include/kfifo.h

   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 #ifndef _LINUX_KFIFO_H
  22 #define _LINUX_KFIFO_H
  23
  24 struct kfifo {
  25         unsigned char *buffer;  /* the buffer holding the data */
  26         unsigned int size;      /* the size of the allocated buffer */
  27         unsigned int in;        /* data is added at offset (in % size) */
  28         unsigned int out;       /* data is extracted from off. (out % size) */
  29 };
  30
  31 struct kfifo *kfifo_init(unsigned char *buffer, unsigned int size);
  32 struct kfifo *kfifo_alloc(unsigned int size);
  33 void kfifo_free(struct kfifo *fifo);
  34
  35 /**
  36  * kfifo_put - puts some data into the FIFO
  37  * @fifo: the fifo to be used.
  38  * @buffer: the data to be added.
  39  * @len: the length of the data to be added.
  40  *
  41  * This function copies at most @len bytes from the @buffer into
  42  * the FIFO depending on the free space, and returns the number of
  43  * bytes copied.
  44  */
  45 unsigned int kfifo_put(struct kfifo *fifo,
  46                                 unsigned char *buffer, unsigned int len);
  47
  48 /**
  49  * kfifo_get - gets some data from the FIFO
  50  * @fifo: the fifo to be used.
  51  * @buffer: where the data must be copied.
  52  * @len: the size of the destination buffer.
  53  *
  54  * This function copies at most @len bytes from the FIFO into the
  55  * @buffer and returns the number of copied bytes.
  56  */
  57 unsigned int kfifo_get(struct kfifo *fifo,
  58                                 unsigned char *buffer, unsigned int len);
  59
  60 /**
  61  * kfifo_reset - removes the entire FIFO contents
  62  * @fifo: the fifo to be emptied.
  63  */
  64 static inline void kfifo_reset(struct kfifo *fifo)
  65 {
  66         fifo->in = fifo->out = 0;
  67 }
  68
  69
  70 /**
  71  * kfifo_len - returns the number of bytes available in the FIFO.
  72  * @fifo: the fifo to be used.
  73  */
  74 static inline unsigned int kfifo_len(struct kfifo *fifo)
  75 {
  76         return fifo->in - fifo->out;
  77 }
  78
  79 void kfifo_putc(struct kfifo *fifo, unsigned char c);
  80 unsigned int kfifo_getc(struct kfifo *fifo, unsigned char *c);
  81
  82 #endif
  83