1 76193d7c 2003-09-30 devnull #include "threadimpl.h"
  2 76193d7c 2003-09-30 devnull 
  3 76193d7c 2003-09-30 devnull static Lock chanlock;		/* central channel access lock */
  4 76193d7c 2003-09-30 devnull 
  5 06bb4ed2 2004-09-17 devnull static void enqueue(Alt*, Thread*);
  6 76193d7c 2003-09-30 devnull static void dequeue(Alt*);
  7 76193d7c 2003-09-30 devnull static int altexec(Alt*, int);
  8 76193d7c 2003-09-30 devnull 
  9 76193d7c 2003-09-30 devnull int _threadhighnentry;
 10 76193d7c 2003-09-30 devnull int _threadnalt;
 11 76193d7c 2003-09-30 devnull 
 12 02a1a5c1 2004-03-05 devnull static void
 13 02a1a5c1 2004-03-05 devnull setuserpc(ulong pc)
 14 02a1a5c1 2004-03-05 devnull {
 15 02a1a5c1 2004-03-05 devnull 	Thread *t;
 16 02a1a5c1 2004-03-05 devnull 
 17 02a1a5c1 2004-03-05 devnull 	t = _threadgetproc()->thread;
 18 02a1a5c1 2004-03-05 devnull 	if(t)
 19 02a1a5c1 2004-03-05 devnull 		t->userpc = pc;
 20 02a1a5c1 2004-03-05 devnull }
 21 02a1a5c1 2004-03-05 devnull 
 22 76193d7c 2003-09-30 devnull static int
 23 76193d7c 2003-09-30 devnull canexec(Alt *a)
 24 76193d7c 2003-09-30 devnull {
 25 76193d7c 2003-09-30 devnull 	int i, otherop;
 26 76193d7c 2003-09-30 devnull 	Channel *c;
 27 76193d7c 2003-09-30 devnull 
 28 76193d7c 2003-09-30 devnull 	c = a->c;
 29 76193d7c 2003-09-30 devnull 	/* are there senders or receivers blocked? */
 30 76193d7c 2003-09-30 devnull 	otherop = (CHANSND+CHANRCV) - a->op;
 31 76193d7c 2003-09-30 devnull 	for(i=0; i<c->nentry; i++)
 32 bcf527a9 2004-09-17 devnull 		if(c->qentry[i] && c->qentry[i]->op==otherop && c->qentry[i]->thread->altc==nil){
 33 76193d7c 2003-09-30 devnull 			_threaddebug(DBGCHAN, "can rendez alt %p chan %p", a, c);
 34 76193d7c 2003-09-30 devnull 			return 1;
 35 76193d7c 2003-09-30 devnull 		}
 36 76193d7c 2003-09-30 devnull 
 37 76193d7c 2003-09-30 devnull 	/* is there room in the channel? */
 38 76193d7c 2003-09-30 devnull 	if((a->op==CHANSND && c->n < c->s)
 39 76193d7c 2003-09-30 devnull 	|| (a->op==CHANRCV && c->n > 0)){
 40 76193d7c 2003-09-30 devnull 		_threaddebug(DBGCHAN, "can buffer alt %p chan %p", a, c);
 41 76193d7c 2003-09-30 devnull 		return 1;
 42 76193d7c 2003-09-30 devnull 	}
 43 76193d7c 2003-09-30 devnull 
 44 76193d7c 2003-09-30 devnull 	return 0;
 45 76193d7c 2003-09-30 devnull }
 46 76193d7c 2003-09-30 devnull 
 47 76193d7c 2003-09-30 devnull static void
 48 76193d7c 2003-09-30 devnull _chanfree(Channel *c)
 49 76193d7c 2003-09-30 devnull {
 50 76193d7c 2003-09-30 devnull 	int i, inuse;
 51 76193d7c 2003-09-30 devnull 
 52 76193d7c 2003-09-30 devnull 	inuse = 0;
 53 76193d7c 2003-09-30 devnull 	for(i = 0; i < c->nentry; i++)
 54 76193d7c 2003-09-30 devnull 		if(c->qentry[i])
 55 76193d7c 2003-09-30 devnull 			inuse = 1;
 56 76193d7c 2003-09-30 devnull 	if(inuse)
 57 76193d7c 2003-09-30 devnull 		c->freed = 1;
 58 76193d7c 2003-09-30 devnull 	else{
 59 76193d7c 2003-09-30 devnull 		if(c->qentry)
