forked from Qortal/Brooklyn
You can not select more than 25 topics
Topics must start with a letter or number, can include dashes ('-') and can be up to 35 characters long.
36 lines
1.0 KiB
36 lines
1.0 KiB
/* |
|
* See Documentation/circular-buffers.txt 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 */
|
|
|