jack1/libjack/port.c

/*
    Copyright (C) 2001-2003 Paul Davis
    Copyright (C) 2005 Jussi Laako
    
    This program is free software; you can redistribute it and/or modify
    it under the terms of the GNU Lesser General Public License as published by
    the Free Software Foundation; either version 2.1 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 Lesser General Public License for more details.
    
    You should have received a copy of the GNU Lesser General Public License
    along with this program; if not, write to the Free Software 
    Foundation, Inc., 59 Temple Place - Suite 330, Boston, MA 02111-1307, USA.

    $Id$
*/

#include <string.h>
#include <stdio.h>
#include <math.h>

#include <config.h>

#include <jack/jack.h>
#include <jack/types.h>
#include <jack/internal.h>
#include <jack/engine.h>
#include <jack/pool.h>
#include <jack/port.h>
#include <jack/midiport.h>
#include <jack/jslist.h>
#include <jack/intsimd.h>

#include "local.h"

static void    jack_generic_buffer_init(void *port_buffer,
                                      size_t buffer_size);

static void    jack_audio_port_mixdown (jack_port_t *port,
					jack_nframes_t nframes);

/* These function pointers are local to each address space.  For
 * internal clients they reside within jackd; for external clients in
 * the application process. */
jack_port_functions_t jack_builtin_audio_functions = {
	.buffer_init    = jack_generic_buffer_init,
	.mixdown = jack_audio_port_mixdown, 
};

extern jack_port_functions_t jack_builtin_midi_functions;

jack_port_functions_t jack_builtin_NULL_functions = {
	.buffer_init    = jack_generic_buffer_init,
	.mixdown = NULL, 
};

/* Only the Audio and MIDI port types are currently built in. */
jack_port_type_info_t jack_builtin_port_types[] = {
	{ .type_name = JACK_DEFAULT_AUDIO_TYPE, 
	  .buffer_scale_factor = 1,
	},
	{ .type_name = JACK_DEFAULT_MIDI_TYPE, 
	  .buffer_scale_factor = 1,
	},
	{ .type_name = "", }
};

/* these functions have been taken from libDSP X86.c  -jl */

#ifdef USE_DYNSIMD

static void (*opt_copy) (float *, const float *, int);
static void (*opt_mix) (float *, const float *, int);

static void
gen_copyf (float *dest, const float *src, int length)
{
	memcpy(dest, src, length * sizeof(float));
}

static void
gen_mixf (float *dest, const float *src, int length)
{
	int n;

	n = length;
	while (n--)
		*dest++ += *src++;
	/*for (iSample = 0; iSample < iDataLength; iSample++)
		fpDest[iSample] += fpSrc[iSample];*/
}

#ifdef ARCH_X86

static void
x86_3dnow_add2f (float *dest, const float *src, int length)
{
	int i, n;
	pv2sf m64p_dest = (pv2sf) dest;
	pv2sf m64p_src = (pv2sf) src;

	n = (length >> 1);
	for (i = 0; i < n; i++)
	{
		asm volatile (
			"movq %1, %%mm0\n\t" \
			"pfadd %2, %%mm0\n\t" \
			"movq %%mm0, %0\n\t"
			: "=m" (m64p_dest[i])
			: "m0" (m64p_dest[i]),
			  "m" (m64p_src[i])
			: "mm0", "memory");
	}
	if (n & 0x1)
	{
		asm volatile (
			"movd %1, %%mm0\n\t" \
			"movd %2, %%mm1\n\t" \
			"pfadd %%mm1, %%mm0\n\t" \
			"movd %%mm0, %0\n\t"
			: "=m" (dest[length - 1])
			: "m0" (dest[length - 1]),
			  "m" (src[length - 1])
			: "mm0", "mm1", "memory");
	}
	asm volatile (
		"femms\n\t" \
		"sfence\n\t");
}

static void
x86_3dnow_copyf (float *dest, const float *src, int length)
{
	int i, n1, n2;
	pv2sf m64p_src = (pv2sf) src;
	pv2sf m64p_dest = (pv2sf) dest;

