Alc/ringbuffer.h

   1 #ifndef RINGBUFFER_H
   2 #define RINGBUFFER_H
   3
   4 #include <stddef.h>
   5
   6 #include <utility>
   7
   8
   9 struct ll_ringbuffer;
  10 using ll_ringbuffer_t = struct ll_ringbuffer;
  11
  12 struct ll_ringbuffer_data {
  13     char *buf;
  14     size_t len;
  15 };
  16 using ll_ringbuffer_data_pair = std::pair<ll_ringbuffer_data,ll_ringbuffer_data>;
  17 using ll_ringbuffer_data_t = struct ll_ringbuffer_data;
  18
  19
  20 /**
  21  * Create a new ringbuffer to hold at least `sz' elements of `elem_sz' bytes.
  22  * The number of elements is rounded up to the next power of two (even if it is
  23  * already a power of two, to ensure the requested amount can be written).
  24  */
  25 ll_ringbuffer_t *ll_ringbuffer_create(size_t sz, size_t elem_sz, int limit_writes);
  26 /** Free all data associated with the ringbuffer `rb'. */
  27 void ll_ringbuffer_free(ll_ringbuffer_t *rb);
  28 /** Reset the read and write pointers to zero. This is not thread safe. */
  29 void ll_ringbuffer_reset(ll_ringbuffer_t *rb);
  30
  31 /**
  32  * The non-copying data reader. Returns two ringbuffer data pointers that hold
  33  * the current readable data at `rb'. If the readable data is in one segment
  34  * the second segment has zero length.
  35  */
  36 ll_ringbuffer_data_pair ll_ringbuffer_get_read_vector(const ll_ringbuffer_t *rb);
  37 /**
  38  * The non-copying data writer. Returns two ringbuffer data pointers that hold
  39  * the current writeable data at `rb'. If the writeable data is in one segment
  40  * the second segment has zero length.
  41  */
  42 ll_ringbuffer_data_pair ll_ringbuffer_get_write_vector(const ll_ringbuffer_t *rb);
  43
  44 /**
  45  * Return the number of elements available for reading. This is the number of
  46  * elements in front of the read pointer and behind the write pointer.
  47  */
  48 size_t ll_ringbuffer_read_space(const ll_ringbuffer_t *rb);
  49 /**
  50  * The copying data reader. Copy at most `cnt' elements from `rb' to `dest'.
  51  * Returns the actual number of elements copied.
  52  */
  53 size_t ll_ringbuffer_read(ll_ringbuffer_t *rb, void *dest, size_t cnt);
  54 /**
  55  * The copying data reader w/o read pointer advance. Copy at most `cnt'
  56  * elements from `rb' to `dest'. Returns the actual number of elements copied.
  57  */
  58 size_t ll_ringbuffer_peek(ll_ringbuffer_t *rb, void *dest, size_t cnt);
  59 /** Advance the read pointer `cnt' places. */
  60 void ll_ringbuffer_read_advance(ll_ringbuffer_t *rb, size_t cnt);
  61
  62 /**
  63  * Return the number of elements available for writing. This is the number of
  64  * elements in front of the write pointer and behind the read pointer.
  65  */
  66 size_t ll_ringbuffer_write_space(const ll_ringbuffer_t *rb);
  67 /**
  68  * The copying data writer. Copy at most `cnt' elements to `rb' from `src'.
  69  * Returns the actual number of elements copied.
  70  */
  71 size_t ll_ringbuffer_write(ll_ringbuffer_t *rb, const void *src, size_t cnt);
  72 /** Advance the write pointer `cnt' places. */
  73 void ll_ringbuffer_write_advance(ll_ringbuffer_t *rb, size_t cnt);
  74
  75 #endif /* RINGBUFFER_H */