session: add "terminate and reset" support for protocol stacks
[libsigrokdecode.git] / instance.c
index 594f144edcabe9dc44ec3a60265e3b5a257ecfa3..6fbdc01fe7e888c57b43e9ad2a3af6cd5dd2788a 100644 (file)
@@ -18,9 +18,9 @@
  * along with this program.  If not, see <http://www.gnu.org/licenses/>.
  */
 
-#include "libsigrokdecode.h" /* First, so we avoid a _POSIX_C_SOURCE warning. */
-#include "libsigrokdecode-internal.h"
-#include "config.h"
+#include <config.h>
+#include "libsigrokdecode-internal.h" /* First, so we avoid a _POSIX_C_SOURCE warning. */
+#include "libsigrokdecode.h"
 #include <glib.h>
 #include <inttypes.h>
 #include <stdlib.h>
 
 /** @cond PRIVATE */
 
-extern GSList *sessions;
+extern SRD_PRIV GSList *sessions;
 
-/* type_logic.c */
-extern SRD_PRIV PyTypeObject srd_logic_type;
+static void srd_inst_join_decode_thread(struct srd_decoder_inst *di);
+static void srd_inst_reset_state(struct srd_decoder_inst *di);
+SRD_PRIV void oldpins_array_seed(struct srd_decoder_inst *di);
+SRD_PRIV void oldpins_array_free(struct srd_decoder_inst *di);
 
 /** @endcond */
 
@@ -64,15 +66,15 @@ extern SRD_PRIV PyTypeObject srd_logic_type;
 SRD_API int srd_inst_option_set(struct srd_decoder_inst *di,
                GHashTable *options)
 {
-       PyObject *py_dec_options, *py_dec_optkeys, *py_di_options, *py_optval;
-       PyObject *py_optlist, *py_classval;
-       Py_UNICODE *py_ustr;
+       struct srd_decoder_option *sdo;
+       PyObject *py_di_options, *py_optval;
        GVariant *value;
-       unsigned long long int val_ull;
+       GSList *l;
+       double val_double;
        gint64 val_int;
-       int num_optkeys, ret, size, i;
+       int ret;
        const char *val_str;
-       char *dbg, *key;
+       PyGILState_STATE gstate;
 
        if (!di) {
                srd_err("Invalid decoder instance.");
@@ -84,8 +86,11 @@ SRD_API int srd_inst_option_set(struct srd_decoder_inst *di,
                return SRD_ERR_ARG;
        }
 
+       gstate = PyGILState_Ensure();
+
        if (!PyObject_HasAttrString(di->decoder->py_dec, "options")) {
                /* Decoder has no options. */
+               PyGILState_Release(gstate);
                if (g_hash_table_size(options) == 0) {
                        /* No options provided. */
                        return SRD_OK;
@@ -97,17 +102,10 @@ SRD_API int srd_inst_option_set(struct srd_decoder_inst *di,
        }
 
        ret = SRD_ERR_PYTHON;
-       key = NULL;
-       py_dec_options = py_dec_optkeys = py_di_options = py_optval = NULL;
-       py_optlist = py_classval = NULL;
-       py_dec_options = PyObject_GetAttrString(di->decoder->py_dec, "options");
-
-       /* All of these are synthesized objects, so they're good. */
-       py_dec_optkeys = PyDict_Keys(py_dec_options);
-       num_optkeys = PyList_Size(py_dec_optkeys);
+       py_optval = NULL;
 
        /*
-        * The 'options' dictionary is a class variable, but we need to
+        * The 'options' tuple is a class variable, but we need to
         * change it. Changing it directly will affect the entire class,
         * so we need to create a new object for it, and populate that
         * instead.
@@ -117,206 +115,176 @@ SRD_API int srd_inst_option_set(struct srd_decoder_inst *di,
        Py_DECREF(py_di_options);
        py_di_options = PyDict_New();
        PyObject_SetAttrString(di->py_inst, "options", py_di_options);
-       for (i = 0; i < num_optkeys; i++) {
-               /* Get the default class value for this option. */
-               py_str_as_str(PyList_GetItem(py_dec_optkeys, i), &key);
-               if (!(py_optlist = PyDict_GetItemString(py_dec_options, key)))
-                       goto err_out;
-               if (!(py_classval = PyList_GetItem(py_optlist, 1)))
-                       goto err_out;
-               if (!PyUnicode_Check(py_classval) && !PyLong_Check(py_classval)) {
-                       srd_err("Options of type %s are not yet supported.",
-                               Py_TYPE(py_classval)->tp_name);
-                       goto err_out;
-               }
 
-               if ((value = g_hash_table_lookup(options, key))) {
-                       dbg = g_variant_print(value, TRUE);
-                       srd_dbg("got option '%s' = %s", key, dbg);
-                       g_free(dbg);
-                       /* An override for this option was provided. */
-                       if (PyUnicode_Check(py_classval)) {
-                               if (!g_variant_is_of_type(value, G_VARIANT_TYPE_STRING)) {
-                                       srd_err("Option '%s' requires a string value.", key);
-                                       goto err_out;
-                               }
-                               val_str = g_variant_get_string(value, NULL);
-                               if (!(py_optval = PyUnicode_FromString(val_str))) {
-                                       /* Some UTF-8 encoding error. */
-                                       PyErr_Clear();
-                                       srd_err("Option '%s' requires a UTF-8 string value.", key);
-                                       goto err_out;
-                               }
-                       } else if (PyLong_Check(py_classval)) {
-                               if (!g_variant_is_of_type(value, G_VARIANT_TYPE_INT64)) {
-                                       srd_err("Option '%s' requires an integer value.", key);
-                                       goto err_out;
-                               }
-                               val_int = g_variant_get_int64(value);
-                               if (!(py_optval = PyLong_FromLong(val_int))) {
-                                       /* ValueError Exception */
-                                       PyErr_Clear();
-                                       srd_err("Option '%s' has invalid integer value.", key);
-                                       goto err_out;
-                               }
+       for (l = di->decoder->options; l; l = l->next) {
+               sdo = l->data;
+               if ((value = g_hash_table_lookup(options, sdo->id))) {
+                       /* A value was supplied for this option. */
+                       if (!g_variant_type_equal(g_variant_get_type(value),
+                                 g_variant_get_type(sdo->def))) {
+                               srd_err("Option '%s' should have the same type "
+                                       "as the default value.", sdo->id);
+                               goto err_out;
                        }
-                       g_hash_table_remove(options, key);
                } else {
-                       /* Use the class default for this option. */
-                       if (PyUnicode_Check(py_classval)) {
-                               /* Make a brand new copy of the string. */
-                               py_ustr = PyUnicode_AS_UNICODE(py_classval);
-                               size = PyUnicode_GET_SIZE(py_classval);
-                               py_optval = PyUnicode_FromUnicode(py_ustr, size);
-                       } else if (PyLong_Check(py_classval)) {
-                               /* Make a brand new copy of the integer. */
-                               val_ull = PyLong_AsUnsignedLongLong(py_classval);
-                               if (val_ull == (unsigned long long)-1) {
-                                       /* OverFlowError exception */
-                                       PyErr_Clear();
-                                       srd_err("Invalid integer value for %s: "
-                                               "expected integer.", key);
-                                       goto err_out;
-                               }
-                               if (!(py_optval = PyLong_FromUnsignedLongLong(val_ull)))
-                                       goto err_out;
+                       /* Use default for this option. */
+                       value = sdo->def;
+               }
+               if (g_variant_is_of_type(value, G_VARIANT_TYPE_STRING)) {
+                       val_str = g_variant_get_string(value, NULL);
+                       if (!(py_optval = PyUnicode_FromString(val_str))) {
+                               /* Some UTF-8 encoding error. */
+                               PyErr_Clear();
+                               srd_err("Option '%s' requires a UTF-8 string value.", sdo->id);
+                               goto err_out;
+                       }
+               } else if (g_variant_is_of_type(value, G_VARIANT_TYPE_INT64)) {
+                       val_int = g_variant_get_int64(value);
+                       if (!(py_optval = PyLong_FromLong(val_int))) {
+                               /* ValueError Exception */
+                               PyErr_Clear();
+                               srd_err("Option '%s' has invalid integer value.", sdo->id);
+                               goto err_out;
+                       }
+               } else if (g_variant_is_of_type(value, G_VARIANT_TYPE_DOUBLE)) {
+                       val_double = g_variant_get_double(value);
+                       if (!(py_optval = PyFloat_FromDouble(val_double))) {
+                               /* ValueError Exception */
+                               PyErr_Clear();
+                               srd_err("Option '%s' has invalid float value.",
+                                       sdo->id);
+                               goto err_out;
                        }
                }
-
-               /*
-                * If we got here, py_optval holds a known good new reference
-                * to the instance option to set.
-                */
-               if (PyDict_SetItemString(py_di_options, key, py_optval) == -1)
+               if (PyDict_SetItemString(py_di_options, sdo->id, py_optval) == -1)
                        goto err_out;
-               g_free(key);
-               key = NULL;
+               /* Not harmful even if we used the default. */
+               g_hash_table_remove(options, sdo->id);
        }
+       if (g_hash_table_size(options) != 0)
+               srd_warn("Unknown options specified for '%s'", di->inst_id);
 
