libc/kernel/common/linux/circ_buf.h

/****************************************************************************
 ****************************************************************************
 ***
 ***   This header was automatically generated from a Linux kernel header
 ***   of the same name, to make information necessary for userspace to
 ***   call into the kernel available to libc.  It contains only constants,
 ***   structures, and macros generated from the original header, and thus,
 ***   contains no copyrightable information.
 ***
 ****************************************************************************
 ****************************************************************************/
#ifndef _LINUX_CIRC_BUF_H
#define _LINUX_CIRC_BUF_H 1

struct circ_buf {
 char *buf;
 int head;
 int tail;
};

#define CIRC_CNT(head,tail,size) (((head) - (tail)) & ((size)-1))

#define CIRC_SPACE(head,tail,size) CIRC_CNT((tail),((head)+1),(size))

#define CIRC_CNT_TO_END(head,tail,size)   ({int end = (size) - (tail);   int n = ((head) + end) & ((size)-1);   n < end ? n : end;})

#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