refactored PD framework, now using new sigrok.Decoder object

This uses the new python unified type/class object API to construct
an object for PDs to subclass. The sigrok.Decoder class has a method
put() which is implemented as a C function, and receives the PD's
object instance as its first parameter.

7 files changed, 720 insertions, 540 deletions

diff --git a/Makefile.am b/Makefile.am
index e6d0710..1c53631 100644
--- a/Makefile.am
+++ b/Makefile.am
@@ -22,7 +22,7 @@ SUBDIRS = decoders
 
 lib_LTLIBRARIES = libsigrokdecode.la
 
-libsigrokdecode_la_SOURCES = decode.c
+libsigrokdecode_la_SOURCES = controller.c decoder.c util.c
 
 libsigrokdecode_la_CPPFLAGS = $(CPPFLAGS_PYTHON) \
 			      -DDECODERS_DIR='"$(DECODERS_DIR)"'
diff --git a/controller.c b/controller.c
new file mode 100644
index 0000000..db2ed9b
--- /dev/null
+++ b/controller.c
@@ -0,0 +1,394 @@
+/*
+ * This file is part of the sigrok project.
+ *
+ * Copyright (C) 2010 Uwe Hermann <uwe@hermann-uwe.de>
+ * Copyright (C) 2011 Bert Vermeulen <bert@biot.com>
+ *
+ * This program is free software: you can redistribute it and/or modify
+ * it under the terms of the GNU General Public License as published by
+ * the Free Software Foundation, either version 3 of the License, or
+ * (at your option) any later version.
+ *
+ * This program 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 General Public License for more details.
+ *
+ * You should have received a copy of the GNU General Public License
+ * along with this program.  If not, see <http://www.gnu.org/licenses/>.
+ */
+
+#include "config.h"
+#include <sigrokdecode.h> /* First, so we avoid a _POSIX_C_SOURCE warning. */
+#include <glib.h>
+
+/* TODO: this should probably be in sigrokdecode.h */
+/* Re-define some string functions for Python >= 3.0. */
+#if PY_VERSION_HEX >= 0x03000000
+#define PyString_AsString PyBytes_AsString
+#define PyString_FromString PyBytes_FromString
+#define PyString_Check PyBytes_Check
+#endif
+
+
+static GSList *pipelines = NULL;
+
+/* lives in decoder.c */
+extern GSList *list_pds;
+extern GSList *decoders;
+
+struct srd_pipeline {
+	int id;
+	GSList *decoders;
+};
+
+
+
+static PyObject *Decoder_init(PyObject *self, PyObject *args)
+{
+	(void)self;
+	(void)args;
+//	printf("init object %x\n", self);
+
+	Py_RETURN_NONE;
+}
+
+
+static PyObject *Decoder_put(PyObject *self, PyObject *args)
+{
+	PyObject *arg;
+
+//	printf("put object %x\n", self);
+
+	if (!PyArg_ParseTuple(args, "O:put", &arg))
+		return NULL;
+
+	// fprintf(stdout, "sigrok.put() called by decoder:\n");
+	PyObject_Print(arg, stdout, Py_PRINT_RAW);
+	puts("");
+
+	Py_RETURN_NONE;
+}
+
+static PyMethodDef no_methods[] = { {NULL, NULL, 0, NULL} };
+static PyMethodDef Decoder_methods[] = {
+	{"__init__", Decoder_init, METH_VARARGS, ""},
+	{"put", Decoder_put, METH_VARARGS,
+	 "Accepts a dictionary with the following keys: time, duration, data"},
+	{NULL, NULL, 0, NULL}
+};
+
+
+// class Decoder(sigrok.Decoder):
+typedef struct {
+	PyObject_HEAD
+} sigrok_Decoder_object;
+
+static PyTypeObject sigrok_Decoder_type = {
+	PyObject_HEAD_INIT(NULL)
+	0,
+	"sigrok.Decoder",
+	sizeof(sigrok_Decoder_object),
+	0,
+	0,
+	0,
+	0,
+	0,
+	0,
+	0,
+	0,
+	0,
+	0,
+	0,
+	0,
+	0,
+	0,
+	0,
+	0,
+	Py_TPFLAGS_DEFAULT | Py_TPFLAGS_BASETYPE,
+	"Sigrok Decoder object",
+	0,
+	0,
+	0,
+	0,
+	0,
+	0,
+	Decoder_methods,
+};
+
+PyMODINIT_FUNC init_sigrok_Decoder(void)
+{
+	PyObject *mod;
+
+	sigrok_Decoder_type.tp_new = PyType_GenericNew;
+	if (PyType_Ready(&sigrok_Decoder_type) < 0)
+		return;
+
+	mod = Py_InitModule3("sigrok", no_methods, "sigrok base classes");
+	Py_INCREF(&sigrok_Decoder_type);
+	PyModule_AddObject(mod, "Decoder", (PyObject *)&sigrok_Decoder_type);
+
+}
+
+
+/**
+ * Initialize libsigrokdecode.
+ *
+ * This initializes the Python interpreter, and creates and initializes
+ * a "sigrok" Python module with a single put() method.
+ *
+ * Then, it searches for sigrok protocol decoder files (*.py) in the
+ * "decoders" subdirectory of the the sigrok installation directory.
+ * All decoders that are found are loaded into memory and added to an
+ * internal list of decoders, which can be queried via srd_list_decoders().
+ *
