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1 619085f0 2004-12-25 devnull #include "u.h"
2 619085f0 2004-12-25 devnull #include "libc.h"
3 619085f0 2004-12-25 devnull #include "thread.h"
4 619085f0 2004-12-25 devnull #include "threadimpl.h"
5 619085f0 2004-12-25 devnull
6 619085f0 2004-12-25 devnull /*
7 619085f0 2004-12-25 devnull * One can go through a lot of effort to avoid this global lock.
8 619085f0 2004-12-25 devnull * You have to put locks in all the channels and all the Alt
9 619085f0 2004-12-25 devnull * structures. At the beginning of an alt you have to lock all
10 619085f0 2004-12-25 devnull * the channels, but then to try to actually exec an op you
11 619085f0 2004-12-25 devnull * have to lock the other guy's alt structure, so that other
12 619085f0 2004-12-25 devnull * people aren't trying to use him in some other op at the
13 619085f0 2004-12-25 devnull * same time.
14 619085f0 2004-12-25 devnull *
15 619085f0 2004-12-25 devnull * For Plan 9 apps, it's just not worth the extra effort.
16 619085f0 2004-12-25 devnull */
17 619085f0 2004-12-25 devnull static QLock chanlock;
18 619085f0 2004-12-25 devnull
19 619085f0 2004-12-25 devnull Channel*
20 619085f0 2004-12-25 devnull chancreate(int elemsize, int bufsize)
21 619085f0 2004-12-25 devnull {
22 619085f0 2004-12-25 devnull Channel *c;
23 619085f0 2004-12-25 devnull
24 619085f0 2004-12-25 devnull c = malloc(sizeof *c+bufsize*elemsize);
25 619085f0 2004-12-25 devnull memset(c, 0, sizeof *c);
26 619085f0 2004-12-25 devnull c->elemsize = elemsize;
27 619085f0 2004-12-25 devnull c->bufsize = bufsize;
28 619085f0 2004-12-25 devnull c->nbuf = 0;
29 619085f0 2004-12-25 devnull c->buf = (uchar*)(c+1);
30 619085f0 2004-12-25 devnull return c;
31 619085f0 2004-12-25 devnull }
32 619085f0 2004-12-25 devnull
33 619085f0 2004-12-25 devnull void
34 619085f0 2004-12-25 devnull chansetname(Channel *c, char *fmt, ...)
35 619085f0 2004-12-25 devnull {
36 619085f0 2004-12-25 devnull char *name;
37 619085f0 2004-12-25 devnull va_list arg;
38 619085f0 2004-12-25 devnull
39 619085f0 2004-12-25 devnull va_start(arg, fmt);
40 619085f0 2004-12-25 devnull name = vsmprint(fmt, arg);
41 619085f0 2004-12-25 devnull va_end(arg);
42 619085f0 2004-12-25 devnull free(c->name);
43 619085f0 2004-12-25 devnull c->name = name;
44 619085f0 2004-12-25 devnull }
45 619085f0 2004-12-25 devnull
46 619085f0 2004-12-25 devnull /* bug - work out races */
47 619085f0 2004-12-25 devnull void
48 619085f0 2004-12-25 devnull chanfree(Channel *c)
49 619085f0 2004-12-25 devnull {
50 619085f0 2004-12-25 devnull if(c == nil)
51 619085f0 2004-12-25 devnull return;
52 619085f0 2004-12-25 devnull free(c->name);
53 619085f0 2004-12-25 devnull free(c->arecv.a);
54 619085f0 2004-12-25 devnull free(c->asend.a);
55 619085f0 2004-12-25 devnull free(c);
56 619085f0 2004-12-25 devnull }
57 619085f0 2004-12-25 devnull
58 619085f0 2004-12-25 devnull static void
59 619085f0 2004-12-25 devnull addarray(_Altarray *a, Alt *alt)
60 619085f0 2004-12-25 devnull {
61 619085f0 2004-12-25 devnull if(a->n == a->m){
62 619085f0 2004-12-25 devnull a->m += 16;
63 619085f0 2004-12-25 devnull a->a = realloc(a->a, a->m*sizeof a->a[0]);
64 619085f0 2004-12-25 devnull }
65 619085f0 2004-12-25 devnull a->a[a->n++] = alt;
66 619085f0 2004-12-25 devnull }
67 619085f0 2004-12-25 devnull
