text: /* Spa ALSA Source
   *
   * Copyright © 2018 Wim Taymans
   *
   * Permission is hereby granted, free of charge, to any person obtaining a
   * copy of this software and associated documentation files (the "Software"),
   * to deal in the Software without restriction, including without limitation
   * the rights to use, copy, modify, merge, publish, distribute, sublicense,
   * and/or sell copies of the Software, and to permit persons to whom the
   * Software is furnished to do so, subject to the following conditions:
   *
   * The above copyright notice and this permission notice (including the next
   * paragraph) shall be included in all copies or substantial portions of the
   * Software.
   *
   * THE SOFTWARE IS PROVIDED "AS IS", WITHOUT WARRANTY OF ANY KIND, EXPRESS OR
   * IMPLIED, INCLUDING BUT NOT LIMITED TO THE WARRANTIES OF MERCHANTABILITY,
   * FITNESS FOR A PARTICULAR PURPOSE AND NONINFRINGEMENT.  IN NO EVENT SHALL
   * THE AUTHORS OR COPYRIGHT HOLDERS BE LIABLE FOR ANY CLAIM, DAMAGES OR OTHER
   * LIABILITY, WHETHER IN AN ACTION OF CONTRACT, TORT OR OTHERWISE, ARISING
   * FROM, OUT OF OR IN CONNECTION WITH THE SOFTWARE OR THE USE OR OTHER
   * DEALINGS IN THE SOFTWARE.
   */
  
  #include <stddef.h>
  #include <ctype.h>
  
  #include <alsa/asoundlib.h>
  
  #include <spa/node/node.h>
  #include <spa/node/utils.h>
  #include <spa/node/keys.h>
  #include <spa/utils/keys.h>
  #include <spa/utils/names.h>
  #include <spa/utils/string.h>
  #include <spa/utils/list.h>
  #include <spa/monitor/device.h>
  #include <spa/param/audio/format.h>
  #include <spa/param/latency-utils.h>
  #include <spa/pod/filter.h>
  
  #include "alsa-seq.h"
  
  #define DEFAULT_DEVICE		"default"
  #define DEFAULT_CLOCK_NAME	"clock.system.monotonic"
  
  static void reset_props(struct props *props)
  {
  	strncpy(props->device, DEFAULT_DEVICE, sizeof(props->device));
  	strncpy(props->clock_name, DEFAULT_CLOCK_NAME, sizeof(props->clock_name));
  }
  
  static int impl_node_enum_params(void *object, int seq,
  				 uint32_t id, uint32_t start, uint32_t num,
  				 const struct spa_pod *filter)
  {
  	struct seq_state *this = object;
  	struct spa_pod *param;
  	uint8_t buffer[1024];
  	struct spa_pod_builder b = { 0 };
  	struct props *p;
  	struct spa_result_node_params result;
  	uint32_t count = 0;
  
  	spa_return_val_if_fail(this != NULL, -EINVAL);
  	spa_return_val_if_fail(num != 0, -EINVAL);
  
  	p = &this->props;
  
  	result.id = id;
  	result.next = start;
        next:
  	result.index = result.next++;
  
  	spa_pod_builder_init(&b, buffer, sizeof(buffer));
  
  	switch (id) {
  	case SPA_PARAM_PropInfo:
  		switch (result.index) {
  		case 0:
  			param = spa_pod_builder_add_object(&b,
  				SPA_TYPE_OBJECT_PropInfo, id,
  				SPA_PROP_INFO_id,   SPA_POD_Id(SPA_PROP_device),
  				SPA_PROP_INFO_name, SPA_POD_String("The ALSA device"),
  				SPA_PROP_INFO_type, SPA_POD_Stringn(p->device, sizeof(p->device)));
  			break;
  		default:
  			return 0;
  		}
  		break;
  
  	case SPA_PARAM_Props:
  		switch (result.index) {
  		case 0:
  			param = spa_pod_builder_add_object(&b,
  				SPA_TYPE_OBJECT_Props, id,
  				SPA_PROP_device,      SPA_POD_Stringn(p->device, sizeof(p->device)));
  			break;
  		default:
  			return 0;
  		}
  		break;
  
  	case SPA_PARAM_IO:
  		switch (result.index) {
  		case 0:
  			param = spa_pod_builder_add_object(&b,
  				SPA_TYPE_OBJECT_ParamIO, id,
  				SPA_PARAM_IO_id,   SPA_POD_Id(SPA_IO_Clock),
  				SPA_PARAM_IO_size, SPA_POD_Int(sizeof(struct spa_io_clock)));
  			break;
  		case 1:
  			param = spa_pod_builder_add_object(&b,
  				SPA_TYPE_OBJECT_ParamIO, id,
  				SPA_PARAM_IO_id,   SPA_POD_Id(SPA_IO_Position),
  				SPA_PARAM_IO_size, SPA_POD_Int(sizeof(struct spa_io_position)));
  			break;
  		default:
  			return 0;
  		}
  		break;
  
