/* $Header$ */

/*
 * Copyright © 1988-2004 Keith Packard and Bart Massey.
 * All Rights Reserved.  See the file COPYING in this directory
 * for licensing information.
 */

#include	<assert.h>
#include	"nickle.h"
#include	"ref.h"

Value   running;
Value   stopped;
int	runnable;
Bool	signalException;

extern void dumpSleep (void), dumpThreads (void);

static void
_ThreadInsert (Value thread)
{
    Value	*prev, t;

    if (Runnable (thread))
	++runnable;
    if (thread->thread.state == ThreadRunning)
	prev = &running;
    else if (thread->thread.state & ThreadFinished)
	return;
    else
	prev = &stopped;
    for (; (t = *prev); prev = &t->thread.next)
	if (t->thread.priority < thread->thread.priority)
	    break;
    thread->thread.next = t;
    *prev = thread;
}

static void
_ThreadRemove (Value thread)
{
    Value	*prev;

    if (Runnable (thread))
	--runnable;
    if (thread->thread.state == ThreadRunning)
	prev = &running;
    else if (thread->thread.state & ThreadFinished)
	return;
    else
	prev = &stopped;
    for (; *prev != thread; prev = &(*prev)->thread.next);
    *prev = thread->thread.next;
}

void
ThreadSetState (Value thread, ThreadState state)
{
    _ThreadRemove (thread);
    thread->thread.state |= state;
    _ThreadInsert (thread);
}

void
ThreadClearState (Value thread, ThreadState state)
{
    _ThreadRemove (thread);
    thread->thread.state &= ~state;
    _ThreadInsert (thread);
}

void
ThreadSleep (Value thread, Value sleep, int priority)
{
    thread->thread.priority = priority;
    thread->thread.sleep = sleep;
    SetSignalSuspend ();
}

void
ThreadStepped (Value thread)
{
    Value   t;
    
    if ((t = thread->thread.next) &&
        thread->thread.priority <= t->thread.priority)
    {
        _ThreadRemove (thread);
        _ThreadInsert (thread);
    }
}

void
ThreadsWakeup (Value sleep, WakeKind kind)
{
    Value	thread, next;

    for (thread = stopped; thread; thread = next)
    {
	next = thread->thread.next;
	if ((thread->thread.state & ThreadSuspended) && 
	    thread->thread.sleep == sleep)
	{
	    thread->thread.sleep = 0;
	    ThreadClearState (thread, ThreadSuspended);
	    if (kind == WakeOne)
		break;
	}
    }
}

Bool	lastThreadError;

void
ThreadFinish (Value thread, Bool error)
{
    ThreadSetState (thread, ThreadFinished);
    ThreadsWakeup (thread, WakeAll);
    lastThreadError = error;
}

void
ThreadsInterrupt (void)
{
    Value   thread, next;
    Value   t;

    if (running)
	t = running;
    else
	t = stopped;
    for (thread = stopped; thread; thread = next)
    {
	next = thread->thread.next;
	if (Runnable (thread))
	    --runnable;
	thread->thread.state |= ThreadInterrupted;
    }
    for (thread = running; thread; thread = next)
    {
	next = thread->thread.next;
	ThreadSetState (thread, ThreadInterrupted);
    }
}

static int
ThreadContinue (void)
{
    Value   thread, next;
    int	    n;

    n = 0;
    for (thread = stopped; thread; thread = next)
    {
	next = thread->thread.next;

	if (thread->thread.state & ThreadInterrupted)
	{
	    n++;
	    ThreadClearState (thread, ThreadInterrupted);
	}
    }
    return n;
}
	    
