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-/*
- * This file is originally from JACK Audio Connection Kit
- *
- * Copyright (C) 2000 Paul Davis
- * Copyright (C) 2003 Rohan Drape
- *
- * This program is free software; you can redistribute it and/or modify
- * it under the terms of the GNU Lesser General Public License as published by
- * the Free Software Foundation; either version 2.1 of the License, or
- * (at your option) any later version.
- *
- * This program is distributed in the hope that it will be useful,
- * but WITHOUT ANY WARRANTY; without even the implied warranty of
- * MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE. See the
- * GNU Lesser General Public License for more details.
- *
- * You should have received a copy of the GNU Lesser General Public License
- * along with this program; if not, write to the Free Software
- * Foundation, Inc., 59 Temple Place - Suite 330, Boston, MA 02111-1307, USA.
- */
-
-#ifndef MPD_RINGBUF_H
-#define MPD_RINGBUF_H
-
-#include <stddef.h>
-#include <sys/uio.h>
-
-/** @file ringbuf.h
- *
- * A set of library functions to make lock-free ringbuffers available
- * to JACK clients. The `capture_client.c' (in the example_clients
- * directory) is a fully functioning user of this API.
- *
- * The key attribute of a ringbuffer is that it can be safely accessed
- * by two threads simultaneously -- one reading from the buffer and
- * the other writing to it -- without using any synchronization or
- * mutual exclusion primitives. For this to work correctly, there can
- * only be a single reader and a single writer thread. Their
- * identities cannot be interchanged.
- */
-
-struct ringbuf {
- unsigned char *buf;
- size_t write_ptr;
- size_t read_ptr;
- size_t size;
- size_t size_mask;
-};
-
-/**
- * Allocates a ringbuffer data structure of a specified size. The
- * caller must arrange for a call to ringbuf_free() to release
- * the memory associated with the ringbuffer.
- *
- * @param sz the ringbuffer size in bytes.
- *
- * @return a pointer to a new struct ringbuf, if successful; NULL
- * otherwise.
- */
-struct ringbuf *ringbuf_create(size_t sz);
-
-/**
- * Frees the ringbuffer data structure allocated by an earlier call to
- * ringbuf_create().
- *
- * @param rb a pointer to the ringbuffer structure.
- */
-void ringbuf_free(struct ringbuf * rb);
-
-/**
- * Fill a data structure with a description of the current readable
- * data held in the ringbuffer. This description is returned in a two
- * element array of struct iovec. Two elements are needed
- * because the data to be read may be split across the end of the
- * ringbuffer.
- *
- * The first element will always contain a valid @a len field, which
- * may be zero or greater. If the @a len field is non-zero, then data
- * can be read in a contiguous fashion using the address given in the
- * corresponding @a buf field.
- *
- * If the second element has a non-zero @a len field, then a second
- * contiguous stretch of data can be read from the address given in
- * its corresponding @a buf field.
- *
- * @param rb a pointer to the ringbuffer structure.
- * @param vec a pointer to a 2 element array of struct iovec.
- *
- * @return total number of bytes readable into both vec elements
- */
-size_t ringbuf_get_read_vector(const struct ringbuf * rb, struct iovec * vec);
-
-/**
- * Fill a data structure with a description of the current writable
- * space in the ringbuffer. The description is returned in a two
- * element array of struct iovec. Two elements are needed
- * because the space available for writing may be split across the end
- * of the ringbuffer.
- *
- * The first element will always contain a valid @a len field, which
- * may be zero or greater. If the @a len field is non-zero, then data
- * can be written in a contiguous fashion using the address given in
- * the corresponding @a buf field.
- *
- * If the second element has a non-zero @a len field, then a second
- * contiguous stretch of data can be written to the address given in
- * the corresponding @a buf field.
- *
- * @param rb a pointer to the ringbuffer structure.
- * @param vec a pointer to a 2 element array of struct iovec.
- *
- * @return total number of bytes writable in both vec elements
- */
-size_t ringbuf_get_write_vector(const struct ringbuf * rb, struct iovec * vec);
-
-/**
- * Read data from the ringbuffer.
- *
- * @param rb a pointer to the ringbuffer structure.
- * @param dest a pointer to a buffer where data read from the
- * ringbuffer will go.
- * @param cnt the number of bytes to read.
- *
- * @return the number of bytes read, which may range from 0 to cnt.
- */
-size_t ringbuf_read(struct ringbuf * rb, void *dest, size_t cnt);
-
-/**
- * Read data from the ringbuffer. Opposed to ringbuf_read()
- * this function does not move the read pointer. Thus it's
- * a convenient way to inspect data in the ringbuffer in a
- * continous fashion. The price is that the data is copied
- * into a user provided buffer. For "raw" non-copy inspection
- * of the data in the ringbuffer use ringbuf_get_read_vector().
- *
- * @param rb a pointer to the ringbuffer structure.
- * @param dest a pointer to a buffer where data read from the
- * ringbuffer will go.
- * @param cnt the number of bytes to read.
- *
- * @return the number of bytes read, which may range from 0 to cnt.
- */
-size_t ringbuf_peek(struct ringbuf * rb, void *dest, size_t cnt);
-
-/**
- * Advance the read pointer.
- *
- * After data have been read from the ringbuffer using the pointers
- * returned by ringbuf_get_read_vector(), use this function to
- * advance the buffer pointers, making that space available for future
- * write operations.
- *
- * @param rb a pointer to the ringbuffer structure.
- * @param cnt the number of bytes read.
- */
-void ringbuf_read_advance(struct ringbuf * rb, size_t cnt);
-
-/**
- * Return the number of bytes available for reading.
- *
- * @param rb a pointer to the ringbuffer structure.
- *
- * @return the number of bytes available to read.
- */
-size_t ringbuf_read_space(const struct ringbuf * rb);
-
-/**
- * Reset the read and write pointers, making an empty buffer.
- *
- * This is not thread safe.
- *
- * @param rb a pointer to the ringbuffer structure.
- */
-void ringbuf_reset(struct ringbuf * rb);
-
-/**
- * Reset the write pointer to the read pointer, making an empty buffer.
- *
- * This should only be called by the writer
- *
- * @param rb a pointer to the ringbuffer structure.
- */
-void ringbuf_writer_reset(struct ringbuf * rb);
-
-/**
- * Reset the read pointer to the write pointer, making an empty buffer.
- *
- * This should only be called by the reader
- *
- * @param rb a pointer to the ringbuffer structure.
- */
-void ringbuf_reader_reset(struct ringbuf * rb);
-
-/**
- * Write data into the ringbuffer.
- *
- * @param rb a pointer to the ringbuffer structure.
- * @param src a pointer to the data to be written to the ringbuffer.
- * @param cnt the number of bytes to write.
- *
- * @return the number of bytes write, which may range from 0 to cnt
- */
-size_t ringbuf_write(struct ringbuf * rb, const void *src, size_t cnt);
-
-/**
- * Advance the write pointer.
- *
- * After data have been written the ringbuffer using the pointers
- * returned by ringbuf_get_write_vector(), use this function
- * to advance the buffer pointer, making the data available for future
- * read operations.
- *
- * @param rb a pointer to the ringbuffer structure.
- * @param cnt the number of bytes written.
- */
-void ringbuf_write_advance(struct ringbuf * rb, size_t cnt);
-
-/**
- * Return the number of bytes available for writing.
- *
- * @param rb a pointer to the ringbuffer structure.
- *
- * @return the amount of free space (in bytes) available for writing.
- */
-size_t ringbuf_write_space(const struct ringbuf * rb);
-
-#endif /* RINGBUF_H */