1 /****************************************************************************
2 ****************************************************************************
3 ***
4 *** This header was automatically generated from a Linux kernel header
5 *** of the same name, to make information necessary for userspace to
6 *** call into the kernel available to libc. It contains only constants,
7 *** structures, and macros generated from the original header, and thus,
8 *** contains no copyrightable information.
9 ***
10 ****************************************************************************
11 ****************************************************************************/
12 #ifndef _LINUX_CIRC_BUF_H
13 #define _LINUX_CIRC_BUF_H 1
15 struct circ_buf {
16 char *buf;
17 int head;
18 int tail;
19 };
21 #define CIRC_CNT(head,tail,size) (((head) - (tail)) & ((size)-1))
23 #define CIRC_SPACE(head,tail,size) CIRC_CNT((tail),((head)+1),(size))
25 #define CIRC_CNT_TO_END(head,tail,size) ({int end = (size) - (tail); int n = ((head) + end) & ((size)-1); n < end ? n : end;})
27 #define CIRC_SPACE_TO_END(head,tail,size) ({int end = (size) - 1 - (head); int n = (end + (tail)) & ((size)-1); n <= end ? n : end+1;})
29 #endif