Subversion Repositories test_project

#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  */