srd: add TODO comment on the SIGROKDECODE_DIR env var's motivation

[libsigrokdecode/gsi.git] / session.c

/*
 * This file is part of the libsigrokdecode project.
 *
 * Copyright (C) 2010 Uwe Hermann <uwe@hermann-uwe.de>
 * Copyright (C) 2013 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>
#include <glib.h>

/**
 * @file
 *
 * Session handling.
 */

/**
 * @defgroup grp_session Session handling
 *
 * Starting and handling decoding sessions.
 *
 * @{
 */

/** @cond PRIVATE */

SRD_PRIV GSList *sessions = NULL;
SRD_PRIV int max_session_id = -1;

/** @endcond */

/**
 * Create a decoding session.
 *
 * A session holds all decoder instances, their stack relationships and
 * output callbacks.
 *
 * @param sess A pointer which will hold a pointer to a newly
 *             initialized session on return. Must not be NULL.
 *
 * @return SRD_OK upon success, a (negative) error code otherwise.
 *
 * @since 0.3.0
 */
SRD_API int srd_session_new(struct srd_session **sess)
{
        if (!sess)
                return SRD_ERR_ARG;

        *sess = g_malloc(sizeof(struct srd_session));
        (*sess)->session_id = ++max_session_id;
        (*sess)->di_list = (*sess)->callbacks = NULL;

        /* Keep a list of all sessions, so we can clean up as needed. */
        sessions = g_slist_append(sessions, *sess);

        srd_dbg("Creating session %d.", (*sess)->session_id);

        return SRD_OK;
}

/**
 * Start a decoding session.
 *
 * Decoders, instances and stack must have been prepared beforehand,
 * and all SRD_CONF parameters set.
 *
 * @param sess The session to start. Must not be NULL.
 *
 * @return SRD_OK upon success, a (negative) error code otherwise.
 *
 * @since 0.3.0
 */
SRD_API int srd_session_start(struct srd_session *sess)
{
        GSList *d;
        struct srd_decoder_inst *di;
        int ret;

        if (!sess)
                return SRD_ERR_ARG;

        srd_dbg("Calling start() of all instances in session %d.", sess->session_id);

        /* Run the start() method of all decoders receiving frontend data. */
        ret = SRD_OK;
        for (d = sess->di_list; d; d = d->next) {
                di = d->data;
                if ((ret = srd_inst_start(di)) != SRD_OK)
                        break;
        }

        return ret;
}

static int srd_inst_send_meta(struct srd_decoder_inst *di, int key,
                GVariant *data)
{
        PyObject *py_ret;
        GSList *l;
        struct srd_decoder_inst *next_di;
        int ret;
        PyGILState_STATE gstate;

        if (key != SRD_CONF_SAMPLERATE)
                /* This is the only key we pass on to the decoder for now. */
                return SRD_OK;

        gstate = PyGILState_Ensure();

        if (PyObject_HasAttrString(di->py_inst, "metadata")) {
                py_ret = PyObject_CallMethod(di->py_inst, "metadata", "lK",
                                (long)SRD_CONF_SAMPLERATE,
                                (unsigned long long)g_variant_get_uint64(data));
                Py_XDECREF(py_ret);
        }

        PyGILState_Release(gstate);

        /* Push metadata to all the PDs stacked on top of this one. */
        for (l = di->next_di; l; l = l->next) {
                next_di = l->data;
                if ((ret = srd_inst_send_meta(next_di, key, data)) != SRD_OK)
                        return ret;
        }

        return SRD_OK;
}

/**
 * Set a metadata configuration key in a session.
 *
 * @param sess The session to configure. Must not be NULL.
 * @param key The configuration key (SRD_CONF_*).
 * @param data The new value for the key, as a GVariant with GVariantType
 *             appropriate to that key. A floating reference can be passed
 *             in; its refcount will be sunk and unreferenced after use.
 *
 * @return SRD_OK upon success, a (negative) error code otherwise.
 *
 * @since 0.3.0
 */
SRD_API int srd_session_metadata_set(struct srd_session *sess, int key,
                GVariant *data)
{
        GSList *l;
        int ret;

        if (!sess)
                return SRD_ERR_ARG;

        if (!key) {
                srd_err("Invalid key.");
                return SRD_ERR_ARG;
        }

        if (!data) {
                srd_err("Invalid value.");
                return SRD_ERR_ARG;
        }

