364 lines
10 KiB
C
364 lines
10 KiB
C
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/*
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This file is part of Kismet
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Kismet is free software; you can redistribute it and/or modify
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it under the terms of the GNU General Public License as published by
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the Free Software Foundation; either version 2 of the License, or
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(at your option) any later version.
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Kismet is distributed in the hope that it will be useful,
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but WITHOUT ANY WARRANTY; without even the implied warranty of
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MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE. See the
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GNU General Public License for more details.
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You should have received a copy of the GNU General Public License
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along with Kismet; if not, write to the Free Software
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Foundation, Inc., 59 Temple Place, Suite 330, Boston, MA 02111-1307 USA
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*/
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/* An extremely basic ring buffer implemented as a complete header in pure C;
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* for use with datasource implementations in C */
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#include <stdint.h>
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#include <stdlib.h>
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#include <string.h>
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#include <stdio.h>
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#include "simple_ringbuf_c.h"
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/* Allocate a ring buffer
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*
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* Returns NULL if allocation failed
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*/
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kis_simple_ringbuf_t *kis_simple_ringbuf_create(size_t size) {
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kis_simple_ringbuf_t *rb;
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rb = (kis_simple_ringbuf_t *) malloc(sizeof(kis_simple_ringbuf_t));
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if (rb == NULL)
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return NULL;
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rb->buffer = (uint8_t *) malloc(size);
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if (rb->buffer == NULL) {
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free(rb);
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return NULL;
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}
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rb->buffer_sz = size;
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rb->start_pos = 0;
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rb->length = 0;
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rb->mid_peek = 0;
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rb->mid_commit = 0;
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rb->free_peek = 0;
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rb->free_commit = 0;
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return rb;
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}
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/* Destroy a ring buffer
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*/
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void kis_simple_ringbuf_free(kis_simple_ringbuf_t *ringbuf) {
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free(ringbuf->buffer);
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free(ringbuf);
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}
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/* Clear ring buffer
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*/
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void kis_simple_ringbuf_clear(kis_simple_ringbuf_t *ringbuf) {
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ringbuf->start_pos = 0;
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ringbuf->length = 0;
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}
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/* Get available space
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*/
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size_t kis_simple_ringbuf_available(kis_simple_ringbuf_t *ringbuf) {
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return ringbuf->buffer_sz - ringbuf->length;
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}
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/* Get used space
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*/
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size_t kis_simple_ringbuf_used(kis_simple_ringbuf_t *ringbuf) {
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return ringbuf->length;
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}
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/* Get total space
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* */
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size_t kis_simple_ringbuf_size(kis_simple_ringbuf_t *ringbuf) {
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return ringbuf->buffer_sz;
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}
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/* Append data
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*
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* Returns amount written
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*/
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size_t kis_simple_ringbuf_write(kis_simple_ringbuf_t *ringbuf,
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void *data, size_t length) {
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size_t copy_start;
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if (kis_simple_ringbuf_available(ringbuf) < length)
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return 0;
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copy_start =
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(ringbuf->start_pos + ringbuf->length) % ringbuf->buffer_sz;
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/* Does the write op fit w/out looping? */
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if (copy_start + length < ringbuf->buffer_sz) {
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memcpy(ringbuf->buffer + copy_start, data, length);
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ringbuf->length += length;
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return length;
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} else {
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/* We have to split up, figure out the length of the two chunks */
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size_t chunk_a = ringbuf->buffer_sz - copy_start;
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size_t chunk_b = length - chunk_a;
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memcpy(ringbuf->buffer + ringbuf->start_pos + ringbuf->length, data, chunk_a);
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memcpy(ringbuf->buffer, (uint8_t *) data + chunk_a, chunk_b);
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/* Increase the length of the buffer */
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ringbuf->length += length;
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return length;
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}
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return 0;
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}
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size_t kis_simple_ringbuf_reserve(kis_simple_ringbuf_t *ringbuf, void **data, size_t size) {
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size_t copy_start;
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if (kis_simple_ringbuf_available(ringbuf) < size)
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return 0;
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if (ringbuf->mid_commit) {
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fprintf(stderr, "ERROR: kis_simple_ringbuf_t mid-commit when reserve called\n");
