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| diff --git a/src/modules/ladspa.h b/src/modules/ladspa.h new file mode 100644 index 00000000..5c30a8a4 --- /dev/null +++ b/src/modules/ladspa.h @@ -0,0 +1,603 @@ +/* ladspa.h + +   Linux Audio Developer's Simple Plugin API Version 1.1[LGPL]. +   Copyright (C) 2000-2002 Richard W.E. Furse, Paul Barton-Davis, +   Stefan Westerfeld. +    +   This library 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 2.1 of +   the License, or (at your option) any later version. +    +   This library 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 library; if not, write to the Free Software +   Foundation, Inc., 59 Temple Place, Suite 330, Boston, MA 02111-1307 +   USA. */ + +#ifndef LADSPA_INCLUDED +#define LADSPA_INCLUDED + +#define LADSPA_VERSION "1.1" +#define LADSPA_VERSION_MAJOR 1 +#define LADSPA_VERSION_MINOR 1 + +#ifdef __cplusplus +extern "C" { +#endif + +/*****************************************************************************/ + +/* Overview:  + +   There is a large number of synthesis packages in use or development +   on the Linux platform at this time. This API (`The Linux Audio +   Developer's Simple Plugin API') attempts to give programmers the +   ability to write simple `plugin' audio processors in C/C++ and link +   them dynamically (`plug') into a range of these packages (`hosts'). +   It should be possible for any host and any plugin to communicate +   completely through this interface. + +   This API is deliberately short and simple. To achieve compatibility +   with a range of promising Linux sound synthesis packages it +   attempts to find the `greatest common divisor' in their logical +   behaviour. Having said this, certain limiting decisions are +   implicit, notably the use of a fixed type (LADSPA_Data) for all +   data transfer and absence of a parameterised `initialisation' +   phase. See below for the LADSPA_Data typedef. + +   Plugins are expected to distinguish between control and audio +   data. Plugins have `ports' that are inputs or outputs for audio or +   control data and each plugin is `run' for a `block' corresponding +   to a short time interval measured in samples. Audio data is +   communicated using arrays of LADSPA_Data, allowing a block of audio +   to be processed by the plugin in a single pass. Control data is +   communicated using single LADSPA_Data values. Control data has a +   single value at the start of a call to the `run()' or `run_adding()' +   function, and may be considered to remain this value for its +   duration. The plugin may assume that all its input and output ports +   have been connected to the relevant data location (see the +   `connect_port()' function below) before it is asked to run. + +   Plugins will reside in shared object files suitable for dynamic +   linking by dlopen() and family. The file will provide a number of +   `plugin types' that can be used to instantiate actual plugins +   (sometimes known as `plugin instances') that can be connected +   together to perform tasks. + +   This API contains very limited error-handling. */ + +/*****************************************************************************/ + +/* Fundamental data type passed in and out of plugin. This data type +   is used to communicate audio samples and control values. It is +   assumed that the plugin will work sensibly given any numeric input +   value although it may have a preferred range (see hints below).  + +   For audio it is generally assumed that 1.0f is the `0dB' reference +   amplitude and is a `normal' signal level. */ + +typedef float LADSPA_Data; + +/*****************************************************************************/ + +/* Special Plugin Properties:  +  +   Optional features of the plugin type are encapsulated in the +   LADSPA_Properties type. This is assembled by ORing individual +   properties together. */ + +typedef int LADSPA_Properties; + +/* Property LADSPA_PROPERTY_REALTIME indicates that the plugin has a +   real-time dependency (e.g. listens to a MIDI device) and so its +   output must not be cached or subject to significant latency. */ +#define LADSPA_PROPERTY_REALTIME        0x1 + +/* Property LADSPA_PROPERTY_INPLACE_BROKEN indicates that the plugin +   may cease to work correctly if the host elects to use the same data +   location for both input and output (see connect_port()). This +   should be avoided as enabling this flag makes it impossible for +   hosts to use the plugin to process audio `in-place.' */ +#define LADSPA_PROPERTY_INPLACE_BROKEN  0x2 + +/* Property LADSPA_PROPERTY_HARD_RT_CAPABLE indicates that the plugin +   is capable