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From: billk@pnet01.cts.com (Bill W. Kelly)
Newsgroups: comp.sys.amiga.tech
Subject: Re: inputs from many windows
Message-ID: <3799@crash.cts.com>
Date: 1 Feb 89 06:36:21 GMT
Sender: bblue@crash.cts.com
Organization: People-Net [pnet01], El Cajon CA
Lines: 34

phil@titan.rice.edu (William LeFebvre) writes:
>In article <3778@crash.cts.com> billk@pnet01.cts.com (Bill W. Kelly) writes:
>>What's the _probem_ with allowing these poor little windows to each have their
>>own IDCMP's?  
>>...
>>Am I missing something?
>
>This is my thinking (and it might be wrong---I'm not sure).  Separate
>IDCMPs means separate message ports.  Separate ports means separate signal
>bits.  And you can only have 32 sigbits, right (only 32 bits in a long)?
>That would imply to me that you can have, at the most, 32 open windows in
>your task, if you use a separate IDCMP for each window.
 
For some reason, that completely slipped my mind.  (Someone else also reminded
me of this via email.)  Each task has 16 (sixteen) user sigbits available to
it.  The other 16 sigbits are reserved for system use.  (For example, bits
12-15 are for ^C, ^D, ^E, and ^F.  For instance if from the CLI you type:
'break 3 C', process number three gets signaled with bit 12 --
SIGBREAKF_CTRL_C.)

>This leads to something for which I don't know the answer:  are sigbits
>allocated on a per-task basis or do they need to be unique throughout the
>entire system?  In other words, can two separate tasks both be using the
>same signal bit for two separate ports?  Seems to me that it would just be
>too restrictive if they couldn't.

Each task has its own set of sigbits.  The signals you have allocated, are
waiting for, and have received are kept track of in the tc_SigAlloc,
tc_SigWait, and tc_SigRecvd fields of each task structure.  (This is the
structure you get the address of when you call FindTask(0).)

--
Bill W. Kelly                                         billk@pnet01.cts.com
{nosc ucsd hplabs!hp-sdd}!crash!pnet01!billk   crash!pnet01!billk@nosc.mil