51 lines
1.2 KiB
C
51 lines
1.2 KiB
C
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// generic circular buffer (bounded queue) implementation
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#ifndef CBUF_H
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#define CBUF_H
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#include <stdbool.h>
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#include <unistd.h>
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// To define a circular buffer type of 20 ints:
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// typedef CBUF(int, 20) my_cbuf_t;
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//
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// data has length CAP + 1 to distinguish empty vs full.
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#define CBUF(TYPE, CAP) { \
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TYPE data[(CAP) + 1]; \
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size_t head; \
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size_t tail; \
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}
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#define cbuf_size_(PCBUF) \
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(sizeof((PCBUF)->data) / sizeof(*(PCBUF)->data))
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#define cbuf_is_empty(PCBUF) \
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((PCBUF)->head == (PCBUF)->tail)
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#define cbuf_is_full(PCBUF) \
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(((PCBUF)->head + 1) % cbuf_size_(PCBUF) == (PCBUF)->tail)
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#define cbuf_init(PCBUF) \
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(void) ((PCBUF)->head = (PCBUF)->tail = 0)
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#define cbuf_push(PCBUF, ITEM) \
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({ \
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bool ok = !cbuf_is_full(PCBUF); \
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if (ok) { \
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(PCBUF)->data[(PCBUF)->head] = (ITEM); \
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(PCBUF)->head = ((PCBUF)->head + 1) % cbuf_size_(PCBUF); \
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} \
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ok; \
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}) \
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#define cbuf_take(PCBUF, PITEM) \
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({ \
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bool ok = !cbuf_is_empty(PCBUF); \
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if (ok) { \
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*(PITEM) = (PCBUF)->data[(PCBUF)->tail]; \
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(PCBUF)->tail = ((PCBUF)->tail + 1) % cbuf_size_(PCBUF); \
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} \
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ok; \
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})
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#endif
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