Path: utzoo!utgpu!utstat!jarvis.csri.toronto.edu!mailrus!iuvax!rutgers!apple!oliveb!amiga!jimm
From: jimm@amiga.UUCP (Jim Mackraz)
Newsgroups: comp.sys.amiga
Subject: Re: How can I flash the power light?
Keywords: flash probably trivial
Message-ID: <3611@amiga.UUCP>
Date: 12 Mar 89 22:44:51 GMT
References: <880@cs-spool.calgary.UUCP>
Reply-To: jimm@cloyd.UUCP (Jim Mackraz)
Organization: Commodore-Amiga Inc, Los Gatos CA
Lines: 36

In article <880@cs-spool.calgary.UUCP> aycock@cpsc.ucalgary.ca (John Aycock) writes:
)Sorry if this is a simple-minded question, but how can I get one of my
)C or assembly programs to flash the power light (for any wise guys, this
)means _without_ crashing the system :-) ???

Thought I'd post the response, since it's so useful.  I've used these macros
a couple of times for diagnostics when I couldn't even get kprintf() to work.

I don't recommend using them for anything else ...

#define TOGGLE_LED (*((char *) 0xbfe001) ^= 2 )
#define FLASH_LED( T ) {long int i; TOGGLE_LED; for(i=(T);--i;); TOGGLE_LED;\
	for(i=(T); --i;);}

/* I also condensed some frequent intervals ... */
#define LONGTIME	64000
#define SHORTTIME	32000
#define LONG_FLASH	FLASH_LED( LONGTIME )
#define SHORT_FLASH	FLASH_LED( SHORTTIME )

I might have to upgrade these macros for the '020 ;^)
I go on to define the full  set of Morse Code ... ;^)

Note that an optimizing compiler will just toss away the delay loops, but
if you can't get kprintf() to work you have no business using the optimizer
yet.

Also, Lattice V5.0 optimizer couldn't even handle these macros (caused
CXERR in lc2), and I haven't used them (or the optimizer) since then.

	jimm
-- 
Jim Mackraz, I and I Computing	   	"Like you said when we crawled down
{cbmvax,well,oliveb}!amiga!jimm          from the trees: We're in transition."
							- Gang of Four
Opinions are my own.  Comments are not to be taken as Commodore official policy.