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authorDavid Robillard <d@drobilla.net>2012-12-31 23:10:27 +0000
committerDavid Robillard <d@drobilla.net>2012-12-31 23:10:27 +0000
commit4a603a28de272c818100185ffbc8693585d7be9f (patch)
treebf8cbadb49bfefd61776185a3e20b192c2a0c64a
parentb09f94596a7361f01b835d811e14269ecec5272a (diff)
downloadlv2-4a603a28de272c818100185ffbc8693585d7be9f.tar.xz
Generate book from example plugin source.
-rw-r--r--plugins/README.txt26
-rw-r--r--plugins/eg-amp.lv2/README.txt21
-rw-r--r--plugins/eg-amp.lv2/amp.c117
-rw-r--r--plugins/eg-amp.lv2/manifest.ttl.in92
-rw-r--r--plugins/eg-metro.lv2/README.txt1
-rw-r--r--plugins/eg-sampler.lv2/README.txt1
-rwxr-xr-xplugins/literasc.py113
-rw-r--r--plugins/wscript37
-rw-r--r--wscript12
9 files changed, 346 insertions, 74 deletions
diff --git a/plugins/README.txt b/plugins/README.txt
new file mode 100644
index 0000000..7eb25d8
--- /dev/null
+++ b/plugins/README.txt
@@ -0,0 +1,26 @@
+= Programming LV2 Plugins =
+David Robillard <d@drobilla.net>
+:Author Initials: DER
+:toc:
+:website: http://lv2plug.in/
+:doctype: book
+
+== Introduction ==
+
+This is a series of well-documented example plugins that demonstrate the various features of LV2.
+Starting with the most basic plugin possible,
+each adds new functionality and explains the features used from a high level perspective.
+
+API and vocabulary reference documentation explains details,
+but not the ``big picture''.
+This book is intended to complement the reference documentation by providing good reference implementations of plugins,
+while also conveying a higher-level understanding of LV2.
+
+The chapters/plugins are arranged so that each builds incrementally on its predecessor.
+Reading this book front to back is a good way to become familiar with modern LV2 programming.
+The reader is expected to be familiar with C, but otherwise no special knowledge is required;
+the first plugin describes the basics in detail.
+
+This book is compiled from plugin source code into a single document for pleasant reading and ease of reference.
+Each chapter corresponds to executable plugin code which can be found in the +plugins+ directory of the LV2 distribution.
+If you prefer to read actual source code, all the content here is also available there, where the book text is included in comments.
diff --git a/plugins/eg-amp.lv2/README.txt b/plugins/eg-amp.lv2/README.txt
new file mode 100644
index 0000000..c2ab37d
--- /dev/null
+++ b/plugins/eg-amp.lv2/README.txt
@@ -0,0 +1,21 @@
+== Simple Amplifier ==
+
+This plugin is a simple example of a basic LV2 plugin with no additional features.
+It has audio ports which contain an array of `float`,
+and control ports which contain a single `float`.
+
+LV2 plugins are defined in two parts: code and data.
+The code is written in C (or any C compatible language, such as C++) and defines the executable portions of the plugin.
+Static data is described separately in human and machine readable files in the http://www.w3.org/TeamSubmission/turtle/[Turtle] syntax.
+Turtle is a syntax for the RDF data model,
+but familiarity with RDF is not required to understand this documentation.
+
+Generally, code is kept minimal,
+and all static information is described in the data.
+There are several advantages to this approach:
+
+ * Hosts can discover and inspect plugins without loading or executing any plugin code
+ * It is simple to work with plugin data using scripting languages, command line tools, etc.
+ * A standard format allows the re-use of existing vocabularies to describe plugins
+ * The data inherently integrates with the web, databases, etc.
+ * Labels and documentation are translatable, and available to hosts for display in user interfaces
diff --git a/plugins/eg-amp.lv2/amp.c b/plugins/eg-amp.lv2/amp.c
index 86f7a81..8dd7b4f 100644
--- a/plugins/eg-amp.lv2/amp.c
+++ b/plugins/eg-amp.lv2/amp.c
@@ -15,30 +15,43 @@
OR IN CONNECTION WITH THE USE OR PERFORMANCE OF THIS SOFTWARE.