 60 76193d7c 2003-09-30 devnull 			free(c->qentry);
 61 76193d7c 2003-09-30 devnull 		free(c);
 62 76193d7c 2003-09-30 devnull 	}
 63 76193d7c 2003-09-30 devnull }
 64 76193d7c 2003-09-30 devnull 
 65 76193d7c 2003-09-30 devnull void
 66 76193d7c 2003-09-30 devnull chanfree(Channel *c)
 67 76193d7c 2003-09-30 devnull {
 68 76193d7c 2003-09-30 devnull 	lock(&chanlock);
 69 76193d7c 2003-09-30 devnull 	_chanfree(c);
 70 76193d7c 2003-09-30 devnull 	unlock(&chanlock);
 71 76193d7c 2003-09-30 devnull }
 72 76193d7c 2003-09-30 devnull 
 73 76193d7c 2003-09-30 devnull int
 74 76193d7c 2003-09-30 devnull chaninit(Channel *c, int elemsize, int elemcnt)
 75 76193d7c 2003-09-30 devnull {
 76 76193d7c 2003-09-30 devnull 	if(elemcnt < 0 || elemsize <= 0 || c == nil)
 77 76193d7c 2003-09-30 devnull 		return -1;
 78 5a8e63b2 2004-02-29 devnull 	memset(c, 0, sizeof *c);
 79 76193d7c 2003-09-30 devnull 	c->e = elemsize;
 80 76193d7c 2003-09-30 devnull 	c->s = elemcnt;
 81 76193d7c 2003-09-30 devnull 	_threaddebug(DBGCHAN, "chaninit %p", c);
 82 76193d7c 2003-09-30 devnull 	return 1;
 83 76193d7c 2003-09-30 devnull }
 84 76193d7c 2003-09-30 devnull 
 85 76193d7c 2003-09-30 devnull Channel*
 86 76193d7c 2003-09-30 devnull chancreate(int elemsize, int elemcnt)
 87 76193d7c 2003-09-30 devnull {
 88 76193d7c 2003-09-30 devnull 	Channel *c;
 89 76193d7c 2003-09-30 devnull 
 90 76193d7c 2003-09-30 devnull 	if(elemcnt < 0 || elemsize <= 0)
 91 76193d7c 2003-09-30 devnull 		return nil;
 92 76193d7c 2003-09-30 devnull 	c = _threadmalloc(sizeof(Channel)+elemsize*elemcnt, 1);
 93 76193d7c 2003-09-30 devnull 	c->e = elemsize;
 94 76193d7c 2003-09-30 devnull 	c->s = elemcnt;
 95 76193d7c 2003-09-30 devnull 	_threaddebug(DBGCHAN, "chancreate %p", c);
 96 76193d7c 2003-09-30 devnull 	return c;
 97 76193d7c 2003-09-30 devnull }
 98 76193d7c 2003-09-30 devnull 
 99 02a1a5c1 2004-03-05 devnull static int
100 02a1a5c1 2004-03-05 devnull _alt(Alt *alts)
101 76193d7c 2003-09-30 devnull {
102 76193d7c 2003-09-30 devnull 	Alt *a, *xa;
103 06bb4ed2 2004-09-17 devnull 	Channel *c;
104 76193d7c 2003-09-30 devnull 	int n, s;
105 76193d7c 2003-09-30 devnull 	Thread *t;
106 76193d7c 2003-09-30 devnull 
107 76193d7c 2003-09-30 devnull 	/*
108 76193d7c 2003-09-30 devnull 	 * The point of going splhi here is that note handlers
109 76193d7c 2003-09-30 devnull 	 * might reasonably want to use channel operations,
110 76193d7c 2003-09-30 devnull 	 * but that will hang if the note comes while we hold the
111 76193d7c 2003-09-30 devnull 	 * chanlock.  Instead, we delay the note until we've dropped
112 76193d7c 2003-09-30 devnull 	 * the lock.
113 5a8e63b2 2004-02-29 devnull 	 */
114 5a8e63b2 2004-02-29 devnull 
115 5a8e63b2 2004-02-29 devnull 	/*
116 5a8e63b2 2004-02-29 devnull 	 * T might be nil here -- the scheduler sends on threadwaitchan
117 5a8e63b2 2004-02-29 devnull 	 * directly (in non-blocking mode, of course!).
