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/**
* Copyright (C) 2018 Joseph Benden <joe@benden.us>
*
* Permission is hereby granted, free of charge, to any person obtaining a
* copy of this software and associated documentation files (the "Software"),
* to deal in the Software without restriction, including without limitation
* the rights to use, copy, modify, merge, publish, distribute, sublicense,
* and/or sell copies of the Software, and to permit persons to whom the
* Software is furnished to do so, subject to the following conditions:
*
* The above copyright notice and this permission notice shall be included in
* all copies or substantial portions of the Software.
*
* THE SOFTWARE IS PROVIDED "AS IS", WITHOUT WARRANTY OF ANY KIND, EXPRESS OR
* IMPLIED, INCLUDING BUT NOT LIMITED TO THE WARRANTIES OF MERCHANTABILITY,
* FITNESS FOR A PARTICULAR PURPOSE AND NONINFRINGEMENT. IN NO EVENT SHALL THE
* AUTHORS OR COPYRIGHT HOLDERS BE LIABLE FOR ANY CLAIM, DAMAGES OR OTHER
* LIABILITY, WHETHER IN AN ACTION OF CONTRACT, TORT OR OTHERWISE, ARISING
* FROM, OUT OF OR IN CONNECTION WITH THE SOFTWARE OR THE USE OR OTHER
* DEALINGS IN THE SOFTWARE.
**/
#ifdef HAVE_CONFIG_H
#include "config.h"
#endif
#include <stdlib.h>
#include <stdint.h>
#include <stdio.h>
#include <stddef.h>
#include <stdbool.h>
#include <string.h>
#include <assert.h>
#include "aircrack-ng/defs.h"
#include "aircrack-ng/adt/circular_buffer.h"
#ifndef NDEBUG
static inline bool is_power_of_two(size_t n)
{
REQUIRE(n > 0);
while ((n % 2) == 0)
{
n /= 2;
}
if (n == 1) return true;
return false;
}
#endif
// The definition of our circular buffer is hidden from the API user.
struct circular_buffer_t
{
uint8_t * buffer; /// Circular buffer's memory location.
size_t read_pos; /// Current read position, as element index.
size_t write_pos; /// Current write position, as element index.
size_t max; /// Number of bytes allocated for whole ring buffer.
size_t size; /// Number of bytes required for a single element.
};
/*
* A circular buffer uses the "Virtual Streams" approach, as described on
* the Ryg blog:
*
* https://fgiesen.wordpress.com/2010/12/14/ring-buffers-and-queues/
*/
#define CBUF_BUFFER_POS(cbuf, which) \
(cbuf->buffer + ((cbuf->which % (cbuf->max / cbuf->size)) * cbuf->size))
static inline void check_invariants(cbuf_handle_t cbuf)
{
#ifdef NDEBUG
(void) cbuf;
#endif
// All writes to structure are always ahead of the reads, unless empty.
INVARIANT(cbuf->write_pos >= cbuf->read_pos);
// All writes are restricted to the inside of our buffer's region.
INVARIANT(cbuf->write_pos - cbuf->read_pos <= (cbuf->max / cbuf->size));
}
API_EXPORT cbuf_handle_t circular_buffer_init(uint8_t * buffer,
size_t bufferSize,
size_t elementSize)
{
REQUIRE(buffer && bufferSize && elementSize);
REQUIRE(bufferSize % elementSize == 0);
REQUIRE(is_power_of_two(bufferSize));
cbuf_handle_t cbuf = calloc(1, sizeof(circular_buffer_t));
ALLEGE(cbuf);
cbuf->buffer = buffer;
cbuf->max = bufferSize;
cbuf->size = elementSize;
circular_buffer_reset(cbuf);
ENSURE(circular_buffer_is_empty(cbuf));
return cbuf;
}
API_EXPORT void circular_buffer_free(cbuf_handle_t cbuf)
{
REQUIRE(cbuf);
cbuf->buffer = NULL;
free(cbuf);
}
API_EXPORT void circular_buffer_reset(cbuf_handle_t cbuf)
{
REQUIRE(cbuf);
cbuf->read_pos = 0;
cbuf->write_pos = 0;
}
API_EXPORT bool circular_buffer_is_empty(cbuf_handle_t cbuf)
{
REQUIRE(cbuf);
return cbuf->read_pos == cbuf->write_pos;
}
API_EXPORT bool circular_buffer_is_full(cbuf_handle_t cbuf)
{
REQUIRE(cbuf);
return cbuf->write_pos == (cbuf->read_pos + (cbuf->max / cbuf->size));
}
API_EXPORT size_t circular_buffer_capacity(cbuf_handle_t cbuf)
{
REQUIRE(cbuf);
return cbuf->max / cbuf->size;
}
API_EXPORT size_t circular_buffer_size(cbuf_handle_t cbuf)
{
REQUIRE(cbuf);
return cbuf->write_pos - cbuf->read_pos;
}
API_EXPORT void
circular_buffer_put(cbuf_handle_t cbuf, void const * const data, size_t size)
{
REQUIRE(cbuf && data && size > 0);
REQUIRE(size <= cbuf->size);
memcpy(CBUF_BUFFER_POS(cbuf, write_pos), data, size); // cannot overlap
if (size < cbuf->size)
{
// zero extra buffer bytes
memset(CBUF_BUFFER_POS(cbuf, write_pos) + size, 0, cbuf->size - size);
}
++cbuf->write_pos;
check_invariants(cbuf);
}
API_EXPORT void
circular_buffer_get(cbuf_handle_t cbuf, void * const * data, size_t size)
{
REQUIRE(cbuf && data && size > 0);
REQUIRE(size <= cbuf->size);
memcpy(*data, CBUF_BUFFER_POS(cbuf, read_pos), size); // cannot overlap
++cbuf->read_pos;
check_invariants(cbuf);
}
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