Value
do_Thread_join (Value target)
{
    ENTER ();
    if (!ValueIsThread(target))
    {
	RaiseStandardException (exception_invalid_argument,
				"Thread::join needs thread argument",
				2, target, Void);
	RETURN (Void);
    }
    if ((target->thread.state & ThreadFinished) == 0)
    {
	ThreadSleep (running, target, PrioritySync);
	RETURN (Void);
    }
    RETURN (target->thread.continuation.value);
}

static void
ThreadListState (Value thread)
{
    int	state = thread->thread.state;
    
    if (state == ThreadRunning)
	FilePuts (FileStdout, " running");
    else
    {
	if (state & ThreadSuspended)
	    FilePuts (FileStdout, " suspended");
	if (state & ThreadInterrupted)
	    FilePuts (FileStdout, " interrupted");
	if (state & ThreadFinished)
	    FilePuts (FileStdout, " finished");
    }
}

Value
do_Thread_list (void)
{
    ENTER ();
    Value   t;

    for (t = running; t; t = t->thread.next)
    {
	FilePrintf (FileStdout, "\t%%%d", t->thread.id);
	ThreadListState (t);
	FileOutput (FileStdout, '\n');
    }
    for (t = stopped; t; t = t->thread.next)
    {
	FilePrintf (FileStdout, "\t%%%d", t->thread.id);
	ThreadListState (t);
	if (t->thread.sleep)
	    FilePrintf (FileStdout, " %g", t->thread.sleep);
	FileOutput (FileStdout, '\n');
    }
    RETURN(Void);
}

Value
do_Thread_id_to_thread (Value id)
{
    ENTER ();
    int	i;
    Value   t;

    i = IntPart (id, "Invalid thread id");
    if (aborting)
	RETURN (Void);
    for (t = running; t; t = t->thread.next)
	if (t->thread.id == i)
	    RETURN (t);
    for (t = stopped; t; t = t->thread.next)
	if (t->thread.id == i)
	    RETURN (t);
    RETURN (Void);
}

Value
do_Thread_current (void)
{
    ENTER ();
    Value   ret;
    if (running)
	ret = running;
    else
	ret = Void;
    RETURN (ret);
}

Value
do_Thread_set_priority (Value thread, Value priority)
{
    ENTER ();
    int	    i;
    if (!ValueIsThread(thread))
    {
	RaiseStandardException (exception_invalid_argument,
				"Thread::set_priority: not a thread",
				2, thread, priority);
	RETURN (Void);
    }
    i = IntPart (priority, "Invalid thread priority");
    if (aborting)
	RETURN (Void);
    if (i != thread->thread.priority)
    {
	_ThreadRemove (thread);
	thread->thread.priority = i;
	_ThreadInsert (thread);
    }
    RETURN (NewInt (thread->thread.priority));
}

Value
do_Thread_get_priority (Value thread)
{
    ENTER ();
    if (!ValueIsThread(thread))
    {
	RaiseStandardException (exception_invalid_argument,
				"Thread::get_priority: not a thread",
				2, thread, Void);
	RETURN (Void);
    }
    RETURN (NewInt (thread->thread.priority));
}

Value
do_Thread_cont (void)
{
    int	    n;
    
    n = ThreadContinue ();
    return NewInt (n);
}

static int
KillThread (Value thread)
{
    int	ret;
    
    if (!ValueIsThread(thread))
    {
	RaiseStandardException (exception_invalid_argument,
				"Thread::kill: not a thread",
				2, thread, Void);
	return 0;
    }
    if (thread->thread.state & ThreadFinished)
	ret = 0;
    else
	ret = 1;
    ThreadFinish (thread, False);
    return ret;
}

Value
do_Thread_kill (int n, Value *p)
{
    ENTER ();
    Value   thread;
    int	    ret = 0;

    if (n == 0)
    {
	thread = lookupVar (0, "thread");
	if (!ValueIsThread(thread))
	    RaiseStandardException (exception_invalid_argument,
				    "Thread::kill: no default thread",
				    2, thread, Void);
	else
	    ret = KillThread (thread);
    }
    else
    {
	while (n--)
	    ret += KillThread (*p++);
    }
    RETURN (NewInt (ret));
}

void
TraceFunction (Value file, FramePtr frame, CodePtr code, ExprPtr name)
{
    int		    fe;
    