+ * The caller is responsible for calling the clean-up function srd_exit(),
+ * which will properly shut down libsigrokdecode and free its allocated memory.
+ *
+ * Multiple calls to srd_init(), without calling srd_exit() inbetween,
+ * are not allowed.
+ *
+ * @return SRD_OK upon success, a (negative) error code otherwise.
+ *         Upon Python errors, return SRD_ERR_PYTHON. If the sigrok decoders
+ *         directory cannot be accessed, return SRD_ERR_DECODERS_DIR.
+ *         If not enough memory could be allocated, return SRD_ERR_MALLOC.
+ */
+int srd_init(void)
+{
+	int ret;
+
+	/* Py_Initialize() returns void and usually cannot fail. */
+	Py_Initialize();
+
+	init_sigrok_Decoder();
+
+	PyRun_SimpleString("import sys;");
+	if ((ret = set_modulepath()) != SRD_OK) {
+		Py_Finalize();
+		return ret;
+	}
+
+	if ((ret = srd_load_all_decoders()) != SRD_OK) {
+		Py_Finalize();
+		return ret;
+	}
+
+	return SRD_OK;
+}
+
+
+/**
+ * Shutdown libsigrokdecode.
+ *
+ * This frees all the memory allocated for protocol decoders and shuts down
+ * the Python interpreter.
+ *
+ * This function should only be called if there was a (successful!) invocation
+ * of srd_init() before. Calling this function multiple times in a row, without
+ * any successful srd_init() calls inbetween, is not allowed.
+ *
+ * @return SRD_OK upon success, a (negative) error code otherwise.
+ */
+int srd_exit(void)
+{
+	/* Unload/free all decoders, and then the list of decoders itself. */
+	/* TODO: Error handling. */
+	srd_unload_all_decoders();
+	g_slist_free(list_pds);
+
+	/* Py_Finalize() returns void, any finalization errors are ignored. */
+	Py_Finalize();
+
+	return SRD_OK;
+}
+
+
+/**
+ * Add search directories for the protocol decoders.
+ *
+ * TODO: add path from env var SIGROKDECODE_PATH, config etc
+ */
+int set_modulepath(void)
+{
+	int ret;
+
+	ret = PyRun_SimpleString("sys.path.append(r'" DECODERS_DIR "');");
+
+	return ret;
+}
+
+
+struct srd_decoder_instance *srd_instance_new(const char *id)
+{
+	struct srd_decoder *dec;
+	struct srd_decoder_instance *di;
+	PyObject *py_args;
+
+	fprintf(stdout, "%s: %s\n", __func__, id);
+
+	if (!(dec = srd_get_decoder_by_id(id)))
+		return NULL;
+
+	/* TODO: Error handling. Use g_try_malloc(). */
+	di = g_malloc(sizeof(*di));
+	di->decoder = dec;
+	di->pd_output = NULL;
+
+	/* Create an empty Python tuple. */
+	if (!(py_args = PyTuple_New(0))) { /* NEWREF */
+		if (PyErr_Occurred())
+			PyErr_Print(); /* Returns void. */
+
+		return NULL; /* TODO: More specific error? */
+	}
+
+	/* Create an instance of the 'Decoder' class. */
+	di->py_instance = PyObject_Call(dec->py_decobj, py_args, NULL);
+	if (!di->py_instance) {
+		if (PyErr_Occurred())
+			PyErr_Print(); /* Returns void. */
+		Py_XDECREF(py_args);
+		return NULL; /* TODO: More specific error? */
+	}
+	decoders = g_slist_append(decoders, di);
+
+	Py_XDECREF(py_args);
+
+	return di;
+}
+
+
+int srd_instance_set_probe(struct srd_decoder_instance *di,
+			   const char *probename, int num)
+{
+	PyObject *probedict, *probenum;
+
+	probedict = PyObject_GetAttrString(di->py_instance, "probes"); /* NEWREF */
+	if (!probedict) {
+		if (PyErr_Occurred())
+			PyErr_Print(); /* Returns void. */
+
+		return SRD_ERR_PYTHON; /* TODO: More specific error? */
+	}
+
+	probenum = PyInt_FromLong(num);
+	PyMapping_SetItemString(probedict, (char *)probename, probenum);
+
+	Py_XDECREF(probenum);
+	Py_XDECREF(probedict);
+
+	return SRD_OK;
+}
+
+
+int srd_session_start(const char *driver, int unitsize, uint64_t starttime,
+		uint64_t samplerate)
+{
+	PyObject *py_res;
+	GSList *d;
+	struct srd_decoder_instance *di;
+
+	fprintf(stdout, "%s: %s\n", __func__, driver);
+
+	for (d = decoders; d; d = d->next) {
+		di = d->data;
+		if (!(py_res = PyObject_CallMethod(di->py_instance, "start",
+						 "{s:s,s:i,s:d}",
+						 "driver", driver,
+						 "unitsize", unitsize,
+						 "starttime", starttime))) {
+			if (PyErr_Occurred())
+				PyErr_Print(); /* Returns void. */
+
+			return SRD_ERR_PYTHON; /* TODO: More specific error? */
+		}
+		Py_XDECREF(py_res);
+	}
+
+	return SRD_OK;
+}
+
+
+/**
+ * Run the specified decoder function.
+ *
+ * @param dec TODO
+ * @param inbuf TODO
+ * @param inbuflen TODO
+ * @param outbuf TODO
+ * @param outbuflen TODO