        ret = SRD_OK;
 
 err_out:
-       Py_XDECREF(py_di_options);
-       Py_XDECREF(py_dec_optkeys);
-       Py_XDECREF(py_dec_options);
-       g_free(key);
+       Py_XDECREF(py_optval);
        if (PyErr_Occurred()) {
-               srd_exception_catch("Stray exception in srd_inst_option_set().");
+               srd_exception_catch("Stray exception in srd_inst_option_set()");
                ret = SRD_ERR_PYTHON;
        }
+       PyGILState_Release(gstate);
 
        return ret;
 }
 
-/* Helper GComparefunc for g_slist_find_custom() in srd_inst_probe_set_all() */
-static gint compare_probe_id(const struct srd_probe *a, const char *probe_id)
+/* Helper GComparefunc for g_slist_find_custom() in srd_inst_channel_set_all() */
+static gint compare_channel_id(const struct srd_channel *pdch,
+                       const char *channel_id)
 {
-       return strcmp(a->id, probe_id);
+       return strcmp(pdch->id, channel_id);
 }
 
 /**
- * Set all probes in a decoder instance.
+ * Set all channels in a decoder instance.
  *
- * This function sets _all_ probes for the specified decoder instance, i.e.,
- * it overwrites any probes that were already defined (if any).
+ * This function sets _all_ channels for the specified decoder instance, i.e.,
+ * it overwrites any channels that were already defined (if any).
  *
  * @param di Decoder instance.
- * @param new_probes A GHashTable of probes to set. Key is probe name, value is
- *                   the probe number. Samples passed to this instance will be
- *                   arranged in this order.
+ * @param new_channels A GHashTable of channels to set. Key is channel name,
+ *                     value is the channel number. Samples passed to this
+ *                     instance will be arranged in this order.
  *
  * @return SRD_OK upon success, a (negative) error code otherwise.
  *
- * @since 0.1.0
+ * @since 0.4.0
  */
-SRD_API int srd_inst_probe_set_all(struct srd_decoder_inst *di,
-               GHashTable *new_probes)
+SRD_API int srd_inst_channel_set_all(struct srd_decoder_inst *di,
+               GHashTable *new_channels)
 {
-       GVariant *probe_val;
+       GVariant *channel_val;
        GList *l;
        GSList *sl;
-       struct srd_probe *p;
-       int *new_probemap, new_probenum, num_required_probes, num_probes, i;
-       char *probe_id;
+       struct srd_channel *pdch;
+       int *new_channelmap, new_channelnum, num_required_channels, i;
+       char *channel_id;
 
-       srd_dbg("set probes called for instance %s with list of %d probes",
-               di->inst_id, g_hash_table_size(new_probes));
+       srd_dbg("Setting channels for instance %s with list of %d channels.",
+               di->inst_id, g_hash_table_size(new_channels));
 
-       if (g_hash_table_size(new_probes) == 0)
-               /* No probes provided. */
+       if (g_hash_table_size(new_channels) == 0)
+               /* No channels provided. */
                return SRD_OK;
 
-       if (di->dec_num_probes == 0) {
-               /* Decoder has no probes. */
-               srd_err("Protocol decoder %s has no probes to define.",
+       if (di->dec_num_channels == 0) {
+               /* Decoder has no channels. */
+               srd_err("Protocol decoder %s has no channels to define.",
                        di->decoder->name);
                return SRD_ERR_ARG;
        }
 
-       new_probemap = NULL;
-
-       if (!(new_probemap = g_try_malloc(sizeof(int) * di->dec_num_probes))) {
-               srd_err("Failed to g_malloc() new probe map.");
-               return SRD_ERR_MALLOC;
-       }
+       new_channelmap = g_malloc(sizeof(int) * di->dec_num_channels);
 
