pjon: introduce decoder for PJON frame inspection

[libsigrokdecode/gsi.git] / type_decoder.c

/*
 * This file is part of the libsigrokdecode project.
 *
 * Copyright (C) 2012 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 "libsigrokdecode-internal.h" /* First, so we avoid a _POSIX_C_SOURCE warning. */
#include "libsigrokdecode.h"
#include <inttypes.h>

/** @cond PRIVATE */
extern SRD_PRIV GSList *sessions;
/** @endcond */

typedef struct {
        PyObject_HEAD
} srd_Decoder;

/* This is only used for nicer srd_dbg() output. */
SRD_PRIV const char *output_type_name(unsigned int idx)
{
        static const char names[][16] = {
                "OUTPUT_ANN",
                "OUTPUT_PYTHON",
                "OUTPUT_BINARY",
                "OUTPUT_META",
                "(invalid)"
        };

        return names[MIN(idx, G_N_ELEMENTS(names) - 1)];
}

static void release_annotation(struct srd_proto_data_annotation *pda)
{
        if (!pda)
                return;
        if (pda->ann_text)
                g_strfreev(pda->ann_text);
}

static int convert_annotation(struct srd_decoder_inst *di, PyObject *obj,
                struct srd_proto_data *pdata)
{
        PyObject *py_tmp;
        struct srd_pd_output *pdo;
        struct srd_proto_data_annotation *pda;
        int ann_class;
        char **ann_text;
        PyGILState_STATE gstate;

        gstate = PyGILState_Ensure();

        /* Should be a list of [annotation class, [string, ...]]. */
        if (!PyList_Check(obj)) {
                srd_err("Protocol decoder %s submitted an annotation that"
                        " is not a list", di->decoder->name);
                goto err;
        }

        /* Should have 2 elements. */
        if (PyList_Size(obj) != 2) {
                srd_err("Protocol decoder %s submitted annotation list with "
                        "%zd elements instead of 2", di->decoder->name,
                        PyList_Size(obj));
                goto err;
        }

        /*
         * The first element should be an integer matching a previously
         * registered annotation class.
         */
        py_tmp = PyList_GetItem(obj, 0);
        if (!PyLong_Check(py_tmp)) {
                srd_err("Protocol decoder %s submitted annotation list, but "
                        "first element was not an integer.", di->decoder->name);
                goto err;
        }
        ann_class = PyLong_AsLong(py_tmp);
        if (!(pdo = g_slist_nth_data(di->decoder->annotations, ann_class))) {
                srd_err("Protocol decoder %s submitted data to unregistered "
                        "annotation class %d.", di->decoder->name, ann_class);
                goto err;
        }

        /* Second element must be a list. */
        py_tmp = PyList_GetItem(obj, 1);
        if (!PyList_Check(py_tmp)) {
                srd_err("Protocol decoder %s submitted annotation list, but "
                        "second element was not a list.", di->decoder->name);
                goto err;
        }
        if (py_strseq_to_char(py_tmp, &ann_text) != SRD_OK) {
                srd_err("Protocol decoder %s submitted annotation list, but "
                        "second element was malformed.", di->decoder->name);
                goto err;
        }

        pda = pdata->data;
        pda->ann_class = ann_class;
        pda->ann_text = ann_text;

        PyGILState_Release(gstate);

        return SRD_OK;

err:
        PyGILState_Release(gstate);

        return SRD_ERR_PYTHON;
}

static void release_binary(struct srd_proto_data_binary *pdb)
{
        if (!pdb)
                return;
        g_free((void *)pdb->data);
}

static int convert_binary(struct srd_decoder_inst *di, PyObject *obj,
                struct srd_proto_data *pdata)
{
        struct srd_proto_data_binary *pdb;
        PyObject *py_tmp;
        Py_ssize_t size;
        int bin_class;
        char *class_name, *buf;
        PyGILState_STATE gstate;

        gstate = PyGILState_Ensure();

        /* Should be a list of [binary class, bytes]. */
        if (!PyList_Check(obj)) {
                srd_err("Protocol decoder %s submitted non-list for SRD_OUTPUT_BINARY.",
                        di->decoder->name);
                goto err;
        }

        /* Should have 2 elements. */
        if (PyList_Size(obj) != 2) {
                srd_err("Protocol decoder %s submitted SRD_OUTPUT_BINARY list "
                                "with %zd elements instead of 2", di->decoder->name,
                                PyList_Size(obj));
                goto err;
        }