+ *
+ * @return SRD_OK upon success, a (negative) error code otherwise.
+ */
+int srd_run_decoder(struct srd_decoder_instance *dec,
+		    uint8_t *inbuf, uint64_t inbuflen)
+{
+	PyObject *py_instance, *py_res;
+	/* FIXME: Don't have a timebase available here. Make one up. */
+	static int _timehack = 0;
+
+	_timehack += inbuflen;
+
+//	fprintf(stdout, "%s: %s\n", __func__, dec->decoder->name);
+
+	/* Return an error upon unusable input. */
+	if (dec == NULL)
+		return SRD_ERR_ARGS; /* TODO: More specific error? */
+	if (inbuf == NULL)
+		return SRD_ERR_ARGS; /* TODO: More specific error? */
+	if (inbuflen == 0) /* No point in working on empty buffers. */
+		return SRD_ERR_ARGS; /* TODO: More specific error? */
+
+	/* TODO: Error handling. */
+	py_instance = dec->py_instance;
+	Py_XINCREF(py_instance);
+
+	if (!(py_res = PyObject_CallMethod(py_instance, "decode",
+					   "{s:i,s:i,s:s#}",
+					   "time", _timehack,
+					   "duration", 10,
+					   "data", inbuf, inbuflen))) { /* NEWREF */
+		if (PyErr_Occurred())
+			PyErr_Print(); /* Returns void. */
+
+		return SRD_ERR_PYTHON; /* TODO: More specific error? */
+	}
+
+	Py_XDECREF(py_res);
+	return SRD_OK;
+}
+
+
+/* Feed logic samples to decoder session. */
+int srd_session_feed(uint8_t *inbuf, uint64_t inbuflen)
+{
+	GSList *d;
+	int ret;
+
+//	fprintf(stdout, "%s: %d bytes\n", __func__, inbuflen);
+
+	for (d = decoders; d; d = d->next) {
+		if ((ret = srd_run_decoder(d->data, inbuf, inbuflen)) != SRD_OK)
+			return ret;
+	}
+
+	return SRD_OK;
+}
+
+
+//int srd_pipeline_new(int plid)
+//{
+//
+//
+//}
+//
+//
+//int pd_output_new(int output_type, char *output_id, char *description)
+//{
+//
+//
+//}
+
+
+
+
diff --git a/decode.c b/decode.c
deleted file mode 100644
index f4b9cdf..0000000
--- a/decode.c
+++ /dev/null
@@ -1,528 +0,0 @@
-/*
- * This file is part of the sigrok project.
- *
- * Copyright (C) 2010 Uwe Hermann <uwe@hermann-uwe.de>
- *
- * This program is free software; you can redistribute it and/or modify
- * it under the terms of the GNU General Public License as published by
- * the Free Software Foundation; either version 2 of the License, or
- * (at your option) any later version.
- *
- * This program 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 General Public License for more details.
- *
- * You should have received a copy of the GNU General Public License
- * along with this program; if not, write to the Free Software
- * Foundation, Inc., 51 Franklin St, Fifth Floor, Boston, MA  02110-1301 USA
- */
-
-#include "config.h"
-#include <sigrokdecode.h> /* First, so we avoid a _POSIX_C_SOURCE warning. */
-#include <stdio.h>
-#include <string.h>
-#include <dirent.h>
-
-/* Re-define some string functions for Python >= 3.0. */
-#if PY_VERSION_HEX >= 0x03000000
-#define PyString_AsString PyBytes_AsString
-#define PyString_FromString PyBytes_FromString
-#define PyString_Check PyBytes_Check
-#endif
-
-/* The list of protocol decoders. */
-static GSList *list_pds = NULL;
-/* The list of protocol decoder instances: struct srd_decoder_instance */
-static GSList *decoders;
-
-/*
- * Here's a quick overview of Python/C API reference counting.
- *
- * Check the Python/C API docs for what type of reference a function returns.
- *
- *  - If it returns a "new reference", you're responsible to Py_XDECREF() it.
- *
- *  - If it returns a "borrowed reference", you MUST NOT Py_XDECREF() it.
- *
- *  - If a function "steals" a reference, you no longer are responsible for
- *    Py_XDECREF()ing it (someone else will do it for you at some point).
- */
-
-static int srd_load_decoder(PyObject *py_res);
-
-static PyObject *emb_register(PyObject *self, PyObject *args)
-{
-	PyObject *arg;
-
-	(void)self;
-
-	if (!PyArg_ParseTuple(args, "O:decoder", &arg))
-		return NULL;
-
-	srd_load_decoder(arg);
-
-	Py_RETURN_NONE;
-}
-
-static PyObject *emb_put(PyObject *self, PyObject *args)
-{
-	PyObject *arg;
-
-	(void)self;
-
-	if (!PyArg_ParseTuple(args, "O:put", &arg))
-		return NULL;
-
-	PyObject_Print(arg, stdout, Py_PRINT_RAW);
-	puts("");
-
-	Py_RETURN_NONE;
-}
-
-static PyMethodDef EmbMethods[] = {
-	{"register", emb_register, METH_VARARGS,
-	 "Register a protocol decoder object with libsigrokdecode."},
