-// TODO: add some command line options like:
-//       -v: verbose/logging
-//       -c file; specify a config file
-int main (void)
-{
-	// open the luminance device
-	luminance_fp = fopen(LUMINANCE_DEV, "r");
-	if (luminance_fp == NULL) {
-		fprintf(stderr, "Could not open luminance device '%s': %s\n",
-		        LUMINANCE_DEV, strerror(errno));
-		return 1;
-	}
-
-	// get max and min brightness
-	FILE *fp = fopen(MAX_BRIGHTNESS_DEV, "r");
-	if (fp == NULL) {
-		fprintf(stderr, "Could not open max_brightness file '%s': %s\n",
-		        MAX_BRIGHTNESS_DEV, strerror(errno));
-		return 1;
-	}
-	int max_brightness = read_int(fp);
-	if (max_brightness < 0) {
-		fprintf(stderr, "Could not read max brightness value: %s\n", strerror(errno));
-		return 1;
-	}
-	int min_brightness = max_brightness * min_brightness_percent;
-	fclose(fp);
-
-
-	// open brightness device
-	FILE *brightness_fp = fopen(BRIGHTNESS_DEV, "w");
-	if (brightness_fp == NULL) {
-		fprintf(stderr, "Could not open brightness device '%s': %s\n",
-		        BRIGHTNESS_DEV, strerror(errno));
-		return 1;
-	}
-
-	// open actual brightness device
-	FILE *actual_brightness_fp = fopen(ACTUAL_BRIGHTNESS_DEV, "r");
-	if (brightness_fp == NULL) {
-		fprintf(stderr, "Could not open actual brightness device '%s': %s\n",
-		        ACTUAL_BRIGHTNESS_DEV, strerror(errno));
-		return 1;
-	}
-
-	int x = get_luminance_raw();
-	if (x < 0) {
-		fprintf(stderr, "Could not read luminance value: %s\n", strerror(errno));
-	}
-	int luminance_samples[MEDIAN_SAMPLES] = {x, x, x, x};
-	int idx = 0;
-	int user_offset = 0;
-	int brightness_target = min_brightness;
-	int brightness_old = min_brightness;
-	int brightness_adjusted = min_brightness;
-	int brightness_delta = 0;
-	while (1) {
-		static float luminance;
-		static float luminance_percent;
-
-		x = get_luminance_raw();
-		if (x >= 0) luminance_samples[idx] = x;
-		idx = (idx + 1) % MEDIAN_SAMPLES;
-
-		luminance = 0;
-		for (int i = 0; i < MEDIAN_SAMPLES; i++) {
-			luminance += luminance_samples[i] / MEDIAN_SAMPLES;
-		}
-		luminance_percent = bezier(MIN(luminance/max_luminance, 1.0));
-
-		brightness_old = brightness_target;
-		brightness_target = MAX((int)(luminance_percent * max_brightness), min_brightness);
-		brightness_delta = ABS((float)(brightness_target - brightness_old)/brightness_old);
-
-		// if the brightness changes by more than 10% reduce the user offset, scaling
-		// with the delta, this accounts for large changes in brightness no longer
-		// corresponding to the adjustments that the user made to the brightness
-		if (brightness_delta > 0.1) {
-			user_offset = user_offset * MAX(MIN(1-(brightness_delta*1.2), 1), 0);
-		}
-
-		brightness_adjusted = MIN(MAX(brightness_target + user_offset, min_brightness), max_brightness);
-		// TODO: put this in write_int() function
-		x = snprintf(STR_BUFFER, sizeof(STR_BUFFER), "%d", brightness_adjusted);
-		if (x <= 0) {
-			fprintf(stderr, "Error in snprintf(): %s\n", strerror(errno));
-		}
-		if (fputs(STR_BUFFER, brightness_fp) == EOF) {
-			fprintf(stderr, "error writing brightness: %s\n", strerror(errno));
-		}
-		rewind(brightness_fp);
-
-		sleep(3);
-
-		// read actual brightness to get the user offset
-		int actual_brightness = 0;
-		int off = 0;
-		actual_brightness = read_int(actual_brightness_fp);
-		if (actual_brightness < 0) {
-			fprintf(stderr, "error reading actual brightness: %s\n", strerror(errno));
-			actual_brightness = brightness_adjusted;
-		}
-
-		off = actual_brightness - brightness_target;
