ack/lang/occam/lib/co.c
1987-02-25 16:41:09 +00:00

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/* co.c - Routines to handle coroutines */
#include "ocm_proc.h"
static void search(), RESUMERR();
void resume(id) identification id;
/* Stops the current process, by saving its stack, and searches for the
* process with identification 'id' in the group the running process
* belongs to. If 'id' cannot be found then repeat these actions with
* the running process' parent. If 'id' is found it is activated. It
* is a fatal error if 'id' cannot be found.
*/
{
if (group!=nil) {
register wordsize size;
size=top_size(group->s_brk);
(*group->active)->stack=alloc((unsigned) size);
if (top_save(size, (*group->active)->stack))
search(id);
else {
free((*group->active)->stack);
load_betweens();
}
} else
RESUMERR();
}
static void search(id) identification id;
/* Searches for the process with identification 'id'.
* If the process is found it is activated and its process tree is
* traversed to find the running process.
*/
{
register struct process **aproc, *proc;
for(;;) {
aproc= &group->first;
while (*aproc!=nil && (*aproc)->id!=id)
aproc= &(*aproc)->next;
if (*aproc!=nil) break;
save_between(group);
if ((group=group->up)==nil)
RESUMERR();
}
group->active=aproc;
proc= *aproc;
highest_group=group;
while (proc->down!=nil) {
group=proc->down;
proc= *group->active;
}
top_load(proc->stack);
}
static void delete_group(group) struct procgroup *group;
/* Removes the whole group and sub-groups recursively from the running
* process.
*/
{
register struct process *proc, *next;
proc=group->first;
while (proc!=nil) {
if (proc->down!=nil)
delete_group(proc->down);
else
free(proc->stack);
next=proc->next;
free( (void *) proc);
proc=next;
}
delete_between(group);
free( (void *) group);
}
void coend()
{
register struct process *proc, *next;
register struct procgroup *junk;
proc=group->first;
while (proc!=nil) {
if (proc!= *group->active) {
if (proc->down!=nil)
delete_group(proc->down);
else
free(proc->stack);
}
next=proc->next;
free( (void *) proc);
proc=next;
}
delete_between(group);
junk=group;
group=group->up;
free( (void *) junk);
if (group!=nil)
(*group->active)->down=nil;
}
static void RESUMERR()
{
write(2, "RESUMERR\n", 9);
abort();
}