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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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