  	default:
  		return -ENOENT;
  	}
  
  	if (spa_pod_filter(&b, &result.param, param, filter) < 0)
  		goto next;
  
  	spa_node_emit_result(&this->hooks, seq, 0, SPA_RESULT_TYPE_NODE_PARAMS, &result);
  
  	if (++count != num)
  		goto next;
  
  	return 0;
  }
  
  static int impl_node_set_io(void *object, uint32_t id, void *data, size_t size)
  {
  	struct seq_state *this = object;
  
  	spa_return_val_if_fail(this != NULL, -EINVAL);
  
  	switch (id) {
  	case SPA_IO_Clock:
  		this->clock = data;
  		if (this->clock != NULL)
  			spa_scnprintf(this->clock->name, sizeof(this->clock->name),
  					"%s", this->props.clock_name);
  		break;
  	case SPA_IO_Position:
  		this->position = data;
  		break;
  	default:
  		return -ENOENT;
  	}
  	spa_alsa_seq_reassign_follower(this);
  	return 0;
  }
  
  static int impl_node_set_param(void *object, uint32_t id, uint32_t flags,
  			       const struct spa_pod *param)
  {
  	struct seq_state *this = object;
  
  	spa_return_val_if_fail(this != NULL, -EINVAL);
  
  	switch (id) {
  	case SPA_PARAM_Props:
  	{
  		struct props *p = &this->props;
  
  		if (param == NULL) {
  			reset_props(p);
  			return 0;
  		}
  		spa_pod_parse_object(param,
  			SPA_TYPE_OBJECT_Props, NULL,
  			SPA_PROP_device,     SPA_POD_OPT_Stringn(p->device, sizeof(p->device)));
  		break;
  	}
  	default:
  		return -ENOENT;
  	}
  
  	return 0;
  }
  
  static int impl_node_send_command(void *object, const struct spa_command *command)
  {
  	struct seq_state *this = object;
  	int res;
  
  	spa_return_val_if_fail(this != NULL, -EINVAL);
  	spa_return_val_if_fail(command != NULL, -EINVAL);
  
  	switch (SPA_NODE_COMMAND_ID(command)) {
  	case SPA_NODE_COMMAND_Start:
  		if ((res = spa_alsa_seq_start(this)) < 0)
  			return res;
  		break;
  	case SPA_NODE_COMMAND_Pause:
  	case SPA_NODE_COMMAND_Suspend:
  		if ((res = spa_alsa_seq_pause(this)) < 0)
  			return res;
  		break;
  	default:
  		return -ENOTSUP;
  	}
  	return 0;
  }
  
  static const struct spa_dict_item node_info_items[] = {
  	{ SPA_KEY_DEVICE_API, "alsa" },
  	{ SPA_KEY_MEDIA_CLASS, "Midi/Bridge" },
  	{ SPA_KEY_NODE_DRIVER, "true" },
  };
  
  static void emit_node_info(struct seq_state *this, bool full)
  {
  	uint64_t old = full ? this->info.change_mask : 0;
  	if (full)
  		this->info.change_mask = this->info_all;
  	if (this->info.change_mask) {
  		this->info.props = &SPA_DICT_INIT_ARRAY(node_info_items);
  		spa_node_emit_info(&this->hooks, &this->info);
  		this->info.change_mask = old;
  	}
  }
  
  static inline void clean_name(char *name)
  {
  	char *c;
  	for (c = name; *c; ++c) {
  		if (!isalnum(*c) && strchr(" /_:()[]", *c) == NULL)
  			*c = '-';
  	}
  }
  
  static void emit_port_info(struct seq_state *this, struct seq_port *port, bool full)
  {
  	uint64_t old = full ? port->info.change_mask : 0;
  	if (full)
  		port->info.change_mask = port->info_all;
  	if (port->info.change_mask) {
  		struct spa_dict_item items[5];
  		uint32_t n_items = 0;
  		int id;
  		snd_seq_port_info_t *info;
  		snd_seq_client_info_t *client_info;
  		char card[8];
  		char name[128];
  		char path[128];
  		char alias[128];
  
  		snd_seq_port_info_alloca(&info);
  		snd_seq_get_any_port_info(this->sys.hndl,
  				port->addr.client, port->addr.port, info);
  
