1 /*
2 This file is part of Deadbeef Player source code
3 http://deadbeef.sourceforge.net
4
5 basic ring buffer implementation
6
7 Copyright (C) 2009-2013 Alexey Yakovenko
8
9 This software is provided 'as-is', without any express or implied
10 warranty. In no event will the authors be held liable for any damages
11 arising from the use of this software.
12
13 Permission is granted to anyone to use this software for any purpose,
14 including commercial applications, and to alter it and redistribute it
15 freely, subject to the following restrictions:
16
17 1. The origin of this software must not be misrepresented; you must not
18 claim that you wrote the original software. If you use this software
19 in a product, an acknowledgment in the product documentation would be
20 appreciated but is not required.
21 2. Altered source versions must be plainly marked as such, and must not be
22 misrepresented as being the original software.
23 3. This notice may not be removed or altered from any source distribution.
24
25 Alexey Yakovenko waker@users.sourceforge.net
26 */
27
28 #include <string.h>
29 #include "ringbuf.h"
30
31 void
ringbuf_init(ringbuf_t * p,char * buffer,size_t size)32 ringbuf_init (ringbuf_t *p, char *buffer, size_t size) {
33 memset (p, 0, sizeof (ringbuf_t));
34 p->bytes = buffer;
35 p->cursor = 0;
36 p->size = size;
37 p->remaining = 0;
38 }
39
40 int
ringbuf_write(ringbuf_t * p,char * bytes,size_t size)41 ringbuf_write (ringbuf_t *p, char *bytes, size_t size) {
42 if (p->size - p->remaining < size) {
43 return -1;
44 }
45
46 size_t cursor = p->cursor + p->remaining;
47 cursor %= p->size;
48
49 if (p->size - cursor >= size) { // split
50 memcpy (p->bytes + cursor, bytes, size);
51 p->remaining += size;
52 }
53 else {
54 size_t n = p->size - cursor;
55 if (n > 0) {
56 memcpy (p->bytes + cursor, bytes, n);
57 p->remaining += n;
58 size -= n;
59 bytes += n;
60 }
61 memcpy (p->bytes, bytes, size);
62 p->remaining += size;
63 }
64 return 0;
65 }
66
67 int
ringbuf_read(ringbuf_t * p,char * bytes,size_t size)68 ringbuf_read (ringbuf_t *p, char *bytes, size_t size) {
69 if (p->remaining < size) {
70 size = p->remaining;
71 }
72 int rb = size;
73
74 if (p->size - p->cursor >= size) {
75 memcpy (bytes, p->bytes + p->cursor, size);
76 p->cursor += size;
77 p->remaining -= size;
78 }
79 else {
80 size_t n = p->size - p->cursor;
81 if (n > 0) {
82 memcpy (bytes, p->bytes + p->cursor, n);
83 p->cursor += n;
84 p->remaining -= n;
85 bytes += n;
86 size -= n;
87 }
88 memcpy (bytes, p->bytes, size);
89 p->cursor = size;
90 p->remaining -= size;
91 }
92 return rb;
93 }
94