    FilePuts (file, "    ");
    if (name)
	PrettyExpr (file, name, -1, 0, False, 0);
    else
	FilePuts (file, "<anonymous>");
    FilePuts (file, " (");
    for (fe = 0; fe < code->base.argc; fe++)
    {
	if (fe)
	    FilePuts (file, ", ");
	FilePrintf (file, "%g", BoxValue (frame->frame, fe));
    }
    FilePuts (file, ")\n");
}

static void
TraceStatement (Value file, ExprPtr stat)
{
    FilePrintf (file, "%A:%d: ", stat->base.file, stat->base.line);
    PrettyStat (file, stat, False);
}

void
TraceFrame (Value file, FramePtr frame, ObjPtr obj, InstPtr pc, int depth)
{
    ENTER ();
    int		max;
    CodePtr	code;

    if (obj && pc)
	TraceStatement (file, ObjStatement (obj, pc));
    for (max = depth; frame && max--; frame = frame->previous)
    {
	code = frame->function->func.code;
	TraceFunction (file, frame, code, code->base.name);
	TraceStatement (file, ObjStatement (frame->saveObj, frame->savePc));
    }
    EXIT ();
}

#ifdef DEBUG_JUMP
static void
TraceIndent (int indent)
{
    while (indent--)
	FilePuts (FileStdout, "    ");
}
#endif

Value
do_Thread_trace (int n, Value *p)
{
    ENTER ();
    Value	v;
    FramePtr	frame;
    InstPtr	pc;
    ObjPtr	obj;
    int		depth = 20;
    
    if (n == 0)
	v = lookupVar (0, "cont");
    else
	v = p[0];
    if (n > 1)
    {
	depth = IntPart (p[1], "Invalid trace depth");
	if (aborting)
	    RETURN (Void);
    }
    switch (ValueTag(v)) {
    case rep_thread:
    case rep_continuation:
	frame = v->continuation.frame;
	pc = v->continuation.pc;
	obj = v->continuation.obj;
	break;
    default:
	if (n == 0)
	    RaiseStandardException (exception_invalid_argument, 
				    "Thread::trace: no default continuation",
				    1, Zero);
	else
	    RaiseStandardException (exception_invalid_argument, 
				    "Thread::trace: neither continuation nor thread",
				    1, v);
	RETURN (Void);
    }
    TraceFrame (FileStdout, frame, obj, pc, depth);
    RETURN(Void);
}

static void
ThreadMark (void *object)
{
    ThreadPtr	thread = object;

    ContinuationMark (&thread->continuation);
    MemReference (thread->jump);
    MemReference (thread->sleep);
    MemReference (thread->next);
}

static Bool
ThreadPrint (Value f, Value av, char format, int base, int width, int prec, int fill)
{
    FilePrintf (f, "%%%d", av->thread.id);
    return True;
}

ValueRep    ThreadRep = {
    { ThreadMark, 0, "ThreadRep" },	/* base */
    rep_thread,	/* tag */
    {			/* binary */
	0,
	0,
	0,
	0,
	0,
	0,
	0,
	ValueEqual,
	0,
	0,
    },
    {			    /* unary */
	0,
	0,
	0,
    },
    0,
    0,
    ThreadPrint,
    0,
};
    
static int  ThreadId;

Value
NewThread (FramePtr frame, ObjPtr code)
{
    ENTER ();
    Value ret;

    ret = ALLOCATE (&ThreadRep.data, sizeof (Thread));
    
    ret->thread.jump = 0;
    ret->thread.state = ThreadRunning;
    ret->thread.priority = 0;
    ret->thread.sleep = 0;
    ret->thread.id = ++ThreadId;
    ret->thread.partial = 0;
    ret->thread.next = 0;
    
    ContinuationInit (&ret->thread.continuation);
    ret->thread.continuation.obj = code;
    ret->thread.continuation.pc = ObjCode (code, 0);
    ret->thread.continuation.frame = frame;
    
    complete = True;
    if (code->error)
	ret->thread.state = ThreadFinished;
    _ThreadInsert (ret);
    RETURN (ret);
}

typedef struct _blockHandler {
    DataType		    *data;
    struct _blockHandler    *next;
    NickleBlockHandler	    handler;
    void		    *closure;
} BlockHandler;

static void
BlockHandlerMark (void *object)
{
    BlockHandler    *bh = object;

