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Diffstat (limited to 'ext/event.lv2/event-helpers.h')
| -rw-r--r-- | ext/event.lv2/event-helpers.h | 243 |
1 files changed, 243 insertions, 0 deletions
diff --git a/ext/event.lv2/event-helpers.h b/ext/event.lv2/event-helpers.h new file mode 100644 index 0000000..14500b8 --- /dev/null +++ b/ext/event.lv2/event-helpers.h @@ -0,0 +1,243 @@ +/* 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.lv2/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 @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 @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 */ + |