  		snd_seq_client_info_alloca(&client_info);
  		snd_seq_get_any_client_info(this->sys.hndl,
  				port->addr.client, client_info);
  
  		snprintf(name, sizeof(name), "%s:(%s_%d) %s",
  				snd_seq_client_info_get_name(client_info),
  				port->direction == SPA_DIRECTION_OUTPUT ? "capture" : "playback",
  				port->addr.port,
  				snd_seq_port_info_get_name(info));
  		clean_name(name);
  
  		snprintf(path, sizeof(path), "alsa:seq:%s:client_%d:%s_%d",
  				this->props.device,
  				port->addr.client,
  				port->direction == SPA_DIRECTION_OUTPUT ? "capture" : "playback",
  				port->addr.port);
  		clean_name(path);
  
  		snprintf(alias, sizeof(alias), "%s:%s",
  				snd_seq_client_info_get_name(client_info),
  				snd_seq_port_info_get_name(info));
  		clean_name(alias);
  
  		items[n_items++] = SPA_DICT_ITEM_INIT(SPA_KEY_FORMAT_DSP, "8 bit raw midi");
  		items[n_items++] = SPA_DICT_ITEM_INIT(SPA_KEY_OBJECT_PATH, path);
  		items[n_items++] = SPA_DICT_ITEM_INIT(SPA_KEY_PORT_NAME, name);
  		items[n_items++] = SPA_DICT_ITEM_INIT(SPA_KEY_PORT_ALIAS, alias);
  		if ((id = snd_seq_client_info_get_card(client_info)) != -1) {
  			snprintf(card, sizeof(card), "%d", id);
  			items[n_items++] = SPA_DICT_ITEM_INIT(SPA_KEY_API_ALSA_CARD, card);
  		}
  		port->info.props = &SPA_DICT_INIT(items, n_items);
  
  		spa_node_emit_port_info(&this->hooks,
  				port->direction, port->id, &port->info);
  		port->info.change_mask = old;
  	}
  }
  
  static void emit_stream_info(struct seq_state *this, struct seq_stream *stream, bool full)
  {
  	uint32_t i;
  
  	for (i = 0; i < MAX_PORTS; i++) {
  		struct seq_port *port = &stream->ports[i];
  		if (port->valid)
  			emit_port_info(this, port, full);
  	}
  }
  
  static int
  impl_node_add_listener(void *object,
  		struct spa_hook *listener,
  		const struct spa_node_events *events,
  		void *data)
  {
  	struct seq_state *this = object;
  	struct spa_hook_list save;
  
  	spa_return_val_if_fail(this != NULL, -EINVAL);
  
  	spa_hook_list_isolate(&this->hooks, &save, listener, events, data);
  
  	emit_node_info(this, true);
  	emit_stream_info(this, &this->streams[SPA_DIRECTION_INPUT], true);
  	emit_stream_info(this, &this->streams[SPA_DIRECTION_OUTPUT], true);
  
  	spa_hook_list_join(&this->hooks, &save);
  
  	return 0;
  }
  
  static int
  impl_node_set_callbacks(void *object,
  			const struct spa_node_callbacks *callbacks,
  			void *data)
  {
  	struct seq_state *this = object;
  
  	spa_return_val_if_fail(this != NULL, -EINVAL);
  
  	this->callbacks = SPA_CALLBACKS_INIT(callbacks, data);
  
  	return 0;
  }
  
  static int impl_node_sync(void *object, int seq)
  {
  	struct seq_state *this = object;
  
  	spa_return_val_if_fail(this != NULL, -EINVAL);
  
  	spa_node_emit_result(&this->hooks, seq, 0, 0, NULL);
  
  	return 0;
  }
  
  static struct seq_port *find_port(struct seq_state *state,
  		struct seq_stream *stream, const snd_seq_addr_t *addr)
  {
  	uint32_t i;
  	for (i = 0; i < stream->last_port; i++) {
  		struct seq_port *port = &stream->ports[i];
  		if (port->valid &&
  		    port->addr.client == addr->client &&
  		    port->addr.port == addr->port)
  			return port;
  	}
  	return NULL;
  }
  
  static struct seq_port *alloc_port(struct seq_state *state, struct seq_stream *stream)
  {
  	uint32_t i;
  	for (i = 0; i < MAX_PORTS; i++) {
  		struct seq_port *port = &stream->ports[i];
  		if (!port->valid) {
  			port->id = i;
  			port->direction = stream->direction;
  			port->valid = true;
  			if (stream->last_port < i + 1)
  				stream->last_port = i + 1;
  			return port;
  		}
  	}
  	return NULL;
  }
  