    MemReference (bh->next);
}

DataType BlockHandlerType = { BlockHandlerMark, 0, "BlockHandlerType" };

static BlockHandler	*blockHandlers;

void
ThreadsRegisterBlockHandler (NickleBlockHandler handler, void *closure)
{
    ENTER ();
    BlockHandler    *bh = ALLOCATE (&BlockHandlerType, sizeof (BlockHandler));
    bh->next = blockHandlers;
    blockHandlers = bh;
    bh->handler = handler;
    bh->closure = closure;
    EXIT ();
}

void
ThreadsUnregisterBlockHandler (NickleBlockHandler handler, void *closure)
{
    ENTER ();
    BlockHandler    **prev, *bh;

    for (prev = &blockHandlers; (bh = *prev); prev = &bh->next)
    {
	if (bh->handler == handler && bh->closure == closure)
	{
	    bh->handler = 0;
	    *prev = bh->next;
	}
    }
    EXIT ();
}

void
ThreadsBlock (void)
{
    BlockHandler    *bh, *next;

    for (bh = blockHandlers; bh; bh = next)
    {
	next = bh->next;
	if (bh->handler)
	    (*bh->handler) (bh->closure);
    }
    if (!running)
    {
	sigset_t	    set, oset;

	sigfillset (&set);
	sigprocmask (SIG_SETMASK, &set, &oset);
	if (!signaling)
	    sigsuspend (&oset);
	sigprocmask (SIG_SETMASK, &oset, &set);
    }
}

ReferencePtr	RunningReference, StoppedReference;
ReferencePtr	BlockHandlerReference;

void
ThreadInit (void)
{
    ENTER ();
    RunningReference = NewReference ((void **) &running);
    MemAddRoot (RunningReference);
    StoppedReference = NewReference ((void **) &stopped);
    MemAddRoot (StoppedReference);
    BlockHandlerReference = NewReference ((void **) &blockHandlers);
    MemAddRoot (BlockHandlerReference);
    EXIT ();
}

DataType FarJumpType = { 0, 0, "FarJumpType" };

FarJumpPtr
NewFarJump (int inst, int twixt, int catch, int frame)
{
    ENTER ();
    FarJumpPtr	farJump;

    farJump = ALLOCATE (&FarJumpType, sizeof (FarJump));
    farJump->inst = inst;
    farJump->twixt = twixt;
    farJump->catch = catch;
    farJump->frame = frame;
    RETURN (farJump);
}

Value
FarJumpContinuation (ContinuationPtr continuation, FarJumpPtr farJump)
{
    ENTER ();
    Value	ret;
    CatchPtr	catch;
    TwixtPtr	twixt;
    FramePtr	frame;
    InstPtr	pc;
    ObjPtr	obj;
    int		twixts;
    int		catches;
    int		frames;

    ret = NewContinuation (continuation, 0);
    
    /*
     * Unwind twixts
     */
    twixts = farJump->twixt;
    twixt = ret->continuation.twixts;
    while (twixts--)
	twixt = twixt->continuation.twixts;
    ret->continuation.twixts = twixt;

    /*
     * Unwind catches
     */
#ifdef DEBUG_JUMP
    FilePrintf (FileStdout, "FarJump catches before: ");
    ThreadCatches (running);
#endif
    catches = farJump->catch;
    catch = ret->continuation.catches;
    while (catches--)
	catch = catch->continuation.catches;
    ret->continuation.catches = catch;
#ifdef DEBUG_JUMP
    FilePrintf (FileStdout, "FarJump catches after: ");
    ThreadCatches (running);
#endif

    /*
     * Unwind frames
     */
    frames = farJump->frame;
    frame = ret->continuation.frame;
    obj = continuation->obj;
    pc = continuation->pc;
    if (farJump->inst < 0)
	frames++;
    while (frames--)
    {
	pc = frame->savePc;
	obj = frame->saveObj;
	frame = frame->previous;
    }
    ret->continuation.frame = frame;
    /* 
     * Set pc for non-return jumps
     */
    if (farJump->inst >= 0)
	pc = ObjCode (obj, farJump->inst);