*/
-/**
- @file amp.c Implementation of the LV2 Amp example plugin.
-
- This is a basic working LV2 plugin, about as small as one can get. It is
- useful as a skeleton to copy to build more advanced plugins. See lv2.h for
- more detailed descriptions of the rules for the various functions.
-*/
-
+/** Include standard C headers */
#include <math.h>
#include <stdlib.h>
-#include <string.h>
+/**
+ LV2 headers are based on the URI of the specification they come from, so a
+ consistent convention can be used even for unofficial extensions. The URI
+ of the core LV2 specification is <http://lv2plug.in/ns/lv2core>, by
+ replacing `http:/` with `lv2` any header in the specification bundle can be
+ included, in this case `lv2.h`.
+*/
#include "lv2/lv2plug.in/ns/lv2core/lv2.h"
+/**
+ The URI is the identifier for a plugin, and how the host associates this
+ implementation in code with its description in data. In this plugin it is
+ only used once in the code, but defining the plugin URI at the top of the
+ file is a good convention to follow. If this URI does not match that used
+ in the data files, the host will fail to load the plugin.
+*/
#define AMP_URI "http://lv2plug.in/plugins/eg-amp"
-/** Port indices. */
+/**
+ In code, ports are referred to by index. An enumeration of port indices
+ should be defined for readability.
+*/
typedef enum {
AMP_GAIN = 0,
AMP_INPUT = 1,
AMP_OUTPUT = 2
} PortIndex;
-/** Plugin instance. */
+/**
+ Every plugin defines a private structure for the plugin instance. All data
+ associated with a plugin instance is stored here, and is available to
+ every instance method. In this simple plugin, only port buffers need to be
+ stored, since there is no additional instance data. */
typedef struct {
// Port buffers
const float* gain;
@@ -46,7 +59,16 @@ typedef struct {
float* output;
} Amp;
-/** Create a new plugin instance. */
+/**
+ The instantiate() function is called by the host to create a new plugin
+ instance. The host passes the plugin descriptor, sample rate, and bundle
+ path for plugins that need to load additional resources (e.g. waveforms).
+ The features parameter contains host-provided features defined in LV2
+ extensions, but this simple plugin does not use any.
+
+ This function is in the ``instantiation'' threading class, so no other
+ methods on this instance will be called concurrently with it.
+*/
static LV2_Handle
instantiate(const LV2_Descriptor* descriptor,
double rate,
@@ -58,7 +80,14 @@ instantiate(const LV2_Descriptor* descriptor,
return (LV2_Handle)amp;
}
-/** Connect a port to a buffer (audio thread, must be RT safe). */
+/**
+ The connect_port() method is called by the host to connect a particular port
+ to a buffer. The plugin must store the data location, but data may not be
+ accessed except in run().
+
+ This method is in the ``audio'' threading class, and is called in the same
+ context as run().
+*/
static void
connect_port(LV2_Handle instance,
uint32_t port,
@@ -79,13 +108,21 @@ connect_port(LV2_Handle instance,
}
}
-/** Initialise and prepare the plugin instance for running. */
+/**
+ The activate() method is called by the host to initialise and prepare the
+ plugin instance for running. The plugin must reset all internal state
+ except for buffer locations set by connect_port(). Since this plugin has
+ no other internal state, this method does nothing.
+
+ This method is in the ``instantiation'' threading class, so no other
+ methods on this instance will be called concurrently with it.
+*/
static void
activate(LV2_Handle instance)
{
- /* Nothing to do here in this trivial mostly stateless plugin. */
}
+/** Define a macro for converting a gain in dB to a coefficient */
#define DB_CO(g) ((g) > -90.0f ? powf(10.0f, (g) * 0.05f) : 0.0f)
/** Process a block of audio (audio thread, must be RT safe). */
@@ -105,28 +142,55 @@ run(LV2_Handle instance, uint32_t n_samples)
}
}
-/** Finish running (counterpart to activate()). */
+/**
+ The deactivate() method is the counterpart to activate() called by the host
+ after running the plugin. It indicates that the host will not call run()
+ again until another call to activate() and is mainly useful for more
+ advanced plugins with ``live'' characteristics such as those with auxiliary
+ processing threads. As with activate(), this plugin has no use for this
+ information so this method does nothing.