  static void free_port(struct seq_state *state, struct seq_stream *stream, struct seq_port *port)
  {
  	port->valid = false;
  
  	if (port->id + 1 == stream->last_port) {
  		int i;
  		for (i = stream->last_port - 1; i >= 0; i--)
  			if (stream->ports[i].valid)
  				break;
  		stream->last_port = i + 1;
  	}
  
  	spa_node_emit_port_info(&state->hooks,
  			port->direction, port->id, NULL);
  	spa_zero(*port);
  }
  
  static void init_port(struct seq_state *state, struct seq_port *port, const snd_seq_addr_t *addr,
  		unsigned int type)
  {
  	enum spa_direction reverse = SPA_DIRECTION_REVERSE(port->direction);
  
  	port->addr = *addr;
  	port->info_all = SPA_PORT_CHANGE_MASK_FLAGS |
  			SPA_PORT_CHANGE_MASK_PROPS |
  			SPA_PORT_CHANGE_MASK_PARAMS;
  	port->info = SPA_PORT_INFO_INIT();
  	port->info.flags = SPA_PORT_FLAG_LIVE;
  	if (type & (SND_SEQ_PORT_TYPE_HARDWARE|SND_SEQ_PORT_TYPE_PORT|SND_SEQ_PORT_TYPE_SPECIFIC))
  		port->info.flags |= SPA_PORT_FLAG_PHYSICAL | SPA_PORT_FLAG_TERMINAL;
  	port->params[PORT_EnumFormat] = SPA_PARAM_INFO(SPA_PARAM_EnumFormat, SPA_PARAM_INFO_READ);
  	port->params[PORT_Meta] = SPA_PARAM_INFO(SPA_PARAM_Meta, SPA_PARAM_INFO_READ);
  	port->params[PORT_IO] = SPA_PARAM_INFO(SPA_PARAM_IO, SPA_PARAM_INFO_READ);
  	port->params[PORT_Format] = SPA_PARAM_INFO(SPA_PARAM_Format, SPA_PARAM_INFO_WRITE);
  	port->params[PORT_Buffers] = SPA_PARAM_INFO(SPA_PARAM_Buffers, 0);
  	port->params[PORT_Latency] = SPA_PARAM_INFO(SPA_PARAM_Latency, SPA_PARAM_INFO_READWRITE);
  	port->info.params = port->params;
  	port->info.n_params = N_PORT_PARAMS;
  
  	spa_list_init(&port->free);
  	spa_list_init(&port->ready);
  
  	port->latency[port->direction] = SPA_LATENCY_INFO(
  			port->direction,
  			.min_quantum = 1.0f,
  			.max_quantum = 1.0f);
  	port->latency[reverse] = SPA_LATENCY_INFO(reverse);
  
  	spa_alsa_seq_activate_port(state, port, true);
  
  	emit_port_info(state, port, true);
  }
  
  static void update_stream_port(struct seq_state *state, struct seq_stream *stream,
  		const snd_seq_addr_t *addr, unsigned int caps, const snd_seq_port_info_t *info)
  {
  	struct seq_port *port = find_port(state, stream, addr);
  
  	if (info == NULL) {
  		spa_log_debug(state->log, "free port %d.%d", addr->client, addr->port);
  		if (port)
  			free_port(state, stream, port);
  	} else {
  		if (port == NULL && (caps & stream->caps) == stream->caps) {
  			spa_log_debug(state->log, "new port %d.%d", addr->client, addr->port);
  			port = alloc_port(state, stream);
  			if (port == NULL)
  				return;
  			init_port(state, port, addr, snd_seq_port_info_get_type(info));
  		} else if (port != NULL) {
  			if ((caps & stream->caps) != stream->caps) {
  				spa_log_debug(state->log, "free port %d.%d", addr->client, addr->port);
  				free_port(state, stream, port);
  			}
  			else {
  				spa_log_debug(state->log, "update port %d.%d", addr->client, addr->port);
  				port->info.change_mask = SPA_PORT_CHANGE_MASK_PROPS;
  				emit_port_info(state, port, false);
  			}
  		}
  	}
  }
  
  static int on_port_info(void *data, const snd_seq_addr_t *addr, const snd_seq_port_info_t *info)
  {
  	struct seq_state *state = data;
  
  	if (info == NULL) {
  		update_stream_port(state, &state->streams[SPA_DIRECTION_INPUT], addr, 0, info);
  		update_stream_port(state, &state->streams[SPA_DIRECTION_OUTPUT], addr, 0, info);
  	} else {
  		unsigned int caps = snd_seq_port_info_get_capability(info);
  