        /*
-        * For now, map all indexes to probe -1 (can be overridden later).
-        * This -1 is interpreted as an unspecified probe later.
+        * For now, map all indexes to channel -1 (can be overridden later).
+        * This -1 is interpreted as an unspecified channel later.
         */
-       for (i = 0; i < di->dec_num_probes; i++)
-               new_probemap[i] = -1;
-
-       num_probes = 0;
-       for (l = g_hash_table_get_keys(new_probes); l; l = l->next) {
-               probe_id = l->data;
-               probe_val = g_hash_table_lookup(new_probes, probe_id);
-               if (!g_variant_is_of_type(probe_val, G_VARIANT_TYPE_INT32)) {
-                       /* Probe name was specified without a value. */
-                       srd_err("No probe number was specified for %s.",
-                                       probe_id);
-                       g_free(new_probemap);
+       for (i = 0; i < di->dec_num_channels; i++)
+               new_channelmap[i] = -1;
+
+       for (l = g_hash_table_get_keys(new_channels); l; l = l->next) {
+               channel_id = l->data;
+               channel_val = g_hash_table_lookup(new_channels, channel_id);
+               if (!g_variant_is_of_type(channel_val, G_VARIANT_TYPE_INT32)) {
+                       /* Channel name was specified without a value. */
+                       srd_err("No channel number was specified for %s.",
+                                       channel_id);
+                       g_free(new_channelmap);
                        return SRD_ERR_ARG;
                }
-               new_probenum = g_variant_get_int32(probe_val);
-               if (!(sl = g_slist_find_custom(di->decoder->probes, probe_id,
-                               (GCompareFunc)compare_probe_id))) {
-                       /* Fall back on optional probes. */
-                       if (!(sl = g_slist_find_custom(di->decoder->opt_probes,
-                            probe_id, (GCompareFunc) compare_probe_id))) {
-                               srd_err("Protocol decoder %s has no probe "
-                                               "'%s'.", di->decoder->name, probe_id);
-                               g_free(new_probemap);
+               new_channelnum = g_variant_get_int32(channel_val);
+               if (!(sl = g_slist_find_custom(di->decoder->channels, channel_id,
+                               (GCompareFunc)compare_channel_id))) {
+                       /* Fall back on optional channels. */
+                       if (!(sl = g_slist_find_custom(di->decoder->opt_channels,
+                            channel_id, (GCompareFunc)compare_channel_id))) {
+                               srd_err("Protocol decoder %s has no channel "
+                                       "'%s'.", di->decoder->name, channel_id);
+                               g_free(new_channelmap);
                                return SRD_ERR_ARG;
                        }
                }
-               p = sl->data;
-               new_probemap[p->order] = new_probenum;
-               srd_dbg("Setting probe mapping: %s (index %d) = probe %d.",
-                       p->id, p->order, new_probenum);
-               num_probes++;
+               pdch = sl->data;
+               new_channelmap[pdch->order] = new_channelnum;
+               srd_dbg("Setting channel mapping: %s (PD ch idx %d) = input data ch idx %d.",
+                       pdch->id, pdch->order, new_channelnum);
        }
-       di->data_unitsize = (num_probes + 7) / 8;
 
-       srd_dbg("Final probe map:");
-       num_required_probes = g_slist_length(di->decoder->probes);
-       for (i = 0; i < di->dec_num_probes; i++) {
-               srd_dbg(" - index %d = probe %d (%s)", i, new_probemap[i],
-                       (i < num_required_probes) ? "required" : "optional");
+       srd_dbg("Final channel map:");
+       num_required_channels = g_slist_length(di->decoder->channels);
+       for (i = 0; i < di->dec_num_channels; i++) {
+               GSList *l = g_slist_nth(di->decoder->channels, i);
+               if (!l)
+                       l = g_slist_nth(di->decoder->opt_channels,
+                               i - num_required_channels);
+               pdch = l->data;
+               srd_dbg(" - PD ch idx %d (%s) = input data ch idx %d (%s)", i,
+                       pdch->id, new_channelmap[i],
+                       (i < num_required_channels) ? "required" : "optional");
        }
 
-       /* Report an error if not all required probes were specified. */
-       for (i = 0; i < num_required_probes; i++) {
-               if (new_probemap[i] != -1)
+       /* Report an error if not all required channels were specified. */
+       for (i = 0; i < num_required_channels; i++) {
+               if (new_channelmap[i] != -1)
                        continue;
-               p = g_slist_nth(di->decoder->probes, i)->data;
-               srd_err("Required probe '%s' (index %d) was not specified.",
-                       p->id, i);
+               pdch = g_slist_nth(di->decoder->channels, i)->data;
+               srd_err("Required channel '%s' (index %d) was not specified.",
+                       pdch->id, i);
                return SRD_ERR;
        }
 
-       g_free(di->dec_probemap);
-       di->dec_probemap = new_probemap;
+       g_free(di->dec_channelmap);
+       di->dec_channelmap = new_channelmap;
 
        return SRD_OK;
 }
@@ -341,7 +309,9 @@ SRD_API struct srd_decoder_inst *srd_inst_new(struct srd_session *sess,
        struct srd_decoder *dec;
        struct srd_decoder_inst *di;
        char *inst_id;
+       PyGILState_STATE gstate;
 
+       i = 1;
        srd_dbg("Creating new %s instance.", decoder_id);
 
        if (session_is_valid(sess) != SRD_OK) {
@@ -354,70 +324,158 @@ SRD_API struct srd_decoder_inst *srd_inst_new(struct srd_session *sess,
                return NULL;
        }
 
-       if (!(di = g_try_malloc0(sizeof(struct srd_decoder_inst)))) {
-               srd_err("Failed to g_malloc() instance.");
-               return NULL;
-       }
+       di = g_malloc0(sizeof(struct srd_decoder_inst));
 
        di->decoder = dec;
        di->sess = sess;
+
        if (options) {
                inst_id = g_hash_table_lookup(options, "id");
-               di->inst_id = g_strdup(inst_id ? inst_id : decoder_id);
+               if (inst_id)
+                       di->inst_id = g_strdup(inst_id);
                g_hash_table_remove(options, "id");
-       } else
-               di->inst_id = g_strdup(decoder_id);
+       }
+
+       /* Create a unique instance ID (as none was provided). */
+       if (!di->inst_id) {
+               di->inst_id = g_strdup_printf("%s-%d", decoder_id, i++);
+               while (srd_inst_find_by_id(sess, di->inst_id)) {
+                       g_free(di->inst_id);
+                       di->inst_id = g_strdup_printf("%s-%d", decoder_id, i++);
+               }
+       }
 
        /*
-        * Prepare a default probe map, where samples come in the
+        * Prepare a default channel map, where samples come in the
         * order in which the decoder class defined them.
         */
-       di->dec_num_probes = g_slist_length(di->decoder->probes) +
-                       g_slist_length(di->decoder->opt_probes);
-       if (di->dec_num_probes) {
-               if (!(di->dec_probemap =
-                               g_try_malloc(sizeof(int) * di->dec_num_probes))) {
-                       srd_err("Failed to g_malloc() probe map.");
-                       g_free(di);
-                       return NULL;
-               }
-               for (i = 0; i < di->dec_num_probes; i++)
-                       di->dec_probemap[i] = i;
-               di->data_unitsize = (di->dec_num_probes + 7) / 8;
+       di->dec_num_channels = g_slist_length(di->decoder->channels) +
+                       g_slist_length(di->decoder->opt_channels);
+       if (di->dec_num_channels) {
+               di->dec_channelmap =
+                               g_malloc(sizeof(int) * di->dec_num_channels);
+               for (i = 0; i < di->dec_num_channels; i++)
+                       di->dec_channelmap[i] = i;
                /*
                 * Will be used to prepare a sample at every iteration
                 * of the instance's decode() method.
                 */
-               if (!(di->probe_samples = g_try_malloc(di->dec_num_probes))) {
-                       srd_err("Failed to g_malloc() sample buffer.");
-                       g_free(di->dec_probemap);
-                       g_free(di);
-                       return NULL;
-               }
+               di->channel_samples = g_malloc(di->dec_num_channels);
        }
 
+       /* Default to the initial pins being the same as in sample 0. */
+       oldpins_array_seed(di);
+
+       gstate = PyGILState_Ensure();
+
        /* Create a new instance of this decoder class. */
        if (!(di->py_inst = PyObject_CallObject(dec->py_dec, NULL))) {
                if (PyErr_Occurred())
-                       srd_exception_catch("failed to create %s instance: ",
+                       srd_exception_catch("Failed to create %s instance",
                                        decoder_id);
-               g_free(di->dec_probemap);
+               PyGILState_Release(gstate);
+               g_free(di->dec_channelmap);
                g_free(di);
                return NULL;
        }
 