+
+ This method is in the ``instantiation'' threading class, so no other
+ methods on this instance will be called concurrently with it.
+*/
static void
deactivate(LV2_Handle instance)
{
- /* Nothing to do here in this trivial mostly stateless plugin. */
}
-/** Destroy a plugin instance (counterpart to instantiate()). */
+/**
+ Destroy a plugin instance (counterpart to instantiate()).
+
+ This method is in the ``instantiation'' threading class, so no other
+ methods on this instance will be called concurrently with it.
+*/
static void
cleanup(LV2_Handle instance)
{
free(instance);
}
-/** Return extension data provided by the plugin. */
+/**
+ The extension_data function returns any extension data supported by the
+ plugin. Note that this is not an instance method, but a function on the
+ plugin descriptor. It is usually used by plugins to implement additional
+ interfaces. This plugin does not have any extension data, so this function
+ returns NULL.
+
+ This method is in the ``discovery'' threading class, so no other functions
+ or methods in this plugin library will be called concurrently with it.
+*/
static const void*
extension_data(const char* uri)
{
- return NULL; /* This plugin has no extension data. */
+ return NULL;
}
-/** The LV2_Descriptor for this plugin. */
+/**
+ Define the LV2_Descriptor for this plugin. It is best to define descriptors
+ statically to avoid leaking memory and non-portable shared library
+ constructors and destructors to clean up properly.
+*/
static const LV2_Descriptor descriptor = {
AMP_URI,
instantiate,
@@ -138,7 +202,16 @@ static const LV2_Descriptor descriptor = {
extension_data
};
-/** Entry point, the host will call this function to access descriptors. */
+/**
+ The lv2_descriptor() function is the entry point to the plugin library. The
+ host will load the library and call this function repeatedly with increasing
+ indices to find all the plugins defined in the library. The index is not an
+ indentifier, the URI of the returned descriptor is used to determine the
+ identify of the plugin.
+
+ This method is in the ``discovery'' threading class, so no other functions
+ or methods in this plugin library will be called concurrently with it.
+*/
LV2_SYMBOL_EXPORT
const LV2_Descriptor*
lv2_descriptor(uint32_t index)
diff --git a/plugins/eg-amp.lv2/manifest.ttl.in b/plugins/eg-amp.lv2/manifest.ttl.in
index 2813473..51f4a79 100644
--- a/plugins/eg-amp.lv2/manifest.ttl.in
+++ b/plugins/eg-amp.lv2/manifest.ttl.in
@@ -9,34 +9,31 @@
# resources) are available. Manifest files should be as small as possible for
# performance reasons.
#
-# The syntax of this file (and most other LV2 data files) is a language called
-# Turtle ("Turse RDF Triple Language").[1] RDF[3] is a data model that
-# expresses the relationship between things as (subject, predicate, object)
-# triples. Turtle is a simple, terse, abbreviated syntax for RDF.
-
-# Namespace Prefixes
+#
+# ==== Namespace Prefixes ====
#
# Turtle files often contain many URIs. To make this more readable, prefixes
-# can be defined. For example, with the lv2 prefix below, instead of
-# <http://lv2plug.in/ns/lv2core#Plugin> the shorter form lv2:Plugin can be
-# used. This is just a shorthand for URIs, the prefixes are not significant.
+# can be defined. For example, with the `lv2:` prefix below, instead of
+# <http://lv2plug.in/ns/lv2core#Plugin> the shorter form `lv2:Plugin` can be
+# used. This is just a shorthand for URIs within a file, the prefixes are not
+# significant otherwise.
@prefix lv2: <http://lv2plug.in/ns/lv2core#> .
@prefix rdfs: <http://www.w3.org/2000/01/rdf-schema#> .
-# Data (list of resources in this bundle, hence "manifest")
+# ==== Data ====
<http://lv2plug.in/plugins/eg-amp>
a lv2:Plugin ;
lv2:binary <amp@LIB_EXT@> ;
rdfs:seeAlso <amp.ttl> .
