diff options
Diffstat (limited to 'pipe.c')
| -rw-r--r-- | pipe.c | 12 |
1 files changed, 5 insertions, 7 deletions
@@ -11,8 +11,8 @@ struct pipe { int readopen; // read fd is still open int writeopen; // write fd is still open - int writep; // next index to write - int readp; // next index to read + uint writep; // next index to write + uint readp; // next index to read struct spinlock lock; char data[PIPESIZE]; }; @@ -83,7 +83,7 @@ pipewrite(struct pipe *p, char *addr, int n) acquire(&p->lock); for(i = 0; i < n; i++){ - while(((p->writep + 1) % PIPESIZE) == p->readp){ + while(p->writep == p->readp + PIPESIZE) { if(p->readopen == 0 || cp->killed){ release(&p->lock); return -1; @@ -91,8 +91,7 @@ pipewrite(struct pipe *p, char *addr, int n) wakeup(&p->readp); sleep(&p->writep, &p->lock); } - p->data[p->writep] = addr[i]; - p->writep = (p->writep + 1) % PIPESIZE; + p->data[p->writep++ % PIPESIZE] = addr[i]; } wakeup(&p->readp); release(&p->lock); @@ -115,8 +114,7 @@ piperead(struct pipe *p, char *addr, int n) for(i = 0; i < n; i++){ if(p->readp == p->writep) break; - addr[i] = p->data[p->readp]; - p->readp = (p->readp + 1) % PIPESIZE; + addr[i] = p->data[p->readp++ % PIPESIZE]; } wakeup(&p->writep); release(&p->lock); |