diff options
Diffstat (limited to 'src/modules/sdlog2/logbuffer.c')
-rw-r--r-- | src/modules/sdlog2/logbuffer.c | 133 |
1 files changed, 133 insertions, 0 deletions
diff --git a/src/modules/sdlog2/logbuffer.c b/src/modules/sdlog2/logbuffer.c new file mode 100644 index 000000000..4205bcf20 --- /dev/null +++ b/src/modules/sdlog2/logbuffer.c @@ -0,0 +1,133 @@ +/**************************************************************************** + * + * Copyright (c) 2013 PX4 Development Team. All rights reserved. + * Author: Anton Babushkin <rk3dov@gmail.com> + * + * Redistribution and use in source and binary forms, with or without + * modification, are permitted provided that the following conditions + * are met: + * + * 1. Redistributions of source code must retain the above copyright + * notice, this list of conditions and the following disclaimer. + * 2. 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. + * 3. Neither the name PX4 nor the names of its contributors may be + * used to endorse or promote products derived from this software + * without specific prior written permission. + * + * 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 + * COPYRIGHT OWNER 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 logbuffer.c + * + * Ring FIFO buffer for binary log data. + * + * @author Anton Babushkin <rk3dov@gmail.com> + */ + +#include <string.h> +#include <stdlib.h> + +#include "logbuffer.h" + +void logbuffer_init(struct logbuffer_s *lb, int size) +{ + lb->size = size; + lb->write_ptr = 0; + lb->read_ptr = 0; + lb->data = malloc(lb->size); +} + +int logbuffer_count(struct logbuffer_s *lb) +{ + int n = lb->write_ptr - lb->read_ptr; + + if (n < 0) { + n += lb->size; + } + + return n; +} + +int logbuffer_is_empty(struct logbuffer_s *lb) +{ + return lb->read_ptr == lb->write_ptr; +} + +bool logbuffer_write(struct logbuffer_s *lb, void *ptr, int size) +{ + // bytes available to write + int available = lb->read_ptr - lb->write_ptr - 1; + + if (available < 0) + available += lb->size; + + if (size > available) { + // buffer overflow + return false; + } + + char *c = (char *) ptr; + int n = lb->size - lb->write_ptr; // bytes to end of the buffer + + if (n < size) { + // message goes over end of the buffer + memcpy(&(lb->data[lb->write_ptr]), c, n); + lb->write_ptr = 0; + + } else { + n = 0; + } + + // now: n = bytes already written + int p = size - n; // number of bytes to write + memcpy(&(lb->data[lb->write_ptr]), &(c[n]), p); + lb->write_ptr = (lb->write_ptr + p) % lb->size; + return true; +} + +int logbuffer_get_ptr(struct logbuffer_s *lb, void **ptr, bool *is_part) +{ + // bytes available to read + int available = lb->write_ptr - lb->read_ptr; + + if (available == 0) { + return 0; // buffer is empty + } + + int n = 0; + + if (available > 0) { + // read pointer is before write pointer, all available bytes can be read + n = available; + *is_part = false; + + } else { + // read pointer is after write pointer, read bytes from read_ptr to end of the buffer + n = lb->size - lb->read_ptr; + *is_part = true; + } + + *ptr = &(lb->data[lb->read_ptr]); + return n; +} + +void logbuffer_mark_read(struct logbuffer_s *lb, int n) +{ + lb->read_ptr = (lb->read_ptr + n) % lb->size; +} |