Path: utzoo!attcan!utgpu!jarvis.csri.toronto.edu!mailrus!cs.utexas.edu!rutgers!texbell!sugar!peter
From: peter@sugar.hackercorp.com (Peter da Silva)
Newsgroups: comp.sys.amiga.tech
Subject: Re: Static limits (Re: AmigaDos directory knowledge + (new) BENCHMARK I DID)
Message-ID: <4669@sugar.hackercorp.com>
Date: 4 Dec 89 13:11:36 GMT
References: <24370@swrinde.nde.swri.edu> <8787@cbmvax.UUCP> <4659@sugar.hackercorp.com> <5649@cps3xx.UUCP>
Reply-To: peter@sugar.hackercorp.com (Peter da Silva)
Organization: Sugar Land Unix - Houston
Lines: 92

In article <5649@cps3xx.UUCP> porkka@frith.UUCP (Joe Porkka) writes:
> In article <4659@sugar.hackercorp.com> peter@sugar.hackercorp.com (Peter da Silva) writes:
> >In article <8787@cbmvax.UUCP> daveh@cbmvax.UUCP (Dave Haynie) writes:
> >> Static limits are a bad thing, period.  MS-DOS even makes you tell it how
> >> many files you'll allow to be open at once.  Apparently OS/2 suffers from
> >> the same faulty thinking...

> >Like the limit of 32 SigBits for an AmigaOS task? The Amiga isn't immune to
> >the static limit problem.

> Yes but sigbits can be shared between multiple event generators.

> It is somewhat harder to share file handles between multiple files :-)

struct FileHandle {
	struct FileHandle *next;
	struct FileHandle *prev;
	FILE *fp;
	char *name;
	char *mode;
	off_t offset;
	int valid;
	long used;
};

struct FileHandle *fhroot; /* circular doubly-linked list */
long seq = 0;

struct FileHandle *fhopen(file, mode)
char *file, *mode;
{
	struct FileHandle *fh;

	fh = new(FileHandle);

	if(!(fh->fp = fopen(name, mode))) {
		recover_fp();
		if(!(fh->fp = fopen(name, mode))) {
			dispose(FileHandle);
			return 0;
		}
	}
	fh->name = clone(name);
	fh->mode = clone(mode);
	fh->used = seq++;
	insert(fh, fhroot);

	return fh;
}

fhclose(fh)
struct FileHandle *fh;
{
	FILE *fp;
	remove(fh);
	fp = fh->fp;
	dispose(fh->name);
	dispose(fh->mode);
	dispose(fh);
	return fp?fclose(fp):SUCCESS;
}

fhread(fh, bytes, count)
{
	if(!fh->valid)
		return 0;
	if(!fh->fp) {
		recover_fp();
		if(!(fh->fp = fopen(fh->name, fh->mode))) {
			fh->valid = 0;
			return 0;
		}
		fseek(fh->fp, fh->seek, 0);
	}
	fh->used = seq++;
	return fread(bytes, count, 1, fh->fp);
}

recover_fp()
{
	Find fh with lowest fh_seq;
	fh->offset = ftell(fh->fp);
	fclose(fh->fp);
	fh->fp = 0;
}

... and so on.
-- 
Peter "Have you hugged your wolf today" da Silva <peter@sugar.hackercorp.com>
`-_-'
 'U` "Really, a video game is nothing more than a Skinner box."
       -- Peter Merel <pete@basser.oz>