-# Explanation
-#
-# The token @LIB_EXT@ above is replaced by the build system (waf) by the
-# appropriate extension for the current platform (e.g. .so, .dylib, .dll),
-# which is why this file is called manifest.ttl.in and not manifest.ttl. This
-# documentation assumes .so for simplicity.
+# The token `@LIB_EXT@` above is replaced by the build system with the
+# appropriate extension for the current platform (e.g. .so, .dylib, .dll).
+# This file is called called `manifest.ttl.in` rather than `manifest.ttl`
+# to indicate that it is not the final file to be installed.
+# This is not necessary, but is a good idea for portable plugins.
+# For reability, the text will assume `.so` is the extension used.
#
# In short, this declares that the resource with URI
# "http://lv2plug.in/plugins/eg-amp" is an LV2 plugin, with executable code in
@@ -44,12 +41,12 @@
# relative to the bundle directory.
#
# There are 3 statements in this description:
-#
-# # | Subject | Predicate | Object
-# -------------------------------------------------------------------
-# 1 | <http://lv2plug.in/plugins/eg-amp> | a | lv2:Plugin
-# 2 | <http://lv2plug.in/plugins/eg-amp> | lv2:binary | <amp.so>
-# 3 | <http://lv2plug.in/plugins/eg-amp> | rdfs:seeAlso | <amp.ttl>
+# |================================================================
+# | Subject | Predicate | Object
+# | <http://lv2plug.in/plugins/eg-amp> | a | lv2:Plugin
+# | <http://lv2plug.in/plugins/eg-amp> | lv2:binary | <amp.so>
+# | <http://lv2plug.in/plugins/eg-amp> | rdfs:seeAlso | <amp.ttl>
+# |================================================================
#
# The semicolon is used to continue the previous subject; an equivalent
# but more verbose syntax for the same data is:
@@ -69,7 +66,8 @@
# a global identifier. It is, however, a good idea to use an actual web
# address if possible, since it can be used to easily access documentation,
# downloads, etc. Note there are compatibility rules for when the URI of a
-# plugin must be changed, see the LV2 specification[4] for details.
+# plugin must be changed, see the http://lv2plug.in/ns/lv2core[LV2 specification]
+# for details.
#
# AUTHORS MUST NOT CREATE URIS AT DOMAINS THEY DO NOT CONTROL WITHOUT
# PERMISSION, AND *ESPECIALLY* MUST NOT CREATE SYNTACTICALLY INVALID URIS,
@@ -80,32 +78,24 @@
# If this is truly impossible, use a URN, e.g. urn:myplugs:superamp.
#
# A detailed explanation of each statement follows.
-#
-# 1: <http://lv2plug.in/plugins/eg-amp> a lv2:Plugin
-#
-# The "a" is a Turtle shortcut for rdf:type and more or less means "is a".
-# lv2:Plugin expands to <http://lv2plug.in/ns/lv2core#Plugin> (using the
-# "lv2:" prefix above) and is the established URI for the type "LV2 Plugin".
-# This statement literally means "this resource is an LV2 plugin".
-#
-# 2: <http://lv2plug.in/plugins/eg-amp> lv2:binary <amp.so>
-#
-# This says "this plugin has executable code ("binary") in the file
-# named "amp.so", which is located in this bundle. The LV2 specification
-# defines that all relative URIs in manifest files are relative to the bundle
-# directory, so this refers to the file amp.so in the same directory as this
-# manifest.ttl file.
-#
-# 3: <http://lv2plug.in/plugins/eg-amp> rdfs:seeAlso <amp.ttl>
-#
-# This says "there is more information about this plugin located in the file
-# "amp.ttl". The host will look at all such files when it needs to actually
-# use or investigate the plugin.
-# Footnotes
-#
-# [1] http://www.w3.org/TeamSubmission/turtle/
-# [2] http://www.w3.org/RDF/
-# http://www.w3.org/TR/2004/REC-rdf-primer-20040210/
-# [3] http://tools.ietf.org/html/rfc3986
-# [4] http://lv2plug.in/ns/lv2core \ No newline at end of file
+<http://lv2plug.in/plugins/eg-amp> a lv2:Plugin .