	n1 = (length >> 4);
	n2 = ((length & 0xf) >> 1);
	for (i = 0; i < n1; i++)
	{
		asm volatile ("movq %0, %%mm0\n\t"
			: : "m" (*m64p_src++) : "mm0", "memory");
		asm volatile ("movq %0, %%mm1\n\t"
			: : "m" (*m64p_src++) : "mm1", "memory");
		asm volatile ("movq %0, %%mm2\n\t"
			: : "m" (*m64p_src++) : "mm2", "memory");
		asm volatile ("movq %0, %%mm3\n\t"
			: : "m" (*m64p_src++) : "mm3", "memory");
		asm volatile ("movq %0, %%mm4\n\t"
			: : "m" (*m64p_src++) : "mm4", "memory");
		asm volatile ("movq %0, %%mm5\n\t"
			: : "m" (*m64p_src++) : "mm5", "memory");
		asm volatile ("movq %0, %%mm6\n\t"
			: : "m" (*m64p_src++) : "mm6", "memory");
		asm volatile ("movq %0, %%mm7\n\t"
			: : "m" (*m64p_src++) : "xmm7", "memory");

		asm volatile ("movq %%mm0, %0\n\t"
			: "=m" (*m64p_dest++) : : "mm0", "memory");
		asm volatile ("movq %%mm1, %0\n\t"
			: "=m" (*m64p_dest++) : : "mm1", "memory");
		asm volatile ("movq %%mm2, %0\n\t"
			: "=m" (*m64p_dest++) : : "mm2", "memory");
		asm volatile ("movq %%mm3, %0\n\t"
			: "=m" (*m64p_dest++) : : "mm3", "memory");
		asm volatile ("movq %%mm4, %0\n\t"
			: "=m" (*m64p_dest++) : : "mm4", "memory");
		asm volatile ("movq %%mm5, %0\n\t"
			: "=m" (*m64p_dest++) : : "mm5", "memory");
		asm volatile ("movq %%mm6, %0\n\t"
			: "=m" (*m64p_dest++) : : "mm6", "memory");
		asm volatile ("movq %%mm7, %0\n\t"
			: "=m" (*m64p_dest++) : : "mm7", "memory");
	}
	for (i = 0; i < n2; i++)
	{
		asm volatile (
			"movq %1, %%mm0\n\t" \
			"movq %%mm0, %0\n\t"
			: "=m" (*m64p_dest++)
			: "m" (*m64p_src++)
			: "mm0", "memory");
	}
	if (length & 0x1)
	{
		asm volatile (
			"movd %1, %%mm0\n\t" \
			"movd %%mm0, %0\n\t"
			: "=m" (dest[length - 1])
			: "m" (src[length - 1])
			: "mm0", "memory");
	}
	asm volatile (
		"femms\n\t" \
		"sfence\n\t");
}

static void
x86_sse_copyf (float *dest, const float *src, int length)
{
	int i, n1, n2, si3;
	pv4sf m128p_src = (pv4sf) src;
	pv4sf m128p_dest = (pv4sf) dest;

	n1 = (length >> 5);
	n2 = ((length & 0x1f) >> 2);
	si3 = (length & ~0x3);
	for (i = 0; i < n1; i++)
	{
		asm volatile ("movaps %0, %%xmm0\n\t"
			: : "m" (*m128p_src++) : "xmm0", "memory");
		asm volatile ("movaps %0, %%xmm1\n\t"
			: : "m" (*m128p_src++) : "xmm1", "memory");
		asm volatile ("movaps %0, %%xmm2\n\t"
			: : "m" (*m128p_src++) : "xmm2", "memory");
		asm volatile ("movaps %0, %%xmm3\n\t"
			: : "m" (*m128p_src++) : "xmm3", "memory");
		asm volatile ("movaps %0, %%xmm4\n\t"
			: : "m" (*m128p_src++) : "xmm4", "memory");
		asm volatile ("movaps %0, %%xmm5\n\t"
			: : "m" (*m128p_src++) : "xmm5", "memory");
		asm volatile ("movaps %0, %%xmm6\n\t"
			: : "m" (*m128p_src++) : "xmm6", "memory");
		asm volatile ("movaps %0, %%xmm7\n\t"
			: : "m" (*m128p_src++) : "xmm7", "memory");

