From mboxrd@z Thu Jan 1 00:00:00 1970 Return-path: Received: from metis.ext.pengutronix.de ([2001:67c:670:201:290:27ff:fe1d:cc33]) by bombadil.infradead.org with esmtps (Exim 4.80.1 #2 (Red Hat Linux)) id 1ZmMHs-0004bR-9m for barebox@lists.infradead.org; Wed, 14 Oct 2015 13:40:15 +0000 From: Steffen Trumtrar Date: Wed, 14 Oct 2015 15:39:35 +0200 Message-Id: <1444829979-1100-2-git-send-email-s.trumtrar@pengutronix.de> In-Reply-To: <1444829979-1100-1-git-send-email-s.trumtrar@pengutronix.de> References: <1444829979-1100-1-git-send-email-s.trumtrar@pengutronix.de> List-Id: List-Unsubscribe: , List-Archive: List-Post: List-Help: List-Subscribe: , MIME-Version: 1.0 Content-Type: text/plain; charset="us-ascii" Content-Transfer-Encoding: 7bit Sender: "barebox" Errors-To: barebox-bounces+u.kleine-koenig=pengutronix.de@lists.infradead.org Subject: [PATCH 2/6] include: linux: add circular buffers To: barebox@lists.infradead.org Cc: Steffen Trumtrar Signed-off-by: Steffen Trumtrar --- 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 _______________________________________________ barebox mailing list barebox@lists.infradead.org http://lists.infradead.org/mailman/listinfo/barebox