obs-studio/libobs/util/circlebuf.h

199 lines
4.7 KiB
C

/*
* Copyright (c) 2013 Hugh Bailey <obs.jim@gmail.com>
*
* Permission to use, copy, modify, and distribute this software for any
* purpose with or without fee is hereby granted, provided that the above
* copyright notice and this permission notice appear in all copies.
*
* THE SOFTWARE IS PROVIDED "AS IS" AND THE AUTHOR DISCLAIMS ALL WARRANTIES
* WITH REGARD TO THIS SOFTWARE INCLUDING ALL IMPLIED WARRANTIES OF
* MERCHANTABILITY AND FITNESS. IN NO EVENT SHALL THE AUTHOR BE LIABLE FOR
* ANY SPECIAL, DIRECT, INDIRECT, OR CONSEQUENTIAL DAMAGES OR ANY DAMAGES
* WHATSOEVER RESULTING FROM LOSS OF USE, DATA OR PROFITS, WHETHER IN AN
* ACTION OF CONTRACT, NEGLIGENCE OR OTHER TORTIOUS ACTION, ARISING OUT OF
* OR IN CONNECTION WITH THE USE OR PERFORMANCE OF THIS SOFTWARE.
*/
#pragma once
#include "c99defs.h"
#include <string.h>
#include <stdlib.h>
#include <assert.h>
#include "bmem.h"
#ifdef __cplusplus
extern "C" {
#endif
/* Dynamic circular buffer */
struct circlebuf {
void *data;
size_t size;
size_t start_pos;
size_t end_pos;
size_t capacity;
};
static inline void circlebuf_init(struct circlebuf *cb)
{
memset(cb, 0, sizeof(struct circlebuf));
}
static inline void circlebuf_free(struct circlebuf *cb)
{
bfree(cb->data);
memset(cb, 0, sizeof(struct circlebuf));
}
static inline void circlebuf_reorder_data(struct circlebuf *cb,
size_t new_capacity)
{
size_t difference;
uint8_t *data;
if (!cb->size || !cb->start_pos || cb->end_pos > cb->start_pos)
return;
difference = new_capacity - cb->capacity;
data = (uint8_t*)cb->data + cb->start_pos;
memmove(data+difference, data, cb->capacity - cb->start_pos);
cb->start_pos += difference;
}
static inline void circlebuf_ensure_capacity(struct circlebuf *cb)
{
size_t new_capacity;
if (cb->size <= cb->capacity)
return;
new_capacity = cb->capacity*2;
if (cb->size > new_capacity)
new_capacity = cb->size;
cb->data = brealloc(cb->data, new_capacity);
circlebuf_reorder_data(cb, new_capacity);
cb->capacity = new_capacity;
}
static inline void circlebuf_reserve(struct circlebuf *cb, size_t capacity)
{
if (capacity <= cb->capacity)
return;
cb->data = brealloc(cb->data, capacity);
circlebuf_reorder_data(cb, capacity);
cb->capacity = capacity;
}
static inline void circlebuf_upsize(struct circlebuf *cb, size_t size)
{
size_t add_size = size - cb->size;
size_t new_end_pos = cb->end_pos + add_size;
if (size <= cb->size)
return;
cb->size = size;
circlebuf_ensure_capacity(cb);
if (new_end_pos > cb->capacity) {
size_t back_size = cb->capacity - cb->end_pos;
size_t loop_size = add_size - back_size;
if (back_size)
memset((uint8_t*)cb->data + cb->end_pos, 0, back_size);
memset(cb->data, 0, loop_size);
new_end_pos -= cb->capacity;
} else {
memset((uint8_t*)cb->data + cb->end_pos, 0, add_size);
}
cb->end_pos = new_end_pos;
}
/** Overwrites data at a specific point in the buffer (relative). */
static inline void circlebuf_place(struct circlebuf *cb, size_t position,
const void *data, size_t size)
{
size_t end_point = position + size;
size_t data_end_pos;
if (end_point > cb->size)
circlebuf_upsize(cb, end_point);
position += cb->start_pos;
if (position >= cb->capacity)
position -= cb->capacity;
data_end_pos = position + size;
if (data_end_pos > cb->capacity) {
size_t back_size = data_end_pos - cb->capacity;
size_t loop_size = size - back_size;
if (back_size)
memcpy((uint8_t*)cb->data + position, data, loop_size);
memcpy(cb->data, (uint8_t*)data + loop_size, back_size);
} else {
memcpy((uint8_t*)cb->data + position, data, size);
}
}
static inline void circlebuf_push_back(struct circlebuf *cb, const void *data,
size_t size)
{
size_t new_end_pos = cb->end_pos + size;
cb->size += size;
circlebuf_ensure_capacity(cb);
if (new_end_pos > cb->capacity) {
size_t back_size = cb->capacity - cb->end_pos;
size_t loop_size = size - back_size;
if (back_size)
memcpy((uint8_t*)cb->data + cb->end_pos, data,
back_size);
memcpy(cb->data, (uint8_t*)data + back_size, loop_size);
new_end_pos -= cb->capacity;
} else {
memcpy((uint8_t*)cb->data + cb->end_pos, data, size);
}
cb->end_pos = new_end_pos;
}
static inline void circlebuf_pop_front(struct circlebuf *cb, void *data,
size_t size)
{
size_t start_size;
assert(size <= cb->size);
start_size = cb->capacity - cb->start_pos;
if (data) {
if (start_size < size) {
memcpy(data, (uint8_t*)cb->data + cb->start_pos,
start_size);
memcpy((uint8_t*)data + start_size, cb->data,
size - start_size);
} else {
memcpy(data, (uint8_t*)cb->data + cb->start_pos, size);
}
}
cb->size -= size;
cb->start_pos += size;
if (cb->start_pos >= cb->capacity)
cb->start_pos -= cb->capacity;
}
#ifdef __cplusplus
}
#endif