mirror of
https://github.com/edk2-porting/linux-next.git
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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
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#define _LINUX_CIRC_BUF_H 1
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struct circ_buf {
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char *buf;
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int head;
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int tail;
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};
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/* Return count in buffer. */
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#define CIRC_CNT(head,tail,size) (((head) - (tail)) & ((size)-1))
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/* Return space available, 0..size-1. We always leave one free char
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as a completely full buffer has head == tail, which is the same as
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empty. */
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#define CIRC_SPACE(head,tail,size) CIRC_CNT((tail),((head)+1),(size))
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/* Return count up to the end of the buffer. Carefully avoid
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accessing head and tail more than once, so they can change
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underneath us without returning inconsistent results. */
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#define CIRC_CNT_TO_END(head,tail,size) \
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({int end = (size) - (tail); \
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int n = ((head) + end) & ((size)-1); \
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n < end ? n : end;})
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/* Return space available up to the end of the buffer. */
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#define CIRC_SPACE_TO_END(head,tail,size) \
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({int end = (size) - 1 - (head); \
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int n = (end + (tail)) & ((size)-1); \
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n <= end ? n : end+1;})
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#endif /* _LINUX_CIRC_BUF_H */
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