118 76193d7c 2003-09-30 devnull 	 */
119 76193d7c 2003-09-30 devnull 	t = _threadgetproc()->thread;
120 5a8e63b2 2004-02-29 devnull 	if((t && t->moribund) || _threadexitsallstatus)
121 76193d7c 2003-09-30 devnull 		yield();	/* won't return */
122 76193d7c 2003-09-30 devnull 	s = _procsplhi();
123 76193d7c 2003-09-30 devnull 	lock(&chanlock);
124 76193d7c 2003-09-30 devnull 
125 76193d7c 2003-09-30 devnull 	/* test whether any channels can proceed */
126 76193d7c 2003-09-30 devnull 	n = 0;
127 76193d7c 2003-09-30 devnull 	a = nil;
128 76193d7c 2003-09-30 devnull 
129 76193d7c 2003-09-30 devnull 	for(xa=alts; xa->op!=CHANEND && xa->op!=CHANNOBLK; xa++){
130 76193d7c 2003-09-30 devnull 		xa->entryno = -1;
131 76193d7c 2003-09-30 devnull 		if(xa->op == CHANNOP)
132 76193d7c 2003-09-30 devnull 			continue;
133 06bb4ed2 2004-09-17 devnull 
134 76193d7c 2003-09-30 devnull 		c = xa->c;
135 76193d7c 2003-09-30 devnull 		if(c==nil){
136 76193d7c 2003-09-30 devnull 			unlock(&chanlock);
137 76193d7c 2003-09-30 devnull 			_procsplx(s);
138 76193d7c 2003-09-30 devnull 			return -1;
139 76193d7c 2003-09-30 devnull 		}
140 76193d7c 2003-09-30 devnull 		if(canexec(xa))
141 76193d7c 2003-09-30 devnull 			if(nrand(++n) == 0)
142 76193d7c 2003-09-30 devnull 				a = xa;
143 76193d7c 2003-09-30 devnull 	}
144 76193d7c 2003-09-30 devnull 
145 76193d7c 2003-09-30 devnull 	if(a==nil){
146 76193d7c 2003-09-30 devnull 		/* nothing can proceed */
147 76193d7c 2003-09-30 devnull 		if(xa->op == CHANNOBLK){
148 76193d7c 2003-09-30 devnull 			unlock(&chanlock);
149 76193d7c 2003-09-30 devnull 			_procsplx(s);
150 76193d7c 2003-09-30 devnull _threadnalt++;
151 76193d7c 2003-09-30 devnull 			return xa - alts;
152 76193d7c 2003-09-30 devnull 		}
153 76193d7c 2003-09-30 devnull 
154 76193d7c 2003-09-30 devnull 		/* enqueue on all channels. */
155 06bb4ed2 2004-09-17 devnull 		t->altc = nil;
156 76193d7c 2003-09-30 devnull 		for(xa=alts; xa->op!=CHANEND; xa++){
157 76193d7c 2003-09-30 devnull 			if(xa->op==CHANNOP)
158 76193d7c 2003-09-30 devnull 				continue;
159 06bb4ed2 2004-09-17 devnull 			enqueue(xa, t);
160 76193d7c 2003-09-30 devnull 		}
161 76193d7c 2003-09-30 devnull 
162 76193d7c 2003-09-30 devnull 		/*
163 76193d7c 2003-09-30 devnull 		 * wait for successful rendezvous.
164 76193d7c 2003-09-30 devnull 		 * we can't just give up if the rendezvous
165 76193d7c 2003-09-30 devnull 		 * is interrupted -- someone else might come
166 76193d7c 2003-09-30 devnull 		 * along and try to rendezvous with us, so
167 76193d7c 2003-09-30 devnull 		 * we need to be here.
168 06bb4ed2 2004-09-17 devnull 		 *
169 06bb4ed2 2004-09-17 devnull 		 * actually, now we're assuming no interrupts.
