TweetFollow Us on Twitter

Sound INIT
Volume Number:9
Issue Number:3
Column Tag:C Workshop

Related Info: Sound Manager The 'INIT' Resource

INIT's: Fun with Sounds

Playing with sounds at startup and using them for different purposes.

By By Randy Thelen, Campbell, California

Note: Source code files accompanying article are located on MacTech CD-ROM or source code disks.

About the author

Randy Thelen has been programming since his father first brought home a Commodore PET 2001 in 1978. He knows half a dozen languages and applies them on his Mac. He loves THINK-C because “it’s easy, fun, and intuitive.” Although, he uses MPW 3.2 because it offers the most integrated development platform for C (his favorite), Pascal (a language he hates), and assembly. Randy has contracted on and off with Apple Computer, Inc. since 1985. He’ll graduate with his first degree in December of 1992. If you see him on the beach, congratulate him: he doesn’t get out often.

Some of you have written System Extensions (or INIT’s, as they were called in the old days), the rest of us are still catching up. An extension is a piece of standalone code that is loaded during startup and put into memory and wham!, it’s executed. The only known code at that point is the system and the system patches. The code can rely on System 7.x having loaded in and being as ready to run as any application can depend. You’re code is given complete control of the system.

This article will show you how to incorporate sound calls into a fun extension that you can type in whether you have THINK-C or MPW. (If you have THINK Pascal, you can challenge yourself by converting this code to Pascal. I know it works because the original extension was written in Pascal, I converted it to C.) The extension is borrowed from the most excellent MPW text I’ve read to date (August ‘92), “Building and Managing Programs in MPW.” (A short plug for the work: Addison-Wesley and Apple Computer guide the reader through the most useful elements of MPW (Macintosh Programmer’s Workshop) with real examples of how to use MPW today, long before reading hundreds of pages of dry manuals. The sections are short, clear, and captivating.)

The sample extension played all the sounds in the System before continuing. Boring! So while my brother digitized the introduction theme to StarTrek: The Next Generation, I extended the init into this code which plays one sound, the intro sound, at start up.

However, if you’ve seen StarTrek: The Next Generation (like a thousand times), it isn’t too long before you tire of the intro. There are times when it’s fun, and the rest when it’s too long to sit through. So I made the following change to the code: when the code gets loaded, it checks for the space bar being pressed down. If it is pressed, then the sound isn’t played. Great! Until you start up your Mac and forget.

The real trick, then, is to play the sound asynchronously. (Yes, it’s a real word which means a lack of synchronicity. Being synchronous would mean happening at the same time. You have to love computer people when they use a word which means only what they want it to mean but not what “Webster’s New World Dictionary” believes it to mean. In the end, computer people believe that asynchronous means happening at the same time. Go figure.) The benefit of an asynchronous sound is that the keyboard can be polled (i.e., continuously checked) during the sound (actually, quite a bit can happen in the background). If the user presses the space bar during the sound, the sound can be stopped immediately. And that’s when a long sound like StarTrek’s introduction can be most enjoyable: when it can be stopped at the press of a key.

Here, let’s look at the code. It’s really quite simple. Remember that /* */ and // are both comments in C. The difference is that /* and */ must be balanced. The // comment out to the end of the line.

/* 1 */

/* Both THINK-C 5.0 and MPW 3.2 includes: */
#include <Types.h>
#include <Resources.h>
#include <Events.h>
#include <Sound.h>

/*  The next couple lines are proto types.  */
/*  KeyPressed returns true if a key is pressed */
Boolean KeyPressed( 
short keyNum, unsigned char *keyMapPtr);
/*  main plays sound ID # 129 until its done or a key is pressed */
void    main( void);



/* Every program needs a bug, this program currently has none, as you 
can clearly see because DEBUG is false.  I encourage you to add to this 
code until it has at least three good bugs.  */
#define DEBUG  false

/*  The KillKey is currently set to the space bar
(0x31).  The list of keys can be found in InsideMac’s Vol. I pg. 251; 
Vol. IV pg. 250, and
Vol. VI pg. 191-2 */
#define KILLKEY  0x31

/*  kSndRsrc holds the resource #, 129 is compatible with cdev’s, see 
Dave Mark’s “Macintosh C Programming Primer Vol. II.”  See chapter 3. 
*/
#define kSndRsrc 129