        /* The first element should be an integer. */
        py_tmp = PyList_GetItem(obj, 0);
        if (!PyLong_Check(py_tmp)) {
                srd_err("Protocol decoder %s submitted SRD_OUTPUT_BINARY list, "
                        "but first element was not an integer.", di->decoder->name);
                goto err;
        }
        bin_class = PyLong_AsLong(py_tmp);
        if (!(class_name = g_slist_nth_data(di->decoder->binary, bin_class))) {
                srd_err("Protocol decoder %s submitted SRD_OUTPUT_BINARY with "
                        "unregistered binary class %d.", di->decoder->name, bin_class);
                goto err;
        }

        /* Second element should be bytes. */
        py_tmp = PyList_GetItem(obj, 1);
        if (!PyBytes_Check(py_tmp)) {
                srd_err("Protocol decoder %s submitted SRD_OUTPUT_BINARY list, "
                        "but second element was not bytes.", di->decoder->name);
                goto err;
        }

        /* Consider an empty set of bytes a bug. */
        if (PyBytes_Size(py_tmp) == 0) {
                srd_err("Protocol decoder %s submitted SRD_OUTPUT_BINARY "
                                "with empty data set.", di->decoder->name);
                goto err;
        }

        if (PyBytes_AsStringAndSize(py_tmp, &buf, &size) == -1)
                goto err;

        PyGILState_Release(gstate);

        pdb = pdata->data;
        pdb->bin_class = bin_class;
        pdb->size = size;
        if (!(pdb->data = g_try_malloc(pdb->size)))
                return SRD_ERR_MALLOC;
        memcpy((void *)pdb->data, (const void *)buf, pdb->size);

        return SRD_OK;

err:
        PyGILState_Release(gstate);

        return SRD_ERR_PYTHON;
}

static inline struct srd_decoder_inst *srd_sess_inst_find_by_obj(
        struct srd_session *sess, const GSList *stack, const PyObject *obj)
{
        const GSList *l;
        struct srd_decoder_inst *tmp, *di;

        if (!sess)
                return NULL;

        di = NULL;
        for (l = stack ? stack : sess->di_list; di == NULL && l != NULL; l = l->next) {
                tmp = l->data;
                if (tmp->py_inst == obj)
                        di = tmp;
                else if (tmp->next_di)
                        di = srd_sess_inst_find_by_obj(sess, tmp->next_di, obj);
        }

        return di;
}

/**
 * Find a decoder instance by its Python object.
 *
 * I.e. find that instance's instantiation of the sigrokdecode.Decoder class.
 * This will recurse to find the instance anywhere in the stack tree of all
 * sessions.
 *
 * @param stack Pointer to a GSList of struct srd_decoder_inst, indicating the
 *              stack to search. To start searching at the bottom level of
 *              decoder instances, pass NULL.
 * @param obj The Python class instantiation.
 *
 * @return Pointer to struct srd_decoder_inst, or NULL if not found.
 *
 * @since 0.1.0
 */
static inline struct srd_decoder_inst *srd_inst_find_by_obj(
                const GSList *stack, const PyObject *obj)
{
        struct srd_decoder_inst *di;
        struct srd_session *sess;
        GSList *l;

        /* Performance shortcut: Handle the most common case first. */
        sess = sessions->data;
        di = sess->di_list->data;
        if (di->py_inst == obj)
                return di;

        di = NULL;
        for (l = sessions; di == NULL && l != NULL; l = l->next) {
                sess = l->data;
                di = srd_sess_inst_find_by_obj(sess, stack, obj);
        }

        return di;
}

static int convert_meta(struct srd_proto_data *pdata, PyObject *obj)
{
        long long intvalue;
        double dvalue;
        PyGILState_STATE gstate;

        gstate = PyGILState_Ensure();

        if (g_variant_type_equal(pdata->pdo->meta_type, G_VARIANT_TYPE_INT64)) {
                if (!PyLong_Check(obj)) {
                        PyErr_Format(PyExc_TypeError, "This output was registered "
                                        "as 'int', but something else was passed.");
                        goto err;
                }
                intvalue = PyLong_AsLongLong(obj);
                if (PyErr_Occurred())
                        goto err;
                pdata->data = g_variant_new_int64(intvalue);
        } else if (g_variant_type_equal(pdata->pdo->meta_type, G_VARIANT_TYPE_DOUBLE)) {
                if (!PyFloat_Check(obj)) {
                        PyErr_Format(PyExc_TypeError, "This output was registered "
                                        "as 'float', but something else was passed.");
                        goto err;
                }
                dvalue = PyFloat_AsDouble(obj);
                if (PyErr_Occurred())
                        goto err;
                pdata->data = g_variant_new_double(dvalue);
        }