170 76193d7c 2003-09-30 devnull 		 */
171 06bb4ed2 2004-09-17 devnull 	    /*Again:*/
172 5a8e63b2 2004-02-29 devnull 		t->alt = alts;
173 5a8e63b2 2004-02-29 devnull 		t->chan = Chanalt;
174 06bb4ed2 2004-09-17 devnull 		t->altrend.l = &chanlock;
175 76193d7c 2003-09-30 devnull 		_procsplx(s);
176 06bb4ed2 2004-09-17 devnull 		_threadsleep(&t->altrend);
177 76193d7c 2003-09-30 devnull 		s = _procsplhi();
178 76193d7c 2003-09-30 devnull 
179 76193d7c 2003-09-30 devnull 		/* dequeue from channels, find selected one */
180 76193d7c 2003-09-30 devnull 		a = nil;
181 06bb4ed2 2004-09-17 devnull 		c = t->altc;
182 76193d7c 2003-09-30 devnull 		for(xa=alts; xa->op!=CHANEND; xa++){
183 76193d7c 2003-09-30 devnull 			if(xa->op==CHANNOP)
184 76193d7c 2003-09-30 devnull 				continue;
185 76193d7c 2003-09-30 devnull 			if(xa->c == c)
186 76193d7c 2003-09-30 devnull 				a = xa;
187 76193d7c 2003-09-30 devnull 			dequeue(xa);
188 76193d7c 2003-09-30 devnull 		}
189 76193d7c 2003-09-30 devnull 		unlock(&chanlock);
190 76193d7c 2003-09-30 devnull 		_procsplx(s);
191 76193d7c 2003-09-30 devnull 		if(a == nil){	/* we were interrupted */
192 76193d7c 2003-09-30 devnull 			assert(c==(Channel*)~0);
193 76193d7c 2003-09-30 devnull 			return -1;
194 76193d7c 2003-09-30 devnull 		}
195 76193d7c 2003-09-30 devnull 	}else{
196 76193d7c 2003-09-30 devnull 		altexec(a, s);	/* unlocks chanlock, does splx */
197 76193d7c 2003-09-30 devnull 	}
198 8c6f0e8a 2004-03-05 devnull 	if(t)
199 8c6f0e8a 2004-03-05 devnull 		t->chan = Channone;
200 76193d7c 2003-09-30 devnull 	return a - alts;
201 76193d7c 2003-09-30 devnull }
202 76193d7c 2003-09-30 devnull 
203 02a1a5c1 2004-03-05 devnull int
204 02a1a5c1 2004-03-05 devnull alt(Alt *alts)
205 02a1a5c1 2004-03-05 devnull {
206 02a1a5c1 2004-03-05 devnull 	setuserpc(getcallerpc(&alts));
207 02a1a5c1 2004-03-05 devnull 	return _alt(alts);
208 02a1a5c1 2004-03-05 devnull }
209 02a1a5c1 2004-03-05 devnull 
210 76193d7c 2003-09-30 devnull static int
211 76193d7c 2003-09-30 devnull runop(int op, Channel *c, void *v, int nb)
212 76193d7c 2003-09-30 devnull {
213 76193d7c 2003-09-30 devnull 	int r;
214 76193d7c 2003-09-30 devnull 	Alt a[2];
215 76193d7c 2003-09-30 devnull 
216 76193d7c 2003-09-30 devnull 	/*
217 76193d7c 2003-09-30 devnull 	 * we could do this without calling alt,
218 76193d7c 2003-09-30 devnull 	 * but the only reason would be performance,
219 76193d7c 2003-09-30 devnull 	 * and i'm not convinced it matters.
220 76193d7c 2003-09-30 devnull 	 */
221 76193d7c 2003-09-30 devnull 	a[0].op = op;
222 76193d7c 2003-09-30 devnull 	a[0].c = c;
223 76193d7c 2003-09-30 devnull 	a[0].v = v;
224 76193d7c 2003-09-30 devnull 	a[1].op = CHANEND;
225 76193d7c 2003-09-30 devnull 	if(nb)
226 76193d7c 2003-09-30 devnull 		a[1].op = CHANNOBLK;
227 02a1a5c1 2004-03-05 devnull 	switch(r=_alt(a)){
228 76193d7c 2003-09-30 devnull 	case -1:	/* interrupted */
229 76193d7c 2003-09-30 devnull 		return -1;
230 76193d7c 2003-09-30 devnull 	case 1:	/* nonblocking, didn't accomplish anything */
231 76193d7c 2003-09-30 devnull 		assert(nb);
232 76193d7c 2003-09-30 devnull 		return 0;
233 76193d7c 2003-09-30 devnull 	case 0:
234 76193d7c 2003-09-30 devnull 		return 1;
235 76193d7c 2003-09-30 devnull 	default:
236 76193d7c 2003-09-30 devnull 		fprint(2, "ERROR: channel alt returned %d\n", r);
237 76193d7c 2003-09-30 devnull 		abort();
