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-rw-r--r--backends/Makefile2
-rw-r--r--backends/python.c419
-rw-r--r--backends/python.h25
-rw-r--r--backends/python.md63
4 files changed, 508 insertions, 1 deletions
diff --git a/backends/Makefile b/backends/Makefile
index 191a495..366d4b4 100644
--- a/backends/Makefile
+++ b/backends/Makefile
@@ -1,7 +1,7 @@
.PHONY: all clean full
LINUX_BACKENDS = midi.so evdev.so
WINDOWS_BACKENDS = artnet.dll osc.dll loopback.dll sacn.dll maweb.dll winmidi.dll openpixelcontrol.dll
-BACKENDS = artnet.so osc.so loopback.so sacn.so lua.so maweb.so jack.so openpixelcontrol.so
+BACKENDS = artnet.so osc.so loopback.so sacn.so lua.so maweb.so jack.so openpixelcontrol.so python.so
OPTIONAL_BACKENDS = ola.so
BACKEND_LIB = libmmbackend.o
diff --git a/backends/python.c b/backends/python.c
new file mode 100644
index 0000000..9fad0ae
--- /dev/null
+++ b/backends/python.c
@@ -0,0 +1,419 @@
+#define BACKEND_NAME "python"
+
+#define PY_SSIZE_T_CLEAN
+#include <string.h>
+#include <Python.h>
+#include "python.h"
+
+#define MMPY_INSTANCE_KEY "midimonster_instance"
+
+/*
+ * TODO might want to export the full MM_API set to python at some point
+ */
+
+static PyThreadState* python_main = NULL;
+static wchar_t* program_name = NULL;
+
+MM_PLUGIN_API int init(){
+ backend python = {
+ .name = BACKEND_NAME,
+ .conf = python_configure,
+ .create = python_instance,
+ .conf_instance = python_configure_instance,
+ .channel = python_channel,
+ .handle = python_set,
+ .process = python_handle,
+ .start = python_start,
+ .shutdown = python_shutdown
+ };
+
+ //register backend
+ if(mm_backend_register(python)){
+ LOG("Failed to register backend");
+ return 1;
+ }
+ return 0;
+}
+
+static int python_configure(char* option, char* value){
+ LOG("No backend configuration possible");
+ return 1;
+}
+
+static int python_prepend_str(PyObject* list, char* str){
+ if(!list || !str){
+ return 1;
+ }
+
+ PyObject* item = PyUnicode_FromString(str);
+ if(!item){
+ return 1;
+ }
+
+ if(PyList_Insert(list, 0, item) < 0){
+ Py_DECREF(item);
+ return 1;
+ }
+ Py_DECREF(item);
+ return 0;
+}
+
+static PyObject* mmpy_output(PyObject* self, PyObject* args){
+ instance* inst = *((instance**) PyModule_GetState(self));
+ python_instance_data* data = (python_instance_data*) inst->impl;
+ const char* channel_name = NULL;
+ channel* chan = NULL;
+ channel_value val = {
+ 0
+ };
+ size_t u;
+
+ if(!PyArg_ParseTuple(args, "sd", &channel_name, &val.normalised)){
+ return NULL;
+ }
+
+ val.normalised = clamp(val.normalised, 1.0, 0.0);
+
+ for(u = 0; u < data->channels; u++){
+ if(!strcmp(data->channel[u].name, channel_name)){
+ DBGPF("Setting channel %s.%s to %f", inst->name, channel_name, val.normalised);
+ chan = mm_channel(inst, u, 0);
+ //this should never happen
+ if(!chan){
+ LOGPF("Failed to fetch parsed channel %s.%s", inst->name, channel_name);
+ break;
+ }
+ data->channel[u].out = val.normalised;
+ mm_channel_event(chan, val);
+ break;
+ }
+ }
+
+ if(u == data->channels){
+ DBGPF("Output on unknown channel %s.%s, no event pushed", inst->name, channel_name);
+ }
+
+ Py_INCREF(Py_None);
+ return Py_None;
+}
+
+static PyObject* mmpy_channel_value(PyObject* self, PyObject* args, uint8_t in){
+ instance* inst = *((instance**) PyModule_GetState(self));
+ python_instance_data* data = (python_instance_data*) inst->impl;
+ const char* channel_name = NULL;
+ size_t u;
+
+ if(!PyArg_ParseTuple(args, "s", &channel_name)){
+ return NULL;
+ }
+
+ for(u = 0; u < data->channels; u++){
+ if(!strcmp(data->channel[u].name, channel_name)){
+ return PyFloat_FromDouble(in ? data->channel[u].in : data->channel[u].out);
+ }
+ }
+
+ Py_INCREF(Py_None);
+ return Py_None;
+}
+
+static PyObject* mmpy_current_handler(PyObject* self, PyObject* args){