+       PyGILState_Release(gstate);
+
        if (options && srd_inst_option_set(di, options) != SRD_OK) {
-               g_free(di->dec_probemap);
+               g_free(di->dec_channelmap);
                g_free(di);
                return NULL;
        }
 
+       di->condition_list = NULL;
+       di->match_array = NULL;
+       di->abs_start_samplenum = 0;
+       di->abs_end_samplenum = 0;
+       di->inbuf = NULL;
+       di->inbuflen = 0;
+       di->abs_cur_samplenum = 0;
+       di->thread_handle = NULL;
+       di->got_new_samples = FALSE;
+       di->handled_all_samples = FALSE;
+       di->want_wait_terminate = FALSE;
+
+       /*
+        * Strictly speaking initialization of statically allocated
+        * condition and mutex variables (or variables allocated on the
+        * stack) is not required, but won't harm either. Explicitly
+        * running init() will better match subsequent clear() calls.
+        */
+       g_cond_init(&di->got_new_samples_cond);
+       g_cond_init(&di->handled_all_samples_cond);
+       g_mutex_init(&di->data_mutex);
+
        /* Instance takes input from a frontend by default. */
        sess->di_list = g_slist_append(sess->di_list, di);
+       srd_dbg("Created new %s instance with ID %s.", decoder_id, di->inst_id);
 
        return di;
 }
 
+static void srd_inst_join_decode_thread(struct srd_decoder_inst *di)
+{
+       if (!di)
+               return;
+       if (!di->thread_handle)
+               return;
+
+       srd_dbg("%s: Joining decoder thread.", di->inst_id);
+
+       /*
+        * Terminate potentially running threads which still
+        * execute the decoder instance's decode() method.
+        */
+       srd_dbg("%s: Raising want_term, sending got_new.", di->inst_id);
+       g_mutex_lock(&di->data_mutex);
+       di->want_wait_terminate = TRUE;
+       g_cond_signal(&di->got_new_samples_cond);
+       g_mutex_unlock(&di->data_mutex);
+
+       srd_dbg("%s: Running join().", di->inst_id);
+       (void)g_thread_join(di->thread_handle);
+       srd_dbg("%s: Call to join() done.", di->inst_id);
+       di->thread_handle = NULL;
+
+       /*
+        * Reset condition and mutex variables, such that next
+        * operations on them will find them in a clean state.
+        */
+       g_cond_clear(&di->got_new_samples_cond);
+       g_cond_init(&di->got_new_samples_cond);
+       g_cond_clear(&di->handled_all_samples_cond);
+       g_cond_init(&di->handled_all_samples_cond);
+       g_mutex_clear(&di->data_mutex);
+       g_mutex_init(&di->data_mutex);
+}
+
+static void srd_inst_reset_state(struct srd_decoder_inst *di)
+{
+       if (!di)
+               return;
+
+       srd_dbg("%s: Resetting decoder state.", di->inst_id);
+
+       /*
+        * Reset internal state of the decoder.
+        */
+       condition_list_free(di);
+       match_array_free(di);
+       di->abs_start_samplenum = 0;
+       di->abs_end_samplenum = 0;
+       di->inbuf = NULL;
+       di->inbuflen = 0;
+       di->abs_cur_samplenum = 0;
+       oldpins_array_free(di);
+       di->got_new_samples = FALSE;
+       di->handled_all_samples = FALSE;
+       di->want_wait_terminate = FALSE;
+       /* Conditions and mutex got reset after joining the thread. */
+}
+
 /**
  * Stack a decoder instance on top of another.
  *
@@ -433,7 +491,6 @@ SRD_API int srd_inst_stack(struct srd_session *sess,
                struct srd_decoder_inst *di_bottom,
                struct srd_decoder_inst *di_top)
 {
-
        if (session_is_valid(sess) != SRD_OK) {
                srd_err("Invalid session.");
                return SRD_ERR_ARG;
@@ -452,16 +509,48 @@ SRD_API int srd_inst_stack(struct srd_session *sess,
        /* Stack on top of source di. */
        di_bottom->next_di = g_slist_append(di_bottom->next_di, di_top);
 
-       srd_dbg("Stacked %s on top of %s.", di_top->inst_id, di_bottom->inst_id);
+       srd_dbg("Stacked %s onto %s.", di_top->inst_id, di_bottom->inst_id);
 
        return SRD_OK;
 }
 
+/**
+ * Search a decoder instance and its stack for instance ID.
+ *
+ * @param[in] inst_id ID to search for.
+ * @param[in] stack A decoder instance, potentially with stacked instances.
+ *
+ * @return The matching instance, or NULL.
+ */
+static struct srd_decoder_inst *srd_inst_find_by_id_stack(const char *inst_id,
+               struct srd_decoder_inst *stack)
+{
+       const GSList *l;
+       struct srd_decoder_inst *tmp, *di;
+
+       if (!strcmp(stack->inst_id, inst_id))
+               return stack;
+
+       /* Otherwise, look recursively in our stack. */
+       di = NULL;
+       if (stack->next_di) {
+               for (l = stack->next_di; l; l = l->next) {
+                       tmp = l->data;
+                       if (!strcmp(tmp->inst_id, inst_id)) {
+                               di = tmp;
+                               break;
+                       }
+               }
+       }
+
+       return di;
+}
+
 /**
  * Find a decoder instance by its instance ID.
  *
- * Only the bottom level of instances are searched -- instances already stacked
- * on top of another one will not be found.
+ * This will recurse to find the instance anywhere in the stack tree of the
+ * given session.
  *
  * @param sess The session holding the protocol decoder instance.
  * @param inst_id The instance ID to be found.
@@ -484,10 +573,8 @@ SRD_API struct srd_decoder_inst *srd_inst_find_by_id(struct srd_session *sess,
        di = NULL;
        for (l = sess->di_list; l; l = l->next) {
                tmp = l->data;
-               if (!strcmp(tmp->inst_id, inst_id)) {
-                       di = tmp;
+               if ((di = srd_inst_find_by_id_stack(inst_id, tmp)) != NULL)
                        break;
-               }
        }
 
        return di;
@@ -551,6 +638,88 @@ SRD_PRIV struct srd_decoder_inst *srd_inst_find_by_obj(const GSList *stack,
        return di;
 }
 
