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.

1 files changed, 160 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;
+}