mirror of
https://github.com/mpv-player/mpv
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bff03a181f
Currently every single AO was implementing it's own ringbuffer, many times with slightly different semantics. This is an attempt to fix the problem. I stole some good ideas from ao_portaudio's ringbuffer and went from there. The main difference is this one stores wpos and rpos which are absolute positions in an "infinite" buffer. To find the actual position for writing / reading just apply modulo size. The producer only modifies wpos while the consumer only modifies rpos. This makes it pretty easy to reason about and make the operations thread safe by using barriers (thread safety is guaranteed only in the Single-Producer/Single- Consumer case). Also adapted ao_coreaudio to use this ringbuffer.
126 lines
3.5 KiB
C
126 lines
3.5 KiB
C
/*
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* This file is part of mpv.
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* Copyright (c) 2012 wm4
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* Copyright (c) 2013 Stefano Pigozzi <stefano.pigozzi@gmail.com>
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*
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* mpv is free software; you can redistribute it and/or modify
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* it under the terms of the GNU General Public License as published by
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* the Free Software Foundation; either version 2 of the License, or
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* (at your option) any later version.
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*
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* mpv is distributed in the hope that it will be useful,
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* but WITHOUT ANY WARRANTY; without even the implied warranty of
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* MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE. See the
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* GNU General Public License for more details.
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*
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* You should have received a copy of the GNU General Public License along
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* with mpv. If not, see <http://www.gnu.org/licenses/>.
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*/
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#ifndef MPV_MP_RING_H
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#define MPV_MP_RING_H
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/**
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* A simple non-blocking SPSC (single producer, single consumer) ringbuffer
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* implementation. Thread safety is accomplished through atomic operations.
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*/
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struct mp_ring;
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/**
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* Instantiate a new ringbuffer
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*
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* talloc_ctx: talloc context of the newly created object
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* size: total size in bytes
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* return: the newly created ringbuffer
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*/
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struct mp_ring *mp_ring_new(void *talloc_ctx, int size);
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/**
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* Read data from the ringbuffer
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*
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* buffer: target ringbuffer instance
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* dest: destination buffer for the read data. If NULL read data is discarded.
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* len: maximum number of bytes to read
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* return: number of bytes read
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*/
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int mp_ring_read(struct mp_ring *buffer, unsigned char *dest, int len);
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/**
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* Read data from the ringbuffer
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*
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* This function behaves similarly to `av_fifo_generic_read` and was actually
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* added for compatibility with code that was written for it.
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* This function will drain the returned amount of bytes from the ringbuffer
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* so you don't have to handle that in inside `func`.
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*
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* buffer: target ringbuffer instance
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* ctx: context for the callback function
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* len: maximum number of bytes to read
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* func: callback function to customize reading behaviour
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* return: number of bytes read
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*/
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int mp_ring_read_cb(struct mp_ring *buffer, void *ctx, int len,
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void (*func)(void*, void*, int));
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/**
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* Write data to the ringbuffer
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*
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* buffer: target ringbuffer instance
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* src: source buffer for the write data
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* len: maximum number of bytes to write
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* return: number of bytes written
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*/
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int mp_ring_write(struct mp_ring *buffer, unsigned char *src, int len);
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/**
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* Drain data from the ringbuffer
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*
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* buffer: target ringbuffer instance
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* len: maximum number of bytes to drain
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* return: number of bytes drained
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*/
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int mp_ring_drain(struct mp_ring *buffer, int len);
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/**
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* Reset the ringbuffer discarding any content
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*
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* buffer: target ringbuffer instance
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*/
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void mp_ring_reset(struct mp_ring *buffer);
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/**
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* Get the available size for writing
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*
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* buffer: target ringbuffer instance
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* return: number of bytes that can be written
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*/
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int mp_ring_available(struct mp_ring *buffer);
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/**
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* Get the total size
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*
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* buffer: target ringbuffer instance
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* return: total ringbuffer size
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*/
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int mp_ring_size(struct mp_ring *buffer);
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/**
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* Get the available size for reading
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*
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* buffer: target ringbuffer instance
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* return: number of bytes ready for reading
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*/
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int mp_ring_buffered(struct mp_ring *buffer);
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/**
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* Get a string representation of the ringbuffer
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*
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* buffer: target ringbuffer instance
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* talloc_ctx: talloc context of the newly created string
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* return: string representing the ringbuffer
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*/
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char *mp_ring_repr(struct mp_ring *buffer, void *talloc_ctx);
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#endif
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