Commit | Line | Data |
---|---|---|
e2887563 JA |
1 | /* |
2 | * A simple kernel FIFO implementation. | |
3 | * | |
4 | * Copyright (C) 2004 Stelian Pop <stelian@popies.net> | |
5 | * | |
6 | * This program is free software; you can redistribute it and/or modify | |
7 | * it under the terms of the GNU General Public License as published by | |
8 | * the Free Software Foundation; either version 2 of the License, or | |
9 | * (at your option) any later version. | |
10 | * | |
11 | * This program is distributed in the hope that it will be useful, | |
12 | * but WITHOUT ANY WARRANTY; without even the implied warranty of | |
13 | * MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE. See the | |
14 | * GNU General Public License for more details. | |
15 | * | |
16 | * You should have received a copy of the GNU General Public License | |
17 | * along with this program; if not, write to the Free Software | |
fa07eaa6 | 18 | * Foundation, Inc., 51 Franklin Street, Fifth Floor, Boston, MA 02110-1301, USA. |
e2887563 JA |
19 | * |
20 | */ | |
21 | ||
22 | #include <stdio.h> | |
23 | #include <stdlib.h> | |
24 | #include <string.h> | |
25 | ||
26 | #include "fifo.h" | |
3d2d14bc | 27 | #include "minmax.h" |
e2887563 JA |
28 | |
29 | struct fifo *fifo_alloc(unsigned int size) | |
30 | { | |
31 | struct fifo *fifo; | |
32 | ||
33 | fifo = malloc(sizeof(struct fifo)); | |
34 | if (!fifo) | |
cc62ea70 | 35 | return NULL; |
e2887563 JA |
36 | |
37 | fifo->buffer = malloc(size); | |
38 | fifo->size = size; | |
f12b323f | 39 | fifo->in = fifo->out = 0; |
e2887563 JA |
40 | |
41 | return fifo; | |
42 | } | |
43 | ||
44 | void fifo_free(struct fifo *fifo) | |
45 | { | |
46 | free(fifo->buffer); | |
47 | free(fifo); | |
48 | } | |
49 | ||
50 | unsigned int fifo_put(struct fifo *fifo, void *buffer, unsigned int len) | |
51 | { | |
52 | unsigned int l; | |
53 | ||
104bc4bd | 54 | len = min(len, fifo_room(fifo)); |
e2887563 JA |
55 | |
56 | /* first put the data starting from fifo->in to buffer end */ | |
57 | l = min(len, fifo->size - (fifo->in & (fifo->size - 1))); | |
58 | memcpy(fifo->buffer + (fifo->in & (fifo->size - 1)), buffer, l); | |
59 | ||
60 | /* then put the rest (if any) at the beginning of the buffer */ | |
61 | memcpy(fifo->buffer, buffer + l, len - l); | |
62 | ||
63 | /* | |
64 | * Ensure that we add the bytes to the fifo -before- | |
65 | * we update the fifo->in index. | |
66 | */ | |
67 | ||
68 | fifo->in += len; | |
69 | ||
70 | return len; | |
71 | } | |
72 | ||
5ec10eaa | 73 | unsigned int fifo_get(struct fifo *fifo, void *buf, unsigned int len) |
e2887563 | 74 | { |
e2887563 JA |
75 | len = min(len, fifo->in - fifo->out); |
76 | ||
5ec10eaa | 77 | if (buf) { |
104bc4bd | 78 | unsigned int l; |
e2887563 | 79 | |
104bc4bd JA |
80 | /* |
81 | * first get the data from fifo->out until the end of the buffer | |
82 | */ | |
83 | l = min(len, fifo->size - (fifo->out & (fifo->size - 1))); | |
5ec10eaa | 84 | memcpy(buf, fifo->buffer + (fifo->out & (fifo->size - 1)), l); |
104bc4bd JA |
85 | |
86 | /* | |
87 | * then get the rest (if any) from the beginning of the buffer | |
88 | */ | |
5ec10eaa | 89 | memcpy(buf + l, fifo->buffer, len - l); |
104bc4bd | 90 | } |
e2887563 JA |
91 | |
92 | fifo->out += len; | |
93 | ||
104bc4bd JA |
94 | if (fifo->in == fifo->out) |
95 | fifo->in = fifo->out = 0; | |
96 | ||
e2887563 JA |
97 | return len; |
98 | } |