  		if (caps & SND_SEQ_PORT_CAP_NO_EXPORT)
  			return 0;
  
  		update_stream_port(state, &state->streams[SPA_DIRECTION_INPUT], addr, caps, info);
  		update_stream_port(state, &state->streams[SPA_DIRECTION_OUTPUT], addr, caps, info);
  	}
  	return 0;
  }
  
  static int impl_node_add_port(void *object, enum spa_direction direction, uint32_t port_id,
  		const struct spa_dict *props)
  {
  	return -ENOTSUP;
  }
  
  static int impl_node_remove_port(void *object, enum spa_direction direction, uint32_t port_id)
  {
  	return -ENOTSUP;
  }
  
  static int
  impl_node_port_enum_params(void *object, int seq,
  			   enum spa_direction direction, uint32_t port_id,
  			   uint32_t id, uint32_t start, uint32_t num,
  			   const struct spa_pod *filter)
  {
  	struct seq_state *this = object;
  	struct seq_port *port;
  	struct spa_pod *param;
  	struct spa_pod_builder b = { 0 };
  	uint8_t buffer[1024];
  	struct spa_result_node_params result;
  	uint32_t count = 0;
  
  	spa_return_val_if_fail(this != NULL, -EINVAL);
  	spa_return_val_if_fail(num != 0, -EINVAL);
  
  	spa_return_val_if_fail(CHECK_PORT(this, direction, port_id), -EINVAL);
  
  	port = GET_PORT(this, direction, port_id);
  
  	result.id = id;
  	result.next = start;
        next:
  	result.index = result.next++;
  
  	spa_pod_builder_init(&b, buffer, sizeof(buffer));
  
  	switch (id) {
  	case SPA_PARAM_EnumFormat:
  		if (result.index > 0)
  			return 0;
  		param = spa_pod_builder_add_object(&b,
  			SPA_TYPE_OBJECT_Format, SPA_PARAM_EnumFormat,
  			SPA_FORMAT_mediaType,      SPA_POD_Id(SPA_MEDIA_TYPE_application),
  			SPA_FORMAT_mediaSubtype,   SPA_POD_Id(SPA_MEDIA_SUBTYPE_control));
  		break;
  
  	case SPA_PARAM_Format:
  		if (!port->have_format)
  			return -EIO;
  		if (result.index > 0)
  			return 0;
  		param = spa_pod_builder_add_object(&b,
  			SPA_TYPE_OBJECT_Format, SPA_PARAM_EnumFormat,
  			SPA_FORMAT_mediaType,      SPA_POD_Id(SPA_MEDIA_TYPE_application),
  			SPA_FORMAT_mediaSubtype,   SPA_POD_Id(SPA_MEDIA_SUBTYPE_control));
  		break;
  
  	case SPA_PARAM_Buffers:
  		if (!port->have_format)
  			return -EIO;
  		if (result.index > 0)
  			return 0;
  
  		param = spa_pod_builder_add_object(&b,
  			SPA_TYPE_OBJECT_ParamBuffers, id,
  			SPA_PARAM_BUFFERS_buffers, SPA_POD_CHOICE_RANGE_Int(2, 1, MAX_BUFFERS),
  			SPA_PARAM_BUFFERS_blocks,  SPA_POD_Int(1),
  			SPA_PARAM_BUFFERS_size,    SPA_POD_CHOICE_RANGE_Int(
  							4096, 4096, INT32_MAX),
  			SPA_PARAM_BUFFERS_stride,  SPA_POD_Int(1),
  			SPA_PARAM_BUFFERS_align,   SPA_POD_Int(16));
  		break;
  
  	case SPA_PARAM_Meta:
  		switch (result.index) {
  		case 0:
  			param = spa_pod_builder_add_object(&b,
  				SPA_TYPE_OBJECT_ParamMeta, id,
  				SPA_PARAM_META_type, SPA_POD_Id(SPA_META_Header),
  				SPA_PARAM_META_size, SPA_POD_Int(sizeof(struct spa_meta_header)));
  			break;
  		default:
  			return 0;
  		}
  		break;
  
  	case SPA_PARAM_IO:
  		switch (result.index) {
  		case 0:
  			param = spa_pod_builder_add_object(&b,
  				SPA_TYPE_OBJECT_ParamIO, id,
  				SPA_PARAM_IO_id,   SPA_POD_Id(SPA_IO_Buffers),
  				SPA_PARAM_IO_size, SPA_POD_Int(sizeof(struct spa_io_buffers)));
  			break;
  		default:
  			return 0;
  		}
  		break;
  
