/* * heatbeat.c -- flash NumLock in an hearthbeat fashion * * Copyright (C) 2001 Alessandro Rubini and Jonathan Corbet * Copyright (C) 2001 O'Reilly & Associates * * The source code in this file can be freely used, adapted, * and redistributed in source or binary form, so long as an * acknowledgment appears in derived source files.  The citation * should list that the code comes from the book "Linux Device * Drivers" by Alessandro Rubini and Jonathan Corbet, published * by O'Reilly & Associates.   No warranty is attached; * we cannot take responsibility for errors or fitness for use. */#include <stdio.h>#include <stdlib.h>#include <unistd.h>#include <string.h>#include <ctype.h>#include <errno.h>#include <sys/types.h>#include <sys/stat.h>#include <fcntl.h>#include <sys/ioctl.h>#include <linux/kd.h>int main(int argc, char **argv){    char led;    int chosenled = 1;    char hearth[]={1,0,1,1,0,0,0,0,0,0,0,0,0};    int udelay = 100000;    int load = 0;    char *prgname = argv[0];    FILE *f;    if (argc > 1 && isdigit(argv[1][0])) { /* the time delay */        udelay = 1000 * atoi(argv[1]);        if (udelay < 1000)            fprintf(stderr, "%s: delay too short\n", prgname);        else {            argv++; argc--;        }    }    nice(-20); /* in case is succeeds... */    udelay *= 100; /* prepare for a later division */    if (argc > 1 && strlen(argv[1]) == 1) {        argv++, argc--;        if (tolower(argv[0][0]) == 's') chosenled = 1; /* scroll lock */        else             if (tolower(argv[0][0]) == 'n') chosenled = 2; /* num lock */        else            if (tolower(argv[0][0]) == 'c') chosenled = 4; /* caps lock */        else {            fprintf(stderr, "%s: unknown led '%s'\n", prgname, argv[1]);            argc++;        }    }    if (argc>1) {        fprintf(stderr, "%s: usage \"%s [delay ms] [ n | c | s ]\"\n",                prgname, prgname);        exit(1);    }           /* ok, now do your loop */    for (;;) {        int consolefd=open("/dev/tty0",O_RDONLY);        int i;        f=fopen("/proc/loadavg", "r");        if (f) {            fscanf(f, "%d.%d", &load, &i);            fclose(f);        } else {            load = i = 0;        }        load = 100 + load * 100 + i;        for (i=0; i < sizeof(hearth)/sizeof(hearth[0]); i++) {            if (ioctl(consolefd, KDGETLED, &led)                || ioctl(consolefd, KDSETLED,                         (led & ~chosenled) | chosenled * hearth[i])) {                fprintf(stderr, "%s: ioctl(): %s\n", prgname, strerror(errno));                exit(2);            }            usleep(udelay/load);        }        close(consolefd);    }    exit(0); /* never happen */}