add kernel kfifo implementation

2 files changed, 167 insertions, 0 deletions

diff --git a/lib/Makefile b/lib/Makefile
index 0aaf53f69a..04c62b17b7 100644
--- a/lib/Makefile
+++ b/lib/Makefile
@@ -10,6 +10,7 @@ obj-y			+= parameter.o
 obj-y			+= xfuncs.o
 obj-y			+= getopt.o
 obj-y 			+= readkey.o
+obj-y			+= kfifo.o
 obj-$(CONFIG_BZLIB)	+= bzlib.o bzlib_crctable.o bzlib_decompress.o bzlib_huffman.o bzlib_randtable.o
 obj-$(CONFIG_ZLIB)	+= zlib.o gunzip.o
 obj-$(CONFIG_CRC32)	+= crc32.o
diff --git a/lib/kfifo.c b/lib/kfifo.c
new file mode 100644
index 0000000000..bf5cee1de0
--- /dev/null
+++ b/lib/kfifo.c
@@ -0,0 +1,166 @@
+/*
+ * 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.
+ *
+ */
+
+#include <common.h>
+#include <malloc.h>
+#include <kfifo.h>
+#include <errno.h>
+
+/**
+ * kfifo_init - allocates a new FIFO using a preallocated buffer
+ * @buffer: the preallocated buffer to be used.
+ * @size: the size of the internal buffer, this have to be a power of 2.
+ * @gfp_mask: get_free_pages mask, passed to kmalloc()
+ * @lock: the lock to be used to protect the fifo buffer
+ *
+ * Do NOT pass the kfifo to kfifo_free() after use! Simply free the
+ * &struct kfifo with free().
+ */
+struct kfifo *kfifo_init(unsigned char *buffer, unsigned int size)
+{
+	struct kfifo *fifo;
+
+	fifo = malloc(sizeof(struct kfifo));
+	if (!fifo)
+		return NULL;
+
+	fifo->buffer = buffer;
+	fifo->size = size;
+	fifo->in = fifo->out = 0;
+
+	return fifo;
+}
+
+/**
+ * kfifo_alloc - allocates a new FIFO and its internal buffer
+ * @size: the size of the internal buffer to be allocated.
+ * @gfp_mask: get_free_pages mask, passed to kmalloc()
+ * @lock: the lock to be used to protect the fifo buffer
+ *
+ * The size will be rounded-up to a power of 2.
+ */
+struct kfifo *kfifo_alloc(unsigned int size)
+{
+	unsigned char *buffer;
+	struct kfifo *ret;
+
+	buffer = malloc(size);
+	if (!buffer)
+		return NULL;
+
+	ret = kfifo_init(buffer, size);
+
+	if (!ret)
+		free(buffer);
+
+	return ret;
+}
+
+/**
+ * kfifo_free - frees the FIFO
+ * @fifo: the fifo to be freed.
+ */
+void kfifo_free(struct kfifo *fifo)
+{
+	free(fifo->buffer);
+	free(fifo);
+}
+
+/**
+ * kfifo_put - puts some data into the FIFO, no locking version
+ * @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)
+{
+	unsigned int l;
+
+	len = min(len, fifo->size - fifo->in + fifo->out);
+
+	/* first put the data starting from fifo->in to buffer end */
+	l = min(len, fifo->size - (fifo->in & (fifo->size - 1)));
+	memcpy(fifo->buffer + (fifo->in & (fifo->size - 1)), buffer, l);
+
+	/* then put the rest (if any) at the beginning of the buffer */
+	memcpy(fifo->buffer, buffer + l, len - l);
+
+	fifo->in += len;
+
+	return len;
+}
+
+/**
+ * kfifo_get - gets some data from the FIFO, no locking version
+ * @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.
+ *
+ * Note that with only one concurrent reader and one concurrent
+ * writer, you don't need extra locking to use these functions.
+ */
+unsigned int kfifo_get(struct kfifo *fifo,
+			 unsigned char *buffer, unsigned int len)
+{
+	unsigned int l;
+
+	len = min(len, fifo->in - fifo->out);
+
+	/* first get the data from fifo->out until the end of the buffer */
+	l = min(len, fifo->size - (fifo->out & (fifo->size - 1)));
+	memcpy(buffer, fifo->buffer + (fifo->out & (fifo->size - 1)), l);
+
+	/* then get the rest (if any) from the beginning of the buffer */
+	memcpy(buffer + l, fifo->buffer, len - l);
+
+	fifo->out += len;
+
+	return len;
+}
+
+void kfifo_putc(struct kfifo *fifo, unsigned char c)
+{
+	*(fifo->buffer + (fifo->in & (fifo->size - 1))) = c;
+	fifo->in++;
+	if (fifo->in - fifo->out > fifo->size)
+		fifo->out++;
+}
+
+unsigned int kfifo_getc(struct kfifo *fifo, unsigned char *c)
+{
+	if (fifo->in == fifo->out)
+		return -1;
+
+	*c = *(fifo->buffer + (fifo->out & (fifo->size - 1)));
+	fifo->out++;
+
+	return 0;
+}
+