		asm volatile ("movaps %%xmm0, %0\n\t"
			: "=m" (*m128p_dest++) : : "xmm0", "memory");
		asm volatile ("movaps %%xmm1, %0\n\t"
			: "=m" (*m128p_dest++) : : "xmm1", "memory");
		asm volatile ("movaps %%xmm2, %0\n\t"
			: "=m" (*m128p_dest++) : : "xmm2", "memory");
		asm volatile ("movaps %%xmm3, %0\n\t"
			: "=m" (*m128p_dest++) : : "xmm3", "memory");
		asm volatile ("movaps %%xmm4, %0\n\t"
			: "=m" (*m128p_dest++) : : "xmm4", "memory");
		asm volatile ("movaps %%xmm5, %0\n\t"
			: "=m" (*m128p_dest++) : : "xmm5", "memory");
		asm volatile ("movaps %%xmm6, %0\n\t"
			: "=m" (*m128p_dest++) : : "xmm6", "memory");
		asm volatile ("movaps %%xmm7, %0\n\t"
			: "=m" (*m128p_dest++) : : "xmm7", "memory");
	}
	for (i = 0; i < n2; i++)
	{
		asm volatile (
			"movaps %1, %%xmm0\n\t" \
			"movaps %%xmm0, %0\n\t"
			: "=m" (*m128p_dest++)
			: "m" (*m128p_src++)
			: "xmm0", "memory");
	}
	for (i = si3; i < length; i++)
	{
		asm volatile (
			"movss %1, %%xmm0\n\t" \
			"movss %%xmm0, %0\n\t"
			: "=m" (dest[i])
			: "m" (src[i])
			: "xmm0", "memory");
	}
}

static void
x86_sse_add2f (float *dest, const float *src, int length)
{
	int i, n, si2;
	pv4sf m128p_src = (pv4sf) src;
	pv4sf m128p_dest = (pv4sf) dest;

	if (__builtin_expect(((long) src & 0xf) || ((long) dest & 0xf), 0))
	{
		/*fprintf(stderr, "x86_sse_add2f(): non aligned pointers!\n");*/
		si2 = 0;
		goto sse_nonalign;
	}
	si2 = (length & ~0x3);
	n = (length >> 2);
	for (i = 0; i < n; i++)
	{
		asm volatile (
			"movaps %1, %%xmm0\n\t" \
			"addps %2, %%xmm0\n\t" \
			"movaps %%xmm0, %0\n\t"
			: "=m" (m128p_dest[i])
			: "m0" (m128p_dest[i]),
			  "m" (m128p_src[i])
			: "xmm0", "memory");
	}
sse_nonalign:
	for (i = si2; i < length; i++)
	{
		asm volatile (
			"movss %1, %%xmm0\n\t" \
			"addss %2, %%xmm0\n\t" \
			"movss %%xmm0, %0\n\t"
			: "=m" (dest[i])
			: "m0" (dest[i]),
			  "m" (src[i])
			: "xmm0", "memory");
	}
}

void jack_port_set_funcs ()
{
	if (ARCH_X86_HAVE_SSE2(cpu_type)) {
		opt_copy = x86_sse_copyf;
		opt_mix = x86_sse_add2f;
	}
	else if (ARCH_X86_HAVE_3DNOW(cpu_type)) {
		opt_copy = x86_3dnow_copyf;
		opt_mix = x86_3dnow_add2f;
	}
	else {
		opt_copy = gen_copyf;
		opt_mix = gen_mixf;
	}
}

#else /* ARCH_X86 */

void jack_port_set_funcs ()
{
	opt_copy = gen_copyf;
	opt_mix = gen_mixf;
}

#endif /* ARCH_X86 */

#endif /* USE_DYNSIMD */

jack_port_functions_t *
jack_get_port_functions(jack_port_type_id_t ptid)
{
	switch (ptid) {
	case JACK_AUDIO_PORT_TYPE:
		return &jack_builtin_audio_functions;
	case JACK_MIDI_PORT_TYPE:
		return &jack_builtin_midi_functions;
	/* no other builtin functions */
	default:
		return NULL;
	}
}

