1
2
3
4
5
6
7
8
9
10
11
12
13
14
15
16
17
18
19
20
21
22
23
24
25
26
27
28
29
30
31
32
33
34
35
36
37
38
39
40
41
42
43
44
45
46
47
48
49
50
51
52
53
54
55
56
57
58
59
60
61
62
63
64
65
66
67
68
69
70
71
72
73
74
75
|
// SPDX-License-Identifier: GPL-2.0-or-later
/* SPDX-FileCopyrightText: 2004-2015 Simon Wunderlich <sw@simonwunderlich.de>
*/
#include "global.h"
#include <stdio.h> /* printf(), getchar() */
#include <stdint.h> /* uint32_t */
#include <string.h> /* memcpy() */
int shm_write(struct buf_t *rb, char *buf, int n)
{
int wrap = 0;
int rs;
int32_t e, s, size;
char *data;
e = rb->end;
s = rb->start;
size = rb->bufsize;
data = ((char *)rb) + sizeof(struct buf_t);
if (e < s) {
wrap = 1;
}
if ((((s + size * (1 - wrap)) - e) < (n + 1))) { /* checking free space */
printf("buffer reached maxsize, no resizing possible");
}
if ((e + n) > size) {
rs = size - e;
memcpy(data + e, buf, rs); /* copy the first part ... */
memcpy(data, buf + rs, n - rs); /* .. end the rest */
} else {
memcpy(data + e, buf, n); /* plain copy */
}
rb->end = e + n; /* update end of the buffer */
if (rb->end >= rb->bufsize)
rb->end -= rb->bufsize;
return 0;
}
int shm_read(struct buf_t *rb, char *buf, int n)
{
int wrap = 0;
int mn;
int rs;
int32_t e, s, size;
char *data;
e = rb->end;
s = rb->start;
size = rb->bufsize;
data = ((char *)rb) + sizeof(struct buf_t);
if (e < s)
wrap = 1;
rs = (e + wrap * size - s);
mn = (n > rs) ? rs : n;
if ((wrap) && (mn > (size - s))) {
rs = size - s; /* size of the first part */
memcpy(buf, data + s, rs);
memcpy(buf + rs, data, mn - rs);
} else { /* no wrap (needed) */
memcpy(buf, data + s, mn);
}
rb->start = s + mn;
if (rb->start >= rb->bufsize)
rb->start -= rb->bufsize;
return mn;
}
void ringbuf_init(char *data, uint32_t init_size)
{
struct buf_t *ringbuf = (struct buf_t *)data;
ringbuf->start = 0;
ringbuf->end = 0;
ringbuf->bufsize = init_size - RB_OVERHEAD;
}
|