68 619085f0 2004-12-25 devnull static void
69 619085f0 2004-12-25 devnull delarray(_Altarray *a, int i)
70 619085f0 2004-12-25 devnull {
71 619085f0 2004-12-25 devnull --a->n;
72 619085f0 2004-12-25 devnull a->a[i] = a->a[a->n];
73 619085f0 2004-12-25 devnull }
74 619085f0 2004-12-25 devnull
75 619085f0 2004-12-25 devnull /*
76 619085f0 2004-12-25 devnull * doesn't really work for things other than CHANSND and CHANRCV
77 619085f0 2004-12-25 devnull * but is only used as arg to chanarray, which can handle it
78 619085f0 2004-12-25 devnull */
79 619085f0 2004-12-25 devnull #define otherop(op) (CHANSND+CHANRCV-(op))
80 619085f0 2004-12-25 devnull
81 619085f0 2004-12-25 devnull static _Altarray*
82 619085f0 2004-12-25 devnull chanarray(Channel *c, uint op)
83 619085f0 2004-12-25 devnull {
84 619085f0 2004-12-25 devnull switch(op){
85 619085f0 2004-12-25 devnull default:
86 619085f0 2004-12-25 devnull return nil;
87 619085f0 2004-12-25 devnull case CHANSND:
88 619085f0 2004-12-25 devnull return &c->asend;
89 619085f0 2004-12-25 devnull case CHANRCV:
90 619085f0 2004-12-25 devnull return &c->arecv;
91 619085f0 2004-12-25 devnull }
92 619085f0 2004-12-25 devnull }
93 619085f0 2004-12-25 devnull
94 619085f0 2004-12-25 devnull static int
95 619085f0 2004-12-25 devnull altcanexec(Alt *a)
96 619085f0 2004-12-25 devnull {
97 619085f0 2004-12-25 devnull _Altarray *ar;
98 619085f0 2004-12-25 devnull Channel *c;
99 619085f0 2004-12-25 devnull
100 619085f0 2004-12-25 devnull if(a->op == CHANNOP)
101 619085f0 2004-12-25 devnull return 0;
102 619085f0 2004-12-25 devnull c = a->c;
103 619085f0 2004-12-25 devnull if(c->bufsize == 0){
104 619085f0 2004-12-25 devnull ar = chanarray(c, otherop(a->op));
105 619085f0 2004-12-25 devnull return ar && ar->n;
106 619085f0 2004-12-25 devnull }else{
107 619085f0 2004-12-25 devnull switch(a->op){
108 619085f0 2004-12-25 devnull default:
109 619085f0 2004-12-25 devnull return 0;
110 619085f0 2004-12-25 devnull case CHANSND:
111 619085f0 2004-12-25 devnull return c->nbuf < c->bufsize;
112 619085f0 2004-12-25 devnull case CHANRCV:
113 619085f0 2004-12-25 devnull return c->nbuf > 0;
114 619085f0 2004-12-25 devnull }
115 619085f0 2004-12-25 devnull }
116 619085f0 2004-12-25 devnull }
117 619085f0 2004-12-25 devnull
118 619085f0 2004-12-25 devnull static void
119 619085f0 2004-12-25 devnull altqueue(Alt *a)
120 619085f0 2004-12-25 devnull {
121 619085f0 2004-12-25 devnull _Altarray *ar;
122 619085f0 2004-12-25 devnull
123 619085f0 2004-12-25 devnull ar = chanarray(a->c, a->op);
124 619085f0 2004-12-25 devnull addarray(ar, a);
125 619085f0 2004-12-25 devnull }
126 619085f0 2004-12-25 devnull
127 619085f0 2004-12-25 devnull static void
128 619085f0 2004-12-25 devnull altdequeue(Alt *a)
129 619085f0 2004-12-25 devnull {
130 619085f0 2004-12-25 devnull int i;
131 619085f0 2004-12-25 devnull _Altarray *ar;
132 619085f0 2004-12-25 devnull
133 619085f0 2004-12-25 devnull ar = chanarray(a->c, a->op);
134 619085f0 2004-12-25 devnull if(ar == nil){
135 619085f0 2004-12-25 devnull fprint(2, "bad use of altdequeue op=%d\n", a->op);
136 619085f0 2004-12-25 devnull abort();
137 619085f0 2004-12-25 devnull }
138 619085f0 2004-12-25 devnull
139 619085f0 2004-12-25 devnull for(i=0; i<ar->n; i++)
140 619085f0 2004-12-25 devnull if(ar->a[i] == a){
