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puffs_cc.3
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.\" $NetBSD: puffs_cc.3,v 1.14 2009/04/11 16:48:53 wiz Exp $
.\"
.\" Copyright (c) 2007, 2008 Antti Kantee. All rights reserved.
.\"
.\" Redistribution and use in source and binary forms, with or without
.\" modification, are permitted provided that the following conditions
.\" are met:
.\" 1. Redistributions of source code must retain the above copyright
.\" notice, this list of conditions and the following disclaimer.
.\" 2. Redistributions in binary form must reproduce the above copyright
.\" notice, this list of conditions and the following disclaimer in the
.\" documentation and/or other materials provided with the distribution.
.\"
.\" THIS SOFTWARE IS PROVIDED BY THE AUTHOR AND CONTRIBUTORS ``AS IS'' AND
.\" ANY EXPRESS OR IMPLIED WARRANTIES, INCLUDING, BUT NOT LIMITED TO, THE
.\" IMPLIED WARRANTIES OF MERCHANTABILITY AND FITNESS FOR A PARTICULAR PURPOSE
.\" ARE DISCLAIMED. IN NO EVENT SHALL THE AUTHOR OR CONTRIBUTORS BE LIABLE
.\" FOR ANY DIRECT, INDIRECT, INCIDENTAL, SPECIAL, EXEMPLARY, OR CONSEQUENTIAL
.\" DAMAGES (INCLUDING, BUT NOT LIMITED TO, PROCUREMENT OF SUBSTITUTE GOODS
.\" OR SERVICES; LOSS OF USE, DATA, OR PROFITS; OR BUSINESS INTERRUPTION)
.\" HOWEVER CAUSED AND ON ANY THEORY OF LIABILITY, WHETHER IN CONTRACT, STRICT
.\" LIABILITY, OR TORT (INCLUDING NEGLIGENCE OR OTHERWISE) ARISING IN ANY WAY
.\" OUT OF THE USE OF THIS SOFTWARE, EVEN IF ADVISED OF THE POSSIBILITY OF
.\" SUCH DAMAGE.
.\"
.Dd January 28, 2008
.Dt PUFFS_CC 3
.Os
.Sh NAME
.Nm puffs_cc
.Nd puffs continuation routines
.Sh LIBRARY
.Lb libpuffs
.Sh SYNOPSIS
.In puffs.h
.Ft void
.Fn puffs_cc_yield "struct puffs_cc *pcc"
.Ft void
.Fn puffs_cc_continue "struct puffs_cc *pcc"
.Ft void
.Fn puffs_cc_schedule "struct puffs_cc *pcc"
.Ft struct puffs_cc *
.Fn puffs_cc_getcc "struct puffs_usermount *pu"
.Sh DESCRIPTION
These routines are used for the cooperative multitasking suite present
in puffs.
.Pp
.Bl -tag -width xxxx
.It Fn puffs_cc_yield "pcc"
Suspend and save the current execution context and return control
to the previous point.
In practice, from the file system author perspective, control returns
back to where either the mainloop or where
.Fn puffs_dispatch_exec
was called from.
.It Fn puffs_cc_continue pcc
Will suspend current execution and return control to where it was
before before calling
.Fn puffs_cc_yield .
This is rarely called directly but rather through
.Fn puffs_dispatch_exec .
.It Fn puffs_cc_schedule "pcc"
Schedule a continuation.
As opposed to
.Fn puffs_cc_continue
this call returns immediately.
.Fa pcc
will be scheduled sometime in the future.
.It Fn puffs_cc_getcc "pu"
Returns the current pcc or
.Dv NULL
if this is the main thread.
.Em NOTE :
The argument
.Ar pu
will most likely disappear at some point.
.El
.Pp
Before calling
.Fn puffs_cc_yield
a file system will typically want to record some cookie value into its
own internal bookkeeping.
This cookie should be hooked to the
.Va pcc
so that the correct continuation can be continued when the event it
was waiting for triggers.
Alternatively, the
.Xr puffs_framebuf 3
framework and
.Fn puffs_mainloop
can be used for handling this automatically.
.Sh SEE ALSO
.Xr puffs 3 ,
.Xr puffs_framebuf 3