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https://github.com/xiaoyifang/goldendict-ng.git
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145 lines
4.5 KiB
C
145 lines
4.5 KiB
C
/*
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* This file is part of FFmpeg.
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*
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* FFmpeg is free software; you can redistribute it and/or
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* modify it under the terms of the GNU Lesser General Public
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* License as published by the Free Software Foundation; either
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* version 2.1 of the License, or (at your option) any later version.
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*
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* FFmpeg 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 GNU
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* Lesser General Public License for more details.
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*
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* You should have received a copy of the GNU Lesser General Public
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* License along with FFmpeg; if not, write to the Free Software
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* Foundation, Inc., 51 Franklin Street, Fifth Floor, Boston, MA 02110-1301 USA
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*/
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/**
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* @file
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* a very simple circular buffer FIFO implementation
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*/
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#ifndef AVUTIL_FIFO_H
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#define AVUTIL_FIFO_H
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#include <stdint.h>
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#include "avutil.h"
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#include "attributes.h"
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typedef struct AVFifoBuffer {
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uint8_t *buffer;
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uint8_t *rptr, *wptr, *end;
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uint32_t rndx, wndx;
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} AVFifoBuffer;
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/**
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* Initialize an AVFifoBuffer.
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* @param size of FIFO
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* @return AVFifoBuffer or NULL in case of memory allocation failure
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*/
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AVFifoBuffer *av_fifo_alloc(unsigned int size);
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/**
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* Free an AVFifoBuffer.
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* @param f AVFifoBuffer to free
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*/
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void av_fifo_free(AVFifoBuffer *f);
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/**
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* Reset the AVFifoBuffer to the state right after av_fifo_alloc, in particular it is emptied.
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* @param f AVFifoBuffer to reset
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*/
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void av_fifo_reset(AVFifoBuffer *f);
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/**
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* Return the amount of data in bytes in the AVFifoBuffer, that is the
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* amount of data you can read from it.
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* @param f AVFifoBuffer to read from
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* @return size
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*/
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int av_fifo_size(AVFifoBuffer *f);
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/**
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* Return the amount of space in bytes in the AVFifoBuffer, that is the
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* amount of data you can write into it.
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* @param f AVFifoBuffer to write into
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* @return size
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*/
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int av_fifo_space(AVFifoBuffer *f);
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/**
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* Feed data from an AVFifoBuffer to a user-supplied callback.
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* @param f AVFifoBuffer to read from
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* @param buf_size number of bytes to read
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* @param func generic read function
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* @param dest data destination
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*/
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int av_fifo_generic_read(AVFifoBuffer *f, void *dest, int buf_size, void (*func)(void*, void*, int));
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/**
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* Feed data from a user-supplied callback to an AVFifoBuffer.
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* @param f AVFifoBuffer to write to
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* @param src data source; non-const since it may be used as a
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* modifiable context by the function defined in func
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* @param size number of bytes to write
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* @param func generic write function; the first parameter is src,
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* the second is dest_buf, the third is dest_buf_size.
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* func must return the number of bytes written to dest_buf, or <= 0 to
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* indicate no more data available to write.
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* If func is NULL, src is interpreted as a simple byte array for source data.
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* @return the number of bytes written to the FIFO
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*/
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int av_fifo_generic_write(AVFifoBuffer *f, void *src, int size, int (*func)(void*, void*, int));
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/**
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* Resize an AVFifoBuffer.
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* In case of reallocation failure, the old FIFO is kept unchanged.
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*
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* @param f AVFifoBuffer to resize
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* @param size new AVFifoBuffer size in bytes
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* @return <0 for failure, >=0 otherwise
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*/
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int av_fifo_realloc2(AVFifoBuffer *f, unsigned int size);
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/**
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* Enlarge an AVFifoBuffer.
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* In case of reallocation failure, the old FIFO is kept unchanged.
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* The new fifo size may be larger than the requested size.
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*
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* @param f AVFifoBuffer to resize
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* @param additional_space the amount of space in bytes to allocate in addition to av_fifo_size()
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* @return <0 for failure, >=0 otherwise
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*/
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int av_fifo_grow(AVFifoBuffer *f, unsigned int additional_space);
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/**
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* Read and discard the specified amount of data from an AVFifoBuffer.
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* @param f AVFifoBuffer to read from
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* @param size amount of data to read in bytes
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*/
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void av_fifo_drain(AVFifoBuffer *f, int size);
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/**
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* Return a pointer to the data stored in a FIFO buffer at a certain offset.
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* The FIFO buffer is not modified.
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*
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* @param f AVFifoBuffer to peek at, f must be non-NULL
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* @param offs an offset in bytes, its absolute value must be less
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* than the used buffer size or the returned pointer will
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* point outside to the buffer data.
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* The used buffer size can be checked with av_fifo_size().
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*/
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static inline uint8_t *av_fifo_peek2(const AVFifoBuffer *f, int offs)
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{
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uint8_t *ptr = f->rptr + offs;
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if (ptr >= f->end)
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ptr = f->buffer + (ptr - f->end);
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else if (ptr < f->buffer)
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ptr = f->end - (f->buffer - ptr);
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return ptr;
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}
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#endif /* AVUTIL_FIFO_H */
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