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Implement most recent LV2 persist extension.

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Plugin state data is saved to a simple RIFF-based binary file.
Cross-endianness and non-POD data not yet implemented.


git-svn-id: svn://localhost/ardour2/branches/3.0@9220 d708f5d6-7413-0410-9779-e7cbd77b26cf
This commit is contained in:
David Robillard 2011-03-28 23:54:08 +00:00
parent 8d86a71f0f
commit 2c0cd4d430
5 changed files with 570 additions and 299 deletions
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20
libs/ardour/ardour/lv2_plugin.h
View File

@ -149,16 +149,18 @@ class LV2Plugin : public ARDOUR::Plugin
static URIMap _uri_map;
static uint32_t _midi_event_type;
static void lv2_persist_store_callback (void* callback_data,
const char* key,
const void* value,
size_t size,
uint32_t type);
static int lv2_persist_store_callback (void* callback_data,
uint32_t key,
const void* value,
size_t size,
uint32_t type,
bool pod);
static const void* lv2_persist_retrieve_callback (void* callback_data,
const char* key,
size_t* size,
uint32_t* type);
static const void* lv2_persist_retrieve_callback (void* callback_data,
uint32_t key,
size_t* size,
uint32_t* type,
bool* pod);
void init (LV2World& world, SLV2Plugin plugin, framecnt_t rate);
void run (pframes_t nsamples);

237
libs/ardour/lv2_pfile.c
View File

@ -1,21 +1,24 @@
/* Portable file-based implementation of LV2 Persist.
* See <http://lv2plug.in/ns/ext/persist> for details.
* Copyright (C) 2010 David Robillard <http://drobilla.net>
*
* This file is free software; you can redistribute it and/or modify it
* under the terms of the GNU General Public License as published by the Free
* Software Foundation; either version 2 of the License, or (at your option)
* any later version.
*
* This file 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 General Public License
* for more details.
*
* You should have received a copy of the GNU General Public License along
* with this file; if not, write to the Free Software Foundation, Inc.,
* 51 Franklin St, Fifth Floor, Boston, MA 02110-1301 USA.
*/
/*
Portable file-based LV2 Persist implementation.
See <http://lv2plug.in/ns/ext/persist> for details.
Copyright 2011 David Robillard <http://drobilla.net>
This is free software; you can redistribute it and/or modify it
under the terms of the GNU General Public License as published by
the Free Software Foundation; either version 2 of the License, or
(at your option) any later version.
This software 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 General Public License for more details.
You should have received a copy of the GNU General Public License
along with this sofware; if not, write to the Free Software
Foundation, Inc., 51 Franklin St, Fifth Floor, Boston, MA
02110-1301 USA.
*/
#include <assert.h>
#include <errno.h>
@ -25,8 +28,16 @@
#include "lv2_pfile.h"
#define CHUNK_ID_LEN 4
static const char FILE_TYPE[CHUNK_ID_LEN] = "LV2F"; /* LV2 RIFF File */
static const char CHUNK_KVAL[CHUNK_ID_LEN] = "KVAL"; /* Key/Value Chunk */
static const char CHUNK_URID[CHUNK_ID_LEN] = "URID"; /* URI ID Chunk */
struct _LV2PFile {
FILE* fd;
FILE* fd;
uint32_t size;
bool write;
};
LV2PFile
@ -38,88 +49,125 @@ lv2_pfile_open(const char* path, bool write)
return NULL;
}
static const char* const magic = "LV2PFILE";
static const size_t magic_len = 8;
uint32_t size = 0;
if (write) {
fwrite(magic, magic_len, 1, fd);
fwrite("RIFF", CHUNK_ID_LEN, 1, fd); /* RIFF chunk ID */