of running not only in a conventional host but also in a +   `hard real-time' environment. To qualify for this the plugin must +   satisfy all of the following: + +   (1) The plugin must not use malloc(), free() or other heap memory +   management within its run() or run_adding() functions. All new +   memory used in run() must be managed via the stack. These +   restrictions only apply to the run() function. + +   (2) The plugin will not attempt to make use of any library +   functions with the exceptions of functions in the ANSI standard C +   and C maths libraries, which the host is expected to provide. + +   (3) The plugin will not access files, devices, pipes, sockets, IPC +   or any other mechanism that might result in process or thread +   blocking. +       +   (4) The plugin will take an amount of time to execute a run() or +   run_adding() call approximately of form (A+B*SampleCount) where A +   and B depend on the machine and host in use. This amount of time +   may not depend on input signals or plugin state. The host is left +   the responsibility to perform timings to estimate upper bounds for +   A and B. */ +#define LADSPA_PROPERTY_HARD_RT_CAPABLE 0x4 + +#define LADSPA_IS_REALTIME(x)        ((x) & LADSPA_PROPERTY_REALTIME) +#define LADSPA_IS_INPLACE_BROKEN(x)  ((x) & LADSPA_PROPERTY_INPLACE_BROKEN) +#define LADSPA_IS_HARD_RT_CAPABLE(x) ((x) & LADSPA_PROPERTY_HARD_RT_CAPABLE) + +/*****************************************************************************/ + +/* Plugin Ports:  + +   Plugins have `ports' that are inputs or outputs for audio or +   data. Ports can communicate arrays of LADSPA_Data (for audio +   inputs/outputs) or single LADSPA_Data values (for control +   input/outputs). This information is encapsulated in the +   LADSPA_PortDescriptor type which is assembled by ORing individual +   properties together. + +   Note that a port must be an input or an output port but not both +   and that a port must be a control or audio port but not both. */ + +typedef int LADSPA_PortDescriptor; + +/* Property LADSPA_PORT_INPUT indicates that the port is an input. */ +#define LADSPA_PORT_INPUT   0x1 + +/* Property LADSPA_PORT_OUTPUT indicates that the port is an output. */ +#define LADSPA_PORT_OUTPUT  0x2 + +/* Property LADSPA_PORT_CONTROL indicates that the port is a control +   port. */ +#define LADSPA_PORT_CONTROL 0x4 + +/* Property LADSPA_PORT_AUDIO indicates that the port is a audio +   port. */ +#define LADSPA_PORT_AUDIO   0x8 + +#define LADSPA_IS_PORT_INPUT(x)   ((x) & LADSPA_PORT_INPUT) +#define LADSPA_IS_PORT_OUTPUT(x)  ((x) & LADSPA_PORT_OUTPUT) +#define LADSPA_IS_PORT_CONTROL(x) ((x) & LADSPA_PORT_CONTROL) +#define LADSPA_IS_PORT_AUDIO(x)   ((x) & LADSPA_PORT_AUDIO) + +/*****************************************************************************/ + +/* Plugin Port Range Hints:  + +   The host may wish to provide a representation of data entering or +   leaving a plugin (e.g. to generate a GUI automatically). To make +   this more meaningful, the plugin should provide `hints' to the host +   describing the usual values taken by the data. +    +   Note that these are only hints. The host may ignore them and the +   plugin must not assume that data supplied to it is meaningful. If +   the plugin receives invalid input data it is expected to continue +   to run without failure and, where possible, produce a sensible +   output (e.g. a high-pass filter given a negative cutoff frequency +   might switch to an all-pass mode). +     +   Hints are meaningful for all input and output ports but hints for +   input control ports are expected to be particularly useful. +    +   More hint information is encapsulated in the +   LADSPA_PortRangeHintDescriptor type which is assembled by ORing +   individual hint types together. Hints may require further +   LowerBound and UpperBound information. + +   All the hint information for a particular port is aggregated in the +   LADSPA_PortRangeHint structure. */ + +typedef int LADSPA_PortRangeHintDescriptor; + +/* Hint LADSPA_HINT_BOUNDED_BELOW indicates that the LowerBound field +   of the LADSPA_PortRangeHint should be considered meaningful. The +   value in this field should be considered the (inclusive) lower +   bound of the valid range. If LADSPA_HINT_SAMPLE_RATE is also +   specified then the value of LowerBound should be multiplied by the +   sample rate. */ +#define LADSPA_HINT_BOUNDED_BELOW   0x1 + +/* Hint LADSPA_HINT_BOUNDED_ABOVE indicates that the UpperBound field +   of the LADSPA_PortRangeHint should be considered meaningful. The +   value in this field should be considered the (inclusive) upper +   bound of the