+
+# The `a` is a Turtle shortcut for rdf:type and more or less means ``is a''.
+# `lv2:Plugin` expands to <http://lv2plug.in/ns/lv2core#Plugin> (using the
+# `lv2:` prefix above) which is the type of all LV2 plugins.
+# This statement means ``<http://lv2plug.in/plugins/eg-amp> is an LV2 plugin''.
+
+<http://lv2plug.in/plugins/eg-amp> lv2:binary <amp@LIB_EXT@> .
+
+# This says "this plugin has executable code ("binary") in the file
+# named "amp.so", which is located in this bundle. The LV2 specification
+# defines that all relative URIs in manifest files are relative to the bundle
+# directory, so this refers to the file amp.so in the same directory as this
+# manifest.ttl file.
+
+<http://lv2plug.in/plugins/eg-amp> rdfs:seeAlso <amp.ttl> .
+
+# This says ``there is more information about this plugin located in the file
+# `amp.ttl`''. The host will look at all such files when it needs to actually
+# use or investigate the plugin.
diff --git a/plugins/eg-metro.lv2/README.txt b/plugins/eg-metro.lv2/README.txt
new file mode 100644
index 0000000..52a650e
--- /dev/null
+++ b/plugins/eg-metro.lv2/README.txt
@@ -0,0 +1 @@
+== Metronome ==
diff --git a/plugins/eg-sampler.lv2/README.txt b/plugins/eg-sampler.lv2/README.txt
new file mode 100644
index 0000000..c1cac46
--- /dev/null
+++ b/plugins/eg-sampler.lv2/README.txt
@@ -0,0 +1 @@
+== Sampler ==
diff --git a/plugins/literasc.py b/plugins/literasc.py
new file mode 100755
index 0000000..b7b65cd
--- /dev/null
+++ b/plugins/literasc.py
@@ -0,0 +1,113 @@
+#!/usr/bin/env python
+# -*- coding: utf-8 -*-
+#
+# Literasc, a simple literate programming tool for C, C++, and Turtle.
+# Copyright 2012 David Robillard <d@drobilla.net>
+#
+# Unlike many LP tools, this tool uses normal source code as input, there is no
+# tangle/weave and no special file format. The literate parts of the program
+# are written in comments, which are emitted as paragraphs of regular text
+# interleaved with code. Asciidoc is both the comment and output syntax.
+
+import os
+import re
+import sys
+
+def format_text(text):
+ 'Format a text (comment) fragment and return it as a marked up string'
+ return '\n\n' + re.sub('\n *', '\n', text.strip()) + '\n\n'
+
+def format_code(lang, code):
+ if code.strip() == '':
+ return code
+
+ head = '[source,%s]' % lang
+ sep = '-' * len(head) + '\n'
+ return head + '\n' + sep + code.strip('\n') + '\n' + sep
+
+def format_c_source(filename, file):
+ output = '=== %s ===\n' % os.path.basename(filename)
+ chunk = ''
+ prev_c = 0
+ in_comment = False
+ in_comment_start = False
+ n_stars = 0
+ code = ''
+ for line in file:
+ code += line
+
+ for c in code:
+ if prev_c == '/' and c == '*':
+ output += format_code('c', chunk[0:len(chunk)-1])
+ in_comment = True
+ in_comment_start = True
+ n_stars = 1
+ chunk = ''
+ elif in_comment and prev_c == '*' and c == '/':
+ if n_stars > 2:
+ output += format_text(chunk[0:len(chunk)-1])
+ in_comment = False
+ in_comment_start = False
+ chunk = ''
+ elif in_comment_start and c == '*':
+ n_stars += 1
+ else:
+ chunk += c
+ prev_c = c
+
+ return output + format_code('c', chunk)
+
+def format_ttl_source(filename, file):
+ output = '=== %s ===\n' % os.path.basename(filename)
+
+ in_comment = False
+ chunk = ''
+ for line in file:
