Mercurial > hg > Members > menikon > CbC_xv6

comparison src/pipe.c @ 0:83c23a36980d

Find changesets by keywords (author, files, the commit message), revision number or hash, or revset expression.
Init
author Tatsuki IHA <e125716@ie.u-ryukyu.ac.jp>
date Fri, 26 May 2017 23:11:05 +0900
parents
children ad1d3b268e2d
comparison
equal deleted inserted replaced
-1:000000000000 0:83c23a36980d
1 #include "types.h"
2 #include "defs.h"
3 #include "param.h"
4 #include "mmu.h"
5 #include "proc.h"
6 #include "fs.h"
7 #include "file.h"
8 #include "spinlock.h"
9
10 #define PIPESIZE 512
11
12 struct pipe {
13 struct spinlock lock;
14 char data[PIPESIZE];
15 uint nread; // number of bytes read
16 uint nwrite; // number of bytes written
17 int readopen; // read fd is still open
18 int writeopen; // write fd is still open
19 };
20
21 int pipealloc(struct file **f0, struct file **f1)
22 {
23 struct pipe *p;
24
25 p = 0;
26 *f0 = *f1 = 0;
27
28 if((*f0 = filealloc()) == 0 || (*f1 = filealloc()) == 0) {
29 goto bad;
30 }
31
32 if((p = kmalloc (get_order(sizeof(*p)))) == 0) {
33 goto bad;
34 }
35
36 p->readopen = 1;
37 p->writeopen = 1;
38 p->nwrite = 0;
39 p->nread = 0;
40
41 initlock(&p->lock, "pipe");
42
43 (*f0)->type = FD_PIPE;
44 (*f0)->readable = 1;
45 (*f0)->writable = 0;
46 (*f0)->pipe = p;
47 (*f1)->type = FD_PIPE;
48 (*f1)->readable = 0;
49 (*f1)->writable = 1;
50 (*f1)->pipe = p;
51
52 return 0;
53
54 //PAGEBREAK: 20
55 bad:
56 if(p) {
57 kfree (p, get_order(sizeof*p));
58 }
59
60 if(*f0) {
61 fileclose(*f0);
62 }
63
64 if(*f1) {
65 fileclose(*f1);
66 }
67
68 return -1;
69 }
70
71 void pipeclose(struct pipe *p, int writable)
72 {
73 acquire(&p->lock);
74
75 if(writable){
76 p->writeopen = 0;
77 wakeup(&p->nread);
78
79 } else {
80 p->readopen = 0;
81 wakeup(&p->nwrite);
82 }
83
84 if(p->readopen == 0 && p->writeopen == 0){
85 release(&p->lock);
86 kfree (p, get_order(sizeof(*p)));
87
88 } else {
89 release(&p->lock);
90 }
91 }
92
93 //PAGEBREAK: 40
94 int pipewrite(struct pipe *p, char *addr, int n)
95 {
96 int i;
97
98 acquire(&p->lock);
99
100 for(i = 0; i < n; i++){
101 while(p->nwrite == p->nread + PIPESIZE){ //DOC: pipewrite-full
102 if(p->readopen == 0 /*|| proc->killed*/){
103 release(&p->lock);
104 return -1;
105 }
106
107 wakeup(&p->nread);
108 sleep(&p->nwrite, &p->lock); //DOC: pipewrite-sleep
109 }
110
111 p->data[p->nwrite++ % PIPESIZE] = addr[i];
112 }
113
114 wakeup(&p->nread); //DOC: pipewrite-wakeup1
115 release(&p->lock);
116 return n;
117 }
118
119 int piperead(struct pipe *p, char *addr, int n)
120 {
121 int i;
122
123 acquire(&p->lock);
124
125 while(p->nread == p->nwrite && p->writeopen){ //DOC: pipe-empty
126 if(proc->killed){
127 release(&p->lock);
128 return -1;
129 }
130
131 sleep(&p->nread, &p->lock); //DOC: piperead-sleep*/
132 }
133
134 for(i = 0; i < n; i++){ //DOC: piperead-copy
135 if(p->nread == p->nwrite) {
136 break;
137 }
138
139 addr[i] = p->data[p->nread++ % PIPESIZE];
140 }
141
142 wakeup(&p->nwrite); //DOC: piperead-wakeup
143 release(&p->lock);
144
145 return i;
146 }