  	case SPA_PARAM_Latency:
  		switch (result.index) {
  		case 0: case 1:
  			param = spa_latency_build(&b, id, &port->latency[result.index]);
  			break;
  		default:
  			return 0;
  		}
  		break;
  
  	default:
  		return -ENOENT;
  	}
  
  	if (spa_pod_filter(&b, &result.param, param, filter) < 0)
  		goto next;
  
  	spa_node_emit_result(&this->hooks, seq, 0, SPA_RESULT_TYPE_NODE_PARAMS, &result);
  
  	if (++count != num)
  		goto next;
  
  	return 0;
  }
  
  static int clear_buffers(struct seq_state *this, struct seq_port *port)
  {
  	if (port->n_buffers > 0) {
  		spa_list_init(&port->free);
  		spa_list_init(&port->ready);
  		port->n_buffers = 0;
  	}
  	return 0;
  }
  
  static int port_set_format(void *object, struct seq_port *port,
  			   uint32_t flags, const struct spa_pod *format)
  {
  	struct seq_state *this = object;
  	int err;
  
  	if (format == NULL) {
  		if (!port->have_format)
  			return 0;
  
  		clear_buffers(this, port);
  		port->have_format = false;
  	} else {
  		struct spa_audio_info info = { 0 };
  
  		if ((err = spa_format_parse(format, &info.media_type, &info.media_subtype)) < 0)
  			return err;
  
  		if (info.media_type != SPA_MEDIA_TYPE_application ||
  		    info.media_subtype != SPA_MEDIA_SUBTYPE_control)
  			return -EINVAL;
  
  		port->current_format = info;
  		port->have_format = true;
  	}
  
  	port->info.change_mask |= SPA_PORT_CHANGE_MASK_RATE;
  	port->info.rate = SPA_FRACTION(1, 1);
  	port->info.change_mask |= SPA_PORT_CHANGE_MASK_PARAMS;
  	if (port->have_format) {
  		port->params[PORT_Format] = SPA_PARAM_INFO(SPA_PARAM_Format, SPA_PARAM_INFO_READWRITE);
  		port->params[PORT_Buffers] = SPA_PARAM_INFO(SPA_PARAM_Buffers, SPA_PARAM_INFO_READ);
  	} else {
  		port->params[PORT_Format] = SPA_PARAM_INFO(SPA_PARAM_Format, SPA_PARAM_INFO_WRITE);
  		port->params[PORT_Buffers] = SPA_PARAM_INFO(SPA_PARAM_Buffers, 0);
  	}
  	emit_port_info(this, port, false);
  
  	return 0;
  }
  
  static int
  impl_node_port_set_param(void *object,
  			 enum spa_direction direction, uint32_t port_id,
  			 uint32_t id, uint32_t flags,
  			 const struct spa_pod *param)
  {
  	struct seq_state *this = object;
  	struct seq_port *port;
  	int res;
  
  	spa_return_val_if_fail(this != NULL, -EINVAL);
  
  	spa_return_val_if_fail(CHECK_PORT(this, direction, port_id), -EINVAL);
  
  	port = GET_PORT(this, direction, port_id);
  
  	switch (id) {
  	case SPA_PARAM_Format:
  		res = port_set_format(this, port, flags, param);
  		break;
  	case SPA_PARAM_Latency:
  	{
  		struct spa_latency_info info;
  		if ((res = spa_latency_parse(param, &info)) < 0)
  			return res;
  		if (direction == info.direction)
  			return -EINVAL;
  
  		port->latency[info.direction] = info;
  		port->info.change_mask |= SPA_PORT_CHANGE_MASK_PARAMS;
  		port->params[PORT_Latency].flags ^= SPA_PARAM_INFO_SERIAL;
  		emit_port_info(this, port, false);
  		break;
  	}
  	default:
  		res = -ENOENT;
  		break;
  	}
  	return res;
  }
  
  static int
  impl_node_port_use_buffers(void *object,
  		enum spa_direction direction, uint32_t port_id,
  		uint32_t flags,
  		struct spa_buffer **buffers, uint32_t n_buffers)
  {
  	struct seq_state *this = object;
  	struct seq_port *port;
  	uint32_t i;
  
  	spa_return_val_if_fail(this != NULL, -EINVAL);
  
  	spa_return_val_if_fail(CHECK_PORT(this, direction, port_id), -EINVAL);
  
  	port = GET_PORT(this, direction, port_id);
  
  	spa_log_debug(this->log, "%p: port %d.%d buffers:%d format:%d", this,
  			direction, port_id, n_buffers, port->have_format);
  
  	if (!port->have_format)
  		return -EIO;
  
