130 lines
2.2 KiB
C
130 lines
2.2 KiB
C
#include "types.h"
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#include "param.h"
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#include "x86.h"
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#include "mmu.h"
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#include "proc.h"
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#include "defs.h"
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#include "file.h"
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#include "spinlock.h"
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#define PIPESIZE 512
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struct pipe {
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int readopen; // read fd is still open
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int writeopen; // write fd is still open
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int writep; // next index to write
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int readp; // next index to read
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struct spinlock lock;
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char data[PIPESIZE];
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};
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int
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pipe_alloc(struct file **f0, struct file **f1)
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{
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*f0 = *f1 = 0;
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struct pipe *p = 0;
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if((*f0 = filealloc()) == 0)
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goto oops;
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if((*f1 = filealloc()) == 0)
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goto oops;
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if((p = (struct pipe*) kalloc(PAGE)) == 0)
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goto oops;
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p->readopen = 1;
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p->writeopen = 1;
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p->writep = 0;
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p->readp = 0;
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initlock(&p->lock, "pipe");
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(*f0)->type = FD_PIPE;
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(*f0)->readable = 1;
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(*f0)->writable = 0;
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(*f0)->pipe = p;
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(*f1)->type = FD_PIPE;
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(*f1)->readable = 0;
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(*f1)->writable = 1;
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(*f1)->pipe = p;
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return 0;
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oops:
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if(p)
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kfree((char*) p, PAGE);
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if(*f0){
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(*f0)->type = FD_NONE;
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fileclose(*f0);
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}
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if(*f1){
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(*f1)->type = FD_NONE;
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fileclose(*f1);
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}
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return -1;
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}
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void
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pipe_close(struct pipe *p, int writable)
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{
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acquire(&p->lock);
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if(writable){
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p->writeopen = 0;
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wakeup(&p->readp);
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} else {
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p->readopen = 0;
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wakeup(&p->writep);
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}
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release(&p->lock);
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if(p->readopen == 0 && p->writeopen == 0)
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kfree((char*) p, PAGE);
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}
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int
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pipe_write(struct pipe *p, char *addr, int n)
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{
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int i;
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acquire(&p->lock);
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for(i = 0; i < n; i++){
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while(((p->writep + 1) % PIPESIZE) == p->readp){
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if(p->readopen == 0){
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release(&p->lock);
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return -1;
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}
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wakeup(&p->readp);
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sleep(&p->writep, &p->lock);
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}
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p->data[p->writep] = addr[i];
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p->writep = (p->writep + 1) % PIPESIZE;
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}
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release(&p->lock);
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wakeup(&p->readp);
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return i;
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}
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int
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pipe_read(struct pipe *p, char *addr, int n)
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{
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int i;
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acquire(&p->lock);
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while(p->readp == p->writep){
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if(p->writeopen == 0){
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release(&p->lock);
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return 0;
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}
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sleep(&p->readp, &p->lock);
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}
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for(i = 0; i < n; i++){
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if(p->readp == p->writep)
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break;
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addr[i] = p->data[p->readp];
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p->readp = (p->readp + 1) % PIPESIZE;
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}
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release(&p->lock);
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wakeup(&p->writep);
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return i;
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}
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