by Jakub Tyszkowski

[permalink] [raw]

Subject: [PATCH 01/22] cbuffer: Circular buffer initial implementation

Adds circular buffer needed by the AT command parser.
---
src/shared/cbuffer.c | 124 ++++++++++++++++++++++++++++++++++++++++++++++++++
src/shared/cbuffer.h | 33 ++++++++++++++
2 files changed, 157 insertions(+)
create mode 100644 src/shared/cbuffer.c
create mode 100644 src/shared/cbuffer.h

diff --git a/src/shared/cbuffer.c b/src/shared/cbuffer.c
new file mode 100644
index 0000000..7dde707
--- /dev/null
+++ b/src/shared/cbuffer.c
@@ -0,0 +1,124 @@
+/*
+ *
+ * BlueZ - Bluetooth protocol stack for Linux
+ *
+ * Copyright (C) 2013 Intel Corporation. All rights reserved.
+ *
+ *
+ * This library is free software; you can redistribute it and/or
+ * modify it under the terms of the GNU Lesser General Public
+ * License as published by the Free Software Foundation; either
+ * version 2.1 of the License, or (at your option) any later version.
+ *
+ * This library is distributed in the hope that it will be useful,
+ * but WITHOUT ANY WARRANTY; without even the implied warranty of
+ * MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE. See the GNU
+ * Lesser General Public License for more details.
+ *
+ * You should have received a copy of the GNU Lesser General Public
+ * License along with this library; if not, write to the Free Software
+ * Foundation, Inc., 51 Franklin St, Fifth Floor, Boston, MA 02110-1301 USA
+ *
+ */
+
+#include <stdlib.h>
+#include <errno.h>
+
+#include "cbuffer.h"
+
+struct circular_buffer {
+ int size;
+ int start;
+ int end;
+ char *data;
+};
+
+/* find next closest power of 2 */
+static int cbuffer_find_next_po2(unsigned int size)
+{
+ size--;
+ size |= size >> 1;
+ size |= size >> 2;
+ size |= size >> 4;
+ size |= size >> 8;
+ size |= size >> 16;
+ size++;
+ return size;
+}
+
+struct circular_buffer *cbuffer_init(unsigned int size)
+{
+ struct circular_buffer *cbuff = malloc(sizeof(struct circular_buffer));
+
+ if (!cbuff)
+ return NULL;
+
+ /* Need 2^x size for this implementation of circular buffer */
+ cbuff->size = cbuffer_find_next_po2(size);
+ cbuff->start = 0;
+ cbuff->end = 0;
+ cbuff->data = NULL;
+
+ cbuff->data = malloc(cbuff->size);
+ if (!cbuff->data) {
+ free(cbuff);
+ return NULL;
+ }
+
+ return cbuff;
+}
+
+void cbuffer_free(struct circular_buffer *cbuff)
+{
+ free(cbuff->data);
+ cbuff->data = NULL;
+ free(cbuff);
+}
+
+void cbuffer_drain(struct circular_buffer *cbuff)
+{
+ cbuff->start = 0;
+ cbuff->end = 0;
+}
+
+int cbuffer_is_full(struct circular_buffer *cbuff)
+{
+ /* Most significant bit inverted for comparison - index mirroring */
+ return cbuff->end == (cbuff->start ^ cbuff->size);
+}
+
+int cbuffer_is_empty(struct circular_buffer *cbuff)
+{
+ return cbuff->end == cbuff->start;
+}
+
+static void cbuffer_incr(struct circular_buffer *cbuff, int *p)
+{
+ /* Modulo 2*size offset incrementation - index mirroring */
+ *p = (*p + 1) & (2 * cbuff->size - 1);
+}
+
+int cbuffer_write(struct circular_buffer *cbuff, char source)
+{
+ if (!cbuffer_is_full(cbuff)) {
+ cbuff->data[cbuff->end & (cbuff->size - 1)] = source;
+ cbuffer_incr(cbuff, &cbuff->end);
+ return 0;
+ }
+ return -ENOSPC;
+}
+
+int cbuffer_read(struct circular_buffer *cbuff, char *dest)
+{
+ if (!cbuffer_is_empty(cbuff)) {
+ *dest = cbuff->data[cbuff->start & (cbuff->size - 1)];
+ cbuffer_incr(cbuff, &cbuff->start);
+ return 0;
+ }
+ return -ENODATA;
+}
+
+unsigned int cbuffer_get_size(struct circular_buffer *cbuff)
+{
+ return cbuff->size;
+}
diff --git a/src/shared/cbuffer.h b/src/shared/cbuffer.h
new file mode 100644
index 0000000..8865f1f
--- /dev/null
+++ b/src/shared/cbuffer.h
@@ -0,0 +1,33 @@
+/*
+ *
+ * BlueZ - Bluetooth protocol stack for Linux
+ *
+ * Copyright (C) 2013 Intel Corporation. All rights reserved.
+ *
+ *
+ * This library is free software; you can redistribute it and/or
+ * modify it under the terms of the GNU Lesser General Public
+ * License as published by the Free Software Foundation; either
+ * version 2.1 of the License, or (at your option) any later version.
+ *
+ * This library is distributed in the hope that it will be useful,
+ * but WITHOUT ANY WARRANTY; without even the implied warranty of
+ * MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE. See the GNU
+ * Lesser General Public License for more details.
+ *
+ * You should have received a copy of the GNU Lesser General Public
+ * License along with this library; if not, write to the Free Software
+ * Foundation, Inc., 51 Franklin St, Fifth Floor, Boston, MA 02110-1301 USA
+ *
+ */
+
+struct circular_buffer;
+
+struct circular_buffer *cbuffer_init(unsigned int size);
+void cbuffer_free(struct circular_buffer *cbuff);
+int cbuffer_write(struct circular_buffer *cbuff, char source);
+int cbuffer_read(struct circular_buffer *cbuff, char *dest);
+void cbuffer_drain(struct circular_buffer *cbuff);
+int cbuffer_is_full(struct circular_buffer *cbuff);
+int cbuffer_is_empty(struct circular_buffer *cbuff);
+unsigned int cbuffer_get_size(struct circular_buffer *cbuff);
--
1.7.9.5