add kernel kfifo implementation

1 files changed, 83 insertions, 0 deletions

diff --git a/include/kfifo.h b/include/kfifo.h
new file mode 100644
index 0000000000..6f8be10f67
--- /dev/null
+++ b/include/kfifo.h
@@ -0,0 +1,83 @@
+/*
+ * A simple kernel FIFO implementation.
+ *
+ * Copyright (C) 2004 Stelian Pop <stelian@popies.net>
+ *
+ * This program is free software; you can redistribute it and/or modify
+ * it under the terms of the GNU General Public License as published by
+ * the Free Software Foundation; either version 2 of the License, or
+ * (at your option) any later version.
+ *
+ * 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.
+ *
+ * You should have received a copy of the GNU General Public License
+ * along with this program; if not, write to the Free Software
+ * Foundation, Inc., 675 Mass Ave, Cambridge, MA 02139, USA.
+ *
+ */
+#ifndef _LINUX_KFIFO_H
+#define _LINUX_KFIFO_H
+
+struct kfifo {
+	unsigned char *buffer;	/* the buffer holding the data */
+	unsigned int size;	/* the size of the allocated buffer */
+	unsigned int in;	/* data is added at offset (in % size) */
+	unsigned int out;	/* data is extracted from off. (out % size) */
+};
+
+struct kfifo *kfifo_init(unsigned char *buffer, unsigned int size);
+struct kfifo *kfifo_alloc(unsigned int size);
+void kfifo_free(struct kfifo *fifo);
+
+/**
+ * kfifo_put - puts some data into the FIFO
+ * @fifo: the fifo to be used.
+ * @buffer: the data to be added.
+ * @len: the length of the data to be added.
+ *
+ * This function copies at most @len bytes from the @buffer into
+ * the FIFO depending on the free space, and returns the number of
+ * bytes copied.
+ */
+unsigned int kfifo_put(struct kfifo *fifo,
+				unsigned char *buffer, unsigned int len);
+
+/**
+ * kfifo_get - gets some data from the FIFO
+ * @fifo: the fifo to be used.
+ * @buffer: where the data must be copied.
+ * @len: the size of the destination buffer.
+ *
+ * This function copies at most @len bytes from the FIFO into the
+ * @buffer and returns the number of copied bytes.
+ */
+unsigned int kfifo_get(struct kfifo *fifo,
+				unsigned char *buffer, unsigned int len);
+
+/**
+ * kfifo_reset - removes the entire FIFO contents
+ * @fifo: the fifo to be emptied.
+ */
+static inline void kfifo_reset(struct kfifo *fifo)
+{
+	fifo->in = fifo->out = 0;
+}
+
+
+/**
+ * kfifo_len - returns the number of bytes available in the FIFO.
+ * @fifo: the fifo to be used.
+ */
+static inline unsigned int kfifo_len(struct kfifo *fifo)
+{
+	return fifo->in - fifo->out;
+}
+
+void kfifo_putc(struct kfifo *fifo, unsigned char c);
+unsigned int kfifo_getc(struct kfifo *fifo, unsigned char *c);
+
+#endif
+