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/*
* QEMU generic buffers
*
* Copyright (c) 2015 Red Hat, Inc.
*
* This library 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 of the License, or (at your option) any later version.
*
* This library 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 library; if not, see <http://www.gnu.org/licenses/>.
*
*/
#ifndef QEMU_BUFFER_H
#define QEMU_BUFFER_H
#include "qemu-common.h"
typedef struct Buffer Buffer;
/**
* Buffer:
*
* The Buffer object provides a simple dynamically resizing
* array, with separate tracking of capacity and usage. This
* is typically useful when buffering I/O or processing data.
*/
struct Buffer {
char *name;
size_t capacity;
size_t offset;
uint64_t avg_size;
uint8_t *buffer;
};
/**
* buffer_init:
* @buffer: the buffer object
* @name: buffer name
*
* Optionally attach a name to the buffer, to make it easier
* to identify in debug traces.
*/
void buffer_init(Buffer *buffer, const char *name, ...)
GCC_FMT_ATTR(2, 3);
/**
* buffer_shrink:
* @buffer: the buffer object
*
* Try to shrink the buffer. Checks current buffer capacity and size
* and reduces capacity in case only a fraction of the buffer is
* actually used.
*/
void buffer_shrink(Buffer *buffer);
/**
* buffer_reserve:
* @buffer: the buffer object
* @len: the minimum required free space
*
* Ensure that the buffer has space allocated for at least
* @len bytes. If the current buffer is too small, it will
* be reallocated, possibly to a larger size than requested.
*/
void buffer_reserve(Buffer *buffer, size_t len);
/**
* buffer_reset:
* @buffer: the buffer object
*
* Reset the length of the stored data to zero, but do
* not free / reallocate the memory buffer
*/
void buffer_reset(Buffer *buffer);
/**
* buffer_free:
* @buffer: the buffer object
*
* Reset the length of the stored data to zero and also
* free the internal memory buffer
*/
void buffer_free(Buffer *buffer);
/**
* buffer_append:
* @buffer: the buffer object
* @data: the data block to append
* @len: the length of @data in bytes
*
* Append the contents of @data to the end of the buffer.
* The caller must ensure that the buffer has sufficient
* free space for @len bytes, typically by calling the
* buffer_reserve() method prior to appending.
*/
void buffer_append(Buffer *buffer, const void *data, size_t len);
/**
* buffer_advance:
* @buffer: the buffer object
* @len: the number of bytes to skip
*
* Remove @len bytes of data from the head of the buffer.
* The internal buffer will not be reallocated, so will
* have at least @len bytes of free space after this
* call completes
*/
void buffer_advance(Buffer *buffer, size_t len);
/**
* buffer_end:
* @buffer: the buffer object
*
* Get a pointer to the tail end of the internal buffer
* The returned pointer is only valid until the next
* call to buffer_reserve().
*
* Returns: the tail of the buffer
*/
uint8_t *buffer_end(Buffer *buffer);
/**
* buffer_empty:
* @buffer: the buffer object
*
* Determine if the buffer contains any current data
*
* Returns: true if the buffer holds data, false otherwise
*/
gboolean buffer_empty(Buffer *buffer);
/**
* buffer_move_empty:
* @to: destination buffer object
* @from: source buffer object
*
* Moves buffer, without copying data. 'to' buffer must be empty.
* 'from' buffer is empty and zero-sized on return.
*/
void buffer_move_empty(Buffer *to, Buffer *from);
/**
* buffer_move:
* @to: destination buffer object
* @from: source buffer object
*
* Moves buffer, copying data (unless 'to' buffer happens to be empty).
* 'from' buffer is empty and zero-sized on return.
*/
void buffer_move(Buffer *to, Buffer *from);
#endif /* QEMU_BUFFER_H */
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