238 76193d7c 2003-09-30 devnull 		return -1;
239 76193d7c 2003-09-30 devnull 	}
240 76193d7c 2003-09-30 devnull }
241 76193d7c 2003-09-30 devnull 
242 76193d7c 2003-09-30 devnull int
243 76193d7c 2003-09-30 devnull recv(Channel *c, void *v)
244 76193d7c 2003-09-30 devnull {
245 02a1a5c1 2004-03-05 devnull 	setuserpc(getcallerpc(&c));
246 76193d7c 2003-09-30 devnull 	return runop(CHANRCV, c, v, 0);
247 76193d7c 2003-09-30 devnull }
248 76193d7c 2003-09-30 devnull 
249 76193d7c 2003-09-30 devnull int
250 76193d7c 2003-09-30 devnull nbrecv(Channel *c, void *v)
251 76193d7c 2003-09-30 devnull {
252 02a1a5c1 2004-03-05 devnull 	setuserpc(getcallerpc(&c));
253 76193d7c 2003-09-30 devnull 	return runop(CHANRCV, c, v, 1);
254 76193d7c 2003-09-30 devnull }
255 76193d7c 2003-09-30 devnull 
256 76193d7c 2003-09-30 devnull int
257 76193d7c 2003-09-30 devnull send(Channel *c, void *v)
258 76193d7c 2003-09-30 devnull {
259 02a1a5c1 2004-03-05 devnull 	setuserpc(getcallerpc(&c));
260 76193d7c 2003-09-30 devnull 	return runop(CHANSND, c, v, 0);
261 76193d7c 2003-09-30 devnull }
262 76193d7c 2003-09-30 devnull 
263 76193d7c 2003-09-30 devnull int
264 76193d7c 2003-09-30 devnull nbsend(Channel *c, void *v)
265 76193d7c 2003-09-30 devnull {
266 02a1a5c1 2004-03-05 devnull 	setuserpc(getcallerpc(&c));
267 76193d7c 2003-09-30 devnull 	return runop(CHANSND, c, v, 1);
268 76193d7c 2003-09-30 devnull }
269 76193d7c 2003-09-30 devnull 
270 76193d7c 2003-09-30 devnull static void
271 76193d7c 2003-09-30 devnull channelsize(Channel *c, int sz)
272 76193d7c 2003-09-30 devnull {
273 76193d7c 2003-09-30 devnull 	if(c->e != sz){
274 a3785ca2 2004-04-21 devnull 		fprint(2, "expected channel with elements of size %d, got size %d\n",
275 76193d7c 2003-09-30 devnull 			sz, c->e);
276 76193d7c 2003-09-30 devnull 		abort();
277 76193d7c 2003-09-30 devnull 	}
278 76193d7c 2003-09-30 devnull }
279 76193d7c 2003-09-30 devnull 
280 76193d7c 2003-09-30 devnull int
281 76193d7c 2003-09-30 devnull sendul(Channel *c, ulong v)
282 76193d7c 2003-09-30 devnull {
283 02a1a5c1 2004-03-05 devnull 	setuserpc(getcallerpc(&c));
284 76193d7c 2003-09-30 devnull 	channelsize(c, sizeof(ulong));
285 76193d7c 2003-09-30 devnull 	return send(c, &v);
286 76193d7c 2003-09-30 devnull }
287 76193d7c 2003-09-30 devnull 
288 76193d7c 2003-09-30 devnull ulong
289 76193d7c 2003-09-30 devnull recvul(Channel *c)
290 76193d7c 2003-09-30 devnull {
291 76193d7c 2003-09-30 devnull 	ulong v;
292 76193d7c 2003-09-30 devnull 
293 02a1a5c1 2004-03-05 devnull 	setuserpc(getcallerpc(&c));
294 76193d7c 2003-09-30 devnull 	channelsize(c, sizeof(ulong));
295 02a1a5c1 2004-03-05 devnull 	if(runop(CHANRCV, c, &v, 0) < 0)
296 76193d7c 2003-09-30 devnull 		return ~0;
297 76193d7c 2003-09-30 devnull 	return v;
298 76193d7c 2003-09-30 devnull }
299 76193d7c 2003-09-30 devnull 
300 76193d7c 2003-09-30 devnull int
301 76193d7c 2003-09-30 devnull sendp(Channel *c, void *v)
302 76193d7c 2003-09-30 devnull {
303 02a1a5c1 2004-03-05 devnull 	setuserpc(getcallerpc(&c));
304 76193d7c 2003-09-30 devnull 	channelsize(c, sizeof(void*));
305 02a1a5c1 2004-03-05 devnull 	return runop(CHANSND, c, &v, 0);
306 76193d7c 2003-09-30 devnull }
307 76193d7c 2003-09-30 devnull 
308 76193d7c 2003-09-30 devnull void*
309 76193d7c 2003-09-30 devnull recvp(Channel *c)
310 76193d7c 2003-09-30 devnull {
