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/**
* Copyright 2011 Bump Technologies, Inc. All rights reserved.
*
* 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.
*
* THIS SOFTWARE IS PROVIDED BY BUMP TECHNOLOGIES, INC. ``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 BUMP TECHNOLOGIES, INC. 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.
*
* The views and conclusions contained in the software and documentation are those of the
* authors and should not be interpreted as representing official policies, either expressed
* or implied, of Bump Technologies, Inc.
*
**/
#include "ringbuffer.h"
#include <assert.h>
/* Initialize a ringbuffer structure to empty */
void ringbuffer_init(ringbuffer *rb) {
rb->head = &rb->slots[0];
rb->tail = &rb->slots[0];
rb->used = 0;
int x;
for (x=0; x<RING_SLOTS; x++)
rb->slots[x].next = &(rb->slots[(x + 1) % RING_SLOTS]);
}
/** READ FUNCTIONS **/
/* Return a char * that represents the current unconsumed buffer */
char * ringbuffer_read_next(ringbuffer *rb, int * length) {
assert(rb->used);
*length = rb->head->left;
return rb->head->ptr;
}
/* Mark consumption of only part of the read head buffer */
void ringbuffer_read_skip(ringbuffer *rb, int length) {
assert(rb->used);
rb->head->ptr += length;
rb->head->left -= length;
}
/* Pop a consumed (fully read) head from the buffer */
void ringbuffer_read_pop(ringbuffer *rb) {
assert(rb->used);
rb->head = rb->head->next;
rb->used--;
}
/** WRITE FUNCTIONS **/
/* Return the tail ptr (current target of new writes) */
char * ringbuffer_write_ptr(ringbuffer *rb) {
assert(rb->used < RING_SLOTS);
return rb->tail->data;
}
/* Mark the tail appended for `length` bytes, and move the cursor
* to the next slot */
void ringbuffer_write_append(ringbuffer *rb, int length) {
assert(rb->used < RING_SLOTS);
rb->used++;
rb->tail->ptr = rb->tail->data;
rb->tail->left = length;
rb->tail = rb->tail->next;
}
/** RING STATE FUNCTIONS **/
/* Used size of the ringbuffer */
int ringbuffer_size(ringbuffer *rb) {
return rb->used;
}
/* Used size of the ringbuffer */
int ringbuffer_capacity(ringbuffer *rb) {
(void) rb;
return RING_SLOTS;
}
/* Is the ringbuffer completely empty (implies: no data to be written) */
int ringbuffer_is_empty(ringbuffer *rb) {
return rb->used == 0;
}
/* Is the ringbuffer completely full (implies: no more data should be read) */
int ringbuffer_is_full(ringbuffer *rb) {
return rb->used == RING_SLOTS;
}