+/**
+ * Set the list of initial (assumed) pin values.
+ *
+ * @param di Decoder instance to use. Must not be NULL.
+ * @param initial_pins A GArray of uint8_t values. Must not be NULL.
+ *
+ * @since 0.5.0
+ */
+SRD_API int srd_inst_initial_pins_set_all(struct srd_decoder_inst *di, GArray *initial_pins)
+{
+       int i;
+       GString *s;
+
+       if (!di) {
+               srd_err("Invalid decoder instance.");
+               return SRD_ERR_ARG;
+       }
+
+       if (!initial_pins)
+               return SRD_ERR_ARG;
+
+       if (initial_pins->len != (guint)di->dec_num_channels) {
+               srd_err("Incorrect number of channels (need %d, got %d).",
+                       di->dec_num_channels, initial_pins->len);
+               return SRD_ERR_ARG;
+       }
+
+       /* Sanity-check initial pin state values. */
+       for (i = 0; i < di->dec_num_channels; i++) {
+               if (initial_pins->data[i] <= 2)
+                       continue;
+               srd_err("Invalid initial channel %d pin state: %d.",
+                       i, initial_pins->data[i]);
+               return SRD_ERR_ARG;
+       }
+
+       s = g_string_sized_new(100);
+       oldpins_array_seed(di);
+       for (i = 0; i < di->dec_num_channels; i++) {
+               di->old_pins_array->data[i] = initial_pins->data[i];
+               g_string_append_printf(s, "%d, ", di->old_pins_array->data[i]);
+       }
+       s = g_string_truncate(s, s->len - 2);
+       srd_dbg("Initial pins: %s.", s->str);
+       g_string_free(s, TRUE);
+
+       return SRD_OK;
+}
+
+/** @private */
+SRD_PRIV void oldpins_array_seed(struct srd_decoder_inst *di)
+{
+       size_t count;
+       GArray *arr;
+
+       if (!di)
+               return;
+       if (di->old_pins_array)
+               return;
+
+       srd_dbg("%s: Seeding old pins, %s().", di->inst_id, __func__);
+       count = di->dec_num_channels;
+       arr = g_array_sized_new(FALSE, TRUE, sizeof(uint8_t), count);
+       g_array_set_size(arr, count);
+       memset(arr->data, SRD_INITIAL_PIN_SAME_AS_SAMPLE0, count);
+       di->old_pins_array = arr;
+}
+
+/** @private */
+SRD_PRIV void oldpins_array_free(struct srd_decoder_inst *di)
+{
+       if (!di)
+               return;
+       if (!di->old_pins_array)
+               return;
+
+       srd_dbg("%s: Releasing initial pin state.", di->inst_id);
+
+       g_array_free(di->old_pins_array, TRUE);
+       di->old_pins_array = NULL;
+}
+
 /** @private */
 SRD_PRIV int srd_inst_start(struct srd_decoder_inst *di)
 {
@@ -558,17 +727,30 @@ SRD_PRIV int srd_inst_start(struct srd_decoder_inst *di)
        GSList *l;
        struct srd_decoder_inst *next_di;
        int ret;
+       PyGILState_STATE gstate;
 
        srd_dbg("Calling start() method on protocol decoder instance %s.",
                        di->inst_id);
 
+       gstate = PyGILState_Ensure();
+
+       /* Run self.start(). */
        if (!(py_res = PyObject_CallMethod(di->py_inst, "start", NULL))) {
-               srd_exception_catch("Protocol decoder instance %s",
+               srd_exception_catch("Protocol decoder instance %s",
                                di->inst_id);
+               PyGILState_Release(gstate);
                return SRD_ERR_PYTHON;
        }
        Py_DecRef(py_res);
 
+       /* Set self.samplenum to 0. */
+       PyObject_SetAttrString(di->py_inst, "samplenum", PyLong_FromLong(0));
+
+       /* Set self.matched to None. */
+       PyObject_SetAttrString(di->py_inst, "matched", Py_None);
+
+       PyGILState_Release(gstate);
+
        /* Start all the PDs stacked on top of this one. */
        for (l = di->next_di; l; l = l->next) {
                next_di = l->data;
@@ -580,33 +762,449 @@ SRD_PRIV int srd_inst_start(struct srd_decoder_inst *di)
 }
 