141 619085f0 2004-12-25 devnull delarray(ar, i);
142 619085f0 2004-12-25 devnull return;
143 619085f0 2004-12-25 devnull }
144 619085f0 2004-12-25 devnull fprint(2, "cannot find self in altdq\n");
145 619085f0 2004-12-25 devnull abort();
146 619085f0 2004-12-25 devnull }
147 619085f0 2004-12-25 devnull
148 619085f0 2004-12-25 devnull static void
149 619085f0 2004-12-25 devnull altalldequeue(Alt *a)
150 619085f0 2004-12-25 devnull {
151 619085f0 2004-12-25 devnull int i;
152 619085f0 2004-12-25 devnull
153 619085f0 2004-12-25 devnull for(i=0; a[i].op!=CHANEND && a[i].op!=CHANNOBLK; i++)
154 619085f0 2004-12-25 devnull if(a[i].op != CHANNOP)
155 619085f0 2004-12-25 devnull altdequeue(&a[i]);
156 619085f0 2004-12-25 devnull }
157 619085f0 2004-12-25 devnull
158 619085f0 2004-12-25 devnull static void
159 619085f0 2004-12-25 devnull amove(void *dst, void *src, uint n)
160 619085f0 2004-12-25 devnull {
161 619085f0 2004-12-25 devnull if(dst){
162 619085f0 2004-12-25 devnull if(src == nil)
163 619085f0 2004-12-25 devnull memset(dst, 0, n);
164 619085f0 2004-12-25 devnull else
165 619085f0 2004-12-25 devnull memmove(dst, src, n);
166 619085f0 2004-12-25 devnull }
167 619085f0 2004-12-25 devnull }
168 619085f0 2004-12-25 devnull
169 619085f0 2004-12-25 devnull /*
170 619085f0 2004-12-25 devnull * Actually move the data around. There are up to three
171 619085f0 2004-12-25 devnull * players: the sender, the receiver, and the channel itself.
172 619085f0 2004-12-25 devnull * If the channel is unbuffered or the buffer is empty,
173 619085f0 2004-12-25 devnull * data goes from sender to receiver. If the channel is full,
174 619085f0 2004-12-25 devnull * the receiver removes some from the channel and the sender
175 619085f0 2004-12-25 devnull * gets to put some in.
176 619085f0 2004-12-25 devnull */
177 619085f0 2004-12-25 devnull static void
178 619085f0 2004-12-25 devnull altcopy(Alt *s, Alt *r)
179 619085f0 2004-12-25 devnull {
180 619085f0 2004-12-25 devnull Alt *t;
181 619085f0 2004-12-25 devnull Channel *c;
182 619085f0 2004-12-25 devnull uchar *cp;
183 619085f0 2004-12-25 devnull
184 619085f0 2004-12-25 devnull /*
185 619085f0 2004-12-25 devnull * Work out who is sender and who is receiver
186 619085f0 2004-12-25 devnull */
187 619085f0 2004-12-25 devnull if(s == nil && r == nil)
188 619085f0 2004-12-25 devnull return;
189 619085f0 2004-12-25 devnull assert(s != nil);
190 619085f0 2004-12-25 devnull c = s->c;
191 619085f0 2004-12-25 devnull if(s->op == CHANRCV){
192 619085f0 2004-12-25 devnull t = s;
193 619085f0 2004-12-25 devnull s = r;
194 619085f0 2004-12-25 devnull r = t;
195 619085f0 2004-12-25 devnull }
196 619085f0 2004-12-25 devnull assert(s==nil || s->op == CHANSND);
197 619085f0 2004-12-25 devnull assert(r==nil || r->op == CHANRCV);
198 619085f0 2004-12-25 devnull
199 619085f0 2004-12-25 devnull /*
200 619085f0 2004-12-25 devnull * Channel is empty (or unbuffered) - copy directly.
201 619085f0 2004-12-25 devnull */
202 619085f0 2004-12-25 devnull if(s && r && c->nbuf == 0){
203 619085f0 2004-12-25 devnull amove(r->v, s->v, c->elemsize);
204 619085f0 2004-12-25 devnull return;
205 619085f0 2004-12-25 devnull }
206 619085f0 2004-12-25 devnull
207 619085f0 2004-12-25 devnull /*
208 619085f0 2004-12-25 devnull * Otherwise it's always okay to receive and then send.