-		if (brightness_target != max_brightness || off < 0){
-			user_offset = off;
-		}
-
-		// TODO: option to turn off logging
-		printf("brightness target: %d;  user offset: %d; brightness adjusted: %d\n", brightness_target, user_offset, brightness_adjusted);
-	}
-
-	return 0;
-}

ambientd.c3

@@ -0,0 +1,297 @@
+module ambientd;
+
+import std::io;
+import std::io::path;
+import std::os::env;
+import std::os::posix;
+import std::collections::list;
+import std::collections::object;
+import std::encoding::ini;
+import std::thread;
+import std::time;
+import std::math;
+import libc;
+
+
+alias StrList = List{String};
+
+
+const String DEF_LIGHT_SENSOR_PATH = "/sys/bus/iio/devices/iio:device0/in_illuminance_raw";
+const String DEF_BACKLIGHT_PATH = "/sys/class/backlight/intel_backlight";
+const float  DEF_SCREEN_NIT = 400.0;
+const float  DEF_SENSOR_K = 0.98;
+const int    DEF_UPDATE_INTERVAL_MS = 200;
+
+const String[*] CONFIG_PATHS = {
+	"$XDG_CONFIG_HOME/ambientd/ambientd.ini",
+	"$HOME/.config/ambientd/ambientd.ini",
+	"/etc/ambientd/ambientd.ini",
+};
+
+
+String light_sensor_path = DEF_LIGHT_SENSOR_PATH;
+String backlight_path = DEF_BACKLIGHT_PATH;
+float backlight_max_luminance = DEF_SCREEN_NIT;
+float light_sensor_k = DEF_SENSOR_K;
+int update_interval_ms = DEF_UPDATE_INTERVAL_MS;
+
+
+struct LuminanceFilter {
+	float x; // estimate
+	float p; // error
+	float r; // mesurement noise
+	float q; // process noise
+}
+
+
+fn float LuminanceFilter.update(&self, int reading, float dt)
+{
+	float x_1 = self.x;
+	float p_1 = self.p + self.q * dt;
+
+	float k = p_1 / (p_1 + self.r);
+
+	self.x = x_1 + k * ((float)reading - x_1);
+	self.p = (1.0 - k) * p_1;
+
+	return self.x;
+}
+
+
+fn void LuminanceFilter.init(&self, int reading)
+{
+	self.p = 0.0;
+	self.x = (float)reading;
+}
+
+
+// TODO: this should be configurable
+LuminanceFilter filter = {.r = 5.0, .q = 0.1};
+
+
+fn String? String.to_expanded_path(&str, Allocator allocator, String[] extra_env = {})
+{
+	@pool() {
+		StrList l;
+		l.tinit();
+		Path str_path = str.to_tpath()!;
+
+		l.push(str_path.basename());
+		Path? p = str_path.parent();
+		while (true) {
+			Path? x;
+			if (try p) {
+				String n = p.basename();
+				l.push("/");
+
+				// env variable
+				if (n.starts_with("$")) {
+					String? e = env::tget_var(n[1..]);
+					if (catch e) {
+						// var is not in regular environment, check extra_env
+						bool in_extra = false;
+						foreach_r (j: extra_env) {
+							if (j.starts_with(n[1..])) {
+								l.push(j.strip_suffix(n[1..])[1..]);
+								in_extra = true;
+								break;
+							}
+						}
+						if (!in_extra) {
+							return NOT_FOUND~;
+						}
+					} else {
+						l.push(e);
+					}
+				} else {
+					l.push(n);
+				}
+
+				x = p.parent();
+			} else {
+				break;
+			}
+			p = x;
+		}
+		l.reverse();
+		String path;
+		path = string::tjoin(l.array_view(), path);
+
+		return (String)path::new(allocator, path);
+	};
+}
+
+
+fn void update_config()
+{
+	bool config_found = false;
+	foreach (c: CONFIG_PATHS) {
+		String? p = c.to_expanded_path(tmem);
+		if (catch e = p) {
+			io::eprintfn("Error expanding path %s: %s", c, e);
+			continue;
+		}
+		if (!file::exists(p)) {
+		io::printfn("%s not present", p);
+		continue;
+		}
+
+		// Read file
+		File f = file::open(p, "r")!!;
+		Object*? o = ini::load_temp(&f).get(ini::GLOBAL);
+		if (catch e = o) {
+			io::eprintfn("Error reading config file %s: %s", p, e);
+			continue;
+		}
+
+		// Read backlight device folder