 /**
- * Run the specified decoder function.
+ * Check whether the specified sample matches the specified term.
  *
- * @param di The decoder instance to call. Must not be NULL.
- * @param start_samplenum The starting sample number for the buffer's sample
- *                       set, relative to the start of capture.
- * @param end_samplenum The ending sample number for the buffer's sample
- *                       set, relative to the start of capture.
- * @param inbuf The buffer to decode. Must not be NULL.
- * @param inbuflen Length of the buffer. Must be > 0.
+ * In the case of SRD_TERM_SKIP, this function can modify
+ * term->num_samples_already_skipped.
  *
- * @return SRD_OK upon success, a (negative) error code otherwise.
+ * @param old_sample The value of the previous sample (0/1).
+ * @param sample The value of the current sample (0/1).
+ * @param term The term that should be checked for a match. Must not be NULL.
+ *
+ * @retval TRUE The current sample matches the specified term.
+ * @retval FALSE The current sample doesn't match the specified term, or an
+ *               invalid term was provided.
+ *
+ * @private
+ */
+static gboolean sample_matches(uint8_t old_sample, uint8_t sample, struct srd_term *term)
+{
+       /* Caller ensures term != NULL. */
+
+       switch (term->type) {
+       case SRD_TERM_HIGH:
+               if (sample == 1)
+                       return TRUE;
+               break;
+       case SRD_TERM_LOW:
+               if (sample == 0)
+                       return TRUE;
+               break;
+       case SRD_TERM_RISING_EDGE:
+               if (old_sample == 0 && sample == 1)
+                       return TRUE;
+               break;
+       case SRD_TERM_FALLING_EDGE:
+               if (old_sample == 1 && sample == 0)
+                       return TRUE;
+               break;
+       case SRD_TERM_EITHER_EDGE:
+               if ((old_sample == 1 && sample == 0) || (old_sample == 0 && sample == 1))
+                       return TRUE;
+               break;
+       case SRD_TERM_NO_EDGE:
+               if ((old_sample == 0 && sample == 0) || (old_sample == 1 && sample == 1))
+                       return TRUE;
+               break;
+       case SRD_TERM_SKIP:
+               if (term->num_samples_already_skipped == term->num_samples_to_skip)
+                       return TRUE;
+               term->num_samples_already_skipped++;
+               break;
+       default:
+               srd_err("Unknown term type %d.", term->type);
+               break;
+       }
+
+       return FALSE;
+}
+
+/** @private */
+SRD_PRIV void match_array_free(struct srd_decoder_inst *di)
+{
+       if (!di || !di->match_array)
+               return;
+
+       g_array_free(di->match_array, TRUE);
+       di->match_array = NULL;
+}
+
+/** @private */
+SRD_PRIV void condition_list_free(struct srd_decoder_inst *di)
+{
+       GSList *l, *ll;
+
+       if (!di)
+               return;
+
+       for (l = di->condition_list; l; l = l->next) {
+               ll = l->data;
+               if (ll)
+                       g_slist_free_full(ll, g_free);
+       }
+
+       di->condition_list = NULL;
+}
+
+static gboolean have_non_null_conds(const struct srd_decoder_inst *di)
+{
+       GSList *l, *cond;
+
+       if (!di)
+               return FALSE;
+
+       for (l = di->condition_list; l; l = l->next) {
+               cond = l->data;
+               if (cond)
+                       return TRUE;
+       }
+
+       return FALSE;
+}
+
+static void update_old_pins_array(struct srd_decoder_inst *di,
+               const uint8_t *sample_pos)
+{
+       uint8_t sample;
+       int i, byte_offset, bit_offset;
+
+       if (!di || !di->dec_channelmap || !sample_pos)
+               return;
+
+       oldpins_array_seed(di);
+       for (i = 0; i < di->dec_num_channels; i++) {
+               byte_offset = di->dec_channelmap[i] / 8;
+               bit_offset = di->dec_channelmap[i] % 8;
+               sample = *(sample_pos + byte_offset) & (1 << bit_offset) ? 1 : 0;
+               di->old_pins_array->data[i] = sample;
+       }
+}
+
+static void update_old_pins_array_initial_pins(struct srd_decoder_inst *di)
+{
+       uint8_t sample;
+       int i, byte_offset, bit_offset;
+       const uint8_t *sample_pos;
+
+       if (!di || !di->dec_channelmap)
+               return;
+
+       sample_pos = di->inbuf + ((di->abs_cur_samplenum - di->abs_start_samplenum) * di->data_unitsize);
+
+       oldpins_array_seed(di);
+       for (i = 0; i < di->dec_num_channels; i++) {
+               if (di->old_pins_array->data[i] != SRD_INITIAL_PIN_SAME_AS_SAMPLE0)
+                       continue;
+               byte_offset = di->dec_channelmap[i] / 8;
+               bit_offset = di->dec_channelmap[i] % 8;
+               sample = *(sample_pos + byte_offset) & (1 << bit_offset) ? 1 : 0;
+               di->old_pins_array->data[i] = sample;
+       }
+}
+
+static gboolean term_matches(const struct srd_decoder_inst *di,
+               struct srd_term *term, const uint8_t *sample_pos)
+{
+       uint8_t old_sample, sample;
+       int byte_offset, bit_offset, ch;
+
+       /* Caller ensures di, di->dec_channelmap, term, sample_pos != NULL. */
+
+       if (term->type == SRD_TERM_SKIP)
+               return sample_matches(0, 0, term);
+
+       ch = term->channel;
+       byte_offset = di->dec_channelmap[ch] / 8;
+       bit_offset = di->dec_channelmap[ch] % 8;
+       sample = *(sample_pos + byte_offset) & (1 << bit_offset) ? 1 : 0;
+       old_sample = di->old_pins_array->data[ch];
+
+       return sample_matches(old_sample, sample, term);
+}
+
+static gboolean all_terms_match(const struct srd_decoder_inst *di,
+               const GSList *cond, const uint8_t *sample_pos)
+{
+       const GSList *l;
+       struct srd_term *term;
+
+       /* Caller ensures di, cond, sample_pos != NULL. */
+
+       for (l = cond; l; l = l->next) {
+               term = l->data;
+               if (!term_matches(di, term, sample_pos))
+                       return FALSE;
+       }
+
+       return TRUE;
+}
+
+static gboolean at_least_one_condition_matched(
+               const struct srd_decoder_inst *di, unsigned int num_conditions)
+{
+       unsigned int i;
+
+       /* Caller ensures di != NULL. */
+
+       for (i = 0; i < num_conditions; i++) {
+               if (di->match_array->data[i])
+                       return TRUE;
+       }
+
+       return FALSE;
+}
+
+static gboolean find_match(struct srd_decoder_inst *di)
+{
+       uint64_t i, j, num_samples_to_process;
+       GSList *l, *cond;
+       const uint8_t *sample_pos;
+       unsigned int num_conditions;
+
+       /* Caller ensures di != NULL. */
+
+       /* Check whether the condition list is NULL/empty. */
+       if (!di->condition_list) {
+               srd_dbg("NULL/empty condition list, automatic match.");
+               return TRUE;
+       }
+
+       /* Check whether we have any non-NULL conditions. */
+       if (!have_non_null_conds(di)) {
+               srd_dbg("Only NULL conditions in list, automatic match.");
+               return TRUE;
+       }
+
+       num_samples_to_process = di->abs_end_samplenum - di->abs_cur_samplenum;
+       num_conditions = g_slist_length(di->condition_list);
+
+       /* di->match_array is NULL here. Create a new GArray. */
+       di->match_array = g_array_sized_new(FALSE, TRUE, sizeof(gboolean), num_conditions);
+       g_array_set_size(di->match_array, num_conditions);
+
+       /* Sample 0: Set di->old_pins_array for SRD_INITIAL_PIN_SAME_AS_SAMPLE0 pins. */
+       if (di->abs_cur_samplenum == 0)
+               update_old_pins_array_initial_pins(di);
+
+       for (i = 0; i < num_samples_to_process; i++, (di->abs_cur_samplenum)++) {
+
+               sample_pos = di->inbuf + ((di->abs_cur_samplenum - di->abs_start_samplenum) * di->data_unitsize);
+
+               /* Check whether the current sample matches at least one of the conditions (logical OR). */
+               /* IMPORTANT: We need to check all conditions, even if there was a match already! */
+               for (l = di->condition_list, j = 0; l; l = l->next, j++) {
+                       cond = l->data;
+                       if (!cond)
+                               continue;
+                       /* All terms in 'cond' must match (logical AND). */
+                       di->match_array->data[j] = all_terms_match(di, cond, sample_pos);
+               }
+
+               update_old_pins_array(di, sample_pos);
+
+               /* If at least one condition matched we're done. */
+               if (at_least_one_condition_matched(di, num_conditions))
+                       return TRUE;
+       }
+
+       return FALSE;
+}
+
+/**
+ * Process available samples and check if they match the defined conditions.
+ *
+ * This function returns if there is an error, or when a match is found, or
+ * when all samples have been processed (whether a match was found or not).
+ * This function immediately terminates when the decoder's wait() method
+ * invocation shall get terminated.
+ *
+ * @param di The decoder instance to use. Must not be NULL.
+ * @param found_match Will be set to TRUE if at least one condition matched,
+ *                    FALSE otherwise. Must not be NULL.
+ *
+ * @retval SRD_OK No errors occured, see found_match for the result.
+ * @retval SRD_ERR_ARG Invalid arguments.
  *
  * @private
+ */
+SRD_PRIV int process_samples_until_condition_match(struct srd_decoder_inst *di, gboolean *found_match)
+{
+       if (!di || !found_match)
+               return SRD_ERR_ARG;
+
+       *found_match = FALSE;
+       if (di->want_wait_terminate)
+               return SRD_OK;
+
+       /* Check if any of the current condition(s) match. */
+       while (TRUE) {
+               /* Feed the (next chunk of the) buffer to find_match(). */
+               *found_match = find_match(di);
+
+               /* Did we handle all samples yet? */
+               if (di->abs_cur_samplenum >= di->abs_end_samplenum) {
+                       srd_dbg("Done, handled all samples (abs cur %" PRIu64
+                               " / abs end %" PRIu64 ").",
+                               di->abs_cur_samplenum, di->abs_end_samplenum);
+                       return SRD_OK;
+               }
+
+               /* If we didn't find a match, continue looking. */
+               if (!(*found_match))
+                       continue;
+
+               /* At least one condition matched, return. */
+               return SRD_OK;
+       }
+
+       return SRD_OK;
+}
+
+/**
+ * Worker thread (per PD-stack).
  *
- * @since 0.1.0
+ * @param data Pointer to the lowest-level PD's device instance.
+ *             Must not be NULL.
+ *
+ * @return NULL if there was an error.
  */
-SRD_PRIV int srd_inst_decode(const struct srd_decoder_inst *di,
-               uint64_t start_samplenum, uint64_t end_samplenum,
-               const uint8_t *inbuf, uint64_t inbuflen)
+static gpointer di_thread(gpointer data)
 {
        PyObject *py_res;
-       srd_logic *logic;
+       struct srd_decoder_inst *di;
+       int wanted_term;
+       PyGILState_STATE gstate;
+
+       if (!data)
+               return NULL;
+
+       di = data;
+
+       srd_dbg("%s: Starting thread routine for decoder.", di->inst_id);
+
+       gstate = PyGILState_Ensure();
+
+       /*
+        * Call self.decode(). Only returns if the PD throws an exception.
+        * "Regular" termination of the decode() method is not expected.
+        */
+       Py_IncRef(di->py_inst);
+       srd_dbg("%s: Calling decode() method.", di->inst_id);
+       py_res = PyObject_CallMethod(di->py_inst, "decode", NULL);
+       srd_dbg("%s: decode() method terminated.", di->inst_id);
+
+       /*
+        * Make sure to unblock potentially pending srd_inst_decode()
+        * calls in application threads after the decode() method might
+        * have terminated, while it neither has processed sample data
+        * nor has terminated upon request. This happens e.g. when "need
+        * a samplerate to decode" exception is thrown.
+        */
+       g_mutex_lock(&di->data_mutex);
+       wanted_term = di->want_wait_terminate;
+       di->want_wait_terminate = TRUE;
+       di->handled_all_samples = TRUE;
+       g_cond_signal(&di->handled_all_samples_cond);
+       g_mutex_unlock(&di->data_mutex);
+
+       /*
+        * Check for the termination cause of the decode() method.
+        * Though this is mostly for information.
+        */
+       if (!py_res && wanted_term) {
+               /*
+                * Silently ignore errors upon return from decode() calls
+                * when termination was requested. Terminate the thread
+                * which executed this instance's decode() logic.
+                */
+               srd_dbg("%s: Thread done (!res, want_term).", di->inst_id);
+               PyErr_Clear();
+               PyGILState_Release(gstate);
+               return NULL;
+       }
+       if (!py_res) {
+               /*
+                * The decode() invocation terminated unexpectedly. Have
+                * the back trace printed, and terminate the thread which
+                * executed the decode() method.
+                */
+               srd_dbg("%s: decode() terminated unrequested.", di->inst_id);
+               srd_exception_catch("Protocol decoder instance %s: ", di->inst_id);
+               srd_dbg("%s: Thread done (!res, !want_term).", di->inst_id);
+               PyGILState_Release(gstate);
+               return NULL;
+       }
 