+ instance* inst = *((instance**) PyModule_GetState(self));
+ python_instance_data* data = (python_instance_data*) inst->impl;
+
+ if(data->current_channel){
+ return PyUnicode_FromString(data->current_channel->name);
+ }
+
+ Py_INCREF(Py_None);
+ return Py_None;
+}
+
+static PyObject* mmpy_output_value(PyObject* self, PyObject* args){
+ return mmpy_channel_value(self, args, 0);
+}
+
+static PyObject* mmpy_input_value(PyObject* self, PyObject* args){
+ return mmpy_channel_value(self, args, 1);
+}
+
+static int mmpy_exec(PyObject* module) {
+ instance** inst = (instance**) PyModule_GetState(module);
+ //FIXME actually use interpreter dict (from python 3.8) here at some point
+ PyObject* capsule = PyDict_GetItemString(PyThreadState_GetDict(), MMPY_INSTANCE_KEY);
+ if(capsule && inst){
+ *inst = PyCapsule_GetPointer(capsule, NULL);
+ return 0;
+ }
+
+ //TODO raise exception
+ return -1;
+}
+
+static int python_configure_instance(instance* inst, char* option, char* value){
+ python_instance_data* data = (python_instance_data*) inst->impl;
+ PyObject* module = NULL;
+
+ //load python script
+ if(!strcmp(option, "module")){
+ //swap to interpreter
+ PyEval_RestoreThread(data->interpreter);
+ //import the module
+ module = PyImport_ImportModule(value);
+ if(!module){
+ LOGPF("Failed to import module %s to instance %s", value, inst->name);
+ PyErr_Print();
+ }
+ Py_XDECREF(module);
+ PyEval_ReleaseThread(data->interpreter);
+ return 0;
+ }
+
+ LOGPF("Unknown instance parameter %s for instance %s", option, inst->name);
+ return 1;
+}
+
+static PyObject* mmpy_init(){
+ static PyModuleDef_Slot mmpy_slots[] = {
+ {Py_mod_exec, (void*) mmpy_exec},
+ {0}
+ };
+
+ static PyMethodDef mmpy_methods[] = {
+ {"output", mmpy_output, METH_VARARGS, "Output a channel event"},
+ {"inputvalue", mmpy_input_value, METH_VARARGS, "Get last input value for a channel"},
+ {"outputvalue", mmpy_output_value, METH_VARARGS, "Get the last output value for a channel"},
+ {"current", mmpy_current_handler, METH_VARARGS, "Get the name of the currently executing channel handler"},
+ {0}
+ };
+
+ static struct PyModuleDef mmpy = {
+ PyModuleDef_HEAD_INIT,
+ "midimonster",
+ NULL, /*doc size*/
+ sizeof(instance*),
+ mmpy_methods,
+ mmpy_slots
+ };
+
+ //single-phase init
+ //return PyModule_Create(&mmpy);
+
+ //multi-phase init
+ return PyModuleDef_Init(&mmpy);
+}
+
+static int python_instance(instance* inst){
+ python_instance_data* data = calloc(1, sizeof(python_instance_data));
+ PyObject* interpreter_dict = NULL;
+ char current_directory[8192];
+ if(!data){
+ LOG("Failed to allocate memory");
+ return 1;
+ }
+
+ //lazy-init because we need the interpreter running before _start,
+ //but don't want it running if no instances are defined
+ if(!python_main){
+ LOG("Initializing main python interpreter");
+ if(PyImport_AppendInittab("midimonster", &mmpy_init)){
+ LOG("Failed to extend python inittab for main interpreter");
+ }
+ program_name = Py_DecodeLocale("midimonster", NULL);
+ Py_SetProgramName(program_name);
+ //initialize python
+ Py_InitializeEx(0);
+ //create, acquire and release the GIL
+ PyEval_InitThreads();
+ python_main = PyEval_SaveThread();
+ }
+
+ //acquire the GIL before creating a new interpreter
+ PyEval_RestoreThread(python_main);
+ //create subinterpreter for new instance
+ data->interpreter = Py_NewInterpreter();
+
+ //push cwd as import path
+ if(getcwd(current_directory, sizeof(current_directory))){
+ if(python_prepend_str(PySys_GetObject("path"), current_directory)){
+ LOG("Failed to push current working directory to python");
+ goto bail;
+ }
+ }
+
+ //push the instance pointer for later module initialization
+ //FIXME python 3.8 introduces interpreter_dict = PyInterpreterState_GetDict(data->interpreter->interp);
+ //for now use thread state...