fwrite(&size, sizeof(size), 1, fd); /* RIFF chunk size */
fwrite(FILE_TYPE, CHUNK_ID_LEN, 1, fd); /* LV2 RIFF file type */
} else {
char file_magic[magic_len];
if (fread(file_magic, magic_len, 1, fd) != 1
|| strncmp(file_magic, magic, magic_len)) {
char magic[CHUNK_ID_LEN];
if (fread(magic, CHUNK_ID_LEN, 1, fd) != 1
|| strncmp(magic, "RIFF", CHUNK_ID_LEN)) {
fclose(fd);
fprintf(stderr, "%s: error: not a RIFF file\n", path);
return NULL;
}
if (fread(&size, sizeof(size), 1, fd) != 1) {
fclose(fd);
fprintf(stderr, "%s: error: missing RIFF chunk size\n", path);
return NULL;
}
if (fread(magic, CHUNK_ID_LEN, 1, fd) != 1
|| strncmp(magic, FILE_TYPE, CHUNK_ID_LEN)) {
fclose(fd);
fprintf(stderr, "%s: error: not an LV2 RIFF file\n", path);
return NULL;
}
}
LV2PFile ret = (LV2PFile)malloc(sizeof(LV2PFile));
ret->fd = fd;
LV2PFile ret = (LV2PFile)malloc(sizeof(struct _LV2PFile));
ret->fd = fd;
ret->size = size;
ret->write = write;
return ret;
}
LV2PFileStatus
lv2_pfile_write(LV2PFile file,
const char* key,
const void* value,
uint64_t size,
const char* type)
{
#define WRITE(ptr, size, nmemb, stream) \
if (fwrite(ptr, size, nmemb, stream) != nmemb) { \
return LV2_PFILE_UNKNOWN_ERROR; \
}
const uint32_t key_len = strlen(key);
WRITE(&key_len, sizeof(key_len), 1, file->fd);
WRITE(key, key_len + 1, 1, file->fd);
const uint32_t type_len = strlen(type);
WRITE(&type_len, sizeof(type_len), 1, file->fd);
WRITE(type, type_len + 1, 1, file->fd);
WRITE(&size, sizeof(size), 1, file->fd);
WRITE(value, size, 1, file->fd);
LV2PFileStatus
lv2_pfile_write_uri(LV2PFile file,
uint32_t id,
const char* uri,
uint32_t len)
{
const uint32_t chunk_size = sizeof(id) + len + 1;
WRITE(CHUNK_URID, CHUNK_ID_LEN, 1, file->fd);
WRITE(&chunk_size, sizeof(chunk_size), 1, file->fd);
WRITE(&id, sizeof(id), 1, file->fd);
WRITE(uri, len + 1, 1, file->fd);
if ((chunk_size % 2)) {
WRITE("", 1, 1, file->fd); /* pad */
}
file->size += 8 + chunk_size;
return LV2_PFILE_OK;
}
LV2PFileStatus
lv2_pfile_read(LV2PFile file,
char** key,
uint32_t* key_len,
char** type,
uint32_t* type_len,
void** value,
uint64_t* size)
lv2_pfile_write_value(LV2PFile file,
uint32_t key,
const void* value,
uint32_t size,
uint32_t type)
{
const uint32_t chunk_size = sizeof(key) + sizeof(type) + sizeof(size) + size;
WRITE(CHUNK_KVAL, CHUNK_ID_LEN, 1, file->fd);
WRITE(&chunk_size, sizeof(chunk_size), 1, file->fd);
WRITE(&key, sizeof(key), 1, file->fd);
WRITE(&type, sizeof(type), 1, file->fd);
WRITE(&size, sizeof(size), 1, file->fd);
WRITE(value, size, 1, file->fd);
if ((size % 2)) {
WRITE("", 1, 1, file->fd); /* write pad */
}
file->size += 8 + chunk_size;
return LV2_PFILE_OK;
}
LV2PFileStatus
lv2_pfile_read_chunk(LV2PFile file,
LV2PFileChunkHeader** buf)
{
if (feof(file->fd))
return LV2_PFILE_EOF;
#define READ(ptr, size, nmemb, stream) \
if (fread(ptr, size, nmemb, stream) != nmemb) { \
assert(false); \
return LV2_PFILE_CORRUPT; \
}
READ(key_len, sizeof(*key_len), 1, file->fd);
*key = (char*)malloc(*key_len + 1);
READ(*key, *key_len + 1, 1, file->fd);
READ(type_len, sizeof(*type_len), 1, file->fd);
*type = (char*)malloc(*type_len + 1);
READ(*type, *type_len + 1, 1, file->fd);
READ(size, sizeof(*size), 1, file->fd);
*value = malloc(*size);
READ(*value, *size, 1, file->fd);
const uint32_t alloc_size = (*buf)->size;
READ((*buf)->type, sizeof((*buf)->type), 1, file->fd);
READ(&(*buf)->size, sizeof((*buf)->size), 1, file->fd);
if ((*buf)->size > alloc_size) {
*buf = realloc(*buf, sizeof(LV2PFileChunkHeader) + (*buf)->size);
