type_decoder: use ALL_ZERO for sentinels in method/member tables

[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_LOGIC",
                "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_logic(struct srd_proto_data_logic *pdl)
{
        if (!pdl)
                return;
        g_free((void *)pdl->data);
}

static int convert_logic(struct srd_decoder_inst *di, PyObject *obj,
                struct srd_proto_data *pdata)
{
        struct srd_proto_data_logic *pdl;
        PyObject *py_tmp;
        Py_ssize_t size;
        int logic_group;
        char *group_name, *buf;
        PyGILState_STATE gstate;

        gstate = PyGILState_Ensure();

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

        /* Should have 2 elements. */
        if (PyList_Size(obj) != 2) {
                srd_err("Protocol decoder %s submitted SRD_OUTPUT_LOGIC 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_LOGIC list, "
                        "but first element was not an integer.", di->decoder->name);
                goto err;
        }
        logic_group = PyLong_AsLong(py_tmp);
        if (!(group_name = g_slist_nth_data(di->decoder->logic_output_channels, logic_group))) {
                srd_err("Protocol decoder %s submitted SRD_OUTPUT_LOGIC with "
                        "unregistered logic group %d.", di->decoder->name, logic_group);
                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_LOGIC 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_LOGIC "
                                "with empty data set.", di->decoder->name);
                goto err;
        }

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

        PyGILState_Release(gstate);

        pdl = pdata->data;
        pdl->logic_group = logic_group;
        /* pdl->repeat_count is set by the caller as it depends on the sample range */
        if (!(pdl->data = g_try_malloc(size)))
                return SRD_ERR_MALLOC;
        memcpy((void *)pdl->data, (const void *)buf, size);

        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);
}

PyDoc_STRVAR(Decoder_put_doc,
        "Put an annotation for the specified span of samples.\n"
        "\n"
        "Arguments: start and end sample number, stream id, annotation data.\n"
        "Annotation data's layout depends on the output stream type."
);

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;
        struct srd_proto_data_logic pdl;
        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_LOGIC:
                if ((cb = srd_pd_output_callback_find(di->sess, pdo->output_type))) {
                        pdata.data = &pdl;
                        /* Convert from PyDict to srd_proto_data_logic. */
                        if (convert_logic(di, py_data, &pdata) != SRD_OK) {
                                /* An error was already logged. */
                                break;
                        }
                        if (end_sample <= start_sample) {
                                srd_err("Ignored SRD_OUTPUT_LOGIC with invalid sample range.");
                                break;
                        }
                        pdl.repeat_count = (end_sample - start_sample) - 1;
                        Py_BEGIN_ALLOW_THREADS
                        cb->cb(&pdata, cb->cb_data);
                        Py_END_ALLOW_THREADS
                        release_logic(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;
}

PyDoc_STRVAR(Decoder_register_doc,
        "Register a new output stream."
);

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;
}

PyDoc_STRVAR(Decoder_wait_doc,
        "Wait for one or more conditions to occur.\n"
        "\n"
        "Returns the sample data at the next position where the condition\n"
        "is seen. When the optional condition is missing or empty, the next\n"
        "sample number is used. The condition can be a dictionary with one\n"
        "condition's details, or a list of dictionaries specifying multiple\n"
        "conditions of which at least one condition must be true. Dicts can\n"
        "contain one or more key/value pairs, all of which must be true for\n"
        "the dict's condition to be considered true. The key either is a\n"
        "channel index or a keyword, the value is the operation's parameter.\n"
        "\n"
        "Supported parameters for channel number keys: 'h', 'l', 'r', 'f',\n"
        "or 'e' for level or edge conditions. Other supported keywords:\n"
        "'skip' to advance over the given number of samples.\n"
);

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;
}

PyDoc_STRVAR(Decoder_has_channel_doc,
        "Check whether input data is supplied for a given channel.\n"
        "\n"
        "Argument: A channel index.\n"
        "Returns: A boolean, True if the channel is connected,\n"
        "False if the channel is open (won't see any input data).\n"
);

/**
 * 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;
        PyObject *bool_ret;

        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);

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

err:
        PyGILState_Release(gstate);

        return NULL;
}

PyDoc_STRVAR(Decoder_doc, "sigrok Decoder base class");

static PyMethodDef Decoder_methods[] = {
        { "put",
          Decoder_put, METH_VARARGS,
          Decoder_put_doc,
        },
        { "register",
          (PyCFunction)(void(*)(void))Decoder_register, METH_VARARGS | METH_KEYWORDS,
          Decoder_register_doc,
        },
        { "wait",
          Decoder_wait, METH_VARARGS,
          Decoder_wait_doc,
        },
        { "has_channel",
          Decoder_has_channel, METH_VARARGS,
          Decoder_has_channel_doc,
        },
        ALL_ZERO,
};

/**
 * 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, Decoder_doc },
                { Py_tp_methods, Decoder_methods },
                { Py_tp_new, (void *)&PyType_GenericNew },
                ALL_ZERO,
        };
        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;
}