+ interpreter_dict = PyThreadState_GetDict();
+ if(!interpreter_dict){
+ LOG("Failed to access per-interpreter data storage");
+ goto bail;
+ }
+ //FIXME this might leak a reference to the capsule
+ if(PyDict_SetItemString(interpreter_dict, MMPY_INSTANCE_KEY, PyCapsule_New(inst, NULL, NULL))){
+ LOG("Failed to set per-interpreter instance pointer");
+ goto bail;
+ }
+
+ //NewInterpreter leaves us with the GIL, drop it
+ PyEval_ReleaseThread(data->interpreter);
+ inst->impl = data;
+ return 0;
+
+bail:
+ if(data->interpreter){
+ PyEval_ReleaseThread(data->interpreter);
+ }
+ free(data);
+ return 1;
+}
+
+static channel* python_channel(instance* inst, char* spec, uint8_t flags){
+ python_instance_data* data = (python_instance_data*) inst->impl;
+ size_t u;
+
+ for(u = 0; u < data->channels; u++){
+ if(!strcmp(data->channel[u].name, spec)){
+ break;
+ }
+ }
+
+ if(u == data->channels){
+ data->channel = realloc(data->channel, (data->channels + 1) * sizeof(mmpython_channel));
+ if(!data->channel){
+ data->channels = 0;
+ LOG("Failed to allocate memory");
+ return NULL;
+ }
+ memset(data->channel + u, 0, sizeof(mmpython_channel));
+
+ data->channel[u].name = strdup(spec);
+ if(!data->channel[u].name){
+ LOG("Failed to allocate memory");
+ return NULL;
+ }
+ data->channels++;
+ }
+
+ return mm_channel(inst, u, 1);
+}
+
+static int python_set(instance* inst, size_t num, channel** c, channel_value* v){
+ python_instance_data* data = (python_instance_data*) inst->impl;
+ mmpython_channel* chan = NULL;
+ PyObject* result = NULL;
+ size_t u;
+
+ //swap to interpreter
+ PyEval_RestoreThread(data->interpreter);
+
+ for(u = 0; u < num; u++){
+ chan = data->channel + c[u]->ident;
+
+ //update input value buffer
+ chan->in = v[u].normalised;
+
+ //call handler if present
+ if(chan->handler){
+ DBGPF("Calling handler for %s.%s", inst->name, chan->name);
+ data->current_channel = chan;
+ result = PyObject_CallFunction(chan->handler, "d", chan->in);
+ Py_XDECREF(result);
+ data->current_channel = NULL;
+ DBGPF("Done with handler for %s.%s", inst->name, chan->name);
+ }
+ }
+
+ PyEval_ReleaseThread(data->interpreter);
+ return 0;
+}
+
+static int python_handle(size_t num, managed_fd* fds){
+ //TODO implement some kind of intervaling functionality before people get it in their heads to start `import threading`
+ return 0;
+}
+
+static int python_start(size_t n, instance** inst){
+ python_instance_data* data = NULL;
+ PyObject* module = NULL;
+ size_t u, p;
+ char* module_name = NULL, *channel_name = NULL;
+
+ //resolve channel references to handler functions
+ for(u = 0; u < n; u++){
+ data = (python_instance_data*) inst[u]->impl;
+
+ //switch to interpreter
+ PyEval_RestoreThread(data->interpreter);
+ for(p = 0; p < data->channels; p++){
+ module = PyImport_AddModule("__main__");
+ channel_name = data->channel[p].name;
+ module_name = strchr(channel_name, '.');
+ if(module_name){
+ *module_name = 0;
+ //returns borrowed reference
+ module = PyImport_AddModule(channel_name);
+
+ if(!module){
+ LOGPF("Module %s for qualified channel %s.%s is not loaded on instance %s", channel_name, channel_name, module_name + 1, inst[u]->name);
+ return 1;
+ }
+
+ *module_name = '.';
+ channel_name = module_name + 1;
+ }
+
+ //returns new reference
+ data->channel[p].handler = PyObject_GetAttrString(module, channel_name);
+ }
+
+ //release interpreter
+ PyEval_ReleaseThread(data->interpreter);
+ }
+ return 0;
+}
+
+static int python_shutdown(size_t n, instance** inst){
+ size_t u, p;
+ python_instance_data* data = NULL;
+
+ //clean up channels
+ //this needs to be done before stopping the interpreters,
+ //because the handler references are refcounted
+ for(u = 0; u < n; u++){
+ data = (python_instance_data*) inst[u]->impl;
+ for(p = 0; p < data->channels; p++){
+ free(data->channel[p].name);
+ Py_XDECREF(data->channel[p].handler);
+ }
+ free(data->channel);
+ //do not free data here, needed for shutting down interpreters
+ }
+
+ if(python_main){
+ //just used to lock the GIL
+ PyEval_RestoreThread(python_main);
+
+ for(u = 0; u < n; u++){
+ data = (python_instance_data*) inst[u]->impl;
+ DBGPF("Shutting down interpreter for instance %s", inst[u]->name);
+ //swap to interpreter and end it, GIL is held after this but state is NULL
+ PyThreadState_Swap(data->interpreter);
+ PyErr_Clear();