        PyGILState_Release(gstate);

        return SRD_OK;

err:
        PyGILState_Release(gstate);

        return SRD_ERR_PYTHON;
}

static void release_meta(GVariant *gvar)
{
        if (!gvar)
                return;
        g_variant_unref(gvar);
}

static PyObject *Decoder_put(PyObject *self, PyObject *args)
{
        GSList *l;
        PyObject *py_data, *py_res;
        struct srd_decoder_inst *di, *next_di;
        struct srd_pd_output *pdo;
        struct srd_proto_data pdata;
        struct srd_proto_data_annotation pda;
        struct srd_proto_data_binary pdb;
        uint64_t start_sample, end_sample;
        int output_id;
        struct srd_pd_callback *cb;
        PyGILState_STATE gstate;

        py_data = NULL;

        gstate = PyGILState_Ensure();

        if (!(di = srd_inst_find_by_obj(NULL, self))) {
                /* Shouldn't happen. */
                srd_dbg("put(): self instance not found.");
                goto err;
        }

        if (!PyArg_ParseTuple(args, "KKiO", &start_sample, &end_sample,
                &output_id, &py_data)) {
                /*
                 * This throws an exception, but by returning NULL here we let
                 * Python raise it. This results in a much better trace in
                 * controller.c on the decode() method call.
                 */
                goto err;
        }

        if (!(l = g_slist_nth(di->pd_output, output_id))) {
                srd_err("Protocol decoder %s submitted invalid output ID %d.",
                        di->decoder->name, output_id);
                goto err;
        }
        pdo = l->data;

        /* Upon SRD_OUTPUT_PYTHON for stacked PDs, we have a nicer log message later. */
        if (pdo->output_type != SRD_OUTPUT_PYTHON && di->next_di != NULL) {
                srd_spew("Instance %s put %" PRIu64 "-%" PRIu64 " %s on "
                         "oid %d (%s).", di->inst_id, start_sample, end_sample,
                         output_type_name(pdo->output_type), output_id,
                         pdo->proto_id);
        }

        pdata.start_sample = start_sample;
        pdata.end_sample = end_sample;
        pdata.pdo = pdo;
        pdata.data = NULL;

        switch (pdo->output_type) {
        case SRD_OUTPUT_ANN:
                /* Annotations are only fed to callbacks. */
                if ((cb = srd_pd_output_callback_find(di->sess, pdo->output_type))) {
                        pdata.data = &pda;
                        /* Convert from PyDict to srd_proto_data_annotation. */
                        if (convert_annotation(di, py_data, &pdata) != SRD_OK) {
                                /* An error was already logged. */
                                break;
                        }
                        Py_BEGIN_ALLOW_THREADS
                        cb->cb(&pdata, cb->cb_data);
                        Py_END_ALLOW_THREADS
                        release_annotation(pdata.data);
                }
                break;
        case SRD_OUTPUT_PYTHON:
                for (l = di->next_di; l; l = l->next) {
                        next_di = l->data;
                        srd_spew("Instance %s put %" PRIu64 "-%" PRIu64 " %s "
                                 "on oid %d (%s) to instance %s.", di->inst_id,
                                 start_sample,
                                 end_sample, output_type_name(pdo->output_type),
                                 output_id, pdo->proto_id, next_di->inst_id);
                        if (!(py_res = PyObject_CallMethod(
                                next_di->py_inst, "decode", "KKO", start_sample,
                                end_sample, py_data))) {
                                srd_exception_catch("Calling %s decode() failed",
                                                        next_di->inst_id);
                        }
                        Py_XDECREF(py_res);
                }
                if ((cb = srd_pd_output_callback_find(di->sess, pdo->output_type))) {
                        /*
                         * Frontends aren't really supposed to get Python
                         * callbacks, but it's useful for testing.
                         */
                        pdata.data = py_data;
                        cb->cb(&pdata, cb->cb_data);
                }
                break;
        case SRD_OUTPUT_BINARY:
                if ((cb = srd_pd_output_callback_find(di->sess, pdo->output_type))) {
                        pdata.data = &pdb;
                        /* Convert from PyDict to srd_proto_data_binary. */
                        if (convert_binary(di, py_data, &pdata) != SRD_OK) {
                                /* An error was already logged. */
                                break;
                        }
                        Py_BEGIN_ALLOW_THREADS
                        cb->cb(&pdata, cb->cb_data);
                        Py_END_ALLOW_THREADS
                        release_binary(pdata.data);
                }
                break;
        case SRD_OUTPUT_META:
                if ((cb = srd_pd_output_callback_find(di->sess, pdo->output_type))) {
                        /* Annotations need converting from PyObject. */
                        if (convert_meta(&pdata, py_data) != SRD_OK) {
                                /* An exception was already set up. */
                                break;
                        }
                        Py_BEGIN_ALLOW_THREADS
                        cb->cb(&pdata, cb->cb_data);
                        Py_END_ALLOW_THREADS
                        release_meta(pdata.data);
                }
                break;
        default:
                srd_err("Protocol decoder %s submitted invalid output type %d.",
                        di->decoder->name, pdo->output_type);
                break;
        }

