output/null: Add a null module that discards all data.

[libsigrok.git] / src / output / output.c

/*
 * This file is part of the libsigrok project.
 *
 * Copyright (C) 2014 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 <string.h>
#include <libsigrok/libsigrok.h>
#include "libsigrok-internal.h"

/** @cond PRIVATE */
#define LOG_PREFIX "output"
/** @endcond */

/**
 * @file
 *
 * Output module handling.
 */

/**
 * @defgroup grp_output Output modules
 *
 * Output module handling.
 *
 * libsigrok supports several output modules for file formats such as binary,
 * VCD, csv, and so on. It provides an output API that frontends can use.
 * New output modules can be added/implemented in libsigrok without having
 * to change the frontends at all.
 *
 * All output modules are fed data in a stream. Devices that can stream data
 * into libsigrok, instead of storing and then transferring the whole buffer,
 * can thus generate output live.
 *
 * Output modules generate a newly allocated GString. The caller is then
 * expected to free this with g_string_free() when finished with it.
 *
 * @{
 */

/** @cond PRIVATE */
extern SR_PRIV struct sr_output_module output_bits;
extern SR_PRIV struct sr_output_module output_hex;
extern SR_PRIV struct sr_output_module output_ascii;
extern SR_PRIV struct sr_output_module output_binary;
extern SR_PRIV struct sr_output_module output_vcd;
extern SR_PRIV struct sr_output_module output_ols;
extern SR_PRIV struct sr_output_module output_chronovu_la8;
extern SR_PRIV struct sr_output_module output_csv;
extern SR_PRIV struct sr_output_module output_analog;
extern SR_PRIV struct sr_output_module output_srzip;
extern SR_PRIV struct sr_output_module output_wav;
extern SR_PRIV struct sr_output_module output_null;
/* @endcond */

static const struct sr_output_module *output_module_list[] = {
	&output_ascii,
	&output_binary,
	&output_bits,
	&output_csv,
	&output_hex,
	&output_ols,
	&output_vcd,
	&output_chronovu_la8,
	&output_analog,
	&output_srzip,
	&output_wav,
	&output_null,
	NULL,
};

/**
 * Returns a NULL-terminated list of all available output modules.
 *
 * @since 0.4.0
 */
SR_API const struct sr_output_module **sr_output_list(void)
{
	return output_module_list;
}

/**
 * Returns the specified output module's ID.
 *
 * @since 0.4.0
 */
SR_API const char *sr_output_id_get(const struct sr_output_module *omod)
{
	if (!omod) {
		sr_err("Invalid output module NULL!");
		return NULL;
	}

	return omod->id;
}

/**
 * Returns the specified output module's name.
 *
 * @since 0.4.0
 */
SR_API const char *sr_output_name_get(const struct sr_output_module *omod)
{
	if (!omod) {
		sr_err("Invalid output module NULL!");
		return NULL;
	}

	return omod->name;
}

/**
 * Returns the specified output module's description.
 *
 * @since 0.4.0
 */
SR_API const char *sr_output_description_get(const struct sr_output_module *omod)
{
	if (!omod) {
		sr_err("Invalid output module NULL!");
		return NULL;
	}

	return omod->desc;
}

/**
 * Returns the specified output module's file extensions typical for the file
 * format, as a NULL terminated array, or returns a NULL pointer if there is
 * no preferred extension.
 * @note these are a suggestions only.
 *
 * @since 0.4.0
 */
SR_API const char *const *sr_output_extensions_get(
		const struct sr_output_module *omod)
{
	if (!omod) {
		sr_err("Invalid output module NULL!");
		return NULL;
	}

	return omod->exts;
}

/*
 * Checks whether a given flag is set.
 *
 * @see sr_output_flag
 * @since 0.4.0
 */
SR_API gboolean sr_output_test_flag(const struct sr_output_module *omod,
		uint64_t flag)
{
	return (flag & omod->flags);
}