}
READ((*buf)->data, (*buf)->size, 1, file->fd);
if (((*buf)->size % 2)) {
char pad;
READ(&pad, 1, 1, file->fd); /* skip pad */
}
return LV2_PFILE_OK;
}
void
lv2_pfile_close(LV2PFile file)
{
if (file)
if (file) {
if (file->write) {
fseek(file->fd, 4, SEEK_SET);
if (fwrite(&file->size, sizeof(file->size), 1, file->fd) != 1) {
fprintf(stderr, "failed to write RIFF header size\n");
}
}
fclose(file->fd);
}
free(file);
}
@ -140,14 +188,23 @@ main(int argc, char** argv)
if (!file)
goto fail;
char wkey[6];
char wval[6];
const char* wtype = "http://example.org/type";
#define NUM_RECORDS 32
for (int i = 0; i < NUM_RECORDS; ++i) {
snprintf(wkey, sizeof(wkey), "KEY%02d", i);
snprintf(wval, sizeof(wval), "VAL%02d", i);
lv2_pfile_write(file, wkey, wval, strlen(wval) + 1, wtype);
static const int N_URIS = 16;
static const int N_RECORDS = 16;
char uri[64];
for (int i = 0; i < N_URIS; ++i) {
snprintf(uri, sizeof(uri), "http://example.org/uri%02d", i + 1);
lv2_pfile_write_uri(file, i + 1, uri, strlen(uri) + 1);
}
char val[6];
for (int i = 0; i < N_RECORDS; ++i) {
snprintf(val, sizeof(val), "VAL%02d", i);
lv2_pfile_write_value(file,
rand() % N_URIS,
val,
sizeof(val),
0);
}
lv2_pfile_close(file);
@ -156,23 +213,31 @@ main(int argc, char** argv)
if (!file)
goto fail;
char* rkey;
uint32_t rkey_len;
char* rtype;
uint32_t rtype_len;
uint64_t rsize;
void* rval;
for (int i = 0; i < NUM_RECORDS; ++i) {
if (lv2_pfile_read(file, &rkey, &rkey_len, &rtype, &rtype_len, &rval, &rsize))
LV2PFileChunkHeader* chunk = malloc(sizeof(LV2PFileChunkHeader));
chunk->size = 0;
for (int i = 0; i < N_URIS; ++i) {
if (lv2_pfile_read_chunk(file, &chunk)
|| strncmp(chunk->type, "URID", 4)) {
fprintf(stderr, "error: expected URID chunk\n");
goto fail;
printf("%s = %s :: %s\n", rkey, (char*)rval, rtype);
free(rkey);
free(rtype);
free(rval);
}
LV2PFileURIChunk* body = (LV2PFileURIChunk*)chunk->data;
printf("URI: %s\n", body->uri);
}
for (int i = 0; i < N_RECORDS; ++i) {
if (lv2_pfile_read_chunk(file, &chunk)
|| strncmp(chunk->type, "KVAL", 4)) {
fprintf(stderr, "error: expected KVAL chunk\n");
goto fail;
}
LV2PFileValueChunk* body = (LV2PFileValueChunk*)chunk->data;
printf("KEY %d = %s\n", body->key, body->value);
}
free(chunk);
lv2_pfile_close(file);
return 0;
fail:

113
libs/ardour/lv2_pfile.h
View File

@ -1,24 +1,37 @@
/* Portable file-based implementation of LV2 Persist.
* See <http://lv2plug.in/ns/ext/persist> for details.
*
* This file is free software; you can redistribute it and/or modify it
* under the terms of the GNU General Public License as published by the Free
* Software Foundation; either version 2 of the License, or (at your option)
* any later version.
*
* This file 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 General Public License
* for more details.
*
* You should have received a copy of the GNU General Public License along
* with this file; if not, write to the Free Software Foundation, Inc.,
* 51 Franklin St, Fifth Floor, Boston, MA 02110-1301 USA.
*/
/*
Portable file-based LV2 Persist implementation.
See <http://lv2plug.in/ns/ext/persist> for details.
Copyright 2011 David Robillard <http://drobilla.net>
This is free software; you can redistribute it and/or modify it
under the terms of the GNU General Public License as published by
the Free Software Foundation; either version 2 of the License, or
(at your option) any later version.
This software 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
General Public License for more details.