209 619085f0 2004-12-25 devnull */
210 619085f0 2004-12-25 devnull if(r){
211 619085f0 2004-12-25 devnull cp = c->buf + c->off*c->elemsize;
212 619085f0 2004-12-25 devnull amove(r->v, cp, c->elemsize);
213 619085f0 2004-12-25 devnull --c->nbuf;
214 619085f0 2004-12-25 devnull if(++c->off == c->bufsize)
215 619085f0 2004-12-25 devnull c->off = 0;
216 619085f0 2004-12-25 devnull }
217 619085f0 2004-12-25 devnull if(s){
218 619085f0 2004-12-25 devnull cp = c->buf + (c->off+c->nbuf)%c->bufsize*c->elemsize;
219 619085f0 2004-12-25 devnull amove(cp, s->v, c->elemsize);
220 619085f0 2004-12-25 devnull ++c->nbuf;
221 619085f0 2004-12-25 devnull }
222 619085f0 2004-12-25 devnull }
223 619085f0 2004-12-25 devnull
224 619085f0 2004-12-25 devnull static void
225 619085f0 2004-12-25 devnull altexec(Alt *a)
226 619085f0 2004-12-25 devnull {
227 619085f0 2004-12-25 devnull int i;
228 619085f0 2004-12-25 devnull _Altarray *ar;
229 619085f0 2004-12-25 devnull Alt *other;
230 619085f0 2004-12-25 devnull Channel *c;
231 619085f0 2004-12-25 devnull
232 619085f0 2004-12-25 devnull c = a->c;
233 619085f0 2004-12-25 devnull ar = chanarray(c, otherop(a->op));
234 619085f0 2004-12-25 devnull if(ar && ar->n){
235 619085f0 2004-12-25 devnull i = rand()%ar->n;
236 619085f0 2004-12-25 devnull other = ar->a[i];
237 619085f0 2004-12-25 devnull altcopy(a, other);
238 619085f0 2004-12-25 devnull altalldequeue(other->xalt);
239 619085f0 2004-12-25 devnull other->xalt[0].xalt = other;
240 619085f0 2004-12-25 devnull _threadready(other->thread);
241 619085f0 2004-12-25 devnull }else
242 619085f0 2004-12-25 devnull altcopy(a, nil);
243 619085f0 2004-12-25 devnull }
244 619085f0 2004-12-25 devnull
245 619085f0 2004-12-25 devnull #define dbgalt 0
246 619085f0 2004-12-25 devnull int
247 619085f0 2004-12-25 devnull chanalt(Alt *a)
248 619085f0 2004-12-25 devnull {
249 619085f0 2004-12-25 devnull int i, j, ncan, n, canblock;
250 619085f0 2004-12-25 devnull Channel *c;
251 619085f0 2004-12-25 devnull _Thread *t;
252 619085f0 2004-12-25 devnull
253 619085f0 2004-12-25 devnull for(i=0; a[i].op != CHANEND && a[i].op != CHANNOBLK; i++)
254 619085f0 2004-12-25 devnull ;
255 619085f0 2004-12-25 devnull n = i;
256 619085f0 2004-12-25 devnull canblock = a[i].op == CHANEND;
257 619085f0 2004-12-25 devnull
258 619085f0 2004-12-25 devnull t = proc()->thread;
259 619085f0 2004-12-25 devnull for(i=0; i<n; i++){
260 619085f0 2004-12-25 devnull a[i].thread = t;
261 619085f0 2004-12-25 devnull a[i].xalt = a;
262 619085f0 2004-12-25 devnull }
263 619085f0 2004-12-25 devnull qlock(&chanlock);
264 619085f0 2004-12-25 devnull if(dbgalt) print("alt ");
265 619085f0 2004-12-25 devnull ncan = 0;
266 619085f0 2004-12-25 devnull for(i=0; i<n; i++){
267 619085f0 2004-12-25 devnull c = a[i].c;
268 619085f0 2004-12-25 devnull if(dbgalt) print(" %c:", "esrnb"[a[i].op]);
269 619085f0 2004-12-25 devnull if(dbgalt) if(c->name) print("%s", c->name); else print("%p", c);
270 619085f0 2004-12-25 devnull if(altcanexec(&a[i])){
271 619085f0 2004-12-25 devnull if(dbgalt) print("*");
272 619085f0 2004-12-25 devnull ncan++;
