Generate book from example plugin source.

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.

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

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)

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
+<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.

plugins/eg-metro.lv2/README.txt

@@ -0,0 +1 @@
+== Metronome ==

plugins/eg-sampler.lv2/README.txt

@@ -0,0 +1 @@
+== Sampler ==

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:])

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')
+    

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')