You should have received a copy of the GNU General Public License
along with this sofware; if not, write to the Free Software
Foundation, Inc., 51 Franklin St, Fifth Floor, Boston, MA
02110-1301 USA.
*/
#ifndef LV2PFILE_H
#define LV2PFILE_H
#include <stdbool.h>
#include <stdint.h>
#ifdef __GNUC__
# define PACKED __attribute__((__packed__))
#else
# define PACKED
#endif
#ifdef __cplusplus
extern "C" {
#endif
@ -33,21 +46,57 @@ typedef enum {
LV2_PFILE_CORRUPT = 3
} LV2PFileStatus;
/** Open/Create a new persist file. */
typedef struct {
char type[4];
uint32_t size;
char data[];
} PACKED LV2PFileChunkHeader;
typedef struct {
uint32_t id;
char uri[];
} PACKED LV2PFileURIChunk;
typedef struct {
uint32_t key;
uint32_t type;
uint32_t size;
char value[];
} PACKED LV2PFileValueChunk;
/**
Open/Create a new persist file.
*/
LV2PFile
lv2_pfile_open(const char* path, bool write);
/** Write a record to a persist file. */
/**
Write a URI ID to @a file.
*/
LV2PFileStatus
lv2_pfile_write(LV2PFile file,
const char* key,
const void* value,
uint64_t size,
const char* type);
lv2_pfile_write_uri(LV2PFile file,
uint32_t id,
const char* uri,
uint32_t size);
/** Read a record from a persist file.
* @a key and @a value are allocated with malloc and must be freed by caller.
*/
/**
Write a key/value record to @a file.
*/
LV2PFileStatus
lv2_pfile_write_value(LV2PFile file,
uint32_t key,
const void* value,
uint32_t size,
uint32_t type);
LV2PFileStatus
lv2_pfile_read_chunk(LV2PFile file,
LV2PFileChunkHeader** buf);
/**
Read a record from a persist file.
@a key and @a value are allocated with malloc and must be freed by caller.
*/
#if 0
LV2PFileStatus
lv2_pfile_read(LV2PFile file,
char** key,
@ -56,13 +105,17 @@ lv2_pfile_read(LV2PFile file,
uint32_t* type_len,
void** value,
uint64_t* size);
#endif
/** Close a persist file.
* After this call, @a file is invalid.
*/
/**
Close @a file.
After this call, @a file is invalid.
*/
void
lv2_pfile_close(LV2PFile file);
#ifdef __cplusplus
} /* extern "C" */
#endif
#endif /* LV2PFILE_H */

168
libs/ardour/lv2_plugin.cc
View File

@ -57,7 +57,7 @@ using namespace std;
using namespace ARDOUR;
using namespace PBD;
URIMap LV2Plugin:: _uri_map;
URIMap LV2Plugin::_uri_map;
uint32_t LV2Plugin::_midi_event_type = _uri_map.uri_to_id(
"http://lv2plug.in/ns/ext/event",
"http://lv2plug.in/ns/ext/midi#MidiEvent");
@ -296,30 +296,108 @@ LV2Plugin::nth_parameter(uint32_t n, bool& ok) const
return 0;
}
void
struct PersistValue {
inline PersistValue(uint32_t k, const void* v, size_t s, uint32_t t, bool p)
: key(k), value(v), size(s), type(t), pod(p)
{}
const uint32_t key;
const void* value;
const size_t size;
const uint32_t type;
const bool pod;
};
struct PersistState {
PersistState(URIMap& map) : uri_map(map) {}
typedef std::map<uint32_t, std::string> URIs;
typedef std::map<uint32_t, PersistValue> Values;
uint32_t file_id_to_runtime_id(uint32_t file_id) const {
URIs::const_iterator i = uris.find(file_id);
if (i == uris.end()) {
error << "LV2 state refers to undefined URI ID" << endmsg;
return 0;
}
return uri_map.uri_to_id(NULL, i->second.c_str());
}
int add_uri(uint32_t file_id, const char* str) {
// TODO: check for clashes (invalid file)
uris.insert(make_pair(file_id, str));
return 0;
}
int add_value(uint32_t file_key,
const void* value,
size_t size,
uint32_t file_type,
bool pod) {
const uint32_t key = file_id_to_runtime_id(file_key);
const uint32_t type = file_id_to_runtime_id(file_type);
if (!key || !type) {
return 1;
}
Values::const_iterator i = values.find(key);
if (i != values.end()) {
error << "LV2 state contains duplicate keys" << endmsg;
return 1;
} else {
void* value_copy = malloc(size);
memcpy(value_copy, value, size); // FIXME: leak
values.insert(
make_pair(key,
PersistValue(key, value_copy, size, type, pod)));
return 0;
}
}
URIMap& uri_map;
URIs uris;
Values values;
};
int
LV2Plugin::lv2_persist_store_callback(void* callback_data,
const char* key,
uint32_t key,
const void* value,
size_t size,