+ //PyThreadState_Clear(data->interpreter);
+ Py_EndInterpreter(data->interpreter);
+
+ free(data);
+ }
+
+ //shut down main interpreter
+ PyThreadState_Swap(python_main);
+ if(Py_FinalizeEx()){
+ LOG("Failed to destroy python interpreters");
+ }
+ PyMem_RawFree(program_name);
+ }
+
+ LOG("Backend shut down");
+ return 0;
+}
diff --git a/backends/python.h b/backends/python.h
new file mode 100644
index 0000000..10411ca
--- /dev/null
+++ b/backends/python.h
@@ -0,0 +1,25 @@
+#include "midimonster.h"
+
+MM_PLUGIN_API int init();
+static int python_configure(char* option, char* value);
+static int python_configure_instance(instance* inst, char* option, char* value);
+static int python_instance(instance* inst);
+static channel* python_channel(instance* inst, char* spec, uint8_t flags);
+static int python_set(instance* inst, size_t num, channel** c, channel_value* v);
+static int python_handle(size_t num, managed_fd* fds);
+static int python_start(size_t n, instance** inst);
+static int python_shutdown(size_t n, instance** inst);
+
+typedef struct /*_python_channel_data*/ {
+ char* name;
+ PyObject* handler;
+ double in;
+ double out;
+} mmpython_channel;
+
+typedef struct /*_python_instance_data*/ {
+ PyThreadState* interpreter;
+ size_t channels;
+ mmpython_channel* channel;
+ mmpython_channel* current_channel;
+} python_instance_data;
diff --git a/backends/python.md b/backends/python.md
new file mode 100644
index 0000000..5f81e70
--- /dev/null
+++ b/backends/python.md
@@ -0,0 +1,63 @@
+### The `python` backend
+
+The `python` backend provides a flexible programming environment, allowing users
+to route, generate and manipulate channel events using the Python 3 scripting languge.
+
+Every instance has its own interpreter, which can be loaded with multiple Python modules.
+These modules may contain member functions accepting a single `float` parameter, which can
+then be used as target channels. For each incoming event, the handler function is called.
+
+To interact with the MIDIMonster core, import the `midimonster` module from within your module.
+
+The `midimonster` module provides the following functions:
+
+| Function | Usage example | Description |
+|-------------------------------|---------------------------------------|-----------------------------------------------|
+| `output(string, float)` | `midimonster.output("foo", 0.75)` | Output a value event to a channel |
+| `inputvalue(string)` | `midimonster.inputvalue("foo")` | Get the last input value on a channel |
+| `outputvalue(string)` | `midimonster.outputvalue("bar")` | Get the last output value on a channel |
+| `current()` | `print(midimonster.current())` | Returns the name of the input channel whose handler function is currently running or `None` if the interpreter was called from another context |
+
+Example Python module:
+```
+import midimonster
+
+def in1(value):
+ midimonster.output("out1", 1 - value)
+```
+
+Input values range between 0.0 and 1.0, output values are clamped to the same range.
+
+#### Global configuration
+
+The `python` backend does not take any global configuration.
+
+#### Instance configuration
+
+| Option | Example value | Default value | Description |
+|---------------|-----------------------|-----------------------|-----------------------------------------------|
+| `module` | `my_handlers.py` | none | (Path to) Python module source file, relative to configuration file location |
+
+A single instance may have multiple `module` options specified. This will make all handlers available within their
+module namespaces (see the section on channel specification).
+
+#### Channel specification
+
+Channel names may be any valid Python function name. To call handler functions in a module,
+specify the channel as the functions qualified path (by prefixing it with the module name and a dot).
+
+Example mappings:
+```
+py1.my_handlers.in1 < py1.foo
+py1.out1 > py2.module.handler
+```
+
+#### Known bugs / problems
+
+Output values will not trigger corresponding input event handlers unless the channel is mapped
+back in the MIDIMonster configuration. This is intentional.
+
+Importing a Python module named `midimonster` may cause problems and is unsupported.
+
+There is currently no functionality for cyclic execution. This may be implemented in a future
+release.