-	{"put", emb_put, METH_VARARGS,
-	 "Accepts a dictionary with the following keys: time, duration, data"},
-	{NULL, NULL, 0, NULL}
-};
-
-/**
- * Initialize libsigrokdecode.
- *
- * This initializes the Python interpreter, and creates and initializes
- * a "sigrok" Python module with a single put() method.
- *
- * Then, it searches for sigrok protocol decoder files (*.py) in the
- * "decoders" subdirectory of the the sigrok installation directory.
- * All decoders that are found are loaded into memory and added to an
- * internal list of decoders, which can be queried via srd_list_decoders().
- *
- * The caller is responsible for calling the clean-up function srd_exit(),
- * which will properly shut down libsigrokdecode and free its allocated memory.
- *
- * Multiple calls to srd_init(), without calling srd_exit() inbetween,
- * are not allowed.
- *
- * @return SRD_OK upon success, a (negative) error code otherwise.
- *         Upon Python errors, return SRD_ERR_PYTHON. If the sigrok decoders
- *         directory cannot be accessed, return SRD_ERR_DECODERS_DIR.
- *         If not enough memory could be allocated, return SRD_ERR_MALLOC.
- */
-int srd_init(void)
-{
-	DIR *dir;
-	struct dirent *dp;
-	char *decodername;
-	struct srd_decoder *dec;
-	int ret;
-
-	/* Py_Initialize() returns void and usually cannot fail. */
-	Py_Initialize();
-
-	/* TODO: Use Py_InitModule3() to add a docstring? */
-	if (!Py_InitModule("sigrok", EmbMethods)) {
-		Py_Finalize(); /* Returns void. */
-		return SRD_ERR_PYTHON;
-	}
-
-	/* Add search directory for the protocol decoders. */
-	/* FIXME: What happens if this function is called multiple times? */
-	ret = PyRun_SimpleString("import sys;"
-				 "sys.path.append(r'" DECODERS_DIR "');");
-	if (ret != 0) {
-		Py_Finalize(); /* Returns void. */
-		return SRD_ERR_PYTHON;
-	}
-
-	if (!(dir = opendir(DECODERS_DIR))) {
-		Py_Finalize(); /* Returns void. */
-		return SRD_ERR_DECODERS_DIR;
-	}
-
-	while ((dp = readdir(dir)) != NULL) {
-		/* Ignore filenames which don't end with ".py". */
-		if (!g_str_has_suffix(dp->d_name, ".py"))
-			continue;
-
-		/* Decoder name == filename (without .py suffix). */
-		decodername = g_strndup(dp->d_name, strlen(dp->d_name) - 3);
-
-		/* TODO: Error handling. Use g_try_malloc(). */
-		if (!(dec = malloc(sizeof(struct srd_decoder)))) {
-			Py_Finalize(); /* Returns void. */
-			return SRD_ERR_MALLOC;
-		}
-
-		/* Load the decoder. */
-		/* "Import" the Python module. */
-		PyObject *py_mod;
-		if (!(py_mod = PyImport_ImportModule(decodername))) { /* NEWREF */
-			PyErr_Print(); /* Returns void. */
-			return SRD_ERR_PYTHON; /* TODO: More specific error? */
-		}
-		/* We release here.  If any decoders were registered they
-		 * will hold references. */
-		Py_XDECREF(py_mod);
-	}
-	closedir(dir);
-
-	return SRD_OK;
-}
-
-/**
- * Returns the list of supported/loaded protocol decoders.
- *
- * This is a GSList containing the names of the decoders as strings.
- *
- * @return List of decoders, NULL if none are supported or loaded.
- */
-GSList *srd_list_decoders(void)
-{
-	return list_pds;
-}
-
-/**
- * Get the decoder with the specified ID.
- *
- * @param id The ID string of the decoder to return.
- * @return The decoder with the specified ID, or NULL if not found.
- */
-struct srd_decoder *srd_get_decoder_by_id(const char *id)
-{
-	GSList *l;
-	struct srd_decoder *dec;
-
-	for (l = srd_list_decoders(); l; l = l->next) {
-		dec = l->data;
-		if (!strcmp(dec->id, id))
-			return dec;
-	}
-
-	return NULL;
-}
-
-/**
- * Helper function to handle Python strings.
- *
- * TODO: @param entries.
- *
- * @return SRD_OK upon success, a (negative) error code otherwise.
- *         The 'outstr' argument points to a malloc()ed string upon success.
- */
-static int h_str(PyObject *py_res, const char *key, char **outstr)
-{
-	PyObject *py_str;
-	char *str;
-	int ret;
-
-	py_str = PyObject_GetAttrString(py_res, (char *)key); /* NEWREF */
-	if (!py_str || !PyString_Check(py_str)) {
-		ret = SRD_ERR_PYTHON; /* TODO: More specific error? */
-		goto err_h_decref_mod;
-	}
-
-	/*
-	 * PyString_AsString()'s returned string refers to an internal buffer
-	 * (not a copy), i.e. the data must not be modified, and the memory