  	clear_buffers(this, port);
  
  	for (i = 0; i < n_buffers; i++) {
  		struct buffer *b = &port->buffers[i];
  		struct spa_data *d = buffers[i]->datas;
  
  		b->buf = buffers[i];
  		b->id = i;
  		b->flags = BUFFER_FLAG_OUT;
  
  		b->h = spa_buffer_find_meta_data(b->buf, SPA_META_Header, sizeof(*b->h));
  
  		if (d[0].data == NULL) {
  			spa_log_error(this->log, "%p: need mapped memory", this);
  			return -EINVAL;
  		}
  		if (direction == SPA_DIRECTION_OUTPUT)
  			spa_alsa_seq_recycle_buffer(this, port, i);
  	}
  	port->n_buffers = n_buffers;
  
  	return 0;
  }
  
  static int
  impl_node_port_set_io(void *object,
  		      enum spa_direction direction,
  		      uint32_t port_id,
  		      uint32_t id,
  		      void *data, size_t size)
  {
  	struct seq_state *this = object;
  	struct seq_port *port;
  
  	spa_return_val_if_fail(this != NULL, -EINVAL);
  
  	spa_return_val_if_fail(CHECK_PORT(this, direction, port_id), -EINVAL);
  
  	port = GET_PORT(this, direction, port_id);
  
  	spa_log_debug(this->log, "%p: io %d.%d %d %p %zd", this,
  			direction, port_id, id, data, size);
  
  	switch (id) {
  	case SPA_IO_Buffers:
  		port->io = data;
  		break;
  	default:
  		return -ENOENT;
  	}
  	return 0;
  }
  
  static int impl_node_port_reuse_buffer(void *object, uint32_t port_id, uint32_t buffer_id)
  {
  	struct seq_state *this = object;
  	struct seq_port *port;
  
  	spa_return_val_if_fail(this != NULL, -EINVAL);
  
  	spa_return_val_if_fail(!CHECK_PORT(this, SPA_DIRECTION_OUTPUT, port_id), -EINVAL);
  
  	port = GET_PORT(this, SPA_DIRECTION_OUTPUT, port_id);
  
  	if (port->n_buffers == 0)
  		return -EIO;
  
  	if (buffer_id >= port->n_buffers)
  		return -EINVAL;
  
  	spa_alsa_seq_recycle_buffer(this, port, buffer_id);
  
  	return 0;
  }
  
  static int impl_node_process(void *object)
  {
  	struct seq_state *this = object;
  
  	spa_return_val_if_fail(this != NULL, -EINVAL);
  
  	return spa_alsa_seq_process(this);
  }
  
  static const struct spa_node_methods impl_node = {
  	SPA_VERSION_NODE_METHODS,
  	.add_listener = impl_node_add_listener,
  	.set_callbacks = impl_node_set_callbacks,
  	.sync = impl_node_sync,
  	.enum_params = impl_node_enum_params,
  	.set_param = impl_node_set_param,
  	.set_io = impl_node_set_io,
  	.send_command = impl_node_send_command,
  	.add_port = impl_node_add_port,
  	.remove_port = impl_node_remove_port,
  	.port_enum_params = impl_node_port_enum_params,
  	.port_set_param = impl_node_port_set_param,
  	.port_use_buffers = impl_node_port_use_buffers,
  	.port_set_io = impl_node_port_set_io,
  	.port_reuse_buffer = impl_node_port_reuse_buffer,
  	.process = impl_node_process,
  };
  
  static int impl_get_interface(struct spa_handle *handle, const char *type, void **interface)
  {
  	struct seq_state *this;
  
  	spa_return_val_if_fail(handle != NULL, -EINVAL);
  	spa_return_val_if_fail(interface != NULL, -EINVAL);
  
  	this = (struct seq_state *) handle;
  
  	if (spa_streq(type, SPA_TYPE_INTERFACE_Node))
  		*interface = &this->node;
  	else
  		return -ENOENT;
  
  	return 0;
  }
  
  static int impl_clear(struct spa_handle *handle)
  {
  	struct seq_state *this;
  
  	spa_return_val_if_fail(handle != NULL, -EINVAL);
  
  	this = (struct seq_state *) handle;
  
  	spa_alsa_seq_close(this);
  	return 0;
  }
  
  static size_t
  impl_get_size(const struct spa_handle_factory *factory,
  	      const struct spa_dict *params)
  {
  	return sizeof(struct seq_state);
  }
  
  static int
  impl_init(const struct spa_handle_factory *factory,
  	  struct spa_handle *handle,
  	  const struct spa_dict *info,
  	  const struct spa_support *support,
  	  uint32_t n_support)
  {
  	struct seq_state *this;
  	uint32_t i;
  	int res;
  