273 619085f0 2004-12-25 devnull }
274 619085f0 2004-12-25 devnull }
275 619085f0 2004-12-25 devnull if(ncan){
276 619085f0 2004-12-25 devnull j = rand()%ncan;
277 619085f0 2004-12-25 devnull for(i=0; i<n; i++){
278 619085f0 2004-12-25 devnull if(altcanexec(&a[i])){
279 619085f0 2004-12-25 devnull if(j-- == 0){
280 619085f0 2004-12-25 devnull if(dbgalt){
281 619085f0 2004-12-25 devnull c = a[i].c;
282 619085f0 2004-12-25 devnull print(" => %c:", "esrnb"[a[i].op]);
283 619085f0 2004-12-25 devnull if(c->name) print("%s", c->name); else print("%p", c);
284 619085f0 2004-12-25 devnull print("\n");
285 619085f0 2004-12-25 devnull }
286 619085f0 2004-12-25 devnull altexec(&a[i]);
287 619085f0 2004-12-25 devnull qunlock(&chanlock);
288 619085f0 2004-12-25 devnull return i;
289 619085f0 2004-12-25 devnull }
290 619085f0 2004-12-25 devnull }
291 619085f0 2004-12-25 devnull }
292 619085f0 2004-12-25 devnull }
293 619085f0 2004-12-25 devnull if(dbgalt)print("\n");
294 619085f0 2004-12-25 devnull
295 619085f0 2004-12-25 devnull if(!canblock){
296 619085f0 2004-12-25 devnull qunlock(&chanlock);
297 619085f0 2004-12-25 devnull return -1;
298 619085f0 2004-12-25 devnull }
299 619085f0 2004-12-25 devnull
300 619085f0 2004-12-25 devnull for(i=0; i<n; i++){
301 619085f0 2004-12-25 devnull if(a[i].op != CHANNOP)
302 619085f0 2004-12-25 devnull altqueue(&a[i]);
303 619085f0 2004-12-25 devnull }
304 619085f0 2004-12-25 devnull qunlock(&chanlock);
305 619085f0 2004-12-25 devnull
306 619085f0 2004-12-25 devnull _threadswitch();
307 619085f0 2004-12-25 devnull
308 619085f0 2004-12-25 devnull /*
309 619085f0 2004-12-25 devnull * the guy who ran the op took care of dequeueing us
310 619085f0 2004-12-25 devnull * and then set a[0].alt to the one that was executed.
311 619085f0 2004-12-25 devnull */
312 619085f0 2004-12-25 devnull return a[0].xalt - a;
313 619085f0 2004-12-25 devnull }
314 619085f0 2004-12-25 devnull
315 619085f0 2004-12-25 devnull static int
316 619085f0 2004-12-25 devnull _chanop(Channel *c, int op, void *p, int canblock)
317 619085f0 2004-12-25 devnull {
318 619085f0 2004-12-25 devnull Alt a[2];
319 619085f0 2004-12-25 devnull
320 619085f0 2004-12-25 devnull a[0].c = c;
321 619085f0 2004-12-25 devnull a[0].op = op;
322 619085f0 2004-12-25 devnull a[0].v = p;
323 619085f0 2004-12-25 devnull a[1].op = canblock ? CHANEND : CHANNOBLK;
324 619085f0 2004-12-25 devnull if(chanalt(a) < 0)
325 619085f0 2004-12-25 devnull return -1;
326 619085f0 2004-12-25 devnull return 1;
327 619085f0 2004-12-25 devnull }
328 619085f0 2004-12-25 devnull
329 619085f0 2004-12-25 devnull int
330 619085f0 2004-12-25 devnull chansend(Channel *c, void *v)
331 619085f0 2004-12-25 devnull {
332 619085f0 2004-12-25 devnull return _chanop(c, CHANSND, v, 1);
333 619085f0 2004-12-25 devnull }
334 619085f0 2004-12-25 devnull
335 619085f0 2004-12-25 devnull int
336 619085f0 2004-12-25 devnull channbsend(Channel *c, void *v)
337 619085f0 2004-12-25 devnull {
338 619085f0 2004-12-25 devnull return _chanop(c, CHANSND, v, 0);
339 619085f0 2004-12-25 devnull }
340 619085f0 2004-12-25 devnull