-	 * must not be free()'d.
-	 */
-	if (!(str = PyString_AsString(py_str))) {
-		ret = SRD_ERR_PYTHON; /* TODO: More specific error? */
-		goto err_h_decref_str;
-	}
-
-	if (!(*outstr = g_strdup(str))) {
-		ret = SRD_ERR_MALLOC;
-		goto err_h_decref_str;
-	}
-
-	Py_XDECREF(py_str);
-
-	return SRD_OK;
-
-err_h_decref_str:
-	Py_XDECREF(py_str);
-err_h_decref_mod:
-
-	if (PyErr_Occurred())
-		PyErr_Print(); /* Returns void. */
-
-	return ret;
-}
-
-/**
- * TODO
- *
- * @param name TODO
- *
- * @return SRD_OK upon success, a (negative) error code otherwise.
- */
-static int srd_load_decoder(PyObject *py_res)
-{
-	struct srd_decoder *d;
-	int r;
-
-	if (!(d = malloc(sizeof(struct srd_decoder))))
-		return SRD_ERR_MALLOC;
-
-	if ((r = h_str(py_res, "id", &(d->id))) < 0)
-		return r;
-
-	if ((r = h_str(py_res, "name", &(d->name))) < 0)
-		return r;
-
-	if ((r = h_str(py_res, "longname",
-		       &(d->longname))) < 0)
-		return r;
-
-	if ((r = h_str(py_res, "desc", &(d->desc))) < 0)
-		return r;
-
-	if ((r = h_str(py_res, "longdesc",
-		       &(d->longdesc))) < 0)
-		return r;
-
-	if ((r = h_str(py_res, "author", &(d->author))) < 0)
-		return r;
-
-	if ((r = h_str(py_res, "email", &(d->email))) < 0)
-		return r;
-
-	if ((r = h_str(py_res, "license", &(d->license))) < 0)
-		return r;
-
-	d->py_decobj = py_res;
-
-	/* TODO: Handle func, inputformats, outputformats. */
-	/* Note: They must at least be set to NULL, will segfault otherwise. */
-	d->func = NULL;
-	d->inputformats = NULL;
-	d->outputformats = NULL;
-
-	Py_INCREF(py_res);
-	fprintf(stderr, "srd: registered '%s'\n", d->id);
-	list_pds = g_slist_append(list_pds, d);
-
-	return SRD_OK;
-}
-
-/** Create a new decoder instance and add to session. */
-struct srd_decoder_instance *srd_instance_new(const char *id)
-{
-	struct srd_decoder *dec;
-	struct srd_decoder_instance *di;
-	PyObject *py_args;
-
-	if (!(dec = srd_get_decoder_by_id(id)))
-		return NULL;
-
-	/* TODO: Error handling. Use g_try_malloc(). */
-	di = g_malloc(sizeof(*di));
-
-	/* Create an empty Python tuple. */
-	if (!(py_args = PyTuple_New(0))) { /* NEWREF */
-		if (PyErr_Occurred())
-			PyErr_Print(); /* Returns void. */
-
-		return NULL; /* TODO: More specific error? */
-	}
-
-	/* Create an instance of the 'Decoder' class. */
-	di->py_instance = PyObject_Call(dec->py_decobj, py_args, NULL);
-	if (!di->py_instance) {
-		if (PyErr_Occurred())
-			PyErr_Print(); /* Returns void. */
-		Py_XDECREF(py_args);
-		return NULL; /* TODO: More specific error? */
-	}
-
-	/* Append to list of PD instances */
-	decoders = g_slist_append(decoders, di);
-
-	Py_XDECREF(py_args);
-
-	return di;
-}
-
-int srd_instance_set_probe(struct srd_decoder_instance *di,
-			   const char *probename, int num)
-{
-	PyObject *probedict, *probenum;
-
-	probedict = PyObject_GetAttrString(di->py_instance, "probes"); /* NEWREF */
-	if (!probedict) {
-		if (PyErr_Occurred())
-			PyErr_Print(); /* Returns void. */
-
-		return SRD_ERR_PYTHON; /* TODO: More specific error? */
-	}
-
-	probenum = PyInt_FromLong(num);
-	PyMapping_SetItemString(probedict, (char *)probename, probenum);
-
-	Py_XDECREF(probenum);
-	Py_XDECREF(probedict);
-
-	return SRD_OK;
-}
-
-/** Start decoding session.  Feed metadata to decoder instances. */
-int srd_session_start(const char *driver, int unitsize, uint64_t starttime,
-			uint64_t samplerate)
-{
-	PyObject *py_res;
-	GSList *d;
-	for (d = decoders; d; d = d->next) {
-		struct srd_decoder_instance *di = d->data;
-		/* TODO: Error handling. */
-		if (!(py_res = PyObject_CallMethod(di->py_instance, "start",
-					"{s:s,s:l,s:l,s:l}", 
-					"driver", driver,
-					"unitsize", (long)unitsize,
-					"starttime", (long)starttime,
-					"samplerate", (long)samplerate))) {
-			if (PyErr_Occurred())
-				PyErr_Print(); /* Returns void. */
-
-			return SRD_ERR_PYTHON; /* TODO: More specific error? */
-		}
-		Py_XDECREF(py_res);
-	}
-
-	return SRD_OK;
-}
-
-/**
- * Run the specified decoder function.
- *
- * @param dec TODO
- * @param inbuf TODO
- * @param inbuflen TODO
- * @param outbuf TODO
- * @param outbuflen TODO
- *
- * @return SRD_OK upon success, a (negative) error code otherwise.
- */
-static int srd_run_decoder(struct srd_decoder_instance *dec,