311 76193d7c 2003-09-30 devnull 	void *v;
312 76193d7c 2003-09-30 devnull 
313 02a1a5c1 2004-03-05 devnull 	setuserpc(getcallerpc(&c));
314 76193d7c 2003-09-30 devnull 	channelsize(c, sizeof(void*));
315 02a1a5c1 2004-03-05 devnull 	if(runop(CHANRCV, c, &v, 0) < 0)
316 76193d7c 2003-09-30 devnull 		return nil;
317 76193d7c 2003-09-30 devnull 	return v;
318 76193d7c 2003-09-30 devnull }
319 76193d7c 2003-09-30 devnull 
320 76193d7c 2003-09-30 devnull int
321 76193d7c 2003-09-30 devnull nbsendul(Channel *c, ulong v)
322 76193d7c 2003-09-30 devnull {
323 02a1a5c1 2004-03-05 devnull 	setuserpc(getcallerpc(&c));
324 76193d7c 2003-09-30 devnull 	channelsize(c, sizeof(ulong));
325 02a1a5c1 2004-03-05 devnull 	return runop(CHANSND, c, &v, 1);
326 76193d7c 2003-09-30 devnull }
327 76193d7c 2003-09-30 devnull 
328 76193d7c 2003-09-30 devnull ulong
329 76193d7c 2003-09-30 devnull nbrecvul(Channel *c)
330 76193d7c 2003-09-30 devnull {
331 76193d7c 2003-09-30 devnull 	ulong v;
332 76193d7c 2003-09-30 devnull 
333 02a1a5c1 2004-03-05 devnull 	setuserpc(getcallerpc(&c));
334 76193d7c 2003-09-30 devnull 	channelsize(c, sizeof(ulong));
335 02a1a5c1 2004-03-05 devnull 	if(runop(CHANRCV, c, &v, 1) == 0)
336 76193d7c 2003-09-30 devnull 		return 0;
337 76193d7c 2003-09-30 devnull 	return v;
338 76193d7c 2003-09-30 devnull }
339 76193d7c 2003-09-30 devnull 
340 76193d7c 2003-09-30 devnull int
341 76193d7c 2003-09-30 devnull nbsendp(Channel *c, void *v)
342 76193d7c 2003-09-30 devnull {
343 02a1a5c1 2004-03-05 devnull 	setuserpc(getcallerpc(&c));
344 76193d7c 2003-09-30 devnull 	channelsize(c, sizeof(void*));
345 02a1a5c1 2004-03-05 devnull 	return runop(CHANSND, c, &v, 1);
346 76193d7c 2003-09-30 devnull }
347 76193d7c 2003-09-30 devnull 
348 76193d7c 2003-09-30 devnull void*
349 76193d7c 2003-09-30 devnull nbrecvp(Channel *c)
350 76193d7c 2003-09-30 devnull {
351 76193d7c 2003-09-30 devnull 	void *v;
352 76193d7c 2003-09-30 devnull 
353 02a1a5c1 2004-03-05 devnull 	setuserpc(getcallerpc(&c));
354 76193d7c 2003-09-30 devnull 	channelsize(c, sizeof(void*));
355 02a1a5c1 2004-03-05 devnull 	if(runop(CHANRCV, c, &v, 1) == 0)
356 76193d7c 2003-09-30 devnull 		return nil;
357 76193d7c 2003-09-30 devnull 	return v;
358 76193d7c 2003-09-30 devnull }
359 76193d7c 2003-09-30 devnull 
360 76193d7c 2003-09-30 devnull static int
361 76193d7c 2003-09-30 devnull emptyentry(Channel *c)
362 76193d7c 2003-09-30 devnull {
363 76193d7c 2003-09-30 devnull 	int i, extra;
364 76193d7c 2003-09-30 devnull 
365 76193d7c 2003-09-30 devnull 	assert((c->nentry==0 && c->qentry==nil) || (c->nentry && c->qentry));
366 76193d7c 2003-09-30 devnull 
367 76193d7c 2003-09-30 devnull 	for(i=0; i<c->nentry; i++)
368 76193d7c 2003-09-30 devnull 		if(c->qentry[i]==nil)
369 76193d7c 2003-09-30 devnull 			return i;
370 76193d7c 2003-09-30 devnull 
371 76193d7c 2003-09-30 devnull 	extra = 16;
372 76193d7c 2003-09-30 devnull 	c->nentry += extra;
373 76193d7c 2003-09-30 devnull if(c->nentry > _threadhighnentry) _threadhighnentry = c->nentry;
374 76193d7c 2003-09-30 devnull 	c->qentry = realloc((void*)c->qentry, c->nentry*sizeof(c->qentry[0]));
375 76193d7c 2003-09-30 devnull 	if(c->qentry == nil)
376 76193d7c 2003-09-30 devnull 		sysfatal("realloc channel entries: %r");
377 76193d7c 2003-09-30 devnull 	_threadmemset(&c->qentry[i], 0, extra*sizeof(c->qentry[0]));