    /*
     * Assertion here -- the stack is OK because
     * only intervening catch frames are on the stack
     * and they never have extra values on the stack
     */
    
    ret->continuation.pc = pc;
    ret->continuation.obj = obj;
    RETURN (ret);
}

void
ContinuationMark (void *object)
{
    ContinuationPtr	continuation = object;

    assert (!continuation->pc || 
	    (ObjCode (continuation->obj, 0) <= continuation->pc &&
	     continuation->pc <= ObjCode (continuation->obj, ObjLast(continuation->obj))));
    MemReference (continuation->obj);
    MemReference (continuation->frame);
    MemReference (continuation->stack);
    MemReference (continuation->value);
    MemReference (continuation->catches);
    MemReference (continuation->twixts);
}

static Bool
ContinuationPrint (Value f, Value av, char format, int base, int width, int prec, int fill)
{
    FilePuts (f, "continutation");
    return True;
}

ValueRep    ContinuationRep = {
    { ContinuationMark, 0, "ContinuationRep" },	/* base */
    rep_continuation,		/* tag */
    {				/* binary */
	0,
	0,
	0,
	0,
	0,
	0,
	0,
	ValueEqual,
	0,
	0,
    },
    {				/* unary */
	0,
	0,
	0,
    },
    0,
    0,
    ContinuationPrint,
    0,
};

Value
NewContinuation (ContinuationPtr continuation, InstPtr pc)
{
    ENTER ();
    Value   ret;

    ret = ALLOCATE (&ContinuationRep.data, sizeof (Continuation));
    ContinuationSet (&ret->continuation, continuation);
    ret->continuation.pc = pc;
    RETURN (ret);
}

static ContinuationPtr
EmptyContinuation (void)
{
    ENTER ();
    Value   ret;

    ret = ALLOCATE (&ContinuationRep.data, sizeof (Continuation));
    ContinuationInit (&ret->continuation);
    RETURN (&ret->continuation);
}

#ifdef DEBUG_JUMP
int dump_jump = 0;

void
ContinuationTrace (char *where, Continuation *continuation, int indent)
{
    int	    s;
    StackObject	*stack = continuation->stack;
    CatchPtr	catches = continuation->catches;
    TwixtPtr	twixts = continuation->twixts;
    ObjPtr	obj = continuation->obj;
    InstPtr	pc = continuation->pc;
    
    if (!dump_jump)
	return;
    TraceIndent (indent);
    FilePuts (FileStdout, "*** ");
    FilePuts (FileStdout, where);
    FilePuts (FileStdout, " ***\n");
    TraceIndent (indent);
    FilePuts (FileStdout, "stack:     ");
    for (s = 0; STACK_TOP(stack) + (s) < STACK_MAX(stack); s++)
    {
	if (s)
	    FilePuts (FileStdout, ", ");
	FilePrintf (FileStdout, "%g", STACK_ELT(stack, s));
    }
    FilePuts (FileStdout, "\n");
    TraceIndent (indent);
    FilePuts (FileStdout, "frame:\nCALLS\n");
    TraceFrame (FileStdout, continuation->frame, obj, pc, 20);
    FilePuts (FileStdout, "END CALLS\n");
    TraceIndent (indent);
    FilePuts (FileStdout, "catches:   ");
    for (s = 0; catches; catches = catches->continuation.catches, s++)
    {
	if (s)
	    FilePuts (FileStdout, ", ");
	FilePrintf (FileStdout, "%A", catches->exception->symbol.name);
    }
    FilePuts (FileStdout, "\n");
    TraceIndent (indent);
    FilePuts (FileStdout, "statement: ");
    if (obj && pc)
	PrettyStat (FileStdout, ObjStatement (obj, pc), False);
    else
	FilePuts (FileStdout, "corrupted continuation!\n");
    for (s = 0; twixts; twixts = twixts->continuation.twixts, s++)
    {
	ContinuationTrace ("twixt", &twixts->continuation, indent+1);
    }
}
#endif