valid range. If LADSPA_HINT_SAMPLE_RATE is also +   specified then the value of UpperBound should be multiplied by the +   sample rate. */ +#define LADSPA_HINT_BOUNDED_ABOVE   0x2 + +/* Hint LADSPA_HINT_TOGGLED indicates that the data item should be +   considered a Boolean toggle. Data less than or equal to zero should +   be considered `off' or `false,' and data above zero should be +   considered `on' or `true.' LADSPA_HINT_TOGGLED may not be used in +   conjunction with any other hint except LADSPA_HINT_DEFAULT_0 or +   LADSPA_HINT_DEFAULT_1. */ +#define LADSPA_HINT_TOGGLED         0x4 + +/* Hint LADSPA_HINT_SAMPLE_RATE indicates that any bounds specified +   should be interpreted as multiples of the sample rate. For +   instance, a frequency range from 0Hz to the Nyquist frequency (half +   the sample rate) could be requested by this hint in conjunction +   with LowerBound = 0 and UpperBound = 0.5. Hosts that support bounds +   at all must support this hint to retain meaning. */ +#define LADSPA_HINT_SAMPLE_RATE     0x8 + +/* Hint LADSPA_HINT_LOGARITHMIC indicates that it is likely that the +   user will find it more intuitive to view values using a logarithmic +   scale. This is particularly useful for frequencies and gains. */ +#define LADSPA_HINT_LOGARITHMIC     0x10 + +/* Hint LADSPA_HINT_INTEGER indicates that a user interface would +   probably wish to provide a stepped control taking only integer +   values. Any bounds set should be slightly wider than the actual +   integer range required to avoid floating point rounding errors. For +   instance, the integer set {0,1,2,3} might be described as [-0.1, +   3.1]. */ +#define LADSPA_HINT_INTEGER         0x20 + +/* The various LADSPA_HINT_HAS_DEFAULT_* hints indicate a `normal' +   value for the port that is sensible as a default. For instance, +   this value is suitable for use as an initial value in a user +   interface or as a value the host might assign to a control port +   when the user has not provided one. Defaults are encoded using a +   mask so only one default may be specified for a port. Some of the +   hints make use of lower and upper bounds, in which case the +   relevant bound or bounds must be available and +   LADSPA_HINT_SAMPLE_RATE must be applied as usual. The resulting +   default must be rounded if LADSPA_HINT_INTEGER is present. Default +   values were introduced in LADSPA v1.1. */ +#define LADSPA_HINT_DEFAULT_MASK    0x3C0 + +/* This default values indicates that no default is provided. */ +#define LADSPA_HINT_DEFAULT_NONE    0x0 + +/* This default hint indicates that the suggested lower bound for the +   port should be used. */ +#define LADSPA_HINT_DEFAULT_MINIMUM 0x40 + +/* This default hint indicates that a low value between the suggested +   lower and upper bounds should be chosen. For ports with +   LADSPA_HINT_LOGARITHMIC, this should be exp(log(lower) * 0.75 + +   log(upper) * 0.25). Otherwise, this should be (lower * 0.75 + upper +   * 0.25). */ +#define LADSPA_HINT_DEFAULT_LOW     0x80 + +/* This default hint indicates that a middle value between the +   suggested lower and upper bounds should be chosen. For ports with +   LADSPA_HINT_LOGARITHMIC, this should be exp(log(lower) * 0.5 + +   log(upper) * 0.5). Otherwise, this should be (lower * 0.5 + upper * +   0.5). */ +#define LADSPA_HINT_DEFAULT_MIDDLE  0xC0 + +/* This default hint indicates that a high value between the suggested +   lower and upper bounds should be chosen. For ports with +   LADSPA_HINT_LOGARITHMIC, this should be exp(log(lower) * 0.25 + +   log(upper) * 0.75). Otherwise, this should be (lower * 0.25 + upper +   * 0.75). */ +#define LADSPA_HINT_DEFAULT_HIGH    0x100 + +/* This default hint indicates that the suggested upper bound for the +   port should be used. */ +#define LADSPA_HINT_DEFAULT_MAXIMUM 0x140 + +/* This default hint indicates that the number 0 should be used. Note +   that this default may be used in conjunction with +   LADSPA_HINT_TOGGLED. */ +#define LADSPA_HINT_DEFAULT_0       0x200 + +/* This default hint indicates that the number 1 should be used. Note +   that this default may be used in conjunction with +   LADSPA_HINT_TOGGLED. */ +#define LADSPA_HINT_DEFAULT_1       0x240 + +/* This default hint indicates that the number 100 should be used. */ +#define LADSPA_HINT_DEFAULT_100     0x280 + +/* This default hint indicates that the Hz frequency of `concert A' +   should be used. This will be 440 unless the host uses an unusual +   tuning convention, in which case it may be within a few Hz. */ +#define LADSPA_HINT_DEFAULT_440     0x2C0 + +#define LADSPA_IS_HINT_BOUNDED_BELOW(x)   ((x) & LADSPA_HINT_BOUNDED_BELOW) +#define LADSPA_IS_HINT_BOUNDED_ABOVE(x)   ((x) & LADSPA_HINT_BOUNDED_ABOVE) +#define LADSPA_IS_HINT_TOGGLED(x)         ((x) & LADSPA_HINT_TOGGLED) +#define LADSPA_IS_HINT_SAMPLE_RATE(x)     ((x) & LADSPA_HINT_SAMPLE_RATE) +#define LADSPA_IS_HINT_LOGARITHMIC(x)     ((x) & LADSPA_HINT_LOGARITHMIC) +#define LADSPA_IS_HINT_INTEGER(x)         ((x) & LADSPA_HINT_INTEGER) + +#define LADSPA_IS_HINT_HAS_DEFAULT(x)     ((x) & LADSPA_HINT_DEFAULT_MASK) +#define LADSPA_IS_HINT_DEFAULT_MINIMUM(x) (((x) & LADSPA_HINT_DEFAULT_MASK)   \ +                                           == LADSPA_HINT_DEFAULT_MINIMUM) +#define LADSPA_IS_HINT_DEFAULT_LOW(x)     (((x) & LADSPA_HINT_DEFAULT_MASK)   \ +                                           == LADSPA_HINT_DEFAULT_LOW) +#define LADSPA_IS_HINT_DEFAULT_MIDDLE(x)  (((x) & LADSPA_HINT_DEFAULT_MASK)   \ +                                           == LADSPA_HINT_DEFAULT_MIDDLE) +#define LADSPA_IS_HINT_DEFAULT_HIGH(x)    (((x) & LADSPA_HINT_DEFAULT_MASK)   \ +                                           == LADSPA_HINT_DEFAULT_HIGH) +#define LADSPA_IS_HINT_DEFAULT_MAXIMUM(x) (((x) & LADSPA_HINT_DEFAULT_MASK)   \ +                                           == LADSPA_HINT_DEFAULT_MAXIMUM) +#define LADSPA_IS_HINT_DEFAULT_0(x)       (((x) & LADSPA_HINT_DEFAULT_MASK)   \ +                                           == LADSPA_HINT_DEFAULT_0) +#define LADSPA_IS_HINT_DEFAULT_1(x)       (((x) & LADSPA_HINT_DEFAULT_MASK)   \ +                                           == LADSPA_HINT_DEFAULT_1) +#define LADSPA_IS_HINT_DEFAULT_100(x)     (((x) & LADSPA_HINT_DEFAULT_MASK)   \ +                                           == LADSPA_HINT_DEFAULT_100) +#define LADSPA_IS_HINT_DEFAULT_440(x)     (((x) & LADSPA_HINT_DEFAULT_MASK)   \ +                                            == LADSPA_HINT_DEFAULT_440) + +typedef struct _LADSPA_PortRangeHint { + +  /* Hints about the port. */ +  LADSPA_PortRangeHintDescriptor HintDescriptor; + +  /* Meaningful when hint LADSPA_HINT_BOUNDED_BELOW is active. When +     LADSPA_HINT_SAMPLE_RATE is also active then this value should be +     multiplied by the relevant sample rate. */ +  LADSPA_Data LowerBound; + +  /* Meaningful when hint LADSPA_HINT_BOUNDED_ABOVE is active. When +     LADSPA_HINT_SAMPLE_RATE is also active then this value should be +     multiplied by the relevant sample rate. */ +  LADSPA_Data UpperBound; + +} LADSPA_PortRangeHint; + +/*****************************************************************************/ + +/* Plugin Handles:  + +   This plugin handle indicates a particular instance of the plugin +   concerned. It is valid to compare this to NULL (0 for C++) but +   otherwise the host should not attempt to interpret it. The plugin +   may use it to reference internal instance data. */ + +typedef void * LADSPA_Handle; + +/*****************************************************************************/ + +/* Descriptor for a Type of Plugin:  + +   This structure is used to describe a plugin type. It provides a +   number of functions to examine the type, instantiate it, link it to +   buffers and workspaces and to run it. */ + +typedef struct _LADSPA_Descriptor {  + +  /* This numeric identifier indicates the plugin type +     uniquely. Plugin programmers may reserve ranges of IDs from a +     central body to avoid clashes. Hosts may assume that IDs are +     below 0x1000000. */ +  unsigned long UniqueID; + +  /* This identifier can be used as a unique, case-sensitive +     identifier for the plugin type within the plugin file. Plugin +     types should be identified by file and label rather than by index +     or plugin name, which may be changed in new plugin +     versions. Labels must not contain white-space characters. */ +  const char * Label; + +  /* This indicates a number of properties of the plugin. */ +  LADSPA_Properties Properties; + +  /* This member points to the null-terminated name of the plugin +     (e.g. "Sine Oscillator"). */ +  const char * Name; + +  /* This member points to the null-terminated string indicating the +     maker of the plugin. This can be an empty string but not NULL. */ +  const char * Maker; + +  /* This member points to the null-terminated string indicating any +     copyright applying to the plugin. If no Copyright applies the +     string "None" should be used. */ +  const char * Copyright; + +  /* This indicates the number of ports (input AND output) present on +     the plugin. */ +  unsigned long PortCount; + +  /* This member indicates an array of port descriptors. Valid indices +     vary from 0 to PortCount-1. */ +  const LADSPA_PortDescriptor * PortDescriptors; + +  /* This member indicates an array of null-terminated strings +     describing ports (e.g. "Frequency (Hz)"). Valid indices vary from +     0 to PortCount-1. */ +  const char * const * PortNames; + +  /* This member indicates an array of range hints for each port (see +     above). Valid indices vary from 0 to PortCount-1. */ +  const LADSPA_PortRangeHint * PortRangeHints; + +  /* This may be used by the plugin developer to pass any custom +     implementation data into an instantiate call. It must not be used +     or interpreted by the host. It is expected that most plugin +     writers will not use this facility as LADSPA_Handle should be +     used to hold instance data. */ +  void * ImplementationData; + +  /* This member is a function pointer that instantiates a plugin. A +     handle is returned indicating the new plugin instance. The +     instantiation function accepts a sample rate as a parameter. The +     plugin descriptor from which this instantiate function was found +     must also be passed. This function must return NULL if +     instantiation fails.  + +     Note that instance initialisation should generally occur in +     activate() rather than here. */ +  LADSPA_Handle (*instantiate)(const struct _LADSPA_Descriptor * Descriptor, +                               unsigned long                     SampleRate); + +  /* This member is a function pointer that connects a port on an +     instantiated plugin to a memory location at which a block of data +     for the port will be read/written. The data location is expected +     to be an array of LADSPA_Data for audio ports or a single +     LADSPA_Data value for control ports. Memory issues will be +     managed by the host. The plugin must read/write the data at these +     locations every time run() or run_adding() is called and the data +     present at the time of this connection call should not be +     considered meaningful. + +     connect_port() may be called more than once for a plugin instance +     to allow the host to change the buffers that the plugin is +     reading or writing. These calls may be made before or after +     activate() or deactivate() calls. + +     connect_port() must be called at least once for each port before +     run() or run_adding() is called. When working with blocks of +     LADSPA_Data the plugin should pay careful attention to the block +     size passed to the run function as the block allocated may only +     just be large enough to contain the block of samples. + +     Plugin writers should be aware that the host may elect to use the +     same buffer for more than one port and even use the same buffer +     for both input and output (see LADSPA_PROPERTY_INPLACE_BROKEN). +     However, overlapped buffers or use of a single buffer for both +     audio and control data may result in unexpected behaviour. */ +   void (*connect_port)(LADSPA_Handle Instance, +                        unsigned long Port, +                        LADSPA_Data * DataLocation); + +  /* This member is a function pointer that initialises a plugin +     instance and activates it for use. This is separated from +     instantiate() to aid real-time support and so that hosts can +     reinitialise a plugin instance by calling deactivate() and then +     activate(). In this case the plugin instance must reset all state +     information dependent on the history of the plugin instance +     except for any data locations provided by connect_port() and any +     gain set by set_run_adding_gain(). If there is nothing for +     activate() to do then the plugin writer may provide a NULL rather +     than an empty function. + +     When present, hosts must call this function once before run() (or +     run_adding()) is called for the first time. This call should be +     made as close to the run() call as possible and indicates to +     real-time plugins that they are now live. Plugins should not rely +     on a prompt call to run() after activate(). activate() may not be +     called again unless deactivate() is called first. Note that +     connect_port() may be called before or after a call to +     activate(). */ +  void (*activate)(LADSPA_Handle Instance); + +  /* This method is a function pointer that runs an instance of a +     plugin for a block. Two parameters are required: the first is a +     handle to the particular instance to be run and the second +     indicates the block size (in samples) for which the plugin +     instance may run. + +     Note that if an activate() function exists then it must be called +     before run() or run_adding(). If deactivate() is called for a +     plugin instance then