Greg Kroah-Hartman
598cf27219
Link: https://lore.kernel.org/r/20260217200002.683975158@linuxfoundation.org Tested-by: Florian Fainelli <florian.fainelli@broadcom.com> Tested-by: Takeshi Ogasawara <takeshi.ogasawara@futuring-girl.com> Tested-by: Peter Schneider <pschneider1968@googlemail.com> Tested-by: Jon Hunter <jonathanh@nvidia.com> Tested-by: Salvatore Bonaccorso <carnil@debian.org> Tested-by: Brett A C Sheffield <bacs@librecast.net> Tested-by: Mark Brown <broonie@kernel.org> Tested-by: Luna Jernberg <droidbittin@gmail.com> Tested-by: Ronald Warsow <rwarsow@gmx.de> Tested-by: Justin M. Forbes <jforbes@fedoraproject.org> Tested-by: Ron Economos <re@w6rz.net> Tested-by: Miguel Ojeda <ojeda@kernel.org> Signed-off-by: Greg Kroah-Hartman <gregkh@linuxfoundation.org>
38 lines
1.1 KiB
C
38 lines
1.1 KiB
C
/* SPDX-License-Identifier: GPL-2.0 */
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/*
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* See Documentation/core-api/circular-buffers.rst for more information.
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*/
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#ifndef _LINUX_CIRC_BUF_H
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#define _LINUX_CIRC_BUF_H 1
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struct circ_buf {
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char *buf;
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int head;
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int tail;
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};
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/* Return count in buffer. */
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#define CIRC_CNT(head,tail,size) (((head) - (tail)) & ((size)-1))
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/* Return space available, 0..size-1. We always leave one free char
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as a completely full buffer has head == tail, which is the same as
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empty. */
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#define CIRC_SPACE(head,tail,size) CIRC_CNT((tail),((head)+1),(size))
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/* Return count up to the end of the buffer. Carefully avoid
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accessing head and tail more than once, so they can change
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underneath us without returning inconsistent results. */
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#define CIRC_CNT_TO_END(head,tail,size) \
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({int end = (size) - (tail); \
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int n = ((head) + end) & ((size)-1); \
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n < end ? n : end;})
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/* Return space available up to the end of the buffer. */
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#define CIRC_SPACE_TO_END(head,tail,size) \
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({int end = (size) - 1 - (head); \
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int n = (end + (tail)) & ((size)-1); \
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n <= end ? n : end+1;})
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#endif /* _LINUX_CIRC_BUF_H */
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