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/** @file
* IPRT - Lock Free Circular Buffer
*/
/*
* Copyright (C) 2010-2025 Oracle and/or its affiliates.
*
* This file is part of VirtualBox base platform packages, as
* available from https://www.virtualbox.org.
*
* 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, in version 3 of the
* License.
*
* 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, see <https://www.gnu.org/licenses>.
*
* The contents of this file may alternatively be used under the terms
* of the Common Development and Distribution License Version 1.0
* (CDDL), a copy of it is provided in the "COPYING.CDDL" file included
* in the VirtualBox distribution, in which case the provisions of the
* CDDL are applicable instead of those of the GPL.
*
* You may elect to license modified versions of this file under the
* terms and conditions of either the GPL or the CDDL or both.
*
* SPDX-License-Identifier: GPL-3.0-only OR CDDL-1.0
*/
#ifndef IPRT_INCLUDED_circbuf_h
#define IPRT_INCLUDED_circbuf_h
#ifndef RT_WITHOUT_PRAGMA_ONCE
# pragma once
#endif
#include <iprt/types.h>
/** @defgroup grp_rt_circbuf RTCircBuf - Lock Free Circular Buffer
* @ingroup grp_rt
*
* Implementation of a lock free circular buffer which could be used in a multi
* threaded environment. Note that only the acquire, release and getter
* functions are threading aware. So don't use reset if the circular buffer is
* still in use.
*
* @{
*/
RT_C_DECLS_BEGIN
/** Pointer to a circular buffer (abstract). */
typedef struct RTCIRCBUF *PRTCIRCBUF;
/**
* Create a circular buffer.
*
* @returns IPRT status code.
*
* @param ppBuf Where to store the buffer.
* @param cbSize The size of the new buffer.
*/
RTDECL(int) RTCircBufCreate(PRTCIRCBUF *ppBuf, size_t cbSize);
/**
* Destroy the circular buffer.
*
* @param pBuf The buffer to destroy. NULL is ignored.
*/
RTDECL(void) RTCircBufDestroy(PRTCIRCBUF pBuf);
/**
* Reset all position information in the circular buffer.
*
* @note This function is not multi threading aware.
*
* @param pBuf The buffer to reset.
*/
RTDECL(void) RTCircBufReset(PRTCIRCBUF pBuf);
/**
* Returns the current free space of the buffer.
*
* @param pBuf The buffer to query.
*/
RTDECL(size_t) RTCircBufFree(PRTCIRCBUF pBuf);
/**
* Returns the current used space of the buffer.
*
* @param pBuf The buffer to query.
*/
RTDECL(size_t) RTCircBufUsed(PRTCIRCBUF pBuf);
/**
* Returns the size of the buffer.
*
* @param pBuf The buffer to query.
*/
RTDECL(size_t) RTCircBufSize(PRTCIRCBUF pBuf);
RTDECL(bool) RTCircBufIsReading(PRTCIRCBUF pBuf);
RTDECL(bool) RTCircBufIsWriting(PRTCIRCBUF pBuf);
/**
* Returns the current read offset (in bytes) within the buffer.
*
* @param pBuf The buffer to query.
*/
RTDECL(size_t) RTCircBufOffsetRead(PRTCIRCBUF pBuf);
/**
* Returns the current write offset (in bytes) within the buffer.
*
* @param pBuf The buffer to query.
*/
RTDECL(size_t) RTCircBufOffsetWrite(PRTCIRCBUF pBuf);
/**
* Acquire a block of the circular buffer for reading.
*
* @param pBuf The buffer to acquire from.
* @param cbReqSize The requested size of the block.
* @param ppvStart The resulting memory pointer.
* @param pcbSize The resulting size of the memory pointer.
*/
RTDECL(void) RTCircBufAcquireReadBlock(PRTCIRCBUF pBuf, size_t cbReqSize, void **ppvStart, size_t *pcbSize);
/**
* Release a block which was acquired by RTCircBufAcquireReadBlock.
*
* @param pBuf The buffer to acquire from.
* @param cbSize The size of the block.
*/
RTDECL(void) RTCircBufReleaseReadBlock(PRTCIRCBUF pBuf, size_t cbSize);
/**
* Acquire a block of the circular buffer for writing.
*
* @param pBuf The buffer to acquire from.
* @param cbReqSize The requested size of the block.
* @param ppvStart The resulting memory pointer.
* @param pcbSize The resulting size of the memory pointer.
*/
RTDECL(void) RTCircBufAcquireWriteBlock(PRTCIRCBUF pBuf, size_t cbReqSize, void **ppvStart, size_t *pcbSize);
/**
* Release a block which was acquired by RTCircBufAcquireWriteBlock.
*
* @param pBuf The buffer to acquire from.
* @param cbSize The size of the block.
*/
RTDECL(void) RTCircBufReleaseWriteBlock(PRTCIRCBUF pBuf, size_t cbSize);
RT_C_DECLS_END
/** @} */
#endif /* !IPRT_INCLUDED_circbuf_h */
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