qtail.c
Click here to get the file
Size
2.9 kB
-
File type
text/plain
File contents
/*ident "@(#)cop4:sparc_task/task/qtail.c 1.1" */
/*******************************************************************************
C++ source for the C++ Language System, Release 3.0. This product
is a new release of the original cfront developed in the computer
science research center of AT&T Bell Laboratories.
Copyright (c) 1991 AT&T and UNIX System Laboratories, Inc.
Copyright (c) 1984, 1989, 1990 AT&T. All Rights Reserved.
THIS IS UNPUBLISHED PROPRIETARY SOURCE CODE of AT&T and UNIX System
Laboratories, Inc. The copyright notice above does not evidence
any actual or intended publication of such source code.
*******************************************************************************/
/*
* Copyright (c) 1990, 1991 by Sun Microsystems, Inc.
*/
#include <task.h>
/* construct qtail <--> oqueue */
qtail::qtail(qmodetype mode, int max)
{
if (0 < max) {
qt_queue = new class oqueue(max);
qt_queue->q_tail = this;
};
qt_mode = mode;
}
/* destroy q if not also pointed to by a qhead */
qtail::~qtail()
{
oqueue* q = qt_queue;
if (q->q_head)
q->q_tail = 0;
else
delete q;
}
/* insert object at rear of q (becoming new value of oqueue->q_ptr) */
// q->q_ptr points to last object. last->o_next points to first object.
// first->o_next points to the next object.
int
qtail::put(object* p)
{
ll:
register oqueue* q = qt_queue;
if (p->o_next) task_error(E_PUTOBJ, this);
if (q->q_count < q->q_max) {
if (q->q_count++) {
register object* oo = q->q_ptr;
p->o_next = oo->o_next;
q->q_ptr = oo->o_next = p;
}
else { // q was empty; alert those waiting on it
qhead* h = q->q_head;
q->q_ptr = p->o_next = p;
if (h) h->alert();
}
return 1;
}
switch (qt_mode) {
case WMODE:
this_task()->sleep(this);
goto ll;
case EMODE:
task_error(E_PUTFULL, this);
goto ll;
case ZMODE:
return 0;
}
return 0;
}
/* create head for this q */
qhead*
qtail::head()
{
oqueue* q = qt_queue;
register qhead* h = q->q_head;
if (h == 0) {
h = new qhead(qt_mode,0);
q->q_head = h;
h->qh_queue = q;
};
return h;
}
/* result: ?qhead<-->? oldq<-->(new)qtail newq<-->(this)qtail */
qtail*
qtail::cut()
{
oqueue* oldq = qt_queue;
qtail* t = new qtail(qt_mode,oldq->q_max);
oqueue* newq = t->qt_queue;
t->qt_queue = oldq;
oldq->q_tail = t;
newq->q_tail = this;
qt_queue = newq;
return t;
}
/* this qtail is supposed to be downstream from the qhead h */
void
qtail::splice(qhead* h)
{
h->splice(this);
}
void
qtail::print(int n, int baseClass)
{
if (!baseClass)
printf("qtail ");
int m = qt_queue->q_max;
int c = qt_queue->q_count;
class qhead * h = qt_queue->q_head;
printf("mode=%d, max=%d, space=%d, head=%d\n",
qt_mode, m, m-c, h);
if (n&VERBOSE) {
int m = n & ~(CHAIN|VERBOSE);
if (h) {
printf("head of queue:\n");
h->print(m);
} else printf("\tno head\n");
qt_queue->print(m);
}
object::print(n, 1);
}