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From: Steffen Trumtrar <s.trumtrar@pengutronix.de>
To: barebox@lists.infradead.org
Cc: Steffen Trumtrar <s.trumtrar@pengutronix.de>
Subject: [PATCH 2/6] include: linux: add circular buffers
Date: Wed, 14 Oct 2015 15:39:35 +0200	[thread overview]
Message-ID: <1444829979-1100-2-git-send-email-s.trumtrar@pengutronix.de> (raw)
In-Reply-To: <1444829979-1100-1-git-send-email-s.trumtrar@pengutronix.de>

Signed-off-by: Steffen Trumtrar <s.trumtrar@pengutronix.de>
---
 include/linux/circ_buf.h | 36 ++++++++++++++++++++++++++++++++++++
 1 file changed, 36 insertions(+)
 create mode 100644 include/linux/circ_buf.h

diff --git a/include/linux/circ_buf.h b/include/linux/circ_buf.h
new file mode 100644
index 000000000000..90f2471dc6f2
--- /dev/null
+++ b/include/linux/circ_buf.h
@@ -0,0 +1,36 @@
+/*
+ * See Documentation/circular-buffers.txt for more information.
+ */
+
+#ifndef _LINUX_CIRC_BUF_H
+#define _LINUX_CIRC_BUF_H 1
+
+struct circ_buf {
+	char *buf;
+	int head;
+	int tail;
+};
+
+/* Return count in buffer.  */
+#define CIRC_CNT(head,tail,size) (((head) - (tail)) & ((size)-1))
+
+/* Return space available, 0..size-1.  We always leave one free char
+   as a completely full buffer has head == tail, which is the same as
+   empty.  */
+#define CIRC_SPACE(head,tail,size) CIRC_CNT((tail),((head)+1),(size))
+
+/* Return count up to the end of the buffer.  Carefully avoid
+   accessing head and tail more than once, so they can change
+   underneath us without returning inconsistent results.  */
+#define CIRC_CNT_TO_END(head,tail,size) \
+	({int end = (size) - (tail); \
+	  int n = ((head) + end) & ((size)-1); \
+	  n < end ? n : end;})
+
+/* Return space available up to the end of the buffer.  */
+#define CIRC_SPACE_TO_END(head,tail,size) \
+	({int end = (size) - 1 - (head); \
+	  int n = (end + (tail)) & ((size)-1); \
+	  n <= end ? n : end+1;})
+
+#endif /* _LINUX_CIRC_BUF_H  */
-- 
2.6.1


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  reply	other threads:[~2015-10-14 13:40 UTC|newest]

Thread overview: 10+ messages / expand[flat|nested]  mbox.gz  Atom feed  top
2015-10-14 13:39 [PATCH 1/6] lib: add base64 helpers Steffen Trumtrar
2015-10-14 13:39 ` Steffen Trumtrar [this message]
2015-10-14 13:39 ` [PATCH 3/6] ARM: imx6qdl: add caam clks Steffen Trumtrar
2015-10-14 13:39 ` [PATCH 4/6] crypto: add i.MX6 CAAM support Steffen Trumtrar
2015-10-14 14:16   ` Lucas Stach
2015-10-23  9:55     ` Steffen Trumtrar
2015-10-19  6:21   ` Sascha Hauer
2015-10-23 10:02     ` Steffen Trumtrar
2015-10-14 13:39 ` [PATCH 5/6] ARM: i.MX6qdl: add caam node Steffen Trumtrar
2015-10-14 13:39 ` [PATCH 6/6] crypto: caam: add blob_gen driver Steffen Trumtrar

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