blob: 10c3c5d09098e108f260e44285194416db7c972b [file] [log] [blame]
/*
* drivers/staging/android/fiq_debugger/fiq_debugger_ringbuf.h
*
* simple lockless ringbuffer
*
* Copyright (C) 2010 Google, Inc.
*
* This software is licensed under the terms of the GNU General Public
* License version 2, as published by the Free Software Foundation, and
* may be copied, distributed, and modified under those terms.
*
* This program is distributed in the hope that it will be useful,
* but WITHOUT ANY WARRANTY; without even the implied warranty of
* MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE. See the
* GNU General Public License for more details.
*/
#include <linux/kernel.h>
#include <linux/slab.h>
struct fiq_debugger_ringbuf {
int len;
int head;
int tail;
u8 buf[];
};
static inline struct fiq_debugger_ringbuf *fiq_debugger_ringbuf_alloc(int len)
{
struct fiq_debugger_ringbuf *rbuf;
rbuf = kzalloc(sizeof(*rbuf) + len, GFP_KERNEL);
if (rbuf == NULL)
return NULL;
rbuf->len = len;
rbuf->head = 0;
rbuf->tail = 0;
smp_mb();
return rbuf;
}
static inline void fiq_debugger_ringbuf_free(struct fiq_debugger_ringbuf *rbuf)
{
kfree(rbuf);
}
static inline int fiq_debugger_ringbuf_level(struct fiq_debugger_ringbuf *rbuf)
{
int level = rbuf->head - rbuf->tail;
if (level < 0)
level = rbuf->len + level;
return level;
}
static inline int fiq_debugger_ringbuf_room(struct fiq_debugger_ringbuf *rbuf)
{
return rbuf->len - fiq_debugger_ringbuf_level(rbuf) - 1;
}
static inline u8
fiq_debugger_ringbuf_peek(struct fiq_debugger_ringbuf *rbuf, int i)
{
return rbuf->buf[(rbuf->tail + i) % rbuf->len];
}
static inline int
fiq_debugger_ringbuf_consume(struct fiq_debugger_ringbuf *rbuf, int count)
{
count = min(count, fiq_debugger_ringbuf_level(rbuf));
rbuf->tail = (rbuf->tail + count) % rbuf->len;
smp_mb();
return count;
}
static inline int
fiq_debugger_ringbuf_push(struct fiq_debugger_ringbuf *rbuf, u8 datum)
{
if (fiq_debugger_ringbuf_room(rbuf) == 0)
return 0;
rbuf->buf[rbuf->head] = datum;
smp_mb();
rbuf->head = (rbuf->head + 1) % rbuf->len;
smp_mb();
return 1;
}