/**
 * Return the output module with the specified ID, or NULL if no module
 * with that id is found.
 *
 * @since 0.4.0
 */
SR_API const struct sr_output_module *sr_output_find(char *id)
{
	int i;

	for (i = 0; output_module_list[i]; i++) {
		if (!strcmp(output_module_list[i]->id, id))
			return output_module_list[i];
	}

	return NULL;
}

/**
 * Returns a NULL-terminated array of struct sr_option, or NULL if the
 * module takes no options.
 *
 * Each call to this function must be followed by a call to
 * sr_output_options_free().
 *
 * @since 0.4.0
 */
SR_API const struct sr_option **sr_output_options_get(const struct sr_output_module *omod)
{
	const struct sr_option *mod_opts, **opts;
	int size, i;

	if (!omod || !omod->options)
		return NULL;

	mod_opts = omod->options();

	for (size = 0; mod_opts[size].id; size++)
		;
	opts = g_malloc((size + 1) * sizeof(struct sr_option *));

	for (i = 0; i < size; i++)
		opts[i] = &mod_opts[i];
	opts[i] = NULL;

	return opts;
}

/**
 * After a call to sr_output_options_get(), this function cleans up all
 * resources returned by that call.
 *
 * @since 0.4.0
 */
SR_API void sr_output_options_free(const struct sr_option **options)
{
	int i;

	if (!options)
		return;

	for (i = 0; options[i]; i++) {
		if (options[i]->def) {
			g_variant_unref(options[i]->def);
			((struct sr_option *)options[i])->def = NULL;
		}

		if (options[i]->values) {
			g_slist_free_full(options[i]->values, (GDestroyNotify)g_variant_unref);
			((struct sr_option *)options[i])->values = NULL;
		}
	}
	g_free(options);
}

/**
 * Create a new output instance using the specified output module.
 *
 * <code>options</code> is a *HashTable with the keys corresponding with
 * the module options' <code>id</code> field. The values should be GVariant
 * pointers with sunk * references, of the same GVariantType as the option's
 * default value.
 *
 * The sr_dev_inst passed in can be used by the instance to determine
 * channel names, samplerate, and so on.
 *
 * @since 0.4.0
 */
SR_API const struct sr_output *sr_output_new(const struct sr_output_module *omod,
		GHashTable *options, const struct sr_dev_inst *sdi,
		const char *filename)
{
	struct sr_output *op;
	const struct sr_option *mod_opts;
	const GVariantType *gvt;
	GHashTable *new_opts;
	GHashTableIter iter;
	gpointer key, value;
	int i;

	op = g_malloc(sizeof(struct sr_output));
	op->module = omod;
	op->sdi = sdi;
	op->filename = g_strdup(filename);

	new_opts = g_hash_table_new_full(g_str_hash, g_str_equal, g_free,
			(GDestroyNotify)g_variant_unref);
	if (omod->options) {
		mod_opts = omod->options();
		for (i = 0; mod_opts[i].id; i++) {
			if (options && g_hash_table_lookup_extended(options,
					mod_opts[i].id, &key, &value)) {
				/* Pass option along. */
				gvt = g_variant_get_type(mod_opts[i].def);
				if (!g_variant_is_of_type(value, gvt)) {
					sr_err("Invalid type for '%s' option.",
						(char *)key);
					g_free(op);
					return NULL;
				}
				g_hash_table_insert(new_opts, g_strdup(mod_opts[i].id),
						g_variant_ref(value));
			} else {
				/* Option not given: insert the default value. */
				g_hash_table_insert(new_opts, g_strdup(mod_opts[i].id),
						g_variant_ref(mod_opts[i].def));
			}
		}

		/* Make sure no invalid options were given. */
		if (options) {
			g_hash_table_iter_init(&iter, options);
			while (g_hash_table_iter_next(&iter, &key, &value)) {
				if (!g_hash_table_lookup(new_opts, key)) {
					sr_err("Output module '%s' has no option '%s'",
						omod->id, (char *)key);
					g_hash_table_destroy(new_opts);
					g_free(op);
					return NULL;
				}
			}
		}
	}

	if (op->module->init && op->module->init(op, new_opts) != SR_OK) {
		g_free(op);
		op = NULL;
	}
	if (new_opts)
		g_hash_table_destroy(new_opts);

	return op;
}

/**
 * Send a packet to the specified output instance.
 *
 * The instance's output is returned as a newly allocated GString,
 * which must be freed by the caller.
 *
 * @since 0.4.0
 */
SR_API int sr_output_send(const struct sr_output *o,
		const struct sr_datafeed_packet *packet, GString **out)
{
	return o->module->receive(o, packet, out);
}

/**
 * Free the specified output instance and all associated resources.
 *
 * @since 0.4.0
 */
SR_API int sr_output_free(const struct sr_output *o)
{
	int ret;

	if (!o)
		return SR_ERR_ARG;

	ret = SR_OK;
	if (o->module->cleanup)
		ret = o->module->cleanup((struct sr_output *)o);
	g_free((char *)o->filename);
	g_free((gpointer)o);

	return ret;
}

/** @} */