DUE DATE: Friday, April 12, 2002, at NOON

(no late submissions accepted!)

Summary

This project continues with our trend of direct hardware access, introducing students to I/O programming under the Linux operating system. In particular, after doing this project, students should be familiar with the design and implementation of device drivers under Linux and file I/O provided through Linux system calls.

Your task is to write a program that will play songs on the PC speaker. (Oh no, not again!) Such a song will be stored in a binary file, format of which is provided below. Your program should read this song file and play the notes contained therein on the PC speaker.

Tune file format

The data in the tune file is stored in binary format. The actual song can be written in x86 assembly language, then assembled to produce a binary file, known as compiled data file. The format of the file is as follows:

• First 8 bytes of every tune file is the file signature. (ASCII string PlayTune .)
• The next word (2 bytes) specifies the number of notes in the file.
• The next word (2 bytes) specifies the tempo value of the song. You can think of this value as the speed at which the song is played.
• After that, everything that follows is a list of notes to play. Every item in the list is a doubleword (4 bytes), where the first two bytes give the frequency of the note to play, and the second two bytes give the duration of the note.

Notes

• Since user-level programs do not have access directly to the hardware, you will also have to implement a kernel module that will program the timer and speaker directly.
• Your program should talk to the kernel module via the usual system call interface.
• The song file to play should be specified on the command line.
• If nothing is specified on the command line, your program should play the song specified by the TUNE environment variable.
• Duration of the note (as specified above) is given in timer ticks. (Yes, the same old timer ticks.) To get the actual delay time value in seconds, you need to multiply the note's duration by the tempo (speed) of the song and divide by 18.2. This will tell you how long that particular note should be played. To create needed delay, use the nanosleep() function. (Read its man page for details.)
• A note (as specified in the file format) is easiest to implement as a C structure as follows:

  	struct note
  	{
  		unsigned short freq;
  		unsigned short duration;
  	};
  

  Then you can dynamically allocate an array of notes at run time to hold all the notes you read in from the file.
• Some song files to use with your player will be provided. (Download them off the class web page.) You may, of course. write your own.
• Remember that all your code has to be written in C and must run under Linux.
• Standard project guidelines apply: be neat, write comments, check for errors.
• Turn in your assignment ON TIME. If it is not in my mailbox at noon on the due date, it is late, and therefore not accepted. Period. Slip it under my door of HRN 539 if the office is closed.

What to turn in

Turn in a printout of your code. Include instructions on running your program. Place your source files in the submit directories for cs235, located under /home/submit/cs235/<username>. You may turn in your source files on a floppy, if you wish.