        PyGILState_Release(gstate);

        Py_RETURN_NONE;

err:
        PyGILState_Release(gstate);

        return NULL;
}

static PyObject *Decoder_register(PyObject *self, PyObject *args,
                PyObject *kwargs)
{
        struct srd_decoder_inst *di;
        struct srd_pd_output *pdo;
        PyObject *py_new_output_id;
        PyTypeObject *meta_type_py;
        const GVariantType *meta_type_gv;
        int output_type;
        char *proto_id, *meta_name, *meta_descr;
        char *keywords[] = { "output_type", "proto_id", "meta", NULL };
        PyGILState_STATE gstate;
        gboolean is_meta;
        GSList *l;
        struct srd_pd_output *cmp;

        gstate = PyGILState_Ensure();

        meta_type_py = NULL;
        meta_type_gv = NULL;
        meta_name = meta_descr = NULL;

        if (!(di = srd_inst_find_by_obj(NULL, self))) {
                PyErr_SetString(PyExc_Exception, "decoder instance not found");
                goto err;
        }

        /* Default to instance ID, which defaults to class ID. */
        proto_id = di->inst_id;
        if (!PyArg_ParseTupleAndKeywords(args, kwargs, "i|s(Oss)", keywords,
                        &output_type, &proto_id,
                        &meta_type_py, &meta_name, &meta_descr)) {
                /* Let Python raise this exception. */
                goto err;
        }

        /* Check if the meta value's type is supported. */
        is_meta = output_type == SRD_OUTPUT_META;
        if (is_meta) {
                if (meta_type_py == &PyLong_Type)
                        meta_type_gv = G_VARIANT_TYPE_INT64;
                else if (meta_type_py == &PyFloat_Type)
                        meta_type_gv = G_VARIANT_TYPE_DOUBLE;
                else {
                        PyErr_Format(PyExc_TypeError, "Unsupported type.");
                        goto err;
                }
        }

        pdo = NULL;
        for (l = di->pd_output; l; l = l->next) {
                cmp = l->data;
                if (cmp->output_type != output_type)
                        continue;
                if (strcmp(cmp->proto_id, proto_id) != 0)
                        continue;
                if (is_meta && cmp->meta_type != meta_type_gv)
                        continue;
                if (is_meta && strcmp(cmp->meta_name, meta_name) != 0)
                        continue;
                if (is_meta && strcmp(cmp->meta_descr, meta_descr) != 0)
                        continue;
                pdo = cmp;
                break;
        }
        if (pdo) {
                py_new_output_id = Py_BuildValue("i", pdo->pdo_id);
                PyGILState_Release(gstate);
                return py_new_output_id;
        }

        pdo = g_malloc(sizeof(struct srd_pd_output));

        /* pdo_id is just a simple index, nothing is deleted from this list anyway. */
        pdo->pdo_id = g_slist_length(di->pd_output);
        pdo->output_type = output_type;
        pdo->di = di;
        pdo->proto_id = g_strdup(proto_id);

        if (output_type == SRD_OUTPUT_META) {
                pdo->meta_type = meta_type_gv;
                pdo->meta_name = g_strdup(meta_name);
                pdo->meta_descr = g_strdup(meta_descr);
        }

        di->pd_output = g_slist_append(di->pd_output, pdo);
        py_new_output_id = Py_BuildValue("i", pdo->pdo_id);