378 76193d7c 2003-09-30 devnull 	return i;
379 76193d7c 2003-09-30 devnull }
380 76193d7c 2003-09-30 devnull 
381 76193d7c 2003-09-30 devnull static void
382 06bb4ed2 2004-09-17 devnull enqueue(Alt *a, Thread *t)
383 76193d7c 2003-09-30 devnull {
384 76193d7c 2003-09-30 devnull 	int i;
385 76193d7c 2003-09-30 devnull 
386 912fba95 2003-11-24 devnull 	_threaddebug(DBGCHAN, "Queueing alt %p on channel %p", a, a->c);
387 06bb4ed2 2004-09-17 devnull 	a->thread = t;
388 76193d7c 2003-09-30 devnull 	i = emptyentry(a->c);
389 76193d7c 2003-09-30 devnull 	a->c->qentry[i] = a;
390 76193d7c 2003-09-30 devnull }
391 76193d7c 2003-09-30 devnull 
392 76193d7c 2003-09-30 devnull static void
393 76193d7c 2003-09-30 devnull dequeue(Alt *a)
394 76193d7c 2003-09-30 devnull {
395 76193d7c 2003-09-30 devnull 	int i;
396 76193d7c 2003-09-30 devnull 	Channel *c;
397 76193d7c 2003-09-30 devnull 
398 76193d7c 2003-09-30 devnull 	c = a->c;
399 76193d7c 2003-09-30 devnull 	for(i=0; i<c->nentry; i++)
400 76193d7c 2003-09-30 devnull 		if(c->qentry[i]==a){
401 76193d7c 2003-09-30 devnull 			_threaddebug(DBGCHAN, "Dequeuing alt %p from channel %p", a, a->c);
402 76193d7c 2003-09-30 devnull 			c->qentry[i] = nil;
403 76193d7c 2003-09-30 devnull 			if(c->freed)
404 76193d7c 2003-09-30 devnull 				_chanfree(c);
405 76193d7c 2003-09-30 devnull 			return;
406 76193d7c 2003-09-30 devnull 		}
407 76193d7c 2003-09-30 devnull }
408 76193d7c 2003-09-30 devnull 
409 76193d7c 2003-09-30 devnull static void*
410 76193d7c 2003-09-30 devnull altexecbuffered(Alt *a, int willreplace)
411 76193d7c 2003-09-30 devnull {
412 76193d7c 2003-09-30 devnull 	uchar *v;
413 76193d7c 2003-09-30 devnull 	Channel *c;
414 76193d7c 2003-09-30 devnull 
415 76193d7c 2003-09-30 devnull 	c = a->c;
416 76193d7c 2003-09-30 devnull 	/* use buffered channel queue */
417 76193d7c 2003-09-30 devnull 	if(a->op==CHANRCV && c->n > 0){
418 76193d7c 2003-09-30 devnull 		_threaddebug(DBGCHAN, "buffer recv alt %p chan %p", a, c);
419 76193d7c 2003-09-30 devnull 		v = c->v + c->e*(c->f%c->s);
420 76193d7c 2003-09-30 devnull 		if(!willreplace)
421 76193d7c 2003-09-30 devnull 			c->n--;
422 76193d7c 2003-09-30 devnull 		c->f++;
423 76193d7c 2003-09-30 devnull 		return v;
424 76193d7c 2003-09-30 devnull 	}
425 76193d7c 2003-09-30 devnull 	if(a->op==CHANSND && c->n < c->s){
426 76193d7c 2003-09-30 devnull 		_threaddebug(DBGCHAN, "buffer send alt %p chan %p", a, c);
427 76193d7c 2003-09-30 devnull 		v = c->v + c->e*((c->f+c->n)%c->s);
428 76193d7c 2003-09-30 devnull 		if(!willreplace)
429 76193d7c 2003-09-30 devnull 			c->n++;
430 76193d7c 2003-09-30 devnull 		return v;
431 76193d7c 2003-09-30 devnull 	}
432 76193d7c 2003-09-30 devnull 	abort();
433 76193d7c 2003-09-30 devnull 	return nil;
434 76193d7c 2003-09-30 devnull }
435 76193d7c 2003-09-30 devnull 
436 76193d7c 2003-09-30 devnull static void
437 76193d7c 2003-09-30 devnull altcopy(void *dst, void *src, int sz)
438 76193d7c 2003-09-30 devnull {
439 76193d7c 2003-09-30 devnull 	if(dst){
440 76193d7c 2003-09-30 devnull 		if(src)
441 76193d7c 2003-09-30 devnull 			memmove(dst, src, sz);
442 76193d7c 2003-09-30 devnull 		else
443 76193d7c 2003-09-30 devnull 			_threadmemset(dst, 0, sz);
444 76193d7c 2003-09-30 devnull 	}
445 76193d7c 2003-09-30 devnull }
446 76193d7c 2003-09-30 devnull 
447 76193d7c 2003-09-30 devnull static int
