diff options
Diffstat (limited to 'plugins')
| -rw-r--r-- | plugins/README.txt | 26 | ||||
| -rw-r--r-- | plugins/eg-amp.lv2/README.txt | 21 | ||||
| -rw-r--r-- | plugins/eg-amp.lv2/amp.c | 117 | ||||
| -rw-r--r-- | plugins/eg-amp.lv2/manifest.ttl.in | 92 | ||||
| -rw-r--r-- | plugins/eg-metro.lv2/README.txt | 1 | ||||
| -rw-r--r-- | plugins/eg-sampler.lv2/README.txt | 1 | ||||
| -rwxr-xr-x | plugins/literasc.py | 113 | ||||
| -rw-r--r-- | plugins/wscript | 37 |
8 files changed, 335 insertions, 73 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') + |