        PyGILState_Release(gstate);

        srd_dbg("Instance %s creating new output type %s as oid %d (%s).",
                di->inst_id, output_type_name(output_type), pdo->pdo_id,
                proto_id);

        return py_new_output_id;

err:
        PyGILState_Release(gstate);

        return NULL;
}

static int get_term_type(const char *v)
{
        switch (v[0]) {
        case 'h':
                return SRD_TERM_HIGH;
        case 'l':
                return SRD_TERM_LOW;
        case 'r':
                return SRD_TERM_RISING_EDGE;
        case 'f':
                return SRD_TERM_FALLING_EDGE;
        case 'e':
                return SRD_TERM_EITHER_EDGE;
        case 'n':
                return SRD_TERM_NO_EDGE;
        default:
                return -1;
        }

        return -1;
}

/**
 * Get the pin values at the current sample number.
 *
 * @param di The decoder instance to use. Must not be NULL.
 *           The number of channels must be >= 1.
 *
 * @return A newly allocated PyTuple containing the pin values at the
 *         current sample number.
 */
static PyObject *get_current_pinvalues(const struct srd_decoder_inst *di)
{
        int i;
        uint8_t sample;
        const uint8_t *sample_pos;
        int byte_offset, bit_offset;
        PyObject *py_pinvalues;
        PyGILState_STATE gstate;

        if (!di) {
                srd_err("Invalid decoder instance.");
                return NULL;
        }

        gstate = PyGILState_Ensure();

        py_pinvalues = PyTuple_New(di->dec_num_channels);

        for (i = 0; i < di->dec_num_channels; i++) {
                /* A channelmap value of -1 means "unused optional channel". */
                if (di->dec_channelmap[i] == -1) {
                        /* Value of unused channel is 0xff, instead of 0 or 1. */
                        PyTuple_SetItem(py_pinvalues, i, PyLong_FromUnsignedLong(0xff));
                } else {
                        sample_pos = di->inbuf + ((di->abs_cur_samplenum - di->abs_start_samplenum) * di->data_unitsize);
                        byte_offset = di->dec_channelmap[i] / 8;
                        bit_offset = di->dec_channelmap[i] % 8;
                        sample = *(sample_pos + byte_offset) & (1 << bit_offset) ? 1 : 0;
                        PyTuple_SetItem(py_pinvalues, i, PyLong_FromUnsignedLong(sample));
                }
        }

        PyGILState_Release(gstate);

        return py_pinvalues;
}

/**
 * Create a list of terms in the specified condition.
 *
 * If there are no terms in the condition, 'term_list' will be NULL.
 *
 * @param di The decoder instance to use. Must not be NULL.
 * @param py_dict A Python dict containing terms. Must not be NULL.
 * @param term_list Pointer to a GSList which will be set to the newly
 *                  created list of terms. Must not be NULL.
 *
 * @return SRD_OK upon success, a negative error code otherwise.
 */
static int create_term_list(struct srd_decoder_inst *di,
        PyObject *py_dict, GSList **term_list)
{
        Py_ssize_t pos = 0;
        PyObject *py_key, *py_value;
        struct srd_term *term;
        int64_t num_samples_to_skip;
        char *term_str;
        PyGILState_STATE gstate;

        if (!py_dict || !term_list)
                return SRD_ERR_ARG;

        /* "Create" an empty GSList of terms. */
        *term_list = NULL;

        gstate = PyGILState_Ensure();

        /* Iterate over all items in the current dict. */
        while (PyDict_Next(py_dict, &pos, &py_key, &py_value)) {
                /* Check whether the current key is a string or a number. */
                if (PyLong_Check(py_key)) {
                        /* The key is a number. */
                        /* Get the value string. */
                        if ((py_pydictitem_as_str(py_dict, py_key, &term_str)) != SRD_OK) {
                                srd_err("Failed to get the value.");
                                goto err;
                        }
                        term = g_malloc(sizeof(struct srd_term));
                        term->type = get_term_type(term_str);
                        term->channel = PyLong_AsLong(py_key);
                        if (term->channel < 0 || term->channel >= di->dec_num_channels)
                                term->type = SRD_TERM_ALWAYS_FALSE;
                        g_free(term_str);
                } else if (PyUnicode_Check(py_key)) {
                        /* The key is a string. */
                        /* TODO: Check if the key is "skip". */
                        if ((py_pydictitem_as_long(py_dict, py_key, &num_samples_to_skip)) != SRD_OK) {
                                srd_err("Failed to get number of samples to skip.");
                                goto err;
                        }
                        term = g_malloc(sizeof(struct srd_term));
                        term->type = SRD_TERM_SKIP;
                        term->num_samples_to_skip = num_samples_to_skip;
                        term->num_samples_already_skipped = 0;
                        if (num_samples_to_skip < 0)
                                term->type = SRD_TERM_ALWAYS_FALSE;
                } else {
                        srd_err("Term key is neither a string nor a number.");
                        goto err;
                }

