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author | Daniel Baumann <daniel.baumann@progress-linux.org> | 2024-04-07 18:49:45 +0000 |
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committer | Daniel Baumann <daniel.baumann@progress-linux.org> | 2024-04-07 18:49:45 +0000 |
commit | 2c3c1048746a4622d8c89a29670120dc8fab93c4 (patch) | |
tree | 848558de17fb3008cdf4d861b01ac7781903ce39 /include/linux/circ_buf.h | |
parent | Initial commit. (diff) | |
download | linux-2c3c1048746a4622d8c89a29670120dc8fab93c4.tar.xz linux-2c3c1048746a4622d8c89a29670120dc8fab93c4.zip |
Adding upstream version 6.1.76.upstream/6.1.76upstream
Signed-off-by: Daniel Baumann <daniel.baumann@progress-linux.org>
Diffstat (limited to 'include/linux/circ_buf.h')
-rw-r--r-- | include/linux/circ_buf.h | 37 |
1 files changed, 37 insertions, 0 deletions
diff --git a/include/linux/circ_buf.h b/include/linux/circ_buf.h new file mode 100644 index 000000000..b3233e820 --- /dev/null +++ b/include/linux/circ_buf.h @@ -0,0 +1,37 @@ +/* SPDX-License-Identifier: GPL-2.0 */ +/* + * See Documentation/core-api/circular-buffers.rst 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 */ |