-       srd_dbg("Calling decode() on instance %s with %" PRIu64 " bytes "
-               "starting at sample %" PRIu64 ".", di->inst_id, inbuflen,
-               start_samplenum);
+       /*
+        * TODO: By design the decode() method is not supposed to terminate.
+        * Nevertheless we have the thread joined, and srd backend calls to
+        * decode() will re-start another thread transparently.
+        */
+       srd_dbg("%s: decode() terminated (req %d).", di->inst_id, wanted_term);
+       Py_DecRef(py_res);
+       PyErr_Clear();
+
+       PyGILState_Release(gstate);
+
+       srd_dbg("%s: Thread done (with res).", di->inst_id);
+
+       return NULL;
+}
 
+/**
+ * Decode a chunk of samples.
+ *
+ * The calls to this function must provide the samples that shall be
+ * used by the protocol decoder
+ *  - in the correct order ([...]5, 6, 4, 7, 8[...] is a bug),
+ *  - starting from sample zero (2, 3, 4, 5, 6[...] is a bug),
+ *  - consecutively, with no gaps (0, 1, 2, 4, 5[...] is a bug).
+ *
+ * The start- and end-sample numbers are absolute sample numbers (relative
+ * to the start of the whole capture/file/stream), i.e. they are not relative
+ * sample numbers within the chunk specified by 'inbuf' and 'inbuflen'.
+ *
+ * Correct example (4096 samples total, 4 chunks @ 1024 samples each):
+ *   srd_inst_decode(di, 0,    1024, inbuf, 1024, 1);
+ *   srd_inst_decode(di, 1024, 2048, inbuf, 1024, 1);
+ *   srd_inst_decode(di, 2048, 3072, inbuf, 1024, 1);
+ *   srd_inst_decode(di, 3072, 4096, inbuf, 1024, 1);
+ *
+ * The chunk size ('inbuflen') can be arbitrary and can differ between calls.
+ *
+ * Correct example (4096 samples total, 7 chunks @ various samples each):
+ *   srd_inst_decode(di, 0,    1024, inbuf, 1024, 1);
+ *   srd_inst_decode(di, 1024, 1124, inbuf,  100, 1);
+ *   srd_inst_decode(di, 1124, 1424, inbuf,  300, 1);
+ *   srd_inst_decode(di, 1424, 1643, inbuf,  219, 1);
+ *   srd_inst_decode(di, 1643, 2048, inbuf,  405, 1);
+ *   srd_inst_decode(di, 2048, 3072, inbuf, 1024, 1);
+ *   srd_inst_decode(di, 3072, 4096, inbuf, 1024, 1);
+ *
+ * INCORRECT example (4096 samples total, 4 chunks @ 1024 samples each, but
+ * the start- and end-samplenumbers are not absolute):
+ *   srd_inst_decode(di, 0,    1024, inbuf, 1024, 1);
+ *   srd_inst_decode(di, 0,    1024, inbuf, 1024, 1);
+ *   srd_inst_decode(di, 0,    1024, inbuf, 1024, 1);
+ *   srd_inst_decode(di, 0,    1024, inbuf, 1024, 1);
+ *
+ * @param di The decoder instance to call. Must not be NULL.
+ * @param abs_start_samplenum The absolute starting sample number for the
+ *             buffer's sample set, relative to the start of capture.
+ * @param abs_end_samplenum The absolute ending sample number for the
+ *             buffer's sample set, relative to the start of capture.
+ * @param inbuf The buffer to decode. Must not be NULL.
+ * @param inbuflen Length of the buffer. Must be > 0.
+ * @param unitsize The number of bytes per sample. Must be > 0.
+ *
+ * @return SRD_OK upon success, a (negative) error code otherwise.
+ *
+ * @private
+ */
+SRD_PRIV int srd_inst_decode(struct srd_decoder_inst *di,
+               uint64_t abs_start_samplenum, uint64_t abs_end_samplenum,
+               const uint8_t *inbuf, uint64_t inbuflen, uint64_t unitsize)
+{
        /* Return an error upon unusable input. */
        if (!di) {
                srd_dbg("empty decoder instance");
@@ -620,28 +1218,118 @@ SRD_PRIV int srd_inst_decode(const struct srd_decoder_inst *di,
                srd_dbg("empty buffer");
                return SRD_ERR_ARG;
        }
+       if (unitsize == 0) {
+               srd_dbg("unitsize 0");
+               return SRD_ERR_ARG;
+       }
+
+       if (abs_start_samplenum != di->abs_cur_samplenum ||
+           abs_end_samplenum < abs_start_samplenum) {
+               srd_dbg("Incorrect sample numbers: start=%" PRIu64 ", cur=%"
+                       PRIu64 ", end=%" PRIu64 ".", abs_start_samplenum,
+                       di->abs_cur_samplenum, abs_end_samplenum);
+               return SRD_ERR_ARG;
+       }
+
+       di->data_unitsize = unitsize;
+
+       srd_dbg("Decoding: abs start sample %" PRIu64 ", abs end sample %"
+               PRIu64 " (%" PRIu64 " samples, %" PRIu64 " bytes, unitsize = "
+               "%d), instance %s.", abs_start_samplenum, abs_end_samplenum,
+               abs_end_samplenum - abs_start_samplenum, inbuflen, di->data_unitsize,
+               di->inst_id);
+
+       /* If this is the first call, start the worker thread. */
+       if (!di->thread_handle) {
+               srd_dbg("No worker thread for this decoder stack "
+                       "exists yet, creating one: %s.", di->inst_id);
+               di->thread_handle = g_thread_new(di->inst_id,
+                                                di_thread, di);
+       }
+
+       /* Push the new sample chunk to the worker thread. */
+       g_mutex_lock(&di->data_mutex);
+       di->abs_start_samplenum = abs_start_samplenum;
+       di->abs_end_samplenum = abs_end_samplenum;
+       di->inbuf = inbuf;
+       di->inbuflen = inbuflen;
+       di->got_new_samples = TRUE;
+       di->handled_all_samples = FALSE;
+       di->want_wait_terminate = FALSE;
+
+       /* Signal the thread that we have new data. */
+       g_cond_signal(&di->got_new_samples_cond);
+       g_mutex_unlock(&di->data_mutex);
+
+       /* When all samples in this chunk were handled, return. */
+       g_mutex_lock(&di->data_mutex);
+       while (!di->handled_all_samples && !di->want_wait_terminate)
+               g_cond_wait(&di->handled_all_samples_cond, &di->data_mutex);
+       g_mutex_unlock(&di->data_mutex);
+
+       return SRD_OK;
+}
+
+/**
+ * Terminate current decoder work, prepare for re-use on new input data.
+ *
+ * Terminates all decoder operations in the specified decoder instance
+ * and the instances stacked on top of it. Resets internal state such
+ * that the previously constructed stack can process new input data that
+ * is not related to previously processed input data. This avoids the
+ * expensive and complex re-construction of decoder stacks.
+ *
+ * Callers are expected to follow up with start, metadata, and decode
+ * calls like they would for newly constructed decoder stacks.
+ *
+ * @param di The decoder instance to call. Must not be NULL.
+ * @return SRD_OK upon success, a (negative) error code otherwise.
+ * @private
+ */
+SRD_PRIV int srd_inst_terminate_reset(struct srd_decoder_inst *di)
+{
+       PyGILState_STATE gstate;
+       PyObject *py_ret;
+       GSList *l;
+       int ret;
+
+       if (!di)
+               return SRD_ERR_ARG;
 