/********************* main *********************/
void main()
{
SCStatussndStatus; // Used while snd plays
Handle  theSnd;  // the snd resource
OSErr   playStatus;  // standard error var
KeyMap  theKeys; // bit map of key presses
// the channel through which sound will come
SndChannelPtr    theChannel;

/* If there are any bugs, then go to the debugger first. */
#if DEBUG
Debugger();
#endif

/* Check to see if the KillKey is pressed */
GetKeys( &theKeys); // Read the keyboard
if(KeyPressed(KILLKEY,
 (unsigned char*)theKeys) == false)
{// if the space bar is not pressed, continue
/* Set the channel ptr to NIL */
 theChannel = (SndChannelPtr) 0l;
/* Allocate a new channel */
 playStatus = SndNewChannel( &theChannel, 0,
 (long int)0, (SndCallBackProcPtr) 0);
/* As long as that worked fine... */
 if( playStatus == noErr)
 {
 /* Read the sound resource into memory */
 theSnd = GetResource('snd ', kSndRsrc);
 /* 0 is returned if there was a res error */
 if( theSnd)
 {
 /* SoundPlay needs the channel, the sound, */
 playStatus = SndPlay( theChannel, theSnd,                     
 true);  // and an ASYNC flag
 /* Sound Channel Status will return, among
  other things, the status of the sound */
 playStatus = SndChannelStatus( theChannel,
 sizeof( sndStatus), &sndStatus);
 /* While the KillKey isn’t pressed, &
 the sound is playing (i.e., busy) */
 while(KeyPressed(KILLKEY,
 (unsigned char*)theKeys) == 0 &&
 sndStatus.scChannelBusy == true)
 {
 /* Read the keyboard */
 GetKeys( &theKeys);
 /* Get the sound channel status */
 playStatus = SndChannelStatus(
 theChannel, sizeof( sndStatus),
 &sndStatus);
 } // END while
 } // END if( theSnd)
 /* Kill the sound (true == dispose now) */
 playStatus = SndDisposeChannel( theChannel, true);
 }  // END if( playStatus == true)
}// END if( KeyPressed( ...) == false
}// END main() {...}


/***************** KeyPressed *****************/
/*  The following algorithm I typed directly
from Symantec’s THINK Reference.  An excellent
tool that I highly recommend! Only $69 */
//  returns
// true == the key is pressed
// false == the key is not pressed
Boolean KeyPressed( short keyNum, 
 unsigned char *keyMapPtr)
{
/* This convoluted but functional and tight
 algorithm determines if the key keyNum
 is pressed... Read InsideMac’s Vol. I pg. 251;
 Vol. IV pg. 250, and Vol. VI pg. 191-2 */
return( (keyMapPtr[keyNum >> 3] 
 >> (keyNum & 7) ) & 1);
}

With MPW 3.2 (which is the latest version), the following build commands will build the extension:


/* 2 */

C -r -sym on SoundINIT.c -w
Link -t INIT 
-c rndm 
-rt INIT=128 
-m main 
-sg SoundINIT 
-sym on 
-mf  
-w 
SoundINIT.c.o 
-o SoundINIT

These instructions were generated with the Create Build Commands menu item from the Build menu. It was pretty easy. The -c is the creator. The -rt is the resource type and ID #. -m is the main subroutine name. -sg is the segment name. -sym on turns symbols on for SADE and MacsBug. -mf is any one’s guess. And, -w turns warnings off.

The following line will put the SoundINIT into the system’s extension folder. Use help duplicate if any part of the line confuses you.

duplicate -y 'SoundINIT' "{SystemFolder}Extensions:"' SoundINIT'

If you’re using THINK-C. The interface is a little more visual. You’ll need to include into the project both MacTraps and MacTraps2. The complete project should look like this:

Use the Set Project Type menu item under the Project menu to get the following dialog. You’ll probably want to put in your own Creator. Mine is rndm. The ID can really be anything you want. I chose 128. Again, this offers compatibility with a cdev. Dave Mark covers this.