uint32_t type)
uint32_t type,
bool pod)
{
LV2PFile file = (LV2PFile)callback_data;
cout << "LV2 PERSIST STORE " << key
<< " = " << value
<< " :: " << type
<< " POD: " << pod << endl;
// FIXME: assumes URIs are mapped in the default context (or not event, at least)
const char* type_uri = LV2Plugin::_uri_map.id_to_uri(NULL, type);
cout << "LV2 PERSIST STORE " << key << " = " << value << " :: " << type_uri << endl;
lv2_pfile_write(file, key, value, size, type_uri);
PersistState* state = (PersistState*)callback_data;
state->add_uri(key, _uri_map.id_to_uri(NULL, key));
state->add_uri(type, _uri_map.id_to_uri(NULL, type));
return state->add_value(key, value, size, type, pod);
}
const void*
LV2Plugin::lv2_persist_retrieve_callback(void* callback_data,
const char* key,
size_t* size,
uint32_t* type)
LV2Plugin::lv2_persist_retrieve_callback(void* callback_data,
uint32_t key,
size_t* size,
uint32_t* type,
bool* pod)
{
//LV2PFile file = (LV2PFile)callback_data;
cout << "LV2 PERSIST RETRIEVE " << key << endl;
return NULL;
cout << "LV2 PERSIST RETRIEVE " << _uri_map.id_to_uri(NULL, key) << endl;
PersistState* state = (PersistState*)callback_data;
PersistState::Values::const_iterator i = state->values.find(key);
if (i == state->values.end()) {
warning << "LV2 plugin attempted to retrieve nonexistent key: "
<< _uri_map.id_to_uri(NULL, key) << endmsg;
return NULL;
}
*size = i->second.size;
*type = i->second.type;
*pod = true; // FIXME
return i->second.value;
}
void
@ -341,7 +419,7 @@ LV2Plugin::add_state(XMLNode* root) const
if (_supports_persist) {
// Create state directory for this plugin instance
const std::string state_filename = _id.to_s() + ".lv2pfile";
const std::string state_filename = _id.to_s() + ".lv2f";
const std::string state_path = Glib::build_filename(
_session.plugins_dir(), state_filename);
@ -357,8 +435,35 @@ LV2Plugin::add_state(XMLNode* root) const
return;
}
// Save plugin state to state object
PersistState state(_uri_map);
persist->save(_instance->lv2_handle,
&LV2Plugin::lv2_persist_store_callback,
&state);
// Open state file
LV2PFile file = lv2_pfile_open(state_path.c_str(), true);
persist->save(_instance->lv2_handle, &LV2Plugin::lv2_persist_store_callback, file);
// Write all referenced URIs to state file
for (PersistState::URIs::const_iterator i = state.uris.begin();
i != state.uris.end(); ++i) {
lv2_pfile_write_uri(file, i->first,
i->second.c_str(), i->second.length() + 1);
}
// Write all values to state file
for (PersistState::Values::const_iterator i = state.values.begin();
i != state.values.end(); ++i) {
const uint32_t key = i->first;
const PersistValue& val = i->second;
lv2_pfile_write_value(file,
key,
val.value,
val.size,
val.type);
}
// Close state file
lv2_pfile_close(file);
root->add_property("state-file", state_filename);
@ -527,9 +632,34 @@ LV2Plugin::set_state(const XMLNode& node, int version)
if (persist) {
cout << "Loading LV2 state from " << state_path << endl;
LV2PFile file = lv2_pfile_open(state_path.c_str(), false);
PersistState state(_uri_map);
// Load file into state object
LV2PFileChunkHeader* chunk = (LV2PFileChunkHeader*)malloc(
sizeof(LV2PFileChunkHeader));
chunk->size = 0;
while (!lv2_pfile_read_chunk(file, &chunk)) {
if (!strncmp(chunk->type, "URID", 4)) {
LV2PFileURIChunk* body = (LV2PFileURIChunk*)chunk->data;
printf("READ URI %u: %s\n", body->id, body->uri);
state.add_uri(body->id, body->uri);
} else if (!strncmp(chunk->type, "KVAL", 4)) {
LV2PFileValueChunk* body = (LV2PFileValueChunk*)chunk->data;
printf("READ VAL %u = %s (size: %u type: %u)\n",
body->key, body->value, body->size, body->type);
state.add_value(body->key,
body->value,
body->size,
body->type,
true);
}
}
free(chunk);
persist->restore(_instance->lv2_handle,
&LV2Plugin::lv2_persist_retrieve_callback,
file);
&state);
lv2_pfile_close(file);
} else {
warning << string_compose(

331
libs/ardour/lv2ext/lv2_persist.h
View File

@ -1,177 +1,198 @@
/* lv2_persist.h - C header file for the LV2 Persist extension.