-		    uint8_t *inbuf, uint64_t inbuflen)
-{
-	PyObject *py_instance, *py_res;
-	/* FIXME: Don't have a timebase available here. Make one up. */
-	static int _timehack = 0;
-
-	_timehack += inbuflen;
-
-	/* TODO: Use #defines for the return codes. */
-
-	/* Return an error upon unusable input. */
-	if (dec == NULL)
-		return SRD_ERR_ARGS; /* TODO: More specific error? */
-	if (inbuf == NULL)
-		return SRD_ERR_ARGS; /* TODO: More specific error? */
-	if (inbuflen == 0) /* No point in working on empty buffers. */
-		return SRD_ERR_ARGS; /* TODO: More specific error? */
-
-	/* TODO: Error handling. */
-	py_instance = dec->py_instance;
-	Py_XINCREF(py_instance);
-
-	if (!(py_res = PyObject_CallMethod(py_instance, "decode",
-					   "{s:i,s:i,s:s#}", 
-					   "time", _timehack,
-					   "duration", 10,
-					   "data", inbuf, inbuflen))) { /* NEWREF */
-		if (PyErr_Occurred())
-			PyErr_Print(); /* Returns void. */
-
-		return SRD_ERR_PYTHON; /* TODO: More specific error? */
-	} 
-
-	Py_XDECREF(py_res);
-	return SRD_OK;
-}
-
-/* Feed logic samples to decoder session. */
-int srd_session_feed(uint8_t *inbuf, uint64_t inbuflen)
-{
-	GSList *d;
-	for (d = decoders; d; d = d->next) {
-		/* TODO: Error handling. */
-		
-		int ret = srd_run_decoder(d->data, inbuf, inbuflen);
-
-		if (ret != SRD_OK) {
-			/* This probably shouldn't fail catastrophically. */
-			fprintf(stderr, "Decoder runtime error (%d)\n", ret);
-			exit(1);
-		}
-	}
-	return SRD_OK;
-}
-
-/**
- * TODO
- */
-static int srd_unload_decoder(struct srd_decoder *dec)
-{
-	g_free(dec->id);
-	g_free(dec->name);
-	g_free(dec->desc);
-	g_free(dec->func);
-
-	/* TODO: Free everything in inputformats and outputformats. */
-
-	if (dec->inputformats != NULL)
-		g_slist_free(dec->inputformats);
-	if (dec->outputformats != NULL)
-		g_slist_free(dec->outputformats);
-
-	Py_XDECREF(dec->py_decobj);
-
-	/* TODO: (g_)free dec itself? */
-
-	return SRD_OK;
-}
-
-/**
- * TODO
- */
-static int srd_unload_all_decoders(void)
-{
-	GSList *l;
-	struct srd_decoder *dec;
-
-	for (l = srd_list_decoders(); l; l = l->next) {
-		dec = l->data;
-		/* TODO: Error handling. */
-		srd_unload_decoder(dec);
-	}
-
-	return SRD_OK;
-}
-
-/**
- * Shutdown libsigrokdecode.
- *
- * This frees all the memory allocated for protocol decoders and shuts down
- * the Python interpreter.
- *
- * This function should only be called if there was a (successful!) invocation
- * of srd_init() before. Calling this function multiple times in a row, without
- * any successful srd_init() calls inbetween, is not allowed.
- *
- * @return SRD_OK upon success, a (negative) error code otherwise.
- */
-int srd_exit(void)
-{
-	/* Unload/free all decoders, and then the list of decoders itself. */
-	/* TODO: Error handling. */
-	srd_unload_all_decoders();
-	g_slist_free(list_pds);
-
-	/* Py_Finalize() returns void, any finalization errors are ignored. */
-	Py_Finalize();
-
-	return SRD_OK;
-}
diff --git a/decoder.c b/decoder.c
new file mode 100644
index 0000000..7753a33
--- /dev/null
+++ b/decoder.c
@@ -0,0 +1,224 @@
+/*
+ * This file is part of the sigrok project.
+ *
+ * Copyright (C) 2010 Uwe Hermann <uwe@hermann-uwe.de>
+ * Copyright (C) 2011 Bert Vermeulen <bert@biot.com>
+ *
+ * This program is free software: you can redistribute it and/or modify
+ * it under the terms of the GNU General Public License as published by
+ * the Free Software Foundation, either version 3 of the License, or
+ * (at your option) any later version.
+ *
+ * This program 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 General Public License for more details.
+ *
+ * You should have received a copy of the GNU General Public License
+ * along with this program.  If not, see <http://www.gnu.org/licenses/>.
+ */
+
+#include "config.h"
+#include <sigrokdecode.h> /* First, so we avoid a _POSIX_C_SOURCE warning. */
+#include <dirent.h>
+
+/* The list of protocol decoders. */
+GSList *list_pds = NULL;
+GSList *decoders = NULL;
+
+
+/**
+ * Returns the list of supported/loaded protocol decoders.
+ *
+ * This is a GSList containing the names of the decoders as strings.
+ *
+ * @return List of decoders, NULL if none are supported or loaded.
+ */
+GSList *srd_list_decoders(void)
+{
+
+	return list_pds;
