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 14 15 struct circ_buf { 16 char *buf; 17 int head; 18 int tail; 19 }; 20 21 #define CIRC_CNT(head,tail,size) (((head) - (tail)) & ((size)-1)) 22 23 #define CIRC_SPACE(head,tail,size) CIRC_CNT((tail),((head)+1),(size)) 24 25 #define CIRC_CNT_TO_END(head,tail,size) ({int end = (size) - (tail); int n = ((head) + end) & ((size)-1); n < end ? n : end;}) 26 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;}) 28 29 #endif 30