* Copyright (C) 2010 Leonard Ritter <paniq@paniq.org>
*
* 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
*/
/*
Copyright (C) 2010-2011 David Robillard <http://drobilla.net>
Copyright (C) 2010 Leonard Ritter <paniq@paniq.org>
/** @file
* C header for the LV2 Persist extension <http://lv2plug.in/ns/ext/persist>.
*/
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
*/
/**
@file
C API for the LV2 Persist extension <http://lv2plug.in/ns/ext/persist>.
*/
#ifndef LV2_PERSIST_H
#define LV2_PERSIST_H
#include <stdbool.h>
#include <stdint.h>
#ifdef __cplusplus
extern "C" {
#endif
#define LV2_PERSIST_URI "http://lv2plug.in/ns/ext/persist"
/** A host-provided function to store a value under a given key.
* @param callback_data Must be the callback_data passed to LV2_Persist.save().
* @param key The URI key (predicate) under which the value is to be stored.
* @param value Pointer to the value (object) to be stored.
* @param size The size of the data at @a value in bytes.
* @param type The type of @a value, as a URI mapped to an integer.
*
* The host passes a callback of this type to LV2_Persist.save(). This
* callback is called repeatedly by the plugin within LV2_Persist.save() to
* store all the key/value records that describe its current state.
*
* Unless @a type is 0, @a value is guaranteed to be POD (i.e. a region
* of memory that does not contain pointers and can safely be copied
* and persisted indefinitely with a simple memcpy). If @a type is 0,
* then @a value is a reference, as defined by the LV2 Atom extension
* <http://lv2plug.in/ns/ext/atom/>. Hosts are not required to support
* references: a plugin MUST NOT expect a host to persist references unless
* the host supports the feature <http://lv2plug.in/ns/ext/atom#blobSupport>.
* Plugins SHOULD express their state entirely with POD values.
*
* Note that @a size MUST be > 0, and @a value MUST point to a valid region of
* memory @a size bytes long (this is required to make restore unambiguous).
*
* The plugin MUST NOT attempt to use this function outside of the
* LV2_Persist.restore() context.
*/
typedef void (*LV2_Persist_Store_Function)(
void* callback_data,
const char* key,
const void* value,
size_t size,
uint32_t type);
/**
A host-provided function to store a value under a given key.
@param callback_data Must be the callback_data passed to LV2_Persist.save().
@param key The key (predicate) to store @a value under (URI mapped integer).
@param value Pointer to the value (object) to be stored.
@param size The size of the data at @a value in bytes.
@param type The type of @a value (URI mapped integer).
@param pod True iff @a value is POD.
@return 0 on success, otherwise a non-zero error code.
/** A host-provided function to retrieve a value under a given key.
* @param callback_data Must be the callback_data passed to LV2_Persist.restore().
* @param key The URI key (predicate) under which a value has been stored.
* @param size (Output) If non-NULL, set to the size of the restored value.
* @param type (Output) If non-NULL, set to the type of the restored value.
* @return A pointer to the restored value (object), or NULL if no value
* has been stored under @a key.
*
* A callback of this type is passed by the host to LV2_Persist.restore(). This
* callback is called repeatedly by the plugin within LV2_Persist.restore() to
* retrieve the values of any keys it requires to restore its state.
*
* The returned value MUST remain valid until LV2_Persist.restore() returns.
*
* The plugin MUST NOT attempt to use this function, or any value returned from
* it, outside of the LV2_Persist.restore() context. Returned values MAY be
* copied for later use if necessary.
*/
The host passes a callback of this type to LV2_Persist.save().