+}
+
+
+/**
+ * Get the decoder with the specified ID.
+ *
+ * @param id The ID string of the decoder to return.
+ * @return The decoder with the specified ID, or NULL if not found.
+ */
+struct srd_decoder *srd_get_decoder_by_id(const char *id)
+{
+	GSList *l;
+	struct srd_decoder *dec;
+
+	for (l = srd_list_decoders(); l; l = l->next) {
+		dec = l->data;
+		if (!strcmp(dec->id, id))
+			return dec;
+	}
+
+	return NULL;
+}
+
+
+/**
+ * TODO
+ *
+ * @param name TODO
+ *
+ * @return SRD_OK upon success, a (negative) error code otherwise.
+ */
+int srd_load_decoder(const char *name, struct srd_decoder **dec)
+{
+	struct srd_decoder *d;
+	PyObject *py_mod, *py_res;
+	int r;
+
+	fprintf(stdout, "%s: %s\n", __func__, name);
+
+	/* "Import" the Python module. */
+	if (!(py_mod = PyImport_ImportModule(name))) { /* NEWREF */
+		PyErr_Print(); /* Returns void. */
+		return SRD_ERR_PYTHON; /* TODO: More specific error? */
+	}
+
+	/* Get the 'Decoder' class as Python object. */
+	py_res = PyObject_GetAttrString(py_mod, "Decoder"); /* NEWREF */
+	if (!py_res) {
+		if (PyErr_Occurred())
+			PyErr_Print(); /* Returns void. */
+		Py_XDECREF(py_mod);
+		fprintf(stderr, "Decoder class not found in PD module %s\n", name);
+		return SRD_ERR_PYTHON; /* TODO: More specific error? */
+	}
+
+	if (!(d = malloc(sizeof(struct srd_decoder))))
+		return SRD_ERR_MALLOC;
+
+	/* We'll just use the name of the module for the ID. */
+	d->id = strdup(name);
+
+	if ((r = h_str(py_res, py_mod, "name", &(d->name))) < 0)
+		return r;
+
+	if ((r = h_str(py_res, py_mod, "longname",
+		       &(d->longname))) < 0)
+		return r;
+
+	if ((r = h_str(py_res, py_mod, "desc", &(d->desc))) < 0)
+		return r;
+
+	if ((r = h_str(py_res, py_mod, "longdesc",
+		       &(d->longdesc))) < 0)
+		return r;
+
+	if ((r = h_str(py_res, py_mod, "author", &(d->author))) < 0)
+		return r;
+
+	if ((r = h_str(py_res, py_mod, "email", &(d->email))) < 0)
+		return r;
+
+	if ((r = h_str(py_res, py_mod, "license", &(d->license))) < 0)
+		return r;
+
+	d->py_mod = py_mod;
+	d->py_decobj = py_res;
+
+	/* TODO: Handle func, inputformats, outputformats. */
+	/* Note: They must at least be set to NULL, will segfault otherwise. */
+	d->func = NULL;
+	d->inputformats = NULL;
+	d->outputformats = NULL;
+
+	*dec = d;
+
+	return SRD_OK;
+}
+
+
+/**
+ * TODO
+ */
+int srd_unload_decoder(struct srd_decoder *dec)
+{
+	g_free(dec->id);
+	g_free(dec->name);
+	g_free(dec->desc);
+	g_free(dec->func);
+
+	/* TODO: Free everything in inputformats and outputformats. */
+
+	if (dec->inputformats != NULL)
+		g_slist_free(dec->inputformats);
+	if (dec->outputformats != NULL)
+		g_slist_free(dec->outputformats);
+
+	Py_XDECREF(dec->py_decobj);
+	Py_XDECREF(dec->py_mod);
+
+	/* TODO: (g_)free dec itself? */
+
+	return SRD_OK;
+}
+
+
+int srd_load_all_decoders(void)
+{
+	DIR *dir;
+	struct dirent *dp;
+	int ret;
+	char *decodername;
+	struct srd_decoder *dec;
+
+	if (!(dir = opendir(DECODERS_DIR))) {
+		Py_Finalize(); /* Returns void. */
+		return SRD_ERR_DECODERS_DIR;
+	}
+
+	while ((dp = readdir(dir)) != NULL) {
+		/* Ignore filenames which don't end with ".py". */
+		if (!g_str_has_suffix(dp->d_name, ".py"))
+			continue;
+
+		/* Decoder name == filename (without .py suffix). */
+		decodername = g_strndup(dp->d_name, strlen(dp->d_name) - 3);
+
+		/* TODO: Error handling. Use g_try_malloc(). */
+		if (!(dec = malloc(sizeof(struct srd_decoder)))) {
+			Py_Finalize(); /* Returns void. */
+			return SRD_ERR_MALLOC;
+		}
+
+		/* Load the decoder. */
+		/* TODO: Warning if loading fails for a decoder. */
+		if ((ret = srd_load_decoder(decodername, &dec)) == SRD_OK) {
+			/* Append it to the list of supported/loaded decoders. */
+			list_pds = g_slist_append(list_pds, dec);
+		}
+	}
+	closedir(dir);
+
+	return SRD_OK;
+}
+
+
+/**
+ * TODO
+ */
+int srd_unload_all_decoders(void)
+{
+	GSList *l;
+	struct srd_decoder *dec;
+
+	for (l = srd_list_decoders(); l; l = l->next) {
+		dec = l->data;
+		/* TODO: Error handling. */
+		srd_unload_decoder(dec);
+	}
+
+	return SRD_OK;
+}
+
+
+
diff --git a/decoders/i2c.py b/decoders/i2c.py
index 16e7491..583c4d0 100644
--- a/decoders/i2c.py
+++ b/decoders/i2c.py
@@ -126,6 +126,8 @@
 #  'signals': [{'SCL': }]}
 #
 