/*
 * Fills buffer with zeroes. For audio ports, engine->silent_buffer relies on it.
 */
static void
jack_generic_buffer_init(void *buffer, size_t size)
{
	memset(buffer, 0, size);
}


jack_port_t *
jack_port_new (const jack_client_t *client, jack_port_id_t port_id,
	       jack_control_t *control)
{
	jack_port_shared_t *shared = &control->ports[port_id];
	jack_port_type_id_t ptid = shared->ptype_id;
	jack_port_t *port = (jack_port_t *) malloc (sizeof (jack_port_t));

	port->mix_buffer = NULL;
	port->client_segment_base = NULL;
	port->shared = shared;
	port->type_info = &client->engine->port_types[ptid];
	pthread_mutex_init (&port->connection_lock, NULL);
	port->connections = 0;
	port->tied = NULL;
	
	if (client->control->id == port->shared->client_id) {
			
		/* It's our port, so initialize the pointers to port
		 * functions within this address space.  These builtin
		 * definitions can be overridden by the client. 
		 */
		jack_port_functions_t *port_functions = jack_get_port_functions(ptid);
		if (port_functions == NULL)
			port_functions = &jack_builtin_NULL_functions;
		port->fptr = *port_functions;
		port->shared->has_mixdown = (port->fptr.mixdown ? TRUE : FALSE);
	}

	/* set up a base address so that port->offset can be used to
	   compute the correct location. we don't store the location
	   directly, because port->client_segment_base and/or
	   port->offset can change if the buffer size or port counts
	   are changed.
	*/

	port->client_segment_base =
		(void **) &client->port_segment[ptid].attached_at;

	return port;
}

jack_port_t *
jack_port_register (jack_client_t *client, 
		    const char *port_name,
		    const char *port_type,
		    unsigned long flags,
		    unsigned long buffer_size)
{
	jack_request_t req;
	jack_port_t *port = 0;
	int length ;

	req.type = RegisterPort;

	length = strlen ((const char *) client->control->name)
		+ 1 + strlen (port_name);
	if ( length >= sizeof (req.x.port_info.name) ) {
	  jack_error ("\"%s:%s\" is too long to be used as a JACK port name.\n"
		      "Please use %lu characters or less.",
		      client->control->name , 
		      port_name,
		      sizeof (req.x.port_info.name) - 1);
	  return NULL ;
	}

	strcpy ((char *) req.x.port_info.name,
		(const char *) client->control->name);
	strcat ((char *) req.x.port_info.name, ":");
	strcat ((char *) req.x.port_info.name, port_name);

	snprintf (req.x.port_info.type, sizeof (req.x.port_info.type),
		  "%s", port_type);
	req.x.port_info.flags = flags;
	req.x.port_info.buffer_size = buffer_size;
	req.x.port_info.client_id = client->control->id;

	if (jack_client_deliver_request (client, &req)) {
		jack_error ("cannot deliver port registration request");
		return NULL;
	}

	if ((port = jack_port_new (client, req.x.port_info.port_id,
				   client->engine)) == NULL) {
		jack_error ("cannot allocate client side port structure");
		return NULL;
	}

	client->ports = jack_slist_prepend (client->ports, port);

	return port;
}

int 
jack_port_unregister (jack_client_t *client, jack_port_t *port)
{
	jack_request_t req;

	req.type = UnRegisterPort;
	req.x.port_info.port_id = port->shared->id;
	req.x.port_info.client_id = client->control->id;

	return jack_client_deliver_request (client, &req);
}

/* LOCAL (in-client) connection querying only */

int
jack_port_connected (const jack_port_t *port)
{
	return jack_slist_length (port->connections);
}

int
jack_port_connected_to (const jack_port_t *port, const char *portname)
{
	JSList *node;
	int ret = FALSE;

