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Path: utzoo!utgpu!water!watmath!clyde!rutgers!cbmvax!andy
From: andy@cbmvax.UUCP
Newsgroups: comp.sys.amiga
Subject: Re: <scream of agony>
Message-ID: <2282@cbmvax.UUCP>
Date: Tue, 1-Sep-87 10:13:35 EDT
Article-I.D.: cbmvax.2282
Posted: Tue Sep  1 10:13:35 1987
Date-Received: Thu, 3-Sep-87 00:47:37 EDT
References: <3826@well.UUCP> <586@sugar.UUCP>
Reply-To: andy@cbmvax.UUCP (Andy Finkel)
Distribution: na
Organization: Commodore Technology, West Chester, PA
Lines: 149
Keywords: MIDI

In article <586@sugar.UUCP> peter@sugar.UUCP (Peter da Silva) writes:
>As the originator of the latest MIDI thread, I'd like to say one thing...
>You also need accurate timing. I have been informed that the Amiga does
>not produce accurate enough timing for professional musicians. I am still
>trying to determine if this is because:
>
>	a) You can still lose timing despite following the rules in
>	   the RKM/Libraries.
>
>	b) The authors of SoundScape, etc, don't follow the rules.
>
>	c) Something else.

All that is needed is a midi.device version of the serial.device
that timestamps the midi events, so that, even if you have to
go away for awhile (because another task would like a bit of time)
you can tell exactly when the event happened.

(occasionally you find musicians complaining about the time intervals
 that a given program lets them use, but that's another story entirely.
 In that case, you just have to point out that program X is placing
 the limit on them, not the Amiga.  No matter what the seller of
 program X says :-)  )

>I'd also like to make a wish. Attention Commodore-Amiga:
>
>	In 1.3, could you please add a mode to timer.device
>	whereby I get periodic signals, and can take the rather
>	complex procedure described in the RKM for keeping time
>	events synched down the toilet?

Timer.device use is *not* complicated.  In fact, its no more complicated
that if I added a mode for repeated events.  But I'd heard this
complaint enough so here's a simple example of using the timer.device
to get a tick every 300 microseconds or so.  Its pretty short...
(Example compiled under Greenhills; your compiler may vary a little)
		

---------------------- CUT HERE ------------------------------------
#include "exec/types.h"
#include "intuition/intuition.h"

struct IntuitionBase *IntuitionBase=NULL;
struct GfxBase *GfxBase=NULL;
struct NewWindow nw = {
    100, 10,
    300,40,
    -1, -1,
    CLOSEWINDOW,
    SMART_REFRESH | NOCAREREFRESH | WINDOWCLOSE,
    NULL,
    NULL,
    "Timer Example", 
    NULL, 
    NULL, 
    10, 10, ~0, ~0,
    WBENCHSCREEN};
    
    
struct Window *window=NULL;
struct MsgPort *timerport=NULL;
struct IOStdReq *timermsg=NULL;
ULONG timerbit=NULL;
UBYTE buffer[80];
struct IntuiText text = {0,1,JAM2,0,0,NULL,buffer,NULL};

SetTimer(sec, micro, timermsg)
ULONG sec, micro;
struct IOStdReq *timermsg;
/* This routine simply sets the timer to interrupt us after secs.micros */
{
    timermsg->io_Command = TR_ADDREQUEST;    /* add a new timer request */
    timermsg->io_Actual = sec;    /* seconds */
    timermsg->io_Length = micro;    /* microseconds */
    SendIO(timermsg);	/* post a request to the timer */
}


main()
{
    ULONG wakeupbits, windowbit;
    struct IntuiMessage *message;
    ULONG class;
    USHORT code;
    int i;

    if(!(IntuitionBase=(struct IntuitionBase *)OpenLibrary("intuition.library",0)
	))cleanup(20);

    if ((window = (struct Window *)OpenWindow(&nw)) == NULL)
	cleanup(20);

    if(!(timerport = (struct MsgPort *)CreatePort(0, 0)))cleanup(20);
    if(!(timermsg = (struct IOStdReq *)CreateStdIO(timerport)))cleanup(20);
    if (OpenDevice(TIMERNAME, UNIT_VBLANK, timermsg, 0))cleanup(20);
    
    timerbit = 1 << timerport->mp_SigBit;
    windowbit = 1 << window->UserPort->mp_SigBit;
    SetTimer(0, 300, timermsg); /* set for first message */

    while (TRUE) {
	wakeupbits = Wait(timerbit | windowbit);

	if (wakeupbits & timerbit) {
	    GetMsg(timerport);	/* this does nothing more than "clear" */
	    SetTimer(0, 300, timermsg);
	    sprintf(buffer,"timer tick %8ld received\0",i++);
	    PrintIText(window->RPort,&text,10,25);
	    }

	if (wakeupbits & windowbit) {
	    message = (struct IntuiMessage *)GetMsg(window->UserPort);
	    class = message->Class;
	    code = message->Code;
	    ReplyMsg(message);
	    switch (class) {
		case CLOSEWINDOW:
		    cleanup(0);
		    break;
	    }
	}
    }
}

cleanup(err)
int err;
{
    if (window) CloseWindow(window);
    if (timerport) {
	Wait(timerbit);
	GetMsg(timerport);
	CloseDevice(timermsg);
	DeleteStdIO(timermsg);
	DeletePort(timerport);
	}
    OpenWorkBench();
    if(IntuitionBase)CloseLibrary(IntuitionBase);
    exit(err);
}
------------------- CUT HERE -------------------------------
-- 
andy finkel		{ihnp4|seismo|allegra}!cbmvax!andy 
Commodore-Amiga, Inc.

"Interfere?  Of course we'll interfere.  Always do what you're best at,
 I always say."

Any expressed opinions are mine; but feel free to share.
I disclaim all responsibilities, all shapes, all sizes, all colors.