This callback is called repeatedly by the plugin within
LV2_Persist.save() to store all the key/value records that describe
its current state.
If @a pod is true, @a value is guaranteed to be architecture-independent POD
(i.e. a region of memory that does not contain pointers or references to
non-persistent resources and can safely be copied and stored with a simple
memcpy). Note that this definition of POD is more strict than exclusively
in-memory definitions since the value MUST be architecture independent;
e.g. endianness must be considered (so basic numeric types are typically NOT
POD). Hosts MAY fail to store the value, particularly if it is
non-POD. Plugins MUST gracefully handle this situation, even though state
may not be fully restored. Hosts SHOULD support any POD value, even if the
host does not know anything about its type. Plugins SHOULD express their
state entirely with POD values whenever possible, and use non-POD values
only where necessary. Plugins SHOULD use common RDF types and/or types from
the Atom extension <http://lv2plug.in/ns/ext/atom> whenever possible since
hosts are likely to already contain the necessary implementation.
Note that @a size MUST be > 0, and @a value MUST point to a valid region of
memory @a size bytes long (this is required to make restore unambiguous).
The plugin MUST NOT attempt to use this function outside of the
LV2_Persist.restore() context.
*/
typedef int (*LV2_Persist_Store_Function)(
void* callback_data,
const uint32_t key,
const void* value,
size_t size,
uint32_t type,
bool pod);
/**
A host-provided function to retrieve a value under a given key.
@param callback_data Must be the callback_data passed to LV2_Persist.restore().
@param key The key (predicate) of the value to retrieve (URI mapped integer).
@param size (Output) If non-NULL, set to the size of the restored value.
@param type (Output) If non-NULL, set to the type of the restored value.
@param pod (Output) If non-NULL, set to true iff @a value is POD.
@return A pointer to the restored value (object), or NULL if no value
has been stored under @a key.
A callback of this type is passed by the host to LV2_Persist.restore(). This
callback is called repeatedly by the plugin within LV2_Persist.restore() to
retrieve the values of any keys it requires to restore its state.
The returned value MUST remain valid until LV2_Persist.restore() returns.
The plugin MUST NOT attempt to use this function, or any value returned from
it, outside of the LV2_Persist.restore() context. Returned values MAY be
copied for later use if necessary, assuming the plugin knows how to
correctly do so (e.g. the value is POD, or the plugin understands the type).
*/
typedef const void* (*LV2_Persist_Retrieve_Function)(
void* callback_data,
const char* key,
size_t* size,
uint32_t* type);
void* callback_data,
uint32_t key,
size_t* size,
uint32_t* type,
bool* pod);
/** When the plugin's extension_data is called with argument LV2_PERSIST_URI,
* the plugin MUST return an LV2_Persist structure, which remains valid for
* the lifetime of the plugin.
*
* The host can use the contained function pointers to save and restore the
* state of a plugin instance at any time (provided the threading restrictions
* for the given function are met).
*
* The typical use case is to save the plugin's state when a project is
* saved, and to restore the state when a project has been loaded. Other
* uses are possible (e.g. cloning plugin instances or taking a snapshot
* of plugin state).
*
* Stored data is only guaranteed to be compatible between instances of plugins
* with the same URI (i.e. if a change to a plugin would cause a fatal error
* when restoring state saved by a previous version of that plugin, the plugin
* URI must change just as it must when a plugin's ports change). Plugin
* authors should consider this possibility, and always store sensible data
* with meaningful types to avoid such compatibility issues in the future.
*/
/**
Persist Extension Data.
When the plugin's extension_data is called with argument LV2_PERSIST_URI,
the plugin MUST return an LV2_Persist structure, which remains valid for
the lifetime of the plugin.
The host can use the contained function pointers to save and restore the
state of a plugin instance at any time (provided the threading restrictions
for the given function are met).
The typical use case is to save the plugin's state when a project is
saved, and to restore the state when a project has been loaded. Other
uses are possible (e.g. cloning plugin instances or taking a snapshot
of plugin state).
Stored data is only guaranteed to be compatible between instances of plugins
with the same URI (i.e. if a change to a plugin would cause a fatal error
when restoring state saved by a previous version of that plugin, the plugin
URI MUST change just as it must when ports change incompatibly). Plugin
authors should consider this possibility, and always store sensible data
with meaningful types to avoid such compatibility issues in the future.
*/
typedef struct _LV2_Persist {
/** Save plugin state using a host-provided @a store callback.
