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From: parkern@jacobs.CS.ORST.EDU (Neil Parker)
Newsgroups: comp.sys.apple2
Subject: Re: What's wrong with this Pascal program?
Message-ID: <1991May25.100117.26892@lynx.CS.ORST.EDU>
Date: 25 May 91 10:01:17 GMT
Article-I.D.: lynx.1991May25.100117.26892
References: <5395@cernvax.cern.ch>
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In article <5395@cernvax.cern.ch> myb@cernvax.cern.ch (michel bornand) writes:
>Hi everybody. Here is a simple Pascal program for Apple IIGS with should
>produce a sound at 16kHz. It does not work. What's wrong with it?
>What did I miss?

Well...now that I'm at home where my manuals are, I guess I'll take a stab
at this...

>Pascal testsound;
 ^^^^^^
 Huh?  Do you mean "Program testsound;"?
>
>uses types,sound;
>
>var gparms:SoundParamBlock;
>    oneangle:array[1..16]of byte;
               ^^^
	       I don't know what version of Pascal you're using, but if
	       it's TML Pascal, you'll need "packed" in front of "array"--
	       otherwise your 8-bit bytes will all be 16 bits wide...
>
>begin
>[lotsa oneangle assignments deleted]
>     gparms.waveStart:=@oneangle[1];
>     gparms.waveSize:=16;
                       ^^
		       This says your waveform is 16 *PAGES* long, not
		       16 bytes!  The smallest possible waveform is 1
		       page.
>     gparms.fredOffset:=311;
>     gparms.DOCBuffer:=1;
                        ^
			Toolbox Ref 3 says the HIGH byte is significant,
			not the low byte--this should be $100, not 1.
>     gparms.bufferSize:=$0800;
                          ^^^^
			  Only the lowest 3 bits of this field are
			  significant.  The DOC buffer will be 2^bufferSize
			  pages long.  (Note that the resolution bits will
			  also be initialized from this value, so changing
			  it will change the pitch of your tone.)
>     gparms.nextWave:=@gparms;
>     gparms.volSetting:=255;
>     FFStartSound($0A01,@gparms);
>
>end.
 ^^^
 Does your Pascal compiler generate an implicit QUIT call when execution
 "runs off the end" like this?  I seem to recall reading somewhere that
 QUIT shuts down the tools, including the Sound Manager...

Speaking of shutting down tools, did you remember to call SoundStartUp?  I
didn't see see it anywhere in your code sample...

Suggestions:

     * Find out how your compiler handles array packing.
     * Make sure the length of your waveform is a multiple of 256.
     * Read pages 47-3 through 47-5 of Toolbox Ref 3.

		    - Neil Parker
--
Neil Parker                 No cute ASCII art...no cute quote...no cute
parkern@jacobs.cs.orst.edu  disclaimer...no deposit, no return...
parker@corona.uoregon.edu   (This space intentionally left blank:           )