	/* XXX this really requires a cross-process lock
	   so that ports/connections cannot go away
	   while we are checking for them. that's hard,
	   and has a non-trivial performance impact
	   for jackd.
	*/  

	pthread_mutex_lock (&((jack_port_t *) port)->connection_lock);

	for (node = port->connections; node; node = jack_slist_next (node)) {
		jack_port_t *other_port = (jack_port_t *) node->data;
		
		if (strcmp (other_port->shared->name, portname) == 0) {
			ret = TRUE;
			break;
		}
	}

	pthread_mutex_unlock (&((jack_port_t *) port)->connection_lock);
	return ret;
}

const char **
jack_port_get_connections (const jack_port_t *port)
{
	const char **ret = NULL;
	JSList *node;
	unsigned int n;

	/* XXX this really requires a cross-process lock
	   so that ports/connections cannot go away
	   while we are checking for them. that's hard,
	   and has a non-trivial performance impact
	   for jackd.
	*/  

	pthread_mutex_lock (&((jack_port_t *) port)->connection_lock);

	if (port->connections != NULL) {

		ret = (const char **)
			malloc (sizeof (char *)
				* (jack_slist_length (port->connections) + 1));
		for (n = 0, node = port->connections; node;
		     node = jack_slist_next (node), ++n) {
			ret[n] = ((jack_port_t *) node->data)->shared->name;
		}
		ret[n] = NULL;
	}

	pthread_mutex_unlock (&((jack_port_t *) port)->connection_lock);
	return ret;
}

/* SERVER-SIDE (all) connection querying */

const char **
jack_port_get_all_connections (const jack_client_t *client,
			       const jack_port_t *port)
{
	const char **ret;
	jack_request_t req;
	jack_port_t *tmp;
	unsigned int i;
	int need_free = FALSE;

	if (port == NULL) {
		return NULL;
	}

	req.type = GetPortConnections;

	req.x.port_info.name[0] = '\0';
	req.x.port_info.type[0] = '\0';
	req.x.port_info.flags = 0;
	req.x.port_info.buffer_size = 0;
	req.x.port_info.client_id = 0;
	req.x.port_info.port_id = port->shared->id;

	jack_client_deliver_request (client, &req);

	if (req.status != 0 || req.x.port_connections.nports == 0) {
		return NULL;
	}

	if (client->request_fd < 0) {
		/* internal client */
		return req.x.port_connections.ports;
	}

	ret = (const char **)
		malloc (sizeof (char *) * (req.x.port_connections.nports + 1));

	for (i = 0; i < req.x.port_connections.nports; ++i ) {
		jack_port_id_t port_id;
		
		if (read (client->request_fd, &port_id, sizeof (port_id))
		    != sizeof (port_id)) {
			jack_error ("cannot read port id from server");
			return 0;
		}
		tmp = jack_port_by_id_int (client, port_id, &need_free);
		ret[i] = tmp->shared->name;
		if (need_free) {
			free (tmp);
			need_free = FALSE;
		}
	}

	ret[i] = NULL;

	return ret;
}

jack_port_t *
jack_port_by_id_int (const jack_client_t *client, jack_port_id_t id, int* free)
{
	JSList *node;

	for (node = client->ports; node; node = jack_slist_next (node)) {
		if (((jack_port_t *) node->data)->shared->id == id) {
			*free = FALSE;
			return (jack_port_t *) node->data;
		}
	}

	if (id >= client->engine->port_max)
		return NULL;

	if (client->engine->ports[id].in_use) {
		*free = TRUE;
		return jack_port_new (client, id, client->engine);
	}

	return NULL;
}

jack_port_t *
jack_port_by_id (jack_client_t *client, jack_port_id_t id)
{
	JSList *node;
	jack_port_t* port;
	int need_free = FALSE;
	for (node = client->ports_ext; node; node = jack_slist_next (node)) {
		port = node->data;
		if (port->shared->id == id) { // Found port, return the cached structure
			return port;
		}
	}
	