+		String? backlight = o.get_string("backlight");
+		if (catch e = backlight) {
+			io::eprintfn("Error reading backlight path from config: %s", e);
+			continue;
+		}
+		if (!file::is_dir(backlight)) {
+			io::eprintfn("Error setting the backlight path: path should be a directory");
+			continue;
+		}
+		backlight_path = backlight;
+
+		// Read light sensor device path
+		String? sensor = o.get_string("sensor");
+		if (catch e = sensor) {
+			io::eprintfn("Error reading luminance sensor path from config: %s", e);
+			continue;
+		}
+		light_sensor_path = sensor;
+
+		// Optional configurations
+
+		// Read the max screen brightness
+		if (try x = o.get_string("max_brightness").to_float()) {
+			backlight_max_luminance = (float)x;
+		}
+
+		// Read the light sensor factor
+		if (try x = o.get_string("sensor_factor").to_float()) {
+			light_sensor_k = (float)x;
+		}
+
+		// Read the light sensor factor
+		if (try x = o.get_string("update_interval").to_int()) {
+			update_interval_ms = x;
+		}
+
+		config_found = true;
+		break;
+	}
+
+	if (!config_found) {
+		io::eprintfn("Keping previous configuration");
+	}
+}
+
+
+macro float @bezier(float t)
+{
+	const float B = 0.66;
+	const float D = 0.28;
+	return 3*B*t+(3*D-6*B)*t*t+(1+3*B-3*D)*t*t*t;
+}
+
+
+// https://docs.kernel.org/admin-guide/abi-stable-files.html#abi-file-stable-sysfs-class-backlight
+macro int? @read_int_from_file(String path) => ((String)file::load_temp(path)[..^2]).to_int();
+macro void @write_int_to_file(String path, int i) => (void)file::save(path, string::tformat("%d\n", i));
+macro int? @get_luminance() => @read_int_from_file(light_sensor_path);
+macro int? @get_max_backlight() => @read_int_from_file(backlight_path.tconcat("/max_brightness"));
+macro int? @get_backlight() => @read_int_from_file(backlight_path.tconcat("/brightness"));
+macro void @set_backlight(int v) => @write_int_to_file(backlight_path.tconcat("/brightness"), v);
+macro bool? @is_screen_on() => @read_int_from_file(backlight_path.tconcat("/bl_power")) == 0;
+
+macro @retry_every(#f, int ms = 100)
+{
+	const sz TRIES = 10;
+	for (sz i = 0; i < TRIES; i++) {
+		if (try x = #f) return x;
+		thread::sleep_ms(ms);
+	}
+	io::eprintfn("ERROR: tried to execute '%s' but it failed too many times (%d)", $stringify(#f), TRIES);
+	std::os::exit(1);
+}
+
+
+fn void sigusr1_handler(CInt sig, void* act, void* oldact)
+{
+	(void)sig;
+	(void)act;
+	(void)oldact;
+	update_config();
+}
+
+
+// TODO: add command line arguments, like -h, -v and -d
+// TODO: daemonization
+// TODO: override config file with arguments
+fn void main(String[] args)
+{
+	bool verbose = false;
+	foreach (a : args[1..]) {
+		switch (a) {
+		case "-v":
+			verbose = true;
+			break;
+		case "-h":
+			io::printfn("ambientd [-hv]");
+			std::os::exit(0);
+		default:
+			io::eprintfn("Unrecognized argument: '%s'", a);
+			std::os::exit(1);
+		}
+	}
+
+	update_config();
+
+	posix::install_signal_handler(libc::SIGUSR1, &sigusr1_handler);
+
+	int _l = @get_luminance() ?? 0;
+	filter.init(_l);
+	float luminance_old = filter.update(_l, 0.0);
+	int brightness_set = @retry_every(@get_backlight());
+	int user_offset = 0;
+	int backlight_max = @get_max_backlight() ?? 0;
+	Time start = time::now();
+
+	while (true) {
+		if (!@is_screen_on() ?? false) {
+			thread::sleep_ms(5000);
+			continue;
+		}
+
+
+		// Check user offset
+		user_offset = @retry_every(@get_backlight(), update_interval_ms/2) - brightness_set;
+		int _lx = @retry_every(@get_luminance(), update_interval_ms/2);
