/*
the big main central interpreter loop.
processes return codes from eval().
0 indicate noerror
yieldtocaller indicates `showpage` has been called using SHOWPAGE_RETURN semantics.
ioblock indicates a blocked io operation.
contextswitch indicates the `yield` operator has been called.
all other values indicate an error condition to be returned to postscript.
*/
int mainloop(Xpost_Context *ctx)
{
int ret;
ctxswitch:
xpost_ctx = ctx = _switch_context(ctx);
itpdata->cid = ctx->id;
while(!ctx->quit)
{
ret = eval(ctx);
if (ret)
switch (ret)
{
case yieldtocaller:
return 1;
case ioblock:
ctx->state = C_IOBLOCK; /* fallthrough */
case contextswitch:
goto ctxswitch;
default:
_onerror(ctx, ret);
}
}
return 0;
}
static void *
_yield(struct coroutine *co) {
assert(_scheduler() == co->sched);
co->stack_lowest = (uint8_t*)&co;
co->result = NULL;
_switch_context(&co->ctx, &co->sched->ctx);
return co->result;
}
inline static void
_resume(struct coroutine *co) {
struct scheduler *s = co->sched;
assert(s == _scheduler());
if (co->inited) {
_copy_stack(co);
} else {
// init in the same thread as coroutine context.
co->inited = true;
_make_context(co, &s->ctx, &s->stack);
}
co->status = STATUS_RUNNING;
_switch_context(&s->ctx, &co->ctx);
}
/** \internal
* \brief Voluntarily release the processor so that another thread
* can be scheduled to run.
*
* \author Wesley Peck <*****@*****.**>
*
* This function is the system call routine which implements the
* hthread_yield functionality for hthreads. The user space function
* hthread_yield invokes this function to yield the processor.
*
* \return The return value is one of the following:
* - SUCCESS : Currently there is no way for this function
* to fail
*/
Hint _syscall_yield( void )
{
Huint curr;
Huint next;
// Print out a trace message about this system call
TRACE_PRINTF( TRACE_FINE, TRACE_SYSCALL, "SYSCALL: (OP=YIELD)\n" );
// Get the currently running thread
curr = _current_thread();
// Get the next thread to run
next = _yield_thread();
// Print out a trace message about this system call
TRACE_PRINTF( TRACE_FINE, TRACE_SYSCALL, "SYSCALL DONE: (OP=YIELD)\n" );
// If they are not the same thread then switch to the new thread
if( curr != next ) _switch_context( curr, next );
return SUCCESS;
}