+ is_comment = line.strip().startswith('#')
+ if in_comment:
+ if is_comment:
+ chunk += line.strip().lstrip('# ') + ' \n'
+ else:
+ output += format_text(chunk)
+ in_comment = False
+ chunk = line
+ else:
+ if is_comment:
+ output += format_code('txt', chunk)
+ in_comment = True
+ chunk = line.strip().lstrip('# ') + ' \n'
+ else:
+ chunk += line
+
+ if in_comment:
+ return output + format_text(chunk)
+ else:
+ return output + format_code('txt', chunk)
+
+def gen(out, filenames):
+ for filename in filenames:
+ file = open(filename)
+ if not file:
+ sys.stderr.write('Failed to open file %s\n' % filename)
+ continue
+
+ if filename.endswith('.c'):
+ out.write(format_c_source(filename, file))
+ elif filename.endswith('.ttl') or filename.endswith('.ttl.in'):
+ out.write(format_ttl_source(filename, file))
+ elif filename.endswith('.txt'):
+ for line in file:
+ out.write(line)
+ out.write('\n')
+ else:
+ sys.stderr.write("Unknown source format `%s'" % (
+ filename[filename.find('.'):]))
+
+ file.close()
+
+if __name__ == "__main__":
+ if len(sys.argv) < 2:
+ sys.stderr.write('Usage: %s FILENAME...\n' % sys.argv[1])
+ sys.exit(1)
+
+ gen(sys.argv[1:])
diff --git a/plugins/wscript b/plugins/wscript
new file mode 100644
index 0000000..e474c78
--- /dev/null
+++ b/plugins/wscript
@@ -0,0 +1,37 @@
+#!/usr/bin/env python
+import os
+
+from waflib.extras import autowaf as autowaf
+import waflib.Logs as Logs
+
+import literasc
+
+def confgure(conf):
+ pass
+
+def bld_book_src(task):
+ filenames = []
+ for i in task.inputs:
+ filenames += [i.abspath()]
+
+ literasc.gen(open(task.outputs[0].abspath(), 'w'), filenames)
+
+
+def build(bld):
+ files = [bld.path.find_node('README.txt')]
+ for i in bld.path.ant_glob('*', src=False, dir=True):
+ for j in bld.path.ant_glob('%s/*.*' % i):
+ name = j.abspath()
+ if (name.endswith('.c') or
+ name.endswith('.txt') or
+ name.endswith('.ttl.in')):
+ files += [j]
+
+ bld(rule = bld_book_src,
+ source = files,
+ target = 'book.txt')
+
+ bld(rule = 'asciidoc -b html -o ${TGT} ${SRC}',
+ source = 'book.txt',
+ target = 'book.html')
+
diff --git a/wscript b/wscript
index 74d76b0..94062d7 100644
--- a/wscript
+++ b/wscript
@@ -55,6 +55,13 @@ def configure(conf):
conf.env.COPY_HEADERS = Options.options.copy_headers
conf.env.ONLINE_DOCS = Options.options.online_docs
+ if conf.env.DOCS or conf.env.ONLINE_DOCS:
+ try:
+ conf.find_program('asciidoc')
+ conf.env.BUILD_BOOK = True
+ except:
+ Logs.warn('Asciidoc not found, book will not be built')
+
# Check for gcov library (for test coverage)
if conf.env.BUILD_TESTS and not conf.is_defined('HAVE_GCOV'):
conf.check_cc(lib='gcov', define_name='HAVE_GCOV', mandatory=False)
@@ -65,7 +72,7 @@ def configure(conf):
conf.env.LV2_BUILD = ['lv2/lv2plug.in/ns/lv2core']
if conf.env.BUILD_PLUGINS:
- for i in conf.path.ant_glob('plugins/*', dir=True):
+ for i in conf.path.ant_glob('plugins/*', src=False, dir=True):
try:
conf.recurse(i.srcpath())
conf.env.LV2_BUILD += [i.srcpath()]
@@ -308,6 +315,9 @@ def build(bld):
for i in bld.env.LV2_BUILD:
bld.recurse(i)
+ if bld.env.BUILD_BOOK:
+ bld.recurse('plugins')
+
if bld.env.DOCS or bld.env.ONLINE_DOCS:
# Build Doxygen documentation (and tags file)
autowaf.build_dox(bld, 'LV2', VERSION, top, out, 'lv2plug.in/doc')