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/* lv2_event_helpers.h - Helper functions for the LV2 events extension.
*
* Copyright (C) 2008-2009 David Robillard <http://drobilla.net>
*
* This header 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 of the License, or
* (at your option) any later version.
*
* This header 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 header; if not, write to the Free Software Foundation,
* Inc., 59 Temple Place, Suite 330, Boston, MA 01222-1307 USA
*/
#ifndef LV2_EVENT_HELPERS_H
#define LV2_EVENT_HELPERS_H
#include <stdint.h>
#include <stdbool.h>
#include <string.h>
#include <stdlib.h>
#include <assert.h>
#include "event.h"
/** @file
* Helper functions for the LV2 Event extension
* <http://lv2plug.in/ns/ext/event>.
*
* These functions are provided for convenience only, use of them is not
* required for supporting lv2ev (i.e. the events extension is defined by the
* raw buffer format described in lv2_event.h and NOT by this API).
*
* Note that these functions are all static inline which basically means:
* do not take the address of these functions. */
/** Pad a size to 64 bits (for event sizes) */
static inline uint16_t
lv2_event_pad_size(uint16_t size)
{
return (size + 7) & (~7);
}
/** Initialize (empty, reset..) an existing event buffer.
* The contents of buf are ignored entirely and overwritten, except capacity
* which is unmodified. */
static inline void
lv2_event_buffer_reset(LV2_Event_Buffer* buf, uint16_t stamp_type, uint8_t *data)
{
buf->data = data;
buf->header_size = sizeof(LV2_Event_Buffer);
buf->stamp_type = stamp_type;
buf->event_count = 0;
buf->size = 0;
}
/** Allocate a new, empty event buffer. */
static inline LV2_Event_Buffer*
lv2_event_buffer_new(uint32_t capacity, uint16_t stamp_type)
{
LV2_Event_Buffer* buf = (LV2_Event_Buffer*)malloc(sizeof(LV2_Event_Buffer) + capacity);
if (buf != NULL) {
buf->capacity = capacity;
lv2_event_buffer_reset(buf, stamp_type, (uint8_t *)(buf + 1));
return buf;
} else {
return NULL;
}
}
/** An iterator over an LV2_Event_Buffer.
*
* Multiple simultaneous read iterators over a single buffer is fine,
* but changing the buffer invalidates all iterators (e.g. RW Lock). */
typedef struct {
LV2_Event_Buffer* buf;
uint32_t offset;
} LV2_Event_Iterator;
/** Reset an iterator to point to the start of @a buf.
* @return True if @a iter is valid, otherwise false (buffer is empty) */
static inline bool
lv2_event_begin(LV2_Event_Iterator* iter,
LV2_Event_Buffer* buf)
{
iter->buf = buf;
iter->offset = 0;
return (buf->size > 0);
}
/** Check if @a iter is valid.
* @return True if @a iter is valid, otherwise false (past end of buffer) */
static inline bool
lv2_event_is_valid(LV2_Event_Iterator* iter)
{
return (iter->offset < iter->buf->size);
}
/** Advance @a iter forward one event.
* @a iter must be valid.
* @return True if @a iter is valid, otherwise false (reached end of buffer) */
static inline bool
lv2_event_increment(LV2_Event_Iterator* iter)
{
assert(lv2_event_is_valid(iter));
LV2_Event* const ev = (LV2_Event*)(
(uint8_t*)iter->buf->data + iter->offset);
iter->offset += lv2_event_pad_size(sizeof(LV2_Event) + ev->size);
return true;
}
/** Dereference an event iterator (get the event currently pointed at).
* @a iter must be valid.
* @a data if non-NULL, will be set to point to the contents of the event
* returned.
* @return A Pointer to the event @a iter is currently pointing at, or NULL
* if the end of the buffer is reached (in which case @a data is
* also set to NULL). */
static inline LV2_Event*
lv2_event_get(LV2_Event_Iterator* iter,
uint8_t** data)
{
assert(lv2_event_is_valid(iter));
LV2_Event* const ev = (LV2_Event*)(
(uint8_t*)iter->buf->data + iter->offset);
if (data)
*data = (uint8_t*)ev + sizeof(LV2_Event);
return ev;
}
/** Write an event at @a iter.
* The event (if any) pointed to by @a iter will be overwritten, and @a iter
* incremented to point to the following event (i.e. several calls to this
* function can be done in sequence without twiddling iter in-between).
* @return True if event was written, otherwise false (buffer is full). */
static inline bool
lv2_event_write(LV2_Event_Iterator* iter,
uint32_t frames,
uint32_t subframes,
uint16_t type,
uint16_t size,
const uint8_t* data)
{
if (iter->buf->capacity - iter->buf->size < sizeof(LV2_Event) + size)
return false;
LV2_Event* const ev = (LV2_Event*)(
(uint8_t*)iter->buf->data + iter->offset);
ev->frames = frames;
ev->subframes = subframes;
ev->type = type;
ev->size = size;
memcpy((uint8_t*)ev + sizeof(LV2_Event), data, size);
++iter->buf->event_count;
size = lv2_event_pad_size(sizeof(LV2_Event) + size);
iter->buf->size += size;
iter->offset += size;
return true;
}
/** Reserve space for an event in the buffer and return a pointer to
the memory where the caller can write the event data, or NULL if there
is not enough room in the buffer. */
static inline uint8_t*
lv2_event_reserve(LV2_Event_Iterator* iter,
uint32_t frames,
uint32_t subframes,
uint16_t type,
uint16_t size)
{
size = lv2_event_pad_size(size);
if (iter->buf->capacity - iter->buf->size < sizeof(LV2_Event) + size)
return NULL;
LV2_Event* const ev = (LV2_Event*)((uint8_t*)iter->buf->data +
iter->offset);
ev->frames = frames;
ev->subframes = subframes;
ev->type = type;
ev->size = size;
++iter->buf->event_count;
size = lv2_event_pad_size(sizeof(LV2_Event) + size);
iter->buf->size += size;
iter->offset += size;
return (uint8_t*)ev + sizeof(LV2_Event);
}
/** Write an event at @a iter.
* The event (if any) pointed to by @a iter will be overwritten, and @a iter
* incremented to point to the following event (i.e. several calls to this
* function can be done in sequence without twiddling iter in-between).
* @return True if event was written, otherwise false (buffer is full). */
static inline bool
lv2_event_write_event(LV2_Event_Iterator* iter,
const LV2_Event* ev,
const uint8_t* data)
{
if (iter->buf->capacity - iter->buf->size < sizeof(LV2_Event) + ev->size)
return false;
LV2_Event* const write_ev = (LV2_Event*)(
(uint8_t*)iter->buf->data + iter->offset);
*write_ev = *ev;
memcpy((uint8_t*)write_ev + sizeof(LV2_Event), data, ev->size);
++iter->buf->event_count;
const uint16_t size = lv2_event_pad_size(sizeof(LV2_Event) + ev->size);
iter->buf->size += size;
iter->offset += size;
return true;
}
#endif /* LV2_EVENT_HELPERS_H */
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