98 lines
1.7 KiB
C
98 lines
1.7 KiB
C
#include <stdio.h>
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#include <stdlib.h>
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void print_usage(char *argv[])
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{
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fprintf(stderr, "Usage: %s <value>\n"
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"\n"
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"value:\n"
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"\t +percent - increase brightness by percent\n"
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"\t -percent - decrease brightness by percent\n",
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argv[0]);
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}
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int read_file(const char *path)
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{
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FILE *file = fopen(path, "r");
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int value;
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int read = fscanf(file, "%d", &value);
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fclose(file);
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if (read != 1)
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{
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printf("Error reading %s\n", path);
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exit(1);
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}
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return value;
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}
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int max_brightness()
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{
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return read_file("/sys/class/backlight/intel_backlight/max_brightness");
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}
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int brightness()
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{
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return read_file("/sys/class/backlight/intel_backlight/brightness");
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}
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int brightness_percent()
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{
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return (brightness() * 100) / max_brightness();
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}
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int main(int argc, char *argv[])
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{
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if (argc < 2)
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{
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printf("%d\n", brightness_percent());
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return 0;
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}
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if (argc > 3)
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{
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print_usage(argv);
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exit(2);
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}
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int positive = 0;
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if (argv[1][0] == '-')
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{
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positive = 0;
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}
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else if (argv[1][0] == '+')
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{
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positive = 1;
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}
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else
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{
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print_usage(argv);
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exit(2);
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}
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int percent;
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char *number_str = argv[1] + 1;
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int read = sscanf(number_str, "%d", &percent);
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if (read != 1)
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{
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print_usage(argv);
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exit(3);
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}
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int current = brightness();
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int max = max_brightness();
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int change = (max * percent) / 100 * (positive ? 1 : -1);
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FILE *file = fopen("/sys/class/backlight/intel_backlight/brightness", "w");
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int set_to = current + change;
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// clamp
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if (set_to > max)
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{
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set_to = max;
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}
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if (set_to < 0)
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{
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set_to = 1;
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}
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fprintf(file, "%d", set_to);
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}
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