  	spa_return_val_if_fail(factory != NULL, -EINVAL);
  	spa_return_val_if_fail(handle != NULL, -EINVAL);
  
  	handle->get_interface = impl_get_interface;
  	handle->clear = impl_clear;
  
  	this = (struct seq_state *) handle;
  
  	this->log = spa_support_find(support, n_support, SPA_TYPE_INTERFACE_Log);
  	alsa_log_topic_init(this->log);
  
  	this->data_system = spa_support_find(support, n_support, SPA_TYPE_INTERFACE_DataSystem);
  	this->data_loop = spa_support_find(support, n_support, SPA_TYPE_INTERFACE_DataLoop);
  	this->main_loop = spa_support_find(support, n_support, SPA_TYPE_INTERFACE_Loop);
  
  	if (this->data_loop == NULL) {
  		spa_log_error(this->log, "a data loop is needed");
  		return -EINVAL;
  	}
  	if (this->data_system == NULL) {
  		spa_log_error(this->log, "a data system is needed");
  		return -EINVAL;
  	}
  
  	this->node.iface = SPA_INTERFACE_INIT(SPA_TYPE_INTERFACE_Node, SPA_VERSION_NODE, &impl_node, this);
  
  	spa_hook_list_init(&this->hooks);
  
  	this->info_all = SPA_NODE_CHANGE_MASK_FLAGS |
  			SPA_NODE_CHANGE_MASK_PROPS |
  			SPA_NODE_CHANGE_MASK_PARAMS;
  	this->info.max_input_ports = MAX_PORTS;
  	this->info.max_output_ports = MAX_PORTS;
  	this->info.flags = SPA_NODE_FLAG_RT;
  	this->params[NODE_PropInfo] = SPA_PARAM_INFO(SPA_PARAM_PropInfo, SPA_PARAM_INFO_READ);
  	this->params[NODE_Props] = SPA_PARAM_INFO(SPA_PARAM_Props, SPA_PARAM_INFO_READWRITE);
  	this->params[NODE_IO] = SPA_PARAM_INFO(SPA_PARAM_IO, SPA_PARAM_INFO_READ);
  	this->info.params = this->params;
  	this->info.n_params = N_NODE_PARAMS;
  	reset_props(&this->props);
  
  	for (i = 0; info && i < info->n_items; i++) {
  		const char *k = info->items[i].key;
  		const char *s = info->items[i].value;
  		if (spa_streq(k, SPA_KEY_API_ALSA_PATH)) {
  			spa_scnprintf(this->props.device,
  					sizeof(this->props.device), "%s", s);
  		} else if (spa_streq(k, "clock.name")) {
  			spa_scnprintf(this->props.clock_name,
  					sizeof(this->props.clock_name), "%s", s);
  		}
  	}
  
  	this->port_info = on_port_info;
  	this->port_info_data = this;
  
  	if ((res = spa_alsa_seq_open(this)) < 0)
  		return res;
  
  	return 0;
  }
  
  static const struct spa_interface_info impl_interfaces[] = {
  	{SPA_TYPE_INTERFACE_Node,},
  };
  
  static int
  impl_enum_interface_info(const struct spa_handle_factory *factory,
  			 const struct spa_interface_info **info,
  			 uint32_t *index)
  {
  	spa_return_val_if_fail(factory != NULL, -EINVAL);
  	spa_return_val_if_fail(info != NULL, -EINVAL);
  	spa_return_val_if_fail(index != NULL, -EINVAL);
  
  	if (*index >= SPA_N_ELEMENTS(impl_interfaces))
  		return 0;
  
  	*info = &impl_interfaces[(*index)++];
  
  	return 1;
  }
  
  static const struct spa_dict_item info_items[] = {
  	{ SPA_KEY_FACTORY_AUTHOR, "Wim Taymans <wim.taymans@gmail.com>" },
  	{ SPA_KEY_FACTORY_DESCRIPTION, "Bridge midi ports with the alsa sequencer API" },
  	{ SPA_KEY_FACTORY_USAGE, "["SPA_KEY_API_ALSA_PATH"=<device>]" },
  };
  
  static const struct spa_dict info = SPA_DICT_INIT_ARRAY(info_items);
  
  const struct spa_handle_factory spa_alsa_seq_bridge_factory = {
  	SPA_VERSION_HANDLE_FACTORY,
  	SPA_NAME_API_ALSA_SEQ_BRIDGE,
  	&info,
  	impl_get_size,
  	impl_init,
  	impl_enum_interface_info,
  };
  