                /* Add the term to the list of terms. */
                *term_list = g_slist_append(*term_list, term);
        }

        PyGILState_Release(gstate);

        return SRD_OK;

err:
        PyGILState_Release(gstate);

        return SRD_ERR;
}

/**
 * Replace the current condition list with the new one.
 *
 * @param self TODO. Must not be NULL.
 * @param args TODO. Must not be NULL.
 *
 * @retval SRD_OK The new condition list was set successfully.
 * @retval SRD_ERR There was an error setting the new condition list.
 *                 The contents of di->condition_list are undefined.
 * @retval 9999 TODO.
 */
static int set_new_condition_list(PyObject *self, PyObject *args)
{
        struct srd_decoder_inst *di;
        GSList *term_list;
        PyObject *py_conditionlist, *py_conds, *py_dict;
        int i, num_conditions, ret;
        PyGILState_STATE gstate;

        if (!self || !args)
                return SRD_ERR_ARG;

        gstate = PyGILState_Ensure();

        /* Get the decoder instance. */
        if (!(di = srd_inst_find_by_obj(NULL, self))) {
                PyErr_SetString(PyExc_Exception, "decoder instance not found");
                goto err;
        }

        /*
         * Return an error condition from .wait() when termination is
         * requested, such that decode() will terminate.
         */
        if (di->want_wait_terminate) {
                srd_dbg("%s: %s: Skip (want_term).", di->inst_id, __func__);
                goto err;
        }

        /*
         * Parse the argument of self.wait() into 'py_conds', and check
         * the data type. The argument is optional, None is assumed in
         * its absence. None or an empty dict or an empty list mean that
         * there is no condition, and the next available sample shall
         * get returned to the caller.
         */
        py_conds = Py_None;
        if (!PyArg_ParseTuple(args, "|O", &py_conds)) {
                /* Let Python raise this exception. */
                goto err;
        }
        if (py_conds == Py_None) {
                /* 'py_conds' is None. */
                goto ret_9999;
        } else if (PyList_Check(py_conds)) {
                /* 'py_conds' is a list. */
                py_conditionlist = py_conds;
                num_conditions = PyList_Size(py_conditionlist);
                if (num_conditions == 0)
                        goto ret_9999; /* The PD invoked self.wait([]). */
                Py_INCREF(py_conditionlist);
        } else if (PyDict_Check(py_conds)) {
                /* 'py_conds' is a dict. */
                if (PyDict_Size(py_conds) == 0)
                        goto ret_9999; /* The PD invoked self.wait({}). */
                /* Make a list and put the dict in there for convenience. */
                py_conditionlist = PyList_New(1);
                Py_INCREF(py_conds);
                PyList_SetItem(py_conditionlist, 0, py_conds);
                num_conditions = 1;
        } else {
                srd_err("Condition list is neither a list nor a dict.");
                goto err;
        }

        /* Free the old condition list. */
        condition_list_free(di);

        ret = SRD_OK;

        /* Iterate over the conditions, set di->condition_list accordingly. */
        for (i = 0; i < num_conditions; i++) {
                /* Get a condition (dict) from the condition list. */
                py_dict = PyList_GetItem(py_conditionlist, i);
                if (!PyDict_Check(py_dict)) {
                        srd_err("Condition is not a dict.");
                        ret = SRD_ERR;
                        break;
                }

                /* Create the list of terms in this condition. */
                if ((ret = create_term_list(di, py_dict, &term_list)) < 0)
                        break;

                /* Add the new condition to the PD instance's condition list. */
                di->condition_list = g_slist_append(di->condition_list, term_list);
        }

        Py_DecRef(py_conditionlist);

