Return-Path: From: Jakub Tyszkowski To: linux-bluetooth@vger.kernel.org Subject: [PATCH 01/22] cbuffer: Circular buffer initial implementation Date: Mon, 14 Oct 2013 10:34:17 +0200 Message-Id: <1381739678-16260-2-git-send-email-jakub.tyszkowski@tieto.com> In-Reply-To: <1381739678-16260-1-git-send-email-jakub.tyszkowski@tieto.com> References: <1381739678-16260-1-git-send-email-jakub.tyszkowski@tieto.com> Sender: linux-bluetooth-owner@vger.kernel.org List-ID: 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 +#include + +#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