341 619085f0 2004-12-25 devnull int
342 619085f0 2004-12-25 devnull chanrecv(Channel *c, void *v)
343 619085f0 2004-12-25 devnull {
344 619085f0 2004-12-25 devnull return _chanop(c, CHANRCV, v, 1);
345 619085f0 2004-12-25 devnull }
346 619085f0 2004-12-25 devnull
347 619085f0 2004-12-25 devnull int
348 619085f0 2004-12-25 devnull channbrecv(Channel *c, void *v)
349 619085f0 2004-12-25 devnull {
350 619085f0 2004-12-25 devnull return _chanop(c, CHANRCV, v, 0);
351 619085f0 2004-12-25 devnull }
352 619085f0 2004-12-25 devnull
353 619085f0 2004-12-25 devnull int
354 619085f0 2004-12-25 devnull chansendp(Channel *c, void *v)
355 619085f0 2004-12-25 devnull {
356 619085f0 2004-12-25 devnull return _chanop(c, CHANSND, (void*)&v, 1);
357 619085f0 2004-12-25 devnull }
358 619085f0 2004-12-25 devnull
359 619085f0 2004-12-25 devnull void*
360 619085f0 2004-12-25 devnull chanrecvp(Channel *c)
361 619085f0 2004-12-25 devnull {
362 619085f0 2004-12-25 devnull void *v;
363 619085f0 2004-12-25 devnull
364 619085f0 2004-12-25 devnull _chanop(c, CHANRCV, (void*)&v, 1);
365 619085f0 2004-12-25 devnull return v;
366 619085f0 2004-12-25 devnull }
367 619085f0 2004-12-25 devnull
368 619085f0 2004-12-25 devnull int
369 619085f0 2004-12-25 devnull channbsendp(Channel *c, void *v)
370 619085f0 2004-12-25 devnull {
371 619085f0 2004-12-25 devnull return _chanop(c, CHANSND, (void*)&v, 0);
372 619085f0 2004-12-25 devnull }
373 619085f0 2004-12-25 devnull
374 619085f0 2004-12-25 devnull void*
375 619085f0 2004-12-25 devnull channbrecvp(Channel *c)
376 619085f0 2004-12-25 devnull {
377 619085f0 2004-12-25 devnull void *v;
378 619085f0 2004-12-25 devnull
379 619085f0 2004-12-25 devnull _chanop(c, CHANRCV, (void*)&v, 0);
380 619085f0 2004-12-25 devnull return v;
381 619085f0 2004-12-25 devnull }
382 619085f0 2004-12-25 devnull
383 619085f0 2004-12-25 devnull int
384 619085f0 2004-12-25 devnull chansendul(Channel *c, ulong val)
385 619085f0 2004-12-25 devnull {
386 619085f0 2004-12-25 devnull return _chanop(c, CHANSND, &val, 1);
387 619085f0 2004-12-25 devnull }
388 619085f0 2004-12-25 devnull
389 619085f0 2004-12-25 devnull ulong
390 619085f0 2004-12-25 devnull chanrecvul(Channel *c)
391 619085f0 2004-12-25 devnull {
392 619085f0 2004-12-25 devnull ulong val;
393 619085f0 2004-12-25 devnull
394 619085f0 2004-12-25 devnull _chanop(c, CHANRCV, &val, 1);
395 619085f0 2004-12-25 devnull return val;
396 619085f0 2004-12-25 devnull }
397 619085f0 2004-12-25 devnull
398 619085f0 2004-12-25 devnull int
399 619085f0 2004-12-25 devnull channbsendul(Channel *c, ulong val)
400 619085f0 2004-12-25 devnull {
401 619085f0 2004-12-25 devnull return _chanop(c, CHANSND, &val, 0);
402 619085f0 2004-12-25 devnull }
403 619085f0 2004-12-25 devnull
404 619085f0 2004-12-25 devnull ulong
405 619085f0 2004-12-25 devnull channbrecvul(Channel *c)
406 619085f0 2004-12-25 devnull {
407 619085f0 2004-12-25 devnull ulong val;
408 619085f0 2004-12-25 devnull
409 619085f0 2004-12-25 devnull _chanop(c, CHANRCV, &val, 0);
410 619085f0 2004-12-25 devnull return val;
411 619085f0 2004-12-25 devnull }
412 619085f0 2004-12-25 devnull