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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 | |
18 | * Foundation, Inc., 675 Mass Ave, Cambridge, MA 02139, USA. | |
19 | * | |
20 | */ | |
21 | ||
22 | #include <stdio.h> | |
23 | #include <stdlib.h> | |
24 | #include <string.h> | |
25 | ||
26 | #include "fifo.h" | |
27 | ||
28 | struct fifo *fifo_alloc(unsigned int size) | |
29 | { | |
30 | struct fifo *fifo; | |
31 | ||
32 | fifo = malloc(sizeof(struct fifo)); | |
33 | if (!fifo) | |
34 | return 0; | |
35 | ||
36 | fifo->buffer = malloc(size); | |
37 | fifo->size = size; | |
f12b323f | 38 | fifo->in = fifo->out = 0; |
e2887563 JA |
39 | |
40 | return fifo; | |
41 | } | |
42 | ||
43 | void fifo_free(struct fifo *fifo) | |
44 | { | |
45 | free(fifo->buffer); | |
46 | free(fifo); | |
47 | } | |
48 | ||
49 | unsigned int fifo_put(struct fifo *fifo, void *buffer, unsigned int len) | |
50 | { | |
51 | unsigned int l; | |
52 | ||
104bc4bd | 53 | len = min(len, fifo_room(fifo)); |
e2887563 JA |
54 | |
55 | /* first put the data starting from fifo->in to buffer end */ | |
56 | l = min(len, fifo->size - (fifo->in & (fifo->size - 1))); | |
57 | memcpy(fifo->buffer + (fifo->in & (fifo->size - 1)), buffer, l); | |
58 | ||
59 | /* then put the rest (if any) at the beginning of the buffer */ | |
60 | memcpy(fifo->buffer, buffer + l, len - l); | |
61 | ||
62 | /* | |
63 | * Ensure that we add the bytes to the fifo -before- | |
64 | * we update the fifo->in index. | |
65 | */ | |
66 | ||
67 | fifo->in += len; | |
68 | ||
69 | return len; | |
70 | } | |
71 | ||
5ec10eaa | 72 | unsigned int fifo_get(struct fifo *fifo, void *buf, unsigned int len) |
e2887563 | 73 | { |
e2887563 JA |
74 | len = min(len, fifo->in - fifo->out); |
75 | ||
5ec10eaa | 76 | if (buf) { |
104bc4bd | 77 | unsigned int l; |
e2887563 | 78 | |
104bc4bd JA |
79 | /* |
80 | * first get the data from fifo->out until the end of the buffer | |
81 | */ | |
82 | l = min(len, fifo->size - (fifo->out & (fifo->size - 1))); | |
5ec10eaa | 83 | memcpy(buf, fifo->buffer + (fifo->out & (fifo->size - 1)), l); |
104bc4bd JA |
84 | |
85 | /* | |
86 | * then get the rest (if any) from the beginning of the buffer | |
87 | */ | |
5ec10eaa | 88 | memcpy(buf + l, fifo->buffer, len - l); |
104bc4bd | 89 | } |
e2887563 JA |
90 | |
91 | fifo->out += len; | |
92 | ||
104bc4bd JA |
93 | if (fifo->in == fifo->out) |
94 | fifo->in = fifo->out = 0; | |
95 | ||
e2887563 JA |
96 | return len; |
97 | } |