+import sigrok
+
 # States
 FIND_START = 0
 FIND_ADDRESS = 1
@@ -142,7 +144,7 @@ def sampleiter(data, unitsize):
     for i in range(0, len(data), unitsize):
         yield(Sample(data[i:i+unitsize]))
 
-class Decoder():
+class Decoder(sigrok.Decoder):
     id = 'i2c'
     name = 'I2C'
     longname = 'Inter-Integrated Circuit (I2C) bus'
@@ -348,9 +350,6 @@ class Decoder():
             self.oldsda = sda
 
         if out != []:
-            sigrok.put(out)
-
-import sigrok
+            self.put(out)
 
-sigrok.register(Decoder)
 
diff --git a/sigrokdecode.h b/sigrokdecode.h
index b856f4f..c1ef9ff 100644
--- a/sigrokdecode.h
+++ b/sigrokdecode.h
@@ -88,24 +88,41 @@ struct srd_decoder {
 	/** TODO */
 	GSList *outputformats;
 
+	/** TODO */
+	PyObject *py_mod;
+
 	/** Python object that performs the decoding */
 	PyObject *py_decobj;
 };
 
 struct srd_decoder_instance {
+	struct srd_decoder *decoder;
 	PyObject *py_instance;
+	GSList *pd_output;
 };
 
 int srd_init(void);
-GSList *srd_list_decoders(void);
-struct srd_decoder *srd_get_decoder_by_id(const char *id);
+int srd_exit(void);
+int set_modulepath(void);
 struct srd_decoder_instance *srd_instance_new(const char *id);
 int srd_instance_set_probe(struct srd_decoder_instance *di,
 				const char *probename, int num);
-int srd_session_start(const char *driver, int unitsize, uint64_t starttime,
-		      uint64_t samplerate);
-int srd_session_feed(uint8_t *inbuf, uint64_t inbuflen);
-int srd_exit(void);
+int srd_instance_start(struct srd_decoder_instance *di,
+			const char *driver, int unitsize, uint64_t starttime);
+int srd_run_decoder(struct srd_decoder_instance *dec,
+		    uint8_t *inbuf, uint64_t inbuflen);
+
+/* decoder.c */
+GSList *srd_list_decoders(void);
+struct srd_decoder *srd_get_decoder_by_id(const char *id);
+int srd_load_decoder(const char *name, struct srd_decoder **dec);
+int srd_unload_decoder(struct srd_decoder *dec);
+int srd_load_all_decoders(void);
+int srd_unload_all_decoders(void);
+
+/* util.c */
+int h_str(PyObject *py_res, PyObject *py_mod, const char *key, char **outstr);
+
 
 #ifdef __cplusplus
 }
diff --git a/util.c b/util.c
new file mode 100644
index 0000000..3aa0fd9
--- /dev/null
+++ b/util.c
@@ -0,0 +1,74 @@
+/*
+ * This file is part of the sigrok project.
+ *
+ * Copyright (C) 2010 Uwe Hermann <uwe@hermann-uwe.de>
+ * Copyright (C) 2011 Bert Vermeulen <bert@biot.com>
+ *
+ * This program is free software: you can redistribute it and/or modify
+ * it under the terms of the GNU General Public License as published by
+ * the Free Software Foundation, either version 3 of the License, or
+ * (at your option) any later version.
+ *
+ * This program 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 General Public License for more details.
+ *
+ * You should have received a copy of the GNU General Public License
+ * along with this program.  If not, see <http://www.gnu.org/licenses/>.
+ */
+
+#include "config.h"
+#include <sigrokdecode.h> /* First, so we avoid a _POSIX_C_SOURCE warning. */
+
+
+/**
+ * Helper function to handle Python strings.
+ *
+ * TODO: @param entries.
+ *
+ * @return SRD_OK upon success, a (negative) error code otherwise.
+ *         The 'outstr' argument points to a malloc()ed string upon success.
+ */
+int h_str(PyObject *py_res, PyObject *py_mod, const char *key, char **outstr)
+{
+	PyObject *py_str;
+	char *str;
+	int ret;
+
+	py_str = PyObject_GetAttrString(py_res, (char *)key); /* NEWREF */
+	if (!py_str || !PyString_Check(py_str)) {
+		ret = SRD_ERR_PYTHON; /* TODO: More specific error? */
+		goto err_h_decref_mod;
+	}
+
+	/*
+	 * PyString_AsString()'s returned string refers to an internal buffer
+	 * (not a copy), i.e. the data must not be modified, and the memory
+	 * must not be free()'d.
+	 */
+	if (!(str = PyString_AsString(py_str))) {
+		ret = SRD_ERR_PYTHON; /* TODO: More specific error? */
+		goto err_h_decref_str;
+	}
+
+	if (!(*outstr = g_strdup(str))) {
+		ret = SRD_ERR_MALLOC;
+		goto err_h_decref_str;
+	}
+
+	Py_XDECREF(py_str);
+
+	return SRD_OK;
+
+err_h_decref_str:
+	Py_XDECREF(py_str);
+err_h_decref_mod:
+	Py_XDECREF(py_mod);
+
+	if (PyErr_Occurred())
+		PyErr_Print(); /* Returns void. */
+
+	return ret;
+}
+