the plugin instance may not be reused until +     activate() has been called again. + +     If the plugin has the property LADSPA_PROPERTY_HARD_RT_CAPABLE +     then there are various things that the plugin should not do +     within the run() or run_adding() functions (see above). */ +  void (*run)(LADSPA_Handle Instance, +              unsigned long SampleCount); + +  /* This method is a function pointer that runs an instance of a +     plugin for a block. This has identical behaviour to run() except +     in the way data is output from the plugin. When run() is used, +     values are written directly to the memory areas associated with +     the output ports. However when run_adding() is called, values +     must be added to the values already present in the memory +     areas. Furthermore, output values written must be scaled by the +     current gain set by set_run_adding_gain() (see below) before +     addition. + +     run_adding() is optional. When it is not provided by a plugin, +     this function pointer must be set to NULL. When it is provided, +     the function set_run_adding_gain() must be provided also. */ +  void (*run_adding)(LADSPA_Handle Instance, +                     unsigned long SampleCount); + +  /* This method is a function pointer that sets the output gain for +     use when run_adding() is called (see above). If this function is +     never called the gain is assumed to default to 1. Gain +     information should be retained when activate() or deactivate() +     are called. + +     This function should be provided by the plugin if and only if the +     run_adding() function is provided. When it is absent this +     function pointer must be set to NULL. */ +  void (*set_run_adding_gain)(LADSPA_Handle Instance, +                              LADSPA_Data   Gain); + +  /* This is the counterpart to activate() (see above). If there is +     nothing for deactivate() to do then the plugin writer may provide +     a NULL rather than an empty function. + +     Hosts must deactivate all activated units after they have been +     run() (or run_adding()) for the last time. This call should be +     made as close to the last run() call as possible and indicates to +     real-time plugins that they are no longer live. Plugins should +     not rely on prompt deactivation. Note that connect_port() may be +     called before or after a call to deactivate(). + +     Deactivation is not similar to pausing as the plugin instance +     will be reinitialised when activate() is called to reuse it. */ +  void (*deactivate)(LADSPA_Handle Instance); + +  /* Once an instance of a plugin has been finished with it can be +     deleted using the following function. The instance handle passed +     ceases to be valid after this call. +   +     If activate() was called for a plugin instance then a +     corresponding call to deactivate() must be made before cleanup() +     is called. */ +  void (*cleanup)(LADSPA_Handle Instance); + +} LADSPA_Descriptor; + +/**********************************************************************/ + +/* Accessing a Plugin: */ + +/* The exact mechanism by which plugins are loaded is host-dependent, +   however all most hosts will need to know is the name of shared +   object file containing the plugin types. To allow multiple hosts to +   share plugin types, hosts may wish to check for environment +   variable LADSPA_PATH. If present, this should contain a +   colon-separated path indicating directories that should be searched +   (in order) when loading plugin types. + +   A plugin programmer must include a function called +   "ladspa_descriptor" with the following function prototype within +   the shared object file. This function will have C-style linkage (if +   you are using C++ this is taken care of by the `extern "C"' clause +   at the top of the file). + +   A host will find the plugin shared object file by one means or +   another, find the ladspa_descriptor() function, call it, and +   proceed from there. + +   Plugin types are accessed by index (not ID) using values from 0 +   upwards. Out of range indexes must result in this function +   returning NULL, so the plugin count can be determined by checking +   for the least index that results in NULL being returned. */ + +const LADSPA_Descriptor * ladspa_descriptor(unsigned long Index); + +/* Datatype corresponding to the ladspa_descriptor() function. */ +typedef const LADSPA_Descriptor *  +(*LADSPA_Descriptor_Function)(unsigned long Index); + +/**********************************************************************/ + +#ifdef __cplusplus +} +#endif + +#endif /* LADSPA_INCLUDED */ + +/* EOF */ | 