So, that’s the code. It’s short (the comments easily doubled it’s length). Allow me to point out some of it’s highlights. First, this extension uses no globals (all you mighty programmers want to know how to use globals in extensions: THINK-C’s User Manual for version 5.0 discusses it on page 119, and Building and Managing MPW Programs discusses it in chapter 9, but it’s a little more in-depth coverage and a little bit more work than with THINK).

Second, the routine main starts the program because it contains the code that is first to be executed. MPW allows you to define which routine begins the code segment; THINK-C puts a BRanch Always to main. Extensions work this way: after the code is loaded, the system jmp’s to the first word.

Third, this version of the extension displays no ICN#. Dave Mark does this in his book Macintosh C Programming Primer Vol. II. See chapter 3 and read the code in appendix B, pp. 397 - 401. If you’ve just begun programming the Mac, I strongly suggest you pick up a copy of Vol. I and II.

Fourth, this code doesn’t include the sound! You’ll need to digitize your favorite sound (something you enjoy listening to, or try this: digitize a siren on your computer; then if anyone but you starts up your computer, a siren will alert to the bad guys presence) and then use ResEdit to copy and paste that sucker in the extension resource. The sound will have to be ID # == 129.

Last, the code shows how to use the rudimentary commands in the Sound Manager. After running this program, I suggest you pick up Inside Macintosh vol. II pg. 221, vol. V pg. 473, & vol. VI chapter 22. They are ‘dehydrated reading’ (just add interest) and give a good insight into the power of the microphone, sound compression, and playing sounds straight from the disk!

Enjoy your code development, whether it be with extensions, drivers, cdev’s, or actual programs. Until next time, this is Random saying “don’t do it right the first time; experiment until you’re sure you can break it.”

 

Community Search:
MacTech Search:

Software Updates via MacUpdate

Is there cross-platform play in slither....
So you've sunken plenty of hours into crawling around in slither.io on your iPhone or iPad. You've got your stories of tragedy and triumph, the times you coiled four snakes at one time balanced out by the others when you had a length of more than... | Read more »
Rodeo Stampede guide to running a better...
In Rodeo Stampede, honing your skills so you can jump from animal to animal and outrun the herd as long as possible is only half the fun. Once you've tamed a few animals, you can bring them home with you. [Read more] | Read more »
VoxSyn (Music)
VoxSyn 1.0 Device: iOS Universal Category: Music Price: $6.99, Version: 1.0 (iTunes) Description: VoxSyn turns your voice into the most flexible vocal sound generator ever. Instantly following even subtle modulations of pitch and... | Read more »
Catch Battleplans on Google Play from Ju...
Real-time strategy title Battleplans is due for release on Google Play on June 30th, following its release for iOS systems last month. With its simple interface and pretty graphics, the crowd-pleaser brings a formerly overlooked genre out for the... | Read more »
iDoyle: The interactive Adventures of Sh...
iDoyle: The interactive Adventures of Sherlock Holmes - A Scandal in Bohemia 1.0 Device: iOS Universal Category: Books Price: $1.99, Version: 1.0 (iTunes) Description: Special Release Price $1.99 (Normally $3.99) | Read more »
Five popular free apps to help you slim...
Thanks to retail and advertising, we're used to thinking one season ahead. Here we are just a week into the summer and we're conditioned to start thinking about the fall. [Read more] | Read more »
How to ride longer and tame more animals...
It's hard to accurately describe Rodeo Stampede to people who haven't seen it yet. It's like if someone took Crossy Roadand Disco Zoo and put them in a blender, yet with a unique game mechanic that's still simple and fun for anyone. [Read more] | Read more »
Teeny Titans - A Teen Titans Go! Figure...
Teeny Titans - A Teen Titans Go! Figure Battling Game 1.0.0 Device: iOS Universal Category: Games Price: $3.99, Version: 1.0.0 (iTunes) Description: Teeny Titans, GO! Join Robin for a figure battling RPG of epic proportions! TEENY... | Read more »
NinjAwesome: Tips and tricks to be a mor...
Sorry about that headline, but I'm going to go ahead and assume that GameResort would not have named its game NinjAwesome without expecting some of that. It is, in fact, pretty awesome the way it combines an endless runner and old school arcade... | Read more »
Into Mirror (Games)
Into Mirror 1.0 Device: iOS Universal Category: Games Price: $1.99, Version: 1.0 (iTunes) Description: "Is all that we see or seem, but a dream within a dream?"- Edgar Allan Poe New game by Lemon Jam Studio, the team behind Pursuit... | Read more »