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return 0;
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}
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copy_start =
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(ringbuf->start_pos + ringbuf->length) % ringbuf->buffer_sz;
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/* Does the write op fit w/out looping? */
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if (copy_start + size < ringbuf->buffer_sz) {
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ringbuf->mid_commit = 1;
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ringbuf->free_commit = 0;
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*data = ringbuf->buffer + copy_start;
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return size;
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} else {
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*data = malloc(size);
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if (*data == NULL) {
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fprintf(stderr, "ERROR: Could not allocate split-op sz write buffer\n");
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return 0;
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}
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ringbuf->mid_commit = 1;
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ringbuf->free_commit = 1;
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return size;
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}
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return 0;
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}
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size_t kis_simple_ringbuf_commit(kis_simple_ringbuf_t *ringbuf, void *data, size_t size) {
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if (!ringbuf->mid_commit) {
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fprintf(stderr, "ERROR: kis_simple_ringbuf_t not in a commit when commit called\n");
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return 0;
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}
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size_t copy_start;
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copy_start =
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(ringbuf->start_pos + ringbuf->length) % ringbuf->buffer_sz;
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if (!ringbuf->free_commit) {
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ringbuf->mid_commit = 0;
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ringbuf->length += size;
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return size;
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} else {
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/* Does the write op fit w/out looping? */
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if (copy_start + size < ringbuf->buffer_sz) {
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memcpy(ringbuf->buffer + copy_start, data, size);
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ringbuf->length += size;
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return size;
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} else {
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/* We have to split up, figure out the length of the two chunks */
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size_t chunk_a = ringbuf->buffer_sz - copy_start;
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size_t chunk_b = size - chunk_a;
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memcpy(ringbuf->buffer + ringbuf->start_pos + ringbuf->length, data, chunk_a);
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memcpy(ringbuf->buffer, (uint8_t *) data + chunk_a, chunk_b);
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/* Increase the length of the buffer */
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ringbuf->length += size;
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return size;
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}
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}
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return 0;
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}
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/* Free a previously reserved chunk without committing it.
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*/
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void kis_simple_ringbuf_reserve_free(kis_simple_ringbuf_t *ringbuf, void *data) {
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if (!ringbuf->mid_commit) {
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fprintf(stderr, "ERROR: kis_simple_ringbuf_t not in a commit when commit_reserve_free called\n");
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}
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if (ringbuf->free_commit)
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free(data);
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ringbuf->mid_commit = 0;
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}
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/* Copies data into provided buffer. Advances ringbuf, clearing consumed data.
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*
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* If requested amount is not available, reads amount available and returns.
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*
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* Returns amount copied
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*/
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size_t kis_simple_ringbuf_read(kis_simple_ringbuf_t *ringbuf, void *ptr,
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size_t size) {
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/* Start with how much we have available - no matter what was
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* requested, we can't read more than this */
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size_t opsize = kis_simple_ringbuf_used(ringbuf);
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if (opsize == 0)
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return 0;
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/* Only read the amount we requested, if more is available */
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if (opsize > size)
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opsize = size;
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/* Simple contiguous read */
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if (ringbuf->start_pos + opsize < ringbuf->buffer_sz) {
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if (ptr != NULL)
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memcpy(ptr, ringbuf->buffer + ringbuf->start_pos, opsize);
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ringbuf->start_pos += opsize;
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ringbuf->length -= opsize;
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return opsize;
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} else {
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/* First chunk, start to end of buffer */
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size_t chunk_a = ringbuf->buffer_sz - ringbuf->start_pos;
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/* Second chunk, 0 to remaining data */
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size_t chunk_b = opsize - chunk_a;
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if (ptr != NULL) {
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memcpy(ptr, ringbuf->buffer + ringbuf->start_pos, chunk_a);
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memcpy((uint8_t *) ptr + chunk_a, ringbuf->buffer, chunk_b);
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}
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/* Fastforward around the ring to where we finished reading */
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ringbuf->start_pos = chunk_b;
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ringbuf->length -= opsize;
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return opsize;
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}
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return 0;
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}
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/* Peeks at data by copying into provided buffer. Does NOT advance ringbuf
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* or consume data.