InstPtr
ContinuationSet (ContinuationPtr dst, ContinuationPtr src)
{
    ENTER ();
    dst->value = src->value;
    dst->pc = 0;
    dst->obj = src->obj;
    dst->frame = src->frame;
    dst->stack = 0;
    dst->catches = src->catches;
    dst->twixts = src->twixts;
    /* last, to make sure remaining entries are initialized before any GC */
    dst->stack = StackCopy (src->stack);
    RETURN (src->pc);
}

void
ContinuationInit (ContinuationPtr dst)
{
    dst->pc = 0;
    dst->obj = 0;
    dst->frame = 0;
    dst->value = Void;
    dst->catches = 0;
    dst->twixts = 0;
    dst->stack = 0;
    dst->stack = StackCreate ();
}

static void
MarkJump (void *object)
{
    JumpPtr jump = object;

    MemReference (jump->enter);
    MemReference (jump->entering);
    MemReference (jump->leave);
    MemReference (jump->parent);
    MemReference (jump->continuation);
    MemReference (jump->ret);
}

DataType    JumpType = { MarkJump, 0, "JumpType" };

JumpPtr
NewJump (TwixtPtr leave, TwixtPtr enter, TwixtPtr parent,
	 ContinuationPtr continuation, Value ret)
{
    ENTER ();
    JumpPtr jump;

    jump = ALLOCATE (&JumpType, sizeof (Jump));
    jump->leave = leave;
    jump->enter = enter;
    jump->entering = TwixtNext (parent, enter);
    jump->parent = parent;
    jump->continuation = continuation;
    jump->ret = ret;
    RETURN (jump);
}

/*
 * An unhandled exception will attempt to jump to NULL,
 * catch that and invoke the debugger.  When the exception
 * was raised, the code carefully pushed a continuation from
 * the point of the exception to pass to the debugger
 */

static void
JumpUnhandledException (Value thread)
{
    Value   continuation = STACK_POP (thread->thread.continuation.stack);
    
    DebugStart (continuation);
    SetSignalError ();
}

/*
 * Figure out where to go next in a longjmp through twixts
 */
Value
JumpContinue (Value thread, InstPtr *next)
{
    ENTER ();
    JumpPtr	jump = thread->thread.jump;
    TwixtPtr	twixt;
    
    if (jump->leave)
    {
	/*
	 * Going up
	 */
	twixt = jump->leave;
	jump->leave = twixt->continuation.twixts;
	/*
	 * Matching element of the twixt chain, next time start
	 * back down the other side
	 */
	if (jump->leave == jump->parent)
	    jump->leave = 0;
	ContinuationSet (&thread->thread.continuation, &twixt->continuation);
	*next = twixt->leave;
    }
    else if (jump->entering)
    {
	/*
	 * Going down
	 */
	twixt = jump->entering;
	jump->entering = TwixtNext (jump->entering, jump->enter);
	*next = ContinuationSet (&thread->thread.continuation, &twixt->continuation);
    }
    else
    {
	/*
	 * All done, set to final continuation and drop the jump object
	 */
	running->thread.jump = 0;
	*next = ContinuationSet (&thread->thread.continuation, jump->continuation);
    }
    if (!*next)
	JumpUnhandledException (thread);
    RETURN (jump->ret);
}

/*
 * Build a Jump that threads through all of the necessary twixt blocks
 * ending up at 'continuation' returning 'ret'
 */
InstPtr
JumpStart (Value thread, ContinuationPtr continuation, Value ret)
{
    ENTER ();
    int	diff;
    TwixtPtr	leave = thread->thread.continuation.twixts;
    TwixtPtr	enter = continuation->twixts;
    TwixtPtr	leave_parent, enter_parent, parent;
    InstPtr	next;

