mirror of https://github.com/0intro/conterm
95 lines
1.1 KiB
C
95 lines
1.1 KiB
C
#include "u.h"
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#include "lib.h"
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#include "dat.h"
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#include "fns.h"
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static void
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queue(Proc **first, Proc **last)
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{
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Proc *t;
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t = *last;
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if(t == 0)
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*first = up;
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else
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t->qnext = up;
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*last = up;
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up->qnext = 0;
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}
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static Proc*
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dequeue(Proc **first, Proc **last)
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{
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Proc *t;
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t = *first;
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if(t == 0)
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return 0;
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*first = t->qnext;
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if(*first == 0)
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*last = 0;
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return t;
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}
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void
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qlock(QLock *q)
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{
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lock(&q->lk);
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if(q->hold == 0) {
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q->hold = up;
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unlock(&q->lk);
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return;
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}
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/*
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* Can't assert this because of RWLock
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assert(q->hold != up);
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*/
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queue((Proc**)&q->first, (Proc**)&q->last);
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unlock(&q->lk);
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procsleep();
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}
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int
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canqlock(QLock *q)
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{
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lock(&q->lk);
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if(q->hold == 0) {
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q->hold = up;
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unlock(&q->lk);
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return 1;
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}
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unlock(&q->lk);
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return 0;
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}
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void
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qunlock(QLock *q)
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{
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Proc *p;
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lock(&q->lk);
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/*
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* Can't assert this because of RWlock
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assert(q->hold == CT);
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*/
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p = dequeue((Proc**)&q->first, (Proc**)&q->last);
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if(p) {
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q->hold = p;
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unlock(&q->lk);
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procwakeup(p);
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} else {
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q->hold = 0;
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unlock(&q->lk);
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}
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}
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int
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holdqlock(QLock *q)
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{
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return q->hold == up;
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}
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