Linux Cross Reference
cvs/emstar/fusd/examples/drums3.c

   /*
    *
    * Copyright (c) 2003 The Regents of the University of California.  All 
    * rights reserved.
    *
    * Redistribution and use in source and binary forms, with or without
    * modification, are permitted provided that the following conditions
    * are met:
    *
   * - Redistributions of source code must retain the above copyright
   *   notice, this list of conditions and the following disclaimer.
   *
   * - Neither the name of the University nor the names of its
   *   contributors may be used to endorse or promote products derived
   *   from this software without specific prior written permission.
   *
   * THIS SOFTWARE IS PROVIDED BY THE REGENTS AND CONTRIBUTORS ``AS IS''
   * AND ANY EXPRESS OR IMPLIED WARRANTIES, INCLUDING, BUT NOT LIMITED TO,
   * THE IMPLIED WARRANTIES OF MERCHANTABILITY AND FITNESS FOR A
   * PARTICULAR  PURPOSE ARE DISCLAIMED. IN NO EVENT SHALL THE REGENTS OR
   * CONTRIBUTORS BE LIABLE FOR ANY DIRECT, INDIRECT, INCIDENTAL, SPECIAL,
   * EXEMPLARY, OR CONSEQUENTIAL DAMAGES (INCLUDING, BUT NOT LIMITED TO,
   * PROCUREMENT OF SUBSTITUTE GOODS OR SERVICES; LOSS OF USE, DATA, OR
   * PROFITS; OR BUSINESS INTERRUPTION) HOWEVER CAUSED AND ON ANY THEORY
   * OF LIABILITY, WHETHER IN CONTRACT, STRICT LIABILITY, OR TORT
   * (INCLUDING NEGLIGENCE OR OTHERWISE) ARISING IN ANY WAY OUT OF THE USE
   * OF THIS SOFTWARE, EVEN IF ADVISED OF THE POSSIBILITY OF SUCH DAMAGE.
   *
   */
   
  
  /*
   * FUSD - The Framework for UserSpace Devices - Example program
   *
   * Jeremy Elson <jelson@circlemud.org>
   *
   * drums3.c: This example shows how to wait for both FUSD and non-FUSD
   * events at the same time.  Instead of using fusd_run, we keep
   * control of main() by using our own select loop.
   *
   * Like the original drums.c, this example creates a bunch of devices
   * in the /dev/drums directory: /dev/drums/bam, /dev/drums/bum, etc.
   * However, it also prints a prompt to the console, asking the user if
   * how loud the drums should be.
   *
   * $Id: drums3.c,v 1.5 2007-12-08 04:05:01 girod Exp $
   */
  
  #include <stdio.h>
  #include <stdlib.h>
  #include <string.h>
  #include <ctype.h>
  #include <errno.h>
  #include <unistd.h>
  #include <sys/select.h>
  
  #include "fusd.h"
  
  #define MIN(x, y) ((x) < (y) ? (x) : (y))
  
  
  static char *drums_strings[] = {"bam", "bum", "beat", "boom",
                                  "bang", "crash", NULL};
  
  int volume = 2; /* default volume is 2 */
  
  ssize_t drums_read(struct fusd_file_info *file, char *user_buffer,
                 size_t user_length, loff_t *offset)
  {
    int len;
    char sound[128], *c;
  
    /* 1st read returns the sound; 2nd returns EOF */
    if (*offset != 0)
      return 0;
  
    if (volume == 1)
      strcpy(sound, "(you hear nothing)");
    else {
      strcpy(sound, (char *) file->device_info);
  
      if (volume >= 3)
        for (c = sound; *c; c++)
          *c = toupper(*c);
  
      if (volume >= 4)
        strcat(sound, "!!!!!");
    }
  
    strcat(sound, "\n");
  
    /* NEVER return more data than the user asked for */
    len = MIN(user_length, strlen(sound));
    memcpy(user_buffer, sound, len);
    *offset += len;
    return len;
  }
  
  
 int do_open_or_close(struct fusd_file_info *file)
 {
   return 0; /* opens and closes always succeed */
 }
 
 
 struct fusd_file_operations drums_fops = {
   open: do_open_or_close,
   read: drums_read,
   close: do_open_or_close
 };
 
 
 void read_volume(int fd)
 {
   char buf[100];
   int new_vol = 0, retval;
 
   if (fd < 0)
     goto prompt;
 
   retval = read(fd, buf, sizeof(buf)-1);
 
   if (retval >= 0) {
     buf[retval] = '\0';
 
     if (*buf == 'q') {
       printf("Goodbye...\n");
       exit(0);
     }
 
     new_vol = atoi(buf);
   }
 
   if (new_vol >= 1 && new_vol <= 4) {
     volume = new_vol;
     printf("Volume changed to %d\n", volume);
   } else {
     printf("Invalid volume!\n");
   }
 
  prompt:
   printf("\nHow loud would you like the /dev/drums?\n");
   printf("   1 - Inaudible\n");
   printf("   2 - Quiet\n");
   printf("   3 - Loud\n");
   printf("   4 - Permanent ear damage!\n");
   printf("   q - Exit program\n");
   printf("Your choice? ");
   fflush(stdout);
 }
 
 
   
 
 int main(int argc, char *argv[])
 {
   int i;
   char buf[128];
   fd_set fds, tmp;
   int max;
 
   for (i = 0; drums_strings[i] != NULL; i++) {
     sprintf(buf, "/dev/drums/%s", drums_strings[i]);
     if (fusd_register(buf, 0666, drums_strings[i], &drums_fops) < 0)
       fprintf(stderr, "%s register failed: %m\n", drums_strings[i]);
   }
 
   /* print the initial prompt to the user */
   read_volume(-1);
 
 /* EXAMPLE START drums3.c */
   /* initialize the set */
   FD_ZERO(&fds);
 
   /* add stdin to the set */
   FD_SET(STDIN_FILENO, &fds);
   max = STDIN_FILENO;
 
   /* add all FUSD fds to the set */
   fusd_fdset_add(&fds, &max);
 
   while (1) {
     tmp = fds;
     if (select(max+1, &tmp, NULL, NULL, NULL) < 0)
       perror("selecting");
     else {
       /* if stdin is readable, read the user's response */
       if (FD_ISSET(STDIN_FILENO, &tmp))
         read_volume(STDIN_FILENO);
 
       /* call any FUSD callbacks that have messages waiting */
       fusd_dispatch_fdset(&tmp);
     }
   }
 /* EXAMPLE STOP drums3.c */
 }