# HG changeset patch
# User Josef 'Jeff' Sipek <jeffpc@josefsipek.net>
# Date 1333057308 14400
# Node ID 887ae564371a870158d73756023b52810014954b
# Parent  6fca4100a8869bf0630f0740b1b6b2a8b9d0b613
include: generic circular buffer code

Signed-off-by: Josef 'Jeff' Sipek <jeffpc@josefsipek.net>

diff -r 6fca4100a886 -r 887ae564371a include/circbuf.h
--- /dev/null	Thu Jan 01 00:00:00 1970 +0000
+++ b/include/circbuf.h	Thu Mar 29 17:41:48 2012 -0400
@@ -0,0 +1,77 @@
+/*
+ * Copyright (c) 2012 Josef 'Jeff' Sipek <jeffpc@josefsipek.net>
+ *
+ * Permission is hereby granted, free of charge, to any person obtaining a copy
+ * of this software and associated documentation files (the "Software"), to deal
+ * in the Software without restriction, including without limitation the rights
+ * to use, copy, modify, merge, publish, distribute, sublicense, and/or sell
+ * copies of the Software, and to permit persons to whom the Software is
+ * furnished to do so, subject to the following conditions:
+ *
+ * The above copyright notice and this permission notice shall be included in
+ * all copies or substantial portions of the Software.
+ *
+ * THE SOFTWARE IS PROVIDED "AS IS", WITHOUT WARRANTY OF ANY KIND, EXPRESS OR
+ * IMPLIED, INCLUDING BUT NOT LIMITED TO THE WARRANTIES OF MERCHANTABILITY,
+ * FITNESS FOR A PARTICULAR PURPOSE AND NONINFRINGEMENT. IN NO EVENT SHALL THE
+ * AUTHORS OR COPYRIGHT HOLDERS BE LIABLE FOR ANY CLAIM, DAMAGES OR OTHER
+ * LIABILITY, WHETHER IN AN ACTION OF CONTRACT, TORT OR OTHERWISE, ARISING FROM,
+ * OUT OF OR IN CONNECTION WITH THE SOFTWARE OR THE USE OR OTHER DEALINGS IN THE
+ * SOFTWARE.
+ */
+
+#ifndef __CIRCBUF_H
+#define __CIRCBUF_H
+
+struct circbuf {
+	u32 start;			/* the oldest entry idx */
+	u32 filled;			/* the number of entries */
+	u32 size;			/* the size of each entry */
+	u32 count;			/* the max number of entries */
+	u8 data[0];
+};
+
+#define CIRCBUF(name, n, s)	struct circbuf name; u8 __circbuf_##name[(n)*sizeof(s)]
+
+#define init_circbuf(c, t, n)	__init_circbuf((c), sizeof(t), (n))
+static inline void __init_circbuf(struct circbuf *c, u32 size, u32 count)
+{
+	c->start = 0;
+	c->filled = 0;
+	c->size = size;
+	c->count = count;
+}
+
+static inline void insert_circbuf(struct circbuf *c, void *data)
+{
+	u32 idx;
+
+	if (c->filled == c->count) {
+		idx = c->start;
+		c->start = (c->start+1) % c->count;
+	} else {
+		idx = (c->start + c->filled) % c->count;
+		c->filled++;
+	}
+
+	memcpy(c->data + (idx * c->size), data, c->size);
+}
+
+static inline int remove_circbuf(struct circbuf *c, void *data)
+{
+	if (!c->filled)
+		return 0;
+
+	memcpy(data, c->data + (c->start * c->size), c->size);
+
+	c->start = (c->start+1) % c->count;
+	c->filled--;
+	return 1;
+}
+
+static inline int pending_circbuf(struct circbuf *c)
+{
+	return c->filled != 0;
+}
+
+#endif