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/*
* Copyright (C) 2003-2011 The Music Player Daemon Project
* http://www.musicpd.org
*
* Redistribution and use in source and binary forms, with or without
* modification, are permitted provided that the following conditions
* are met:
*
* - Redistributions of source code must retain the above copyright
* notice, this list of conditions and the following disclaimer.
*
* - Redistributions in binary form must reproduce the above copyright
* notice, this list of conditions and the following disclaimer in the
* documentation and/or other materials provided with the
* distribution.
*
* THIS SOFTWARE IS PROVIDED BY THE COPYRIGHT HOLDERS AND CONTRIBUTORS
* ``AS IS'' AND ANY EXPRESS OR IMPLIED WARRANTIES, INCLUDING, BUT NOT
* LIMITED TO, THE IMPLIED WARRANTIES OF MERCHANTABILITY AND FITNESS
* FOR A PARTICULAR PURPOSE ARE DISCLAIMED. IN NO EVENT SHALL THE
* FOUNDATION OR CONTRIBUTORS BE LIABLE FOR ANY DIRECT, INDIRECT,
* INCIDENTAL, SPECIAL, EXEMPLARY, OR CONSEQUENTIAL DAMAGES
* (INCLUDING, BUT NOT LIMITED TO, PROCUREMENT OF SUBSTITUTE GOODS OR
* SERVICES; LOSS OF USE, DATA, OR PROFITS; OR BUSINESS INTERRUPTION)
* HOWEVER CAUSED AND ON ANY THEORY OF LIABILITY, WHETHER IN CONTRACT,
* STRICT LIABILITY, OR TORT (INCLUDING NEGLIGENCE OR OTHERWISE)
* ARISING IN ANY WAY OUT OF THE USE OF THIS SOFTWARE, EVEN IF ADVISED
* OF THE POSSIBILITY OF SUCH DAMAGE.
*/
#include "config.h"
#include "fifo_buffer.h"
#include <glib.h>
#include <assert.h>
#include <string.h>
struct fifo_buffer {
size_t size, start, end;
unsigned char buffer[sizeof(size_t)];
};
struct fifo_buffer *
fifo_buffer_new(size_t size)
{
struct fifo_buffer *buffer;
assert(size > 0);
buffer = (struct fifo_buffer *)g_malloc(sizeof(*buffer) -
sizeof(buffer->buffer) + size);
buffer->size = size;
buffer->start = 0;
buffer->end = 0;
return buffer;
}
static void
fifo_buffer_move(struct fifo_buffer *buffer);
struct fifo_buffer *
fifo_buffer_realloc(struct fifo_buffer *buffer, size_t new_size)
{
if (buffer == NULL)
return new_size > 0
? fifo_buffer_new(new_size)
: NULL;
/* existing data must fit in new size */
assert(new_size >= buffer->end - buffer->start);
if (new_size == 0) {
fifo_buffer_free(buffer);
return NULL;
}
/* compress the buffer when we're shrinking and the tail of
the buffer would exceed the new size */
if (buffer->end > new_size)
fifo_buffer_move(buffer);
/* existing data must fit in new size: second check */
assert(buffer->end <= new_size);
buffer = g_realloc(buffer, sizeof(*buffer) - sizeof(buffer->buffer) +
new_size);
buffer->size = new_size;
return buffer;
}
void
fifo_buffer_free(struct fifo_buffer *buffer)
{
assert(buffer != NULL);
g_free(buffer);
}
size_t
fifo_buffer_capacity(const struct fifo_buffer *buffer)
{
assert(buffer != NULL);
return buffer->size;
}
size_t
fifo_buffer_available(const struct fifo_buffer *buffer)
{
assert(buffer != NULL);
return buffer->end - buffer->start;
}
void
fifo_buffer_clear(struct fifo_buffer *buffer)
{
assert(buffer != NULL);
buffer->start = 0;
buffer->end = 0;
}
const void *
fifo_buffer_read(const struct fifo_buffer *buffer, size_t *length_r)
{
assert(buffer != NULL);
assert(buffer->end >= buffer->start);
assert(length_r != NULL);
if (buffer->start == buffer->end)
/* the buffer is empty */
return NULL;
*length_r = buffer->end - buffer->start;
return buffer->buffer + buffer->start;
}
void
fifo_buffer_consume(struct fifo_buffer *buffer, size_t length)
{
assert(buffer != NULL);
assert(buffer->end >= buffer->start);
assert(buffer->start + length <= buffer->end);
buffer->start += length;
}
/**
* Move data to the beginning of the buffer, to make room at the end.
*/
static void
fifo_buffer_move(struct fifo_buffer *buffer)
{
if (buffer->start == 0)
return;
if (buffer->end > buffer->start)
memmove(buffer->buffer,
buffer->buffer + buffer->start,
buffer->end - buffer->start);
buffer->end -= buffer->start;
buffer->start = 0;
}
void *
fifo_buffer_write(struct fifo_buffer *buffer, size_t *max_length_r)
{
assert(buffer != NULL);
assert(buffer->end <= buffer->size);
assert(max_length_r != NULL);
if (buffer->end == buffer->size) {
fifo_buffer_move(buffer);
if (buffer->end == buffer->size)
return NULL;
} else if (buffer->start > 0 && buffer->start == buffer->end) {
buffer->start = 0;
buffer->end = 0;
}
*max_length_r = buffer->size - buffer->end;
return buffer->buffer + buffer->end;
}
void
fifo_buffer_append(struct fifo_buffer *buffer, size_t length)
{
assert(buffer != NULL);
assert(buffer->end >= buffer->start);
assert(buffer->end + length <= buffer->size);
buffer->end += length;
}
bool
fifo_buffer_is_empty(struct fifo_buffer *buffer)
{
return buffer->start == buffer->end;
}
bool
fifo_buffer_is_full(struct fifo_buffer *buffer)
{
return buffer->start == 0 && buffer->end == buffer->size;
}
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