        PyGILState_Release(gstate);

        return ret;

err:
        PyGILState_Release(gstate);

        return SRD_ERR;

ret_9999:
        PyGILState_Release(gstate);

        return 9999;
}

/**
 * Create a SKIP condition list for condition-less .wait() calls.
 *
 * @param di Decoder instance.
 * @param count Number of samples to skip.
 *
 * @retval SRD_OK The new condition list was set successfully.
 * @retval SRD_ERR There was an error setting the new condition list.
 *                 The contents of di->condition_list are undefined.
 *
 * This routine is a reduced and specialized version of the @ref
 * set_new_condition_list() and @ref create_term_list() routines which
 * gets invoked when .wait() was called without specifications for
 * conditions. This minor duplication of the SKIP term list creation
 * simplifies the logic and avoids the creation of expensive Python
 * objects with "constant" values which the caller did not pass in the
 * first place. It results in maximum sharing of match handling code
 * paths.
 */
static int set_skip_condition(struct srd_decoder_inst *di, uint64_t count)
{
        struct srd_term *term;
        GSList *term_list;

        condition_list_free(di);
        term = g_malloc(sizeof(*term));
        term->type = SRD_TERM_SKIP;
        term->num_samples_to_skip = count;
        term->num_samples_already_skipped = 0;
        term_list = g_slist_append(NULL, term);
        di->condition_list = g_slist_append(di->condition_list, term_list);

        return SRD_OK;
}

static PyObject *Decoder_wait(PyObject *self, PyObject *args)
{
        int ret;
        uint64_t skip_count;
        unsigned int i;
        gboolean found_match;
        struct srd_decoder_inst *di;
        PyObject *py_pinvalues, *py_matched, *py_samplenum;
        PyGILState_STATE gstate;

        if (!self || !args)
                return NULL;

        gstate = PyGILState_Ensure();

        if (!(di = srd_inst_find_by_obj(NULL, self))) {
                PyErr_SetString(PyExc_Exception, "decoder instance not found");
                PyGILState_Release(gstate);
                Py_RETURN_NONE;
        }

        ret = set_new_condition_list(self, args);
        if (ret < 0) {
                srd_dbg("%s: %s: Aborting wait().", di->inst_id, __func__);
                goto err;
        }
        if (ret == 9999) {
                /*
                 * Empty condition list, automatic match. Arrange for the
                 * execution of regular match handling code paths such that
                 * the next available sample is returned to the caller.
                 * Make sure to skip one sample when "anywhere within the
                 * stream", yet make sure to not skip sample number 0.
                 */
                if (di->abs_cur_samplenum)
                        skip_count = 1;
                else if (!di->condition_list)
                        skip_count = 0;
                else
                        skip_count = 1;
                ret = set_skip_condition(di, skip_count);
                if (ret < 0) {
                        srd_dbg("%s: %s: Cannot setup condition-less wait().",
                                di->inst_id, __func__);
                        goto err;
                }
        }

        while (1) {

                Py_BEGIN_ALLOW_THREADS

                /* Wait for new samples to process, or termination request. */
                g_mutex_lock(&di->data_mutex);
                while (!di->got_new_samples && !di->want_wait_terminate)
                        g_cond_wait(&di->got_new_samples_cond, &di->data_mutex);

                /*
                 * Check whether any of the current condition(s) match.
                 * Arrange for termination requests to take a code path which
                 * won't find new samples to process, pretends to have processed
                 * previously stored samples, and returns to the main thread,
                 * while the termination request still gets signalled.
                 */
                found_match = FALSE;

                /* Ignore return value for now, should never be negative. */
                (void)process_samples_until_condition_match(di, &found_match);

                Py_END_ALLOW_THREADS

                /* If there's a match, set self.samplenum etc. and return. */
                if (found_match) {
                        /* Set self.samplenum to the (absolute) sample number that matched. */
                        py_samplenum = PyLong_FromUnsignedLongLong(di->abs_cur_samplenum);
                        PyObject_SetAttrString(di->py_inst, "samplenum", py_samplenum);
                        Py_DECREF(py_samplenum);

                        if (di->match_array && di->match_array->len > 0) {
                                py_matched = PyTuple_New(di->match_array->len);
                                for (i = 0; i < di->match_array->len; i++)
                                        PyTuple_SetItem(py_matched, i, PyBool_FromLong(di->match_array->data[i]));
                                PyObject_SetAttrString(di->py_inst, "matched", py_matched);
                                Py_DECREF(py_matched);
                                match_array_free(di);
                        } else {
                                PyObject_SetAttrString(di->py_inst, "matched", Py_None);
                        }

