From f9fc3a42cc859c90b55c10743bd84832fa156b98 Mon Sep 17 00:00:00 2001 From: Max Kellermann Date: Tue, 15 Jan 2013 01:00:59 +0100 Subject: fifo_buffer: move to util/ --- src/util/fifo_buffer.c | 210 +++++++++++++++++++++++++++++++++++++++++++++++++ 1 file changed, 210 insertions(+) create mode 100644 src/util/fifo_buffer.c (limited to 'src/util/fifo_buffer.c') diff --git a/src/util/fifo_buffer.c b/src/util/fifo_buffer.c new file mode 100644 index 000000000..915fb0579 --- /dev/null +++ b/src/util/fifo_buffer.c @@ -0,0 +1,210 @@ +/* + * 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 + +#include +#include + +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; +} -- cgit v1.2.3