	// Otherwise possibly allocate a new port structure, keep it in the ports_ext list for later use
	port = jack_port_by_id_int (client,id,&need_free);
	if (port != NULL && need_free)
		client->ports_ext =
			jack_slist_prepend (client->ports_ext, port);
	return port;
}

jack_port_t *
jack_port_by_name_int (jack_client_t *client, const char *port_name)
{
	unsigned long i, limit;
	jack_port_shared_t *port;
	
	limit = client->engine->port_max;
	port = &client->engine->ports[0];
	
	for (i = 0; i < limit; i++) {
		if (port[i].in_use && strcmp (port[i].name, port_name) == 0) {
			return jack_port_new (client, port[i].id,
					      client->engine);
		}
	}

	return NULL;
}

jack_port_t *
jack_port_by_name (jack_client_t *client,  const char *port_name)
{
	JSList *node;
	jack_port_t* port;
	for (node = client->ports_ext; node; node = jack_slist_next (node)) {
		port = node->data;
		if (strcmp (port->shared->name, port_name) == 0) {
			/* Found port, return the cached structure. */
			return port;
		}
	}
	
	/* Otherwise allocate a new port structure, keep it in the
	 * ports_ext list for later use. */
	port = jack_port_by_name_int (client, port_name);
	if (port != NULL)
		client->ports_ext =
			jack_slist_prepend (client->ports_ext, port);
	return port;
}

jack_nframes_t
jack_port_get_latency (jack_port_t *port)
{
	return port->shared->latency;
}

jack_nframes_t
jack_port_get_total_latency (jack_client_t *client, jack_port_t *port)
{
	return port->shared->total_latency;
}

void
jack_port_set_latency (jack_port_t *port, jack_nframes_t nframes)
{
	port->shared->latency = nframes;
}

void *
jack_port_get_buffer (jack_port_t *port, jack_nframes_t nframes)
{
	JSList *node, *next;

	/* Output port.  The buffer was assigned by the engine
	   when the port was registered.
	*/
	if (port->shared->flags & JackPortIsOutput) {
		if (port->tied) {
			return jack_port_get_buffer (port->tied, nframes);
		}

		return jack_output_port_buffer (port);
	}

	/* Input port.  Since this can only be called from the
	   process() callback, and since no connections can be
	   made/broken during this phase (enforced by the jack
	   server), there is no need to take the connection lock here
	*/
	if ((node = port->connections) == NULL) {
		
		/* no connections; return a zero-filled buffer */
		return (void *) (*(port->client_segment_base) + port->type_info->zero_buffer_offset);
	}

	if ((next = jack_slist_next (node)) == NULL) {

		/* one connection: use zero-copy mode - just pass
		   the buffer of the connected (output) port.
		*/
		return jack_port_get_buffer (((jack_port_t *) node->data),
					     nframes);
	}

	/* Multiple connections.  Use a local buffer and mix the
	   incoming data into that buffer.  We have already
	   established the existence of a mixdown function during the
	   connection process.
	*/
	if (port->mix_buffer == NULL) {
		size_t buffer_size = 
				port->type_info->buffer_scale_factor
				* sizeof (jack_default_audio_sample_t)
				* nframes;
		port->mix_buffer = jack_pool_alloc (buffer_size);
		port->fptr.buffer_init (port->mix_buffer, buffer_size);
	}
	port->fptr.mixdown (port, nframes);
	return (void *) port->mix_buffer;
}

int
jack_port_tie (jack_port_t *src, jack_port_t *dst)

{
	if (dst->shared->client_id != src->shared->client_id) {
		jack_error ("cannot tie ports not owned by the same client");
		return -1;
	}

	if (dst->shared->flags & JackPortIsOutput) {
		jack_error ("cannot tie an input port");
		return -1;
	}

	dst->tied = src;
	return 0;
}

int
jack_port_untie (jack_port_t *port)

{
	if (port->tied == NULL) {
		jack_error ("port \"%s\" is not tied", port->shared->name);
		return -1;
	}
	port->tied = NULL;
	return 0;
}

int 
jack_port_request_monitor (jack_port_t *port, int onoff)

{
	if (onoff) {
		port->shared->monitor_requests++;
	} else if (port->shared->monitor_requests) {
		port->shared->monitor_requests--;
	}

	if ((port->shared->flags & JackPortIsOutput) == 0) {

		JSList *node;

		/* this port is for input, so recurse over each of the 
		   connected ports.
		 */

		pthread_mutex_lock (&port->connection_lock);
		for (node = port->connections; node;
		     node = jack_slist_next (node)) {
			