    /*
     * Make both lists the same length.  Note that either can be empty
     */
    leave_parent = leave;
    enter_parent = enter;
    diff = TwixtDepth (leave_parent) - TwixtDepth (enter_parent);
    if (diff >= 0)
	while (diff-- > 0)
	    leave_parent = leave_parent->continuation.twixts;
    else
	while (diff++ < 0)
	    enter_parent = enter_parent->continuation.twixts;
    /*
     * Now find the common parent
     */
    while (leave_parent != enter_parent)
    {
	leave_parent = leave_parent->continuation.twixts;
	enter_parent = enter_parent->continuation.twixts;
    }

    parent = enter_parent;
    /*
     * Build a data structure to get from leave to enter via parent
     */
    thread->thread.jump = NewJump (leave, enter, parent, continuation, ret);
    /*
     * Don't need the jump return value yet; we're off to the twixt
     * blocks; after that, the return value will get retrieved by the
     * final OpLeaveDone or OpEnterDone instruction
     */
    (void) JumpContinue (thread, &next);
    RETURN (next);
}

Value
ContinuationJump (Value thread, ContinuationPtr continuation, Value ret, InstPtr *next)
{
#ifdef DEBUG_JUMP
    ContinuationTrace ("ContinuationJump from", &thread->thread.continuation, 1);
    ContinuationTrace ("ContinuationJump to", continuation, 1);
#endif
    ENTER ();
    /*
     * If there are twixt enter or leave blocks to execute, build a Jump
     * that walks them and then resets the continuation.
     *
     * Otherwise, just jump
     */
    if (thread->thread.continuation.twixts != continuation->twixts)
	*next = JumpStart (thread, continuation, ret);
    else
	*next = ContinuationSet (&thread->thread.continuation, continuation);
    if (!*next)
	JumpUnhandledException (thread);
    RETURN (ret);
}

/*
 * It is necessary that SetJump and LongJump have the same number
 * of arguments -- the arguments pushed by SetJump will have to be
 * popped when LongJump executes.  If this is not so, the stack copy
 * created here should be adjusted to account for this difference
 */
Value
do_setjmp (Value continuation_ref, Value ret)
{
    ENTER ();
    Value	continuation;
    
    if (!ValueIsRef(continuation_ref))
    {
	RaiseStandardException (exception_invalid_argument,
				"setjump: not a reference",
				1, continuation_ref);
	RETURN (Void);
    }
    continuation = NewContinuation (&running->thread.continuation,
				    running->thread.continuation.pc + 1);
    /*
     * Adjust stack for set jump return
     */
    STACK_DROP (continuation->continuation.stack, 2);
    RefValueSet (continuation_ref, continuation);
#ifdef DEBUG_JUMP
    ContinuationTrace ("do_setjmp", &continuation->continuation, 1);
#endif
    RETURN (ret);
}

Value
do_longjmp (InstPtr *next, Value continuation, Value ret)
{
    ENTER ();

    if (!running)
	RETURN (Void);
    if (!ValueIsContinuation(continuation))
    {
	RaiseStandardException (exception_invalid_argument,
				"longjmp: non-continuation argument",
				1, continuation);
	RETURN (Void);
    }
    RETURN (ContinuationJump (running, &continuation->continuation, ret, next));
}

static void
CatchMark (void *object)
{
    CatchPtr	catch = object;

    ContinuationMark (&catch->continuation);
    MemReference (catch->exception);
}

DataType    CatchType = { CatchMark, 0, "CatchType" };

CatchPtr
NewCatch (Value thread, SymbolPtr exception)
{
    ENTER();
    CatchPtr	catch;

    catch = ALLOCATE (&CatchType, sizeof (Catch));
    catch->exception = exception;
    ContinuationSet (&catch->continuation, &thread->thread.continuation);
    catch->continuation.pc = thread->thread.continuation.pc + 1;
    RETURN (catch);
}

static void
TwixtMark (void *object)
{
    TwixtPtr	twixt = object;

    ContinuationMark (&twixt->continuation);
    MemReference (twixt->leave);
}

DataType    TwixtType = { TwixtMark, 0, "TwixtType" };

