V10/man/man9/newproc.9

.TH NEWPROC 9.2
.CT 2 proc_man
.SH NAME
P, newproc, muxnewwind, newwindow, tolayer, debug, getproc, getproctab, putname, getname \- jerq process control
.SH SYNOPSIS
.B #include <jerq.h>
.PP
.B extern struct Proc *P;
.PP
.B struct Proc *newproc(f)
.B void (*f)();
.PP
.B struct Proc *newwindow(f);
.B void (*f)();
.PP
.B void tolayer(l)
.B Layer *l;
.PP
.B void debug();
.PP
.B struct Proc *getproc();
.PP
.B struct Proc *getproctab();
.PP
.B int putname(string, data)
.B char *string; long data;
.PP
.B struct Nqueue *getname(string)
.B char *string;
.PP
.B #include <msgs.h>
.br
.B void muxnewwind(p, c)
.B struct Proc *p; int c;
.SH DESCRIPTION
Processes in the jerq consist of a coroutine-style process
structure and an associated layer
(see
.IR newlayer (9.2)),
allocated independently.
This section describes the process allocation and control
primitives.
They are direct links to the system's own
control structures, so given
.IR mux 's
open addressing, they should be used with care.
.PP
Each process has a global variable
.I P
that points to its process structure.
The only regular use of
.I P
is to check that the process has been moved or reshaped:
.IP
.EX
if(P->state & RESHAPED){
	do_reshape();
	P->state &= ~RESHAPED;
}
.EE
.PP
The definition of
.B struct Proc
is in the include file
.BR <jerqproc.h> ,
which is included automatically by
.BR <jerq.h> .
.PP
.I Newproc
allocates a new process, returning a pointer to it, or 0
if one cannot be allocated.
Argument
.I f
points to the program text to be executed.
The special case
.IR f =0
creates a process running the default terminal program,
and is almost always how
.I newproc
should be called; use
.IR 32ld (9.1)
to run non-standard programs.
A process is disabled by setting
.I p->state
to zero.
After calling
.IR newproc,
the process must be bound to a layer and
Unix told of its presence, typically as:
.IP
.EX
struct Proc *p;
Rectangle r;
p = newproc((struct Proc *)0);
if(p == 0)
	error();
p->layer = newlayer(r);
if(p->layer == 0){
	p->state = 0;
	error();
}
p->rect = r;
muxnewwind(p, C_NEW);
.EE
.PP
The second argument to
.I muxnewwind
should be
.B C_RESHAPE
if an existing process is being given a new layer.
If the process is
.I not
running the default terminal program, its variables
.L display
and
.L Drect
must be set:
.IP
.EX
struct udata *u=((struct udata *)p->data);
u->Drect=p->rect;
u->Jdisplayp=p->layer;
.EE
This procedure works regardless of whether the process being manipulated is itself.
.PP
.I Newwindow
creates a process by the above procedure, going through the
standard user interface to select the rectangle for the process's
layer.
.PP
.I Tolayer
takes an argument
.I layer
pointer and makes the process in that layer the receiver of
mouse and keyboard events.
.PP
.I Getproc
presents the user with a gunsight cursor and returns the
address of the process whose layer is indicated with the mouse.
.I Getproctab
simply returns the address of the base of the process table array.
This is an array of
.B NPROC
process structures.
.B NPROC
is stored in the word immediately lower in address than the
process table.
.PP
.I Debug
announces to the system that the calling process is prepared
to handle exceptions by other processes.
.PP
.I Putname
and 
.I getname
manage a bulletin board for interprocess communication.
Further communication may be arranged through shared memory.
.I Putname
associates
.I data
with
.I string,
returning nonzero normally, or 0 if the data could not be stored.
.I Getname
returns a pointer 
to a structure which contains
.TP
.B struct Proc *proc
pointer to the process structure of the layer that
most recently announced the string
.TP
.B long data
the corresponding data
.LP
.I Getname
returns 0 if no such string has been announced.
A pointer returned by
.I getname
remains valid: a client may rendezvous with a server by
calling
.I getname
once and repeatedly testing
the associated
.B proc
pointer thereafter.
.SH BUGS
These primitives are awkward at best, and are
subject to change.
.br
Creating a process without a layer or
.I
vice versa
is dangerous.