                        py_pinvalues = get_current_pinvalues(di);

                        g_mutex_unlock(&di->data_mutex);

                        PyGILState_Release(gstate);

                        return py_pinvalues;
                }

                /* No match, reset state for the next chunk. */
                di->got_new_samples = FALSE;
                di->handled_all_samples = TRUE;
                di->abs_start_samplenum = 0;
                di->abs_end_samplenum = 0;
                di->inbuf = NULL;
                di->inbuflen = 0;

                /* Signal the main thread that we handled all samples. */
                g_cond_signal(&di->handled_all_samples_cond);

                /*
                 * When termination of wait() and decode() was requested,
                 * then exit the loop after releasing the mutex.
                 */
                if (di->want_wait_terminate) {
                        srd_dbg("%s: %s: Will return from wait().",
                                di->inst_id, __func__);
                        g_mutex_unlock(&di->data_mutex);
                        goto err;
                }

                g_mutex_unlock(&di->data_mutex);
        }

        PyGILState_Release(gstate);

        Py_RETURN_NONE;

err:
        PyGILState_Release(gstate);

        return NULL;
}

/**
 * Return whether the specified channel was supplied to the decoder.
 *
 * @param self TODO. Must not be NULL.
 * @param args TODO. Must not be NULL.
 *
 * @retval Py_True The channel has been supplied by the frontend.
 * @retval Py_False The channel has been supplied by the frontend.
 * @retval NULL An error occurred.
 */
static PyObject *Decoder_has_channel(PyObject *self, PyObject *args)
{
        int idx, count;
        struct srd_decoder_inst *di;
        PyGILState_STATE gstate;

        if (!self || !args)
                return NULL;

        gstate = PyGILState_Ensure();

        if (!(di = srd_inst_find_by_obj(NULL, self))) {
                PyErr_SetString(PyExc_Exception, "decoder instance not found");
                goto err;
        }

        /*
         * Get the integer argument of self.has_channel(). Check for
         * the range of supported PD input channel numbers.
         */
        if (!PyArg_ParseTuple(args, "i", &idx)) {
                /* Let Python raise this exception. */
                goto err;
        }

        count = g_slist_length(di->decoder->channels) +
                g_slist_length(di->decoder->opt_channels);
        if (idx < 0 || idx >= count) {
                srd_err("Invalid index %d, PD channel count %d.", idx, count);
                PyErr_SetString(PyExc_IndexError, "invalid channel index");
                goto err;
        }

        PyGILState_Release(gstate);

        return (di->dec_channelmap[idx] == -1) ? Py_False : Py_True;

err:
        PyGILState_Release(gstate);

        return NULL;
}

static PyMethodDef Decoder_methods[] = {
        { "put", Decoder_put, METH_VARARGS,
          "Accepts a dictionary with the following keys: startsample, endsample, data" },
        { "register", (PyCFunction)(void(*)(void))Decoder_register, METH_VARARGS|METH_KEYWORDS,
                        "Register a new output stream" },
        { "wait", Decoder_wait, METH_VARARGS,
                        "Wait for one or more conditions to occur" },
        { "has_channel", Decoder_has_channel, METH_VARARGS,
                        "Report whether a channel was supplied" },
        {NULL, NULL, 0, NULL}
};

/**
 * Create the sigrokdecode.Decoder type.
 *
 * @return The new type object.
 *
 * @private
 */
SRD_PRIV PyObject *srd_Decoder_type_new(void)
{
        PyType_Spec spec;
        PyType_Slot slots[] = {
                { Py_tp_doc, "sigrok Decoder base class" },
                { Py_tp_methods, Decoder_methods },
                { Py_tp_new, (void *)&PyType_GenericNew },
                { 0, NULL }
        };
        PyObject *py_obj;
        PyGILState_STATE gstate;

        gstate = PyGILState_Ensure();

        spec.name = "sigrokdecode.Decoder";
        spec.basicsize = sizeof(srd_Decoder);
        spec.itemsize = 0;
        spec.flags = Py_TPFLAGS_DEFAULT | Py_TPFLAGS_BASETYPE;
        spec.slots = slots;

        py_obj = PyType_FromSpec(&spec);

        PyGILState_Release(gstate);

        return py_obj;
}