TwixtPtr
NewTwixt (ContinuationPtr	continuation,
	  InstPtr	enter,
	  InstPtr	leave)
{
    ENTER ();
    TwixtPtr	twixt;

    twixt = ALLOCATE (&TwixtType, sizeof (Twixt));
    twixt->leave = leave;
    if (continuation->twixts)
	twixt->depth = continuation->twixts->depth + 1;
    else
	twixt->depth = 1;
    ContinuationSet (&twixt->continuation, continuation);
    twixt->continuation.pc = enter;
    RETURN (twixt);
}

/*
 * Twixts are chained deepest first.  Walking
 * down the list is a bit of work
 */

TwixtPtr
TwixtNext (TwixtPtr twixt, TwixtPtr last)
{
    if (last == twixt)
	return 0;
    while (last->continuation.twixts != twixt)
	last = last->continuation.twixts;
    return last;
}

void
RaiseException (Value thread, SymbolPtr except, Value args, InstPtr *next)
{
    ENTER ();
    CatchPtr	    catch;
    ContinuationPtr continuation = 0;
    
    for (catch = thread->thread.continuation.catches; 
	 catch; 
	 catch = catch->continuation.catches)
    {
	if (catch->exception == except)
	{
	    continuation = &catch->continuation;
	    /*
	     * Hold a reference to this nested value because
	     * ContinuationJump is about to smash the thread
	     */
	    REFERENCE (catch);
	    break;
	}
    }
    /* unhandled exception -- build an empty continuation and jump to it */
    if (!continuation)
    {
	int	i;
	InstPtr	pc = thread->thread.continuation.pc;
	
	PrintError ("Unhandled exception %A (", except->symbol.name);
	if (args)
	{
	    int	    dim = ArrayLimits(&args->array)[0];
	    for (i = 0; i < dim; i++)
	    {
		PrintError ("%g", ArrayValue (&args->array, i));
		if (i < dim - 1)
		    PrintError (", ");
	    }
	}
	PrintError (")\n");
	TraceFrame (FileStderr, thread->thread.continuation.frame,
		    thread->thread.continuation.obj,
		    pc,
		    20);
	continuation = EmptyContinuation();
	STACK_PUSH (continuation->stack, 
		    NewContinuation (&thread->thread.continuation, pc));
    }
    ContinuationJump (thread, continuation, args, next);
    EXIT ();
}

SymbolPtr	    standardExceptions[_num_standard_exceptions];
StandardException   standardException;
Value		    standardExceptionArgs;
ReferencePtr	    standardExceptionArgsRef;

void
RegisterStandardException (StandardException	se,
			   SymbolPtr		sym)
{
    ENTER ();
    standardExceptions[se] = sym;
    MemAddRoot (sym);
    if (!standardExceptionArgsRef)
    {
	standardExceptionArgsRef = NewReference ((void **) &standardExceptionArgs);
	MemAddRoot (standardExceptionArgsRef);
    }
    EXIT ();
}

SymbolPtr
CheckStandardException (void)
{
    SymbolPtr		except = standardExceptions[standardException];
    
    signalException = False;
    standardException = exception_none;
    standardExceptionArgs = 0;
    return except;
}

void
RaiseStandardException (StandardException   se,
			char		    *string,
			int		    argc,
			...)
{
    ENTER ();
    Value	args;
    int		i;
    va_list	va;
    
    va_start (va, argc);
    i = argc + 1;
    args = NewArray (False, False, typePoly, 1, &i);
    ArrayValueSet (&args->array, 0, NewStrString (string));
    if (argc)
	for (i = 0; i < argc; i++)
	    ArrayValueSet (&args->array, i + 1, va_arg (va, Value));
    standardException = se;
    standardExceptionArgs = args;
    SetSignalException ();
    EXIT ();
}

Value
JumpStandardException (Value thread, InstPtr *next)
{
    ENTER ();
    SymbolPtr		except = standardExceptions[standardException];
    Value		args = standardExceptionArgs;
    
    aborting = False;
    if (except)
	RaiseException (thread, except, args, next);
    standardException = exception_none;
    standardExceptionArgs = 0;
    RETURN (args);
}