        /* Hardcoded to samplerate/uint64 for now. */

        if (key != SRD_CONF_SAMPLERATE) {
                srd_err("Unknown config key %d.", key);
                return SRD_ERR_ARG;
        }
        if (!g_variant_is_of_type(data, G_VARIANT_TYPE_UINT64)) {
                srd_err("Invalid value type: expected uint64, got %s",
                                g_variant_get_type_string(data));
                return SRD_ERR_ARG;
        }

        srd_dbg("Setting session %d samplerate to %"G_GUINT64_FORMAT".",
                        sess->session_id, g_variant_get_uint64(data));

        ret = SRD_OK;
        for (l = sess->di_list; l; l = l->next) {
                if ((ret = srd_inst_send_meta(l->data, key, data)) != SRD_OK)
                        break;
        }

        g_variant_unref(data);

        return ret;
}

/**
 * Send a chunk of logic sample data to a running decoder session.
 *
 * If no channel map has been set up, the logic samples must be arranged
 * in channel order, in the least amount of space possible. The default
 * channel set consists of all required channels + all optional channels.
 *
 * The size of a sample in inbuf is 'unitsize' bytes. If no channel map
 * has been configured, it is the minimum number of bytes needed to store
 * the default channels.
 *
 * 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_session_send(s, 0,    1023, inbuf, 1024, 1);
 *   srd_session_send(s, 1024, 2047, inbuf, 1024, 1);
 *   srd_session_send(s, 2048, 3071, inbuf, 1024, 1);
 *   srd_session_send(s, 3072, 4095, 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_session_send(s, 0,    1023, inbuf, 1024, 1);
 *   srd_session_send(s, 1024, 1123, inbuf,  100, 1);
 *   srd_session_send(s, 1124, 1423, inbuf,  300, 1);
 *   srd_session_send(s, 1424, 1642, inbuf,  219, 1);
 *   srd_session_send(s, 1643, 2047, inbuf,  405, 1);
 *   srd_session_send(s, 2048, 3071, inbuf, 1024, 1);
 *   srd_session_send(s, 3072, 4095, inbuf, 1024, 1);
 *
 * INCORRECT example (4096 samples total, 4 chunks @ 1024 samples each, but
 * the start- and end-samplenumbers are not absolute):
 *   srd_session_send(s, 0,    1023, inbuf, 1024, 1);
 *   srd_session_send(s, 0,    1023, inbuf, 1024, 1);
 *   srd_session_send(s, 0,    1023, inbuf, 1024, 1);
 *   srd_session_send(s, 0,    1023, inbuf, 1024, 1);
 *
 * @param sess The session to use. 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 Pointer to sample data. Must not be NULL.
 * @param inbuflen Length in bytes 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.
 *
 * @since 0.4.0
 */
SRD_API int srd_session_send(struct srd_session *sess,
                uint64_t abs_start_samplenum, uint64_t abs_end_samplenum,
                const uint8_t *inbuf, uint64_t inbuflen, uint64_t unitsize)
{
        GSList *d;
        int ret;

        if (!sess)
                return SRD_ERR_ARG;

        for (d = sess->di_list; d; d = d->next) {
                if ((ret = srd_inst_decode(d->data, abs_start_samplenum,
                                abs_end_samplenum, inbuf, inbuflen, unitsize)) != SRD_OK)
                        return ret;
        }

        return SRD_OK;
}

/**
 * Communicate the end of the stream of sample data to the session.
 *
 * @param[in] sess The session. Must not be NULL.
 *
 * @return SRD_OK upon success. A (negative) error code otherwise.
 *
 * @since 0.6.0
 */
SRD_API int srd_session_send_eof(struct srd_session *sess)
{
        GSList *d;
        int ret;