*
* @param instance The instance handle of the plugin.
* @param store The host-provided store callback.
* @param callback_data An opaque pointer to host data, e.g. the map or
* file where the values are to be stored. If @a store is called,
* this MUST be passed as its callback_data parameter.
*
* The plugin is expected to store everything necessary to completely
* restore its state later (possibly much later, in a different
* process, on a completely different machine, etc.)
*
* The @a callback_data pointer and @a store function MUST NOT be
* used beyond the scope of save().
*
* This function has its own special threading class: it may not be
* called concurrently with any "Instantiation" function, but it
* may be called concurrently with functions in any other class,
* unless the definition of that class prohibits it (e.g. it may
* not be called concurrently with a "Discovery" function, but it
* may be called concurrently with an "Audio" function. The plugin
* is responsible for any locking or lock-free techniques necessary
* to make this possible.
*
* Note that in the simple case where state is only modified by
* restore(), there are no synchronization issues since save() is
* never called concurrently with restore() (though run() may read
* it during a save).
*
* Plugins that dynamically modify state while running, however,
* must take care to do so in such a way that a concurrent call to
* save() will save a consistent representation of plugin state for a
* single instant in time. The simplest way to do this is to modify a
* copy of the state map and atomically swap a pointer to the entire
* map once the changes are complete (for very large state maps,
* a purely functional map data structure may be more appropriate
* since a complete copy is not necessary).
*/
/**
Save plugin state using a host-provided @a store callback.
@param instance The instance handle of the plugin.
@param store The host-provided store callback.
@param callback_data An opaque pointer to host data, e.g. the map or
file where the values are to be stored. If @a store is called,
this MUST be passed as its callback_data parameter.
The plugin is expected to store everything necessary to completely
restore its state later (possibly much later, in a different
process, on a completely different machine, etc.)
The @a callback_data pointer and @a store function MUST NOT be
used beyond the scope of save().
This function has its own special threading class: it may not be
called concurrently with any "Instantiation" function, but it
may be called concurrently with functions in any other class,
unless the definition of that class prohibits it (e.g. it may
not be called concurrently with a "Discovery" function, but it
may be called concurrently with an "Audio" function. The plugin
is responsible for any locking or lock-free techniques necessary
to make this possible.
Note that in the simple case where state is only modified by
restore(), there are no synchronization issues since save() is
never called concurrently with restore() (though run() may read
it during a save).
Plugins that dynamically modify state while running, however,
must take care to do so in such a way that a concurrent call to
save() will save a consistent representation of plugin state for a
single instant in time.
*/
void (*save)(LV2_Handle instance,
LV2_Persist_Store_Function store,
void* callback_data);
/** Restore plugin state using a host-provided @a retrieve callback.
*
* @param instance The instance handle of the plugin.
* @param retrieve The host-provided retrieve callback.
* @param callback_data An opaque pointer to host data, e.g. the map or
* file from which the values are to be restored. If @a retrieve is
* called, this MUST be passed as its callback_data parameter.
*
* The plugin MAY assume a restored value was set by a previous call to
* LV2_Persist.save() by a plugin with the same URI.
*
* The plugin MUST gracefully fall back to a default value when a
* value can not be retrieved. This allows the host to reset the
* plugin state with an empty map.
*
* The @a callback_data pointer and @a store function MUST NOT be used
* beyond the scope of restore().
*
* This function is in the "Instantiation" threading class as defined
* by LV2. This means it MUST NOT be called concurrently with any other
* function on the same plugin instance.
*/
/**
Restore plugin state using a host-provided @a retrieve callback.
@param instance The instance handle of the plugin.
@param retrieve The host-provided retrieve callback.
@param callback_data An opaque pointer to host data, e.g. the map or
file from which the values are to be restored. If @a retrieve is
called, this MUST be passed as its callback_data parameter.
The plugin MAY assume a restored value was set by a previous call to
LV2_Persist.save() by a plugin with the same URI.
The plugin MUST gracefully fall back to a default value when a
value can not be retrieved. This allows the host to reset the
plugin state with an empty map.
The @a callback_data pointer and @a store function MUST NOT be used
beyond the scope of restore().
This function is in the "Instantiation" threading class as defined
by LV2. This means it MUST NOT be called concurrently with any other
function on the same plugin instance.
*/
void (*restore)(LV2_Handle instance,
LV2_Persist_Retrieve_Function retrieve,
void* callback_data);