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*
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* If requested amount of data is not available, peeks amount available and
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* returns;
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*
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* Returns amount copied
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*/
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size_t kis_simple_ringbuf_peek(kis_simple_ringbuf_t *ringbuf, void *ptr,
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size_t size) {
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/* Start with how much we have available - no matter what was
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* requested, we can't read more than this */
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size_t opsize = kis_simple_ringbuf_used(ringbuf);
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if (opsize == 0)
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return 0;
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/* Only read the amount we requested, if more is available */
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if (opsize > size)
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opsize = size;
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/* Simple contiguous read */
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if (ringbuf->start_pos + opsize < ringbuf->buffer_sz) {
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memcpy(ptr, ringbuf->buffer + ringbuf->start_pos, opsize);
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return opsize;
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} else {
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/* First chunk, start to end of buffer */
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size_t chunk_a = ringbuf->buffer_sz - ringbuf->start_pos;
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/* Second chunk, 0 to remaining data */
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size_t chunk_b = opsize - chunk_a;
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memcpy(ptr, ringbuf->buffer + ringbuf->start_pos, chunk_a);
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memcpy((uint8_t *) ptr + chunk_a, ringbuf->buffer, chunk_b);
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return opsize;
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}
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return 0;
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}
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size_t kis_simple_ringbuf_peek_zc(kis_simple_ringbuf_t *ringbuf, void **ptr, size_t size) {
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/* Start with how much we have available - no matter what was
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* requested, we can't read more than this */
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size_t opsize = kis_simple_ringbuf_used(ringbuf);
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if (ringbuf->mid_peek) {
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fprintf(stderr, "ERROR: simple_ringbuf_peek_zc mid-peek already\n");
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return 0;
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}
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if (opsize == 0)
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return 0;
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/* Only read the amount we requested, if more is available */
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if (opsize > size)
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opsize = size;
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/* Simple contiguous read */
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if (ringbuf->start_pos + opsize < ringbuf->buffer_sz) {
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ringbuf->mid_peek = 1;
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ringbuf->free_peek = 0;
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*ptr = ringbuf->buffer + ringbuf->start_pos;
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return opsize;
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} else {
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/* First chunk, start to end of buffer */
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size_t chunk_a = ringbuf->buffer_sz - ringbuf->start_pos;
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/* Second chunk, 0 to remaining data */
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size_t chunk_b = opsize - chunk_a;
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*ptr = malloc(opsize);
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if (*ptr == NULL) {
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fprintf(stderr, "ERROR: simple_ringbuf_peek_zc could not allocate buffer for split peek\n");
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return 0;
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}
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ringbuf->mid_peek = 1;
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ringbuf->free_peek = 1;
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memcpy(*ptr, ringbuf->buffer + ringbuf->start_pos, chunk_a);
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memcpy((uint8_t *) *ptr + chunk_a, ringbuf->buffer, chunk_b);
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return opsize;
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}
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return 0;
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}
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void kis_simple_ringbuf_peek_free(kis_simple_ringbuf_t *ringbuf, void *ptr) {
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if (!ringbuf->mid_peek) {
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fprintf(stderr, "ERROR: kis_simple_ringbuf_peek_free called with no peeked data\n");
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return;
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}
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if (ringbuf->free_peek)
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free(ptr);
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ringbuf->mid_peek = 0;
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}
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