mirror of
https://github.com/edk2-porting/linux-next.git
synced 2024-12-27 14:43:58 +08:00
1da177e4c3
Initial git repository build. I'm not bothering with the full history, even though we have it. We can create a separate "historical" git archive of that later if we want to, and in the meantime it's about 3.2GB when imported into git - space that would just make the early git days unnecessarily complicated, when we don't have a lot of good infrastructure for it. Let it rip!
33 lines
1000 B
C
33 lines
1000 B
C
#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 */
|