2 * A simple kernel FIFO implementation.
4 * Copyright (C) 2004 Stelian Pop <stelian@popies.net>
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.
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.
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., 51 Franklin Street, Fifth Floor, Boston, MA 02110-1301, USA.
29 struct fifo *fifo_alloc(unsigned int size)
33 fifo = malloc(sizeof(struct fifo));
37 fifo->buffer = malloc(size);
39 fifo->in = fifo->out = 0;
44 void fifo_free(struct fifo *fifo)
50 unsigned int fifo_put(struct fifo *fifo, void *buffer, unsigned int len)
54 len = min(len, fifo_room(fifo));
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);
60 /* then put the rest (if any) at the beginning of the buffer */
61 memcpy(fifo->buffer, buffer + l, len - l);
64 * Ensure that we add the bytes to the fifo -before-
65 * we update the fifo->in index.
73 unsigned int fifo_get(struct fifo *fifo, void *buf, unsigned int len)
75 len = min(len, fifo->in - fifo->out);
81 * first get the data from fifo->out until the end of the buffer
83 l = min(len, fifo->size - (fifo->out & (fifo->size - 1)));
84 memcpy(buf, fifo->buffer + (fifo->out & (fifo->size - 1)), l);
87 * then get the rest (if any) from the beginning of the buffer
89 memcpy(buf + l, fifo->buffer, len - l);
94 if (fifo->in == fifo->out)
95 fifo->in = fifo->out = 0;