        if (!sess)
                return SRD_ERR_ARG;

        for (d = sess->di_list; d; d = d->next) {
                ret = srd_inst_send_eof(d->data);
                if (ret != SRD_OK)
                        return ret;
        }

        return SRD_OK;
}

/**
 * Terminate currently executing decoders in a session, reset internal state.
 *
 * All decoder instances have their .wait() method terminated, which
 * shall terminate .decode() as well. Afterwards the decoders' optional
 * .reset() method gets executed.
 *
 * This routine allows callers to abort pending expensive operations,
 * when they are no longer interested in the decoders' results. Note
 * that the decoder state is lost and aborted work cannot resume.
 *
 * This routine also allows callers to re-use previously created decoder
 * stacks to process new input data which is not related to previously
 * processed input data. This avoids the necessity to re-construct the
 * decoder stack.
 *
 * @param sess The session in which to terminate decoders. Must not be NULL.
 *
 * @return SRD_OK upon success, a (negative) error code otherwise.
 *
 * @since 0.5.1
 */
SRD_API int srd_session_terminate_reset(struct srd_session *sess)
{
        GSList *d;
        int ret;

        if (!sess)
                return SRD_ERR_ARG;

        for (d = sess->di_list; d; d = d->next) {
                ret = srd_inst_terminate_reset(d->data);
                if (ret != SRD_OK)
                        return ret;
        }

        return SRD_OK;
}

/**
 * Destroy a decoding session.
 *
 * All decoder instances and output callbacks are properly released.
 *
 * @param sess The session to be destroyed. Must not be NULL.
 *
 * @return SRD_OK upon success, a (negative) error code otherwise.
 *
 * @since 0.3.0
 */
SRD_API int srd_session_destroy(struct srd_session *sess)
{
        int session_id;

        if (!sess)
                return SRD_ERR_ARG;

        session_id = sess->session_id;
        if (sess->di_list)
                srd_inst_free_all(sess);
        if (sess->callbacks)
                g_slist_free_full(sess->callbacks, g_free);
        sessions = g_slist_remove(sessions, sess);
        g_free(sess);

        srd_dbg("Destroyed session %d.", session_id);

        return SRD_OK;
}

/**
 * Register/add a decoder output callback function.
 *
 * The function will be called when a protocol decoder sends output back
 * to the PD controller (except for Python objects, which only go up the
 * stack).
 *
 * @param sess The output session in which to register the callback.
 *             Must not be NULL.
 * @param output_type The output type this callback will receive. Only one
 *                    callback per output type can be registered.
 * @param cb The function to call. Must not be NULL.
 * @param cb_data Private data for the callback function. Can be NULL.
 *
 * @since 0.3.0
 */
SRD_API int srd_pd_output_callback_add(struct srd_session *sess,
                int output_type, srd_pd_output_callback cb, void *cb_data)
{
        struct srd_pd_callback *pd_cb;

        if (!sess)
                return SRD_ERR_ARG;

        srd_dbg("Registering new callback for output type %s.",
                output_type_name(output_type));

        pd_cb = g_malloc(sizeof(struct srd_pd_callback));
        pd_cb->output_type = output_type;
        pd_cb->cb = cb;
        pd_cb->cb_data = cb_data;
        sess->callbacks = g_slist_append(sess->callbacks, pd_cb);

        return SRD_OK;
}

/** @private */
SRD_PRIV struct srd_pd_callback *srd_pd_output_callback_find(
                struct srd_session *sess, int output_type)
{
        GSList *l;
        struct srd_pd_callback *tmp, *pd_cb;

        if (!sess)
                return NULL;

        pd_cb = NULL;
        for (l = sess->callbacks; l; l = l->next) {
                tmp = l->data;
                if (tmp->output_type == output_type) {
                        pd_cb = tmp;
                        break;
                }
        }

        return pd_cb;
}

/** @} */