448 76193d7c 2003-09-30 devnull altexec(Alt *a, int spl)
449 76193d7c 2003-09-30 devnull {
450 76193d7c 2003-09-30 devnull 	volatile Alt *b;
451 76193d7c 2003-09-30 devnull 	int i, n, otherop;
452 76193d7c 2003-09-30 devnull 	Channel *c;
453 76193d7c 2003-09-30 devnull 	void *me, *waiter, *buf;
454 76193d7c 2003-09-30 devnull 
455 76193d7c 2003-09-30 devnull 	c = a->c;
456 76193d7c 2003-09-30 devnull 
457 76193d7c 2003-09-30 devnull 	/* rendezvous with others */
458 76193d7c 2003-09-30 devnull 	otherop = (CHANSND+CHANRCV) - a->op;
459 76193d7c 2003-09-30 devnull 	n = 0;
460 76193d7c 2003-09-30 devnull 	b = nil;
461 76193d7c 2003-09-30 devnull 	me = a->v;
462 76193d7c 2003-09-30 devnull 	for(i=0; i<c->nentry; i++)
463 bcf527a9 2004-09-17 devnull 		if(c->qentry[i] && c->qentry[i]->op==otherop && c->qentry[i]->thread->altc==nil)
464 76193d7c 2003-09-30 devnull 			if(nrand(++n) == 0)
465 76193d7c 2003-09-30 devnull 				b = c->qentry[i];
466 76193d7c 2003-09-30 devnull 	if(b != nil){
467 76193d7c 2003-09-30 devnull 		_threaddebug(DBGCHAN, "rendez %s alt %p chan %p alt %p", a->op==CHANRCV?"recv":"send", a, c, b);
468 76193d7c 2003-09-30 devnull 		waiter = b->v;
469 76193d7c 2003-09-30 devnull 		if(c->s && c->n){
470 76193d7c 2003-09-30 devnull 			/*
471 76193d7c 2003-09-30 devnull 			 * if buffer is full and there are waiters
472 76193d7c 2003-09-30 devnull 			 * and we're meeting a waiter,
473 76193d7c 2003-09-30 devnull 			 * we must be receiving.
474 76193d7c 2003-09-30 devnull 			 *
475 76193d7c 2003-09-30 devnull 			 * we use the value in the channel buffer,
476 76193d7c 2003-09-30 devnull 			 * copy the waiter's value into the channel buffer
477 76193d7c 2003-09-30 devnull 			 * on behalf of the waiter, and then wake the waiter.
478 76193d7c 2003-09-30 devnull 			 */
479 76193d7c 2003-09-30 devnull 			if(a->op!=CHANRCV)
480 76193d7c 2003-09-30 devnull 				abort();
481 76193d7c 2003-09-30 devnull 			buf = altexecbuffered(a, 1);
482 76193d7c 2003-09-30 devnull 			altcopy(me, buf, c->e);
483 76193d7c 2003-09-30 devnull 			altcopy(buf, waiter, c->e);
484 76193d7c 2003-09-30 devnull 		}else{
485 76193d7c 2003-09-30 devnull 			if(a->op==CHANRCV)
486 76193d7c 2003-09-30 devnull 				altcopy(me, waiter, c->e);
487 76193d7c 2003-09-30 devnull 			else
488 76193d7c 2003-09-30 devnull 				altcopy(waiter, me, c->e);
489 76193d7c 2003-09-30 devnull 		}
490 06bb4ed2 2004-09-17 devnull 		b->thread->altc = c;
491 bcf527a9 2004-09-17 devnull 		_threadwakeup(&b->thread->altrend);
492 06bb4ed2 2004-09-17 devnull 		_threaddebug(DBGCHAN, "chanlock is %lud", *(ulong*)(void*)&chanlock);
493 76193d7c 2003-09-30 devnull 		_threaddebug(DBGCHAN, "unlocking the chanlock");
494 76193d7c 2003-09-30 devnull 		unlock(&chanlock);
495 76193d7c 2003-09-30 devnull 		_procsplx(spl);
496 76193d7c 2003-09-30 devnull 		return 1;
497 76193d7c 2003-09-30 devnull 	}
498 76193d7c 2003-09-30 devnull 
499 76193d7c 2003-09-30 devnull 	buf = altexecbuffered(a, 0);
500 76193d7c 2003-09-30 devnull 	if(a->op==CHANRCV)
501 76193d7c 2003-09-30 devnull 		altcopy(me, buf, c->e);
502 76193d7c 2003-09-30 devnull 	else
503 76193d7c 2003-09-30 devnull 		altcopy(buf, me, c->e);
504 76193d7c 2003-09-30 devnull 
505 76193d7c 2003-09-30 devnull 	unlock(&chanlock);
506 76193d7c 2003-09-30 devnull 	_procsplx(spl);
507 76193d7c 2003-09-30 devnull 	return 1;
508 76193d7c 2003-09-30 devnull }