        /*
-        * Create new srd_logic object. Each iteration around the PD's loop
-        * will fill one sample into this object.
+        * Request termination and wait for previously initiated
+        * background operation to finish. Reset internal state, but
+        * do not start releasing resources yet. This shall result in
+        * decoders' state just like after creation. This block handles
+        * the C language library side.
         */
-       logic = PyObject_New(srd_logic, &srd_logic_type);
-       Py_INCREF(logic);
-       logic->di = (struct srd_decoder_inst *)di;
-       logic->start_samplenum = start_samplenum;
-       logic->itercnt = 0;
-       logic->inbuf = (uint8_t *)inbuf;
-       logic->inbuflen = inbuflen;
-       logic->sample = PyList_New(2);
-       Py_INCREF(logic->sample);
+       srd_dbg("Terminating instance %s", di->inst_id);
+       srd_inst_join_decode_thread(di);
+       srd_inst_reset_state(di);
 
-       Py_IncRef(di->py_inst);
-       if (!(py_res = PyObject_CallMethod(di->py_inst, "decode",
-                       "KKO", start_samplenum, end_samplenum, logic))) {
-               srd_exception_catch("Protocol decoder instance %s: ", di->inst_id);
-               return SRD_ERR_PYTHON;
+       /*
+        * Have the Python side's .reset() method executed (if the PD
+        * implements it). It's assumed that .reset() assigns variables
+        * very much like __init__() used to do in the past. Thus memory
+        * that was allocated in previous calls gets released by Python
+        * as it's not referenced any longer.
+        */
+       gstate = PyGILState_Ensure();
+       if (PyObject_HasAttrString(di->py_inst, "reset")) {
+               srd_dbg("Calling .reset() of instance %s", di->inst_id);
+               py_ret = PyObject_CallMethod(di->py_inst, "reset", NULL);
+               Py_XDECREF(py_ret);
+       }
+       PyGILState_Release(gstate);
+
+       /*
+        * Pass the "restart" request to all stacked decoders.
+        */
+       for (l = di->next_di; l; l = l->next) {
+               ret = srd_inst_terminate_reset(l->data);
+               if (ret != SRD_OK)
+                       return ret;
        }
-       Py_DecRef(py_res);
 
        return SRD_OK;
 }
@@ -651,12 +1339,21 @@ SRD_PRIV void srd_inst_free(struct srd_decoder_inst *di)
 {
        GSList *l;
        struct srd_pd_output *pdo;
+       PyGILState_STATE gstate;
 
        srd_dbg("Freeing instance %s", di->inst_id);
 
+       srd_inst_join_decode_thread(di);
+
+       srd_inst_reset_state(di);
+
+       gstate = PyGILState_Ensure();
        Py_DecRef(di->py_inst);
+       PyGILState_Release(gstate);
+
        g_free(di->inst_id);
-       g_free(di->dec_probemap);
+       g_free(di->dec_channelmap);
+       g_free(di->channel_samples);
        g_slist_free(di->next_di);
        for (l = di->pd_output; l; l = l->next) {
                pdo = l->data;
@@ -668,28 +1365,14 @@ SRD_PRIV void srd_inst_free(struct srd_decoder_inst *di)
 }
 
 /** @private */
-SRD_PRIV void srd_inst_free_all(struct srd_session *sess, GSList *stack)
+SRD_PRIV void srd_inst_free_all(struct srd_session *sess)
 {
-       GSList *l;
-       struct srd_decoder_inst *di;
-
        if (session_is_valid(sess) != SRD_OK) {
                srd_err("Invalid session.");
                return;
        }
 
-       di = NULL;
-       for (l = stack ? stack : sess->di_list; di == NULL && l != NULL; l = l->next) {
-               di = l->data;
-               if (di->next_di)
-                       srd_inst_free_all(sess, di->next_di);
-               srd_inst_free(di);
-       }
-       if (!stack) {
-               g_slist_free(sess->di_list);
-               sess->di_list = NULL;
-       }
+       g_slist_free_full(sess->di_list, (GDestroyNotify)srd_inst_free);
 }
 
 /** @} */
-