Price Scanner via MacPrices.net

15-inch Retina MacBook Pros on sale for $200-...
B&H Photo has 15″ Retina MacBook Pros on sale for up to $210 off MSRP. Shipping is free, and B&H charges NY tax only: - 15″ 2.2GHz Retina MacBook Pro: $1799.99 $200 off MSRP - 15″ 2.5GHz... Read more
Mac minis on sale for up to $100 off MSRP
B&H Photo has Mac minis on sale for up to $100 off MSRP including free shipping plus NY sales tax only: - 1.4GHz Mac mini: $449 $50 off MSRP - 2.6GHz Mac mini: $649 $50 off MSRP - 2.8GHz Mac mini... Read more
Clearance 2015 13-inch MacBook Airs available...
B&H Photo has clearance 2015 13″ MacBook Airs available for $300 off original MSRP. Shipping is free, and B&H charges NY sales tax only: - 13″ 1.6GHz/4GB/128GB MacBook Air (MJVE2LL/A): $799.... Read more
Apple refurbished Mac minis available for up...
Apple has Certified Refurbished Mac minis available starting at $419. Apple’s one-year warranty is included with each mini, and shipping is free: - 1.4GHz Mac mini: $419 $80 off MSRP - 2.6GHz Mac... Read more
ABBYY TextGrabber: 1,000,000 Installs in 5 Da...
ABBYY, an international OCR technologies provider, has announced that their image-to-text application TextGrabber, got installed 1,000,000 times in just five days while being featured by the App... Read more
New SkinIt Waterproof Case For iPhone 6
With its impact and waterproof design, the Skinit Waterproof case provides security and protection to guarantee your phone will get you through even the most demanding outdoor conditions. The impact-... Read more
iMacs on sale for up to $150 off MSRP
B&H Photo has 21″ and 27″ iMacs on sale for up to $150 off MSRP including free shipping plus NY sales tax only: - 27″ 3.3GHz iMac 5K: $2181.11 $118 off MSRP - 27″ 3.2GHz/1TB Fusion iMac 5K: $1949... Read more
12-inch 1.1GHz Retina MacBooks on sale for $5...
B&H Photo has 2016 12″ 1.1GHz/256GB Retina MacBooks on sale for up to $50 off MSRP. Shipping is free, and B&H charges NY tax only: - 12″ 1.1GHz Space Gray Retina MacBook: $1249 $50 off MSRP... Read more
WWDC Announcements Revisited Still Underwhelm...
I was disappointed that no new MacBook hardware was announced at this year’s all-software World Wide Developer’s Conference. Not even a hint about what’s in the development pipeline. Of course, we... Read more
Twelve South Compass 2 iPad Stand Now Availab...
Twelve South has updated its most popular iPad stand, Compass 2, with the introduction of two new colors — Gold and Rose Gold. These new color options n perfectly complement the new Rose Gold iPad... Read more

Jobs Board

*Apple* iPhone 6s and New Products Tester Ne...
…we therefore look forward to put out products to quality test for durability. Apple leads the digital music revolution with its iPods and iTunes online store, Read more
Music Marketing Lead, iTunes & *Apple*...
…Music Marketing Lead is responsible for developing robust marketing campaigns and programs for Apple Music and iTunes across the whole of Apple ecosystem. This Read more
*Apple* Valley Medical Clinic is Hiring - AP...
Apple Valley Medical Clinic is Hiring! Apple Valley Medical Clinic is an independently owned practice operating a Family Medicine Clinic, a 24/7 Urgent Care, Read more
*Apple* New Products Testers Needed - Apple...
…we therefore look forward to put out products to quality test for durability. Apple leads the digital music revolution with its iPods and iTunes online store, Read more
*Apple* Solutions Consultant - APPLE (United...
Job Summary As an Apple Solutions Consultant, you'll be the link between our future customers and our products. You'll showcase your entrepreneurial spirit as you Read more
All contents are Copyright 1984-2011 by Xplain Corporation. All rights reserved. Theme designed by Icreon.