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authorMax Kellermann <max@duempel.org>2009-03-14 17:30:00 +0100
committerMax Kellermann <max@duempel.org>2009-03-14 17:30:00 +0100
commitc76d35969be2acba2dbdcc3e972cad279b22938a (patch)
tree408d0d361ac330983493fb7ed16b73fcac10a57e /src
parent24bc277b6955278bfef9d7e5adf0e28fd28cdc87 (diff)
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fifo_buffer: added buffering library
It is a library which I have written years ago for other projects. This library is licensed under BSD 2-clause, because it is very generic.
Diffstat (limited to 'src')
-rw-r--r--src/fifo_buffer.c160
-rw-r--r--src/fifo_buffer.h128
2 files changed, 288 insertions, 0 deletions
diff --git a/src/fifo_buffer.c b/src/fifo_buffer.c
new file mode 100644
index 000000000..adee438c0
--- /dev/null
+++ b/src/fifo_buffer.c
@@ -0,0 +1,160 @@
+/*
+ * Copyright (C) 2003-2009 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 "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;
+}
+
+void
+fifo_buffer_free(struct fifo_buffer *buffer)
+{
+ assert(buffer != NULL);
+
+ g_free(buffer);
+}
+
+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;
+}
diff --git a/src/fifo_buffer.h b/src/fifo_buffer.h
new file mode 100644
index 000000000..4af6bde3b
--- /dev/null
+++ b/src/fifo_buffer.h
@@ -0,0 +1,128 @@
+/*
+ * Copyright (C) 2003-2009 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.
+ */
+
+/** \file
+ *
+ * This is a general purpose FIFO buffer library. You may append data
+ * at the end, while another instance reads data from the beginning.
+ * It is optimized for zero-copy usage: you get pointers to the real
+ * buffer, where you may operate on.
+ *
+ * This library is not thread safe.
+ */
+
+#ifndef MPD_FIFO_BUFFER_H
+#define MPD_FIFO_BUFFER_H
+
+#include <stdbool.h>
+#include <stddef.h>
+
+struct fifo_buffer;
+
+/**
+ * Creates a new #fifo_buffer object. Free this object with
+ * fifo_buffer_free().
+ *
+ * @param size the size of the buffer in bytes
+ * @return the new #fifo_buffer object
+ */
+struct fifo_buffer *
+fifo_buffer_new(size_t size);
+
+/**
+ * Frees the resources consumed by this #fifo_buffer object.
+ */
+void
+fifo_buffer_free(struct fifo_buffer *buffer);
+
+/**
+ * Clears all data currently in this #fifo_buffer object. This does
+ * not overwrite the actuall buffer; it just resets the internal
+ * pointers.
+ */
+void
+fifo_buffer_clear(struct fifo_buffer *buffer);
+
+/**
+ * Reads from the beginning of the buffer. To remove consumed data
+ * from the buffer, call fifo_buffer_consume().
+ *
+ * @param buffer the #fifo_buffer object
+ * @param length_r the maximum amount to read is returned here
+ * @return a pointer to the beginning of the buffer, or NULL if the
+ * buffer is empty
+ */
+const void *
+fifo_buffer_read(const struct fifo_buffer *buffer, size_t *length_r);
+
+/**
+ * Marks data at the beginning of the buffer as "consumed".
+ *
+ * @param buffer the #fifo_buffer object
+ * @param length the number of bytes which were consumed
+ */
+void
+fifo_buffer_consume(struct fifo_buffer *buffer, size_t length);
+
+/**
+ * Prepares writing to the buffer. This returns a buffer which you
+ * can write to. To commit the write operation, call
+ * fifo_buffer_append().
+ *
+ * @param buffer the #fifo_buffer object
+ * @param max_length_r the maximum amount to write is returned here
+ * @return a pointer to the end of the buffer, or NULL if the buffer
+ * is already full
+ */
+void *
+fifo_buffer_write(struct fifo_buffer *buffer, size_t *max_length_r);
+
+/**
+ * Commits the write operation initiated by fifo_buffer_write().
+ *
+ * @param buffer the #fifo_buffer object
+ * @param length the number of bytes which were written
+ */
+void
+fifo_buffer_append(struct fifo_buffer *buffer, size_t length);
+
+/**
+ * Checks if the buffer is empty.
+ */
+bool
+fifo_buffer_is_empty(struct fifo_buffer *buffer);
+
+/**
+ * Checks if the buffer is full.
+ */
+bool
+fifo_buffer_is_full(struct fifo_buffer *buffer);
+
+#endif