			/* drop the lock because if there is a feedback loop,
			   we will deadlock. XXX much worse things will
			   happen if there is a feedback loop !!!
			*/

			pthread_mutex_unlock (&port->connection_lock);
			jack_port_request_monitor ((jack_port_t *) node->data,
						   onoff);
			pthread_mutex_lock (&port->connection_lock);
		}
		pthread_mutex_unlock (&port->connection_lock);
	}

	return 0;
}
	
int 
jack_port_request_monitor_by_name (jack_client_t *client,
				   const char *port_name, int onoff)

{
	jack_port_t *port;
	unsigned long i, limit;
	jack_port_shared_t *ports;

	limit = client->engine->port_max;
	ports = &client->engine->ports[0];
	
	for (i = 0; i < limit; i++) {
		if (ports[i].in_use &&
		    strcmp (ports[i].name, port_name) == 0) {
			port = jack_port_new (client, ports[i].id,
					      client->engine);
			return jack_port_request_monitor (port, onoff);
			free (port);
			return 0;
		}
	}

	return -1;
}

int
jack_port_ensure_monitor (jack_port_t *port, int yn)
{
	if (yn) {
		if (port->shared->monitor_requests == 0) {
			port->shared->monitor_requests++;
		}
	} else {
		if (port->shared->monitor_requests > 0) {
			port->shared->monitor_requests = 0;
		}
	}

	return 0;
}

int
jack_port_monitoring_input (jack_port_t *port)
{
	return port->shared->monitor_requests > 0;
}

const char *
jack_port_name (const jack_port_t *port)
{
	return port->shared->name;
}

const char *
jack_port_short_name (const jack_port_t *port)
{
	/* we know there is always a colon, because we put
	   it there ...
	*/

	return strchr (port->shared->name, ':') + 1;
}

int 
jack_port_is_mine (const jack_client_t *client, const jack_port_t *port)
{
	return port->shared->client_id == client->control->id;
}

int
jack_port_flags (const jack_port_t *port)
{
	return port->shared->flags;
}

const char *
jack_port_type (const jack_port_t *port)
{
	return port->type_info->type_name;
}

int
jack_port_set_name (jack_port_t *port, const char *new_name)
{
	char *colon;
	int len;

	colon = strchr (port->shared->name, ':');
	len = sizeof (port->shared->name) -
		((int) (colon - port->shared->name)) - 2;
	snprintf (colon+1, len, "%s", new_name);
	
	return 0;
}

/* AUDIO PORT SUPPORT */

static inline float f_max(float x, float a)
{
	x -= a;
	x += fabs (x);
	x *= 0.5;
	x += a;

	return (x);
}

static void 
jack_audio_port_mixdown (jack_port_t *port, jack_nframes_t nframes)
{
	JSList *node;
	jack_port_t *input;
#ifndef ARCH_X86
	jack_nframes_t n;
	jack_default_audio_sample_t *dst, *src;
#endif
	jack_default_audio_sample_t *buffer;

	/* by the time we've called this, we've already established
	   the existence of more than one connection to this input
	   port and allocated a mix_buffer.
	*/

	/* no need to take connection lock, since this is called
	   from the process() callback, and the jack server
	   ensures that no changes to connections happen
	   during this time.
	*/

	node = port->connections;
	input = (jack_port_t *) node->data;
	buffer = port->mix_buffer;

#ifndef USE_DYNSIMD
	memcpy (buffer, jack_output_port_buffer (input),
		sizeof (jack_default_audio_sample_t) * nframes);
#else /* USE_DYNSIMD */
	opt_copy (buffer, jack_output_port_buffer (input), nframes);
#endif /* USE_DYNSIMD */

	for (node = jack_slist_next (node); node;
	     node = jack_slist_next (node)) {

		input = (jack_port_t *) node->data;

#ifndef USE_DYNSIMD
		n = nframes;
		dst = buffer;
		src = jack_output_port_buffer (input);

		while (n--) {
			*dst++ += *src++;
		}
#else /* USE_DYNSIMD */
		opt_mix (buffer, jack_output_port_buffer (input), nframes);
#endif /* USE_DYNSIMD */
	}
}