+
+		Time now = time::now();
+		Time dt = (Time)(now - start);
+
+		// Filtered luminance, depends heavily on the type of sensor, for the CF-SV7
+		// seems to be in lux
+		float luminance = filter.update(_lx, (float)dt.to_seconds()) * light_sensor_k;
+		// Percent of the luminance received compared to what the panel can output
+		float p = min((luminance/backlight_max_luminance), 1.0f);
+
+		// int new_brightness = (int)(@bezier(p)*backlight_max);
+		// The panel should output slightly more light than the ambient, moreover the
+		// relationship between a percent increase in the backlight power and the
+		// perceived luminance is non-linear, I think the inverse square law is correct
+		int new_brightness = (int)(math::pow(p*1.1f, 0.5f)*backlight_max);
+		brightness_set = new_brightness;
+		@set_backlight(max(brightness_set + user_offset, 0));
+
+		if (verbose) io::printfn("%f, %d, %d", luminance, brightness_set, user_offset);
+
+		start = now;
+		thread::sleep_ms(update_interval_ms);
+	}
+}

ambientd.py

@@ -1,73 +0,0 @@
-#!/usr/bin/python
-
-# Simple daemon to change brightness based on luminance
-# TODO: add a config
-# TODO: add debug option
-# TODO: add dry-run
-# TODO automatically find the right brightness path and do not assume intel_backlight
-
-import time
-
-# Open the luminance sensor device file
-try:
-    luminance_file = open('/sys/bus/iio/devices/iio:device0/in_illuminance_raw', 'r')
-except OSError as err:
-    print(err)
-    exit(1)
-
-# max luminance of the screen - 100 (maybe)
-max_luminance = 400
-
-# get luminance value, on fail return the max
-def get_luminance():
-    try:
-        l = int(luminance_file.read())
-        luminance_file.seek(0)
-    except:
-        l = max_luminance
-    return l
-
-# Get the max brightness 
-max_brightness = 100
-with open('/sys/class/backlight/intel_backlight/max_brightness', 'r') as f:
-    max_brightness = int(f.read())
-min_brightness = int(max_brightness * 0.05)
-
-# loop delay in seconds
-delay = 3
-
-lum = [get_luminance()]*4
-user_offset = 0
-brightness_target = min_brightness
-brightness_old = min_brightness
-while True:
-    lum.append(lum.pop(0))
-    lum[0] = get_luminance()
-    
-    luminance = sum(lum)/len(lum)
-    luminance_percent = min(luminance/max_luminance, 1.0)
-    brightness_old = brightness_target
-    brightness_target = max(int(luminance_percent * max_brightness), min_brightness)
-    brightness_delta = abs((brightness_target - brightness_old)/brightness_old)
-
-    # if the brightness changes by more than 10% reduce the user offset, scaling
-    # with the delta, this accounts for large changes in brightness no longer
-    # corresponding to the adjustments that the user made to the brightness
-    if brightness_delta > 0.1:
-        user_offset = int(user_offset * max(min(1-(brightness_delta*1.2), 1), 0))
-
-    brightness_adjusted = min(max(brightness_target + user_offset, min_brightness), max_brightness)
-    b = open('/sys/class/backlight/intel_backlight/brightness', 'w')
-    b.write(str(brightness_adjusted))
-    b.close()
-
-    time.sleep(delay)
-
-    # if the value of the brightness changed then update the user offset
-    a = open('/sys/class/backlight/intel_backlight/actual_brightness')
-    x = int(a.read()) - brightness_target
-    a.close()
-    if brightness_target != max_brightness or x < 0:
-        user_offset = x
-
-    print("brightness target: ", brightness_target, "user offset: ", user_offset, "brightness adjusted: ", brightness_adjusted)