path: root/shared/common/mifi.c

/* Copyright (c) 2001-2003 krzYszcz and others.
 * For information on usage and redistribution, and for a DISCLAIMER OF ALL
 * WARRANTIES, see the file, "LICENSE.txt," in this distribution.  */

/* reading/writing midifiles, a prototype version */

#ifdef NT
#include <io.h>
#else
#include <unistd.h>
#endif
#include <stdlib.h>
#include <stdio.h>
#include <string.h>
#include <errno.h>
#include "m_pd.h"
#include "shared.h"
#include "common/sq.h"
#include "common/bifi.h"
#include "common/mifi.h"

#if 1
#define MIFI_VERBOSE
#if 0
#define MIFI_DEBUG
#endif
#endif

#define MIFI_SHORTEST_EVENT         2  /* singlebyte delta and one databyte */
#define MIFI_EVENT_NALLOC          32  /* LATER do some research (average max?) */
#define MIFI_HEADER_SIZE           14  /* in case t_mifi_header is padded to 16 */
#define MIFI_HEADERDATA_SIZE        6
#define MIFI_TRACKHEADER_SIZE       8

/* header structures for midifile and track */

typedef struct _mifi_header
{
    char    h_type[4];
    uint32  h_length;
    uint16  h_format;
    uint16  h_ntracks;
    uint16  h_division;
} t_mifi_header;

typedef struct _mifi_trackheader
{
    char    h_type[4];
    uint32  h_length;
} t_mifi_trackheader;

/* reading helpers */

static void mifi_earlyeof(t_mifi_stream *x)
{
    x->s_bytesleft = 0;
    x->s_eof = 1;
}

/* Get next byte from track data.
   On error: return 0 (which is a valid result) and set x->s_eof.
*/
static uchar mifi_getbyte(t_mifi_stream *x)
{
    if (x->s_bytesleft)
    {
	int c;
	if ((c = fgetc(x->s_fp)) == EOF)
	{
	    mifi_earlyeof(x);
	    return (0);
	}
	else {
	    x->s_bytesleft--;
	    return ((uchar)c);
	}
    }
    else return (0);
}

static uint32 mifi_readbytes(t_mifi_stream *x, uchar *buf, uint32 size)
{
    size_t res;
    if (size > x->s_bytesleft)
	size = x->s_bytesleft;
    if ((res = fread(buf, 1, (size_t)size, x->s_fp)) == size)
	x->s_bytesleft -= res;
    else
	mifi_earlyeof(x);
    return (res);
}

static int mifi_skipbytes(t_mifi_stream *x, uint32 size)
{
    if (size > x->s_bytesleft)
	size = x->s_bytesleft;
    if (size)
    {
	int res = fseek(x->s_fp, size, SEEK_CUR);
	if (res < 0)
	    mifi_earlyeof(x);
	else
	    x->s_bytesleft -= size;
	return res;
    }
    else return (0);
}

/* helpers handling variable-length quantities */

static size_t mifi_writevarlen(t_mifi_stream *x, uint32 n)
{
    uint32 buf = n & 0x7f;
    size_t length = 1;
    while ((n >>= 7) > 0)
    {
	buf <<= 8;
	buf |= 0x80;
	buf += n & 0x7f;
	length++;
    }
    return ((fwrite(&buf, 1, length, x->s_fp) == length) ? length : 0);
}

static uint32 mifi_readvarlen(t_mifi_stream *x)
{
    uint32 n = 0;
    uchar c;
    uint32 count = x->s_bytesleft;
    if (count > 4) count = 4;
    while (count--)
    {
	n = (n << 7) + ((c = mifi_getbyte(x)) & 0x7f);
	if ((c & 0x80) == 0)
	    break;
    }
    return (n);
}

/* other helpers */

static int mifi_read_start_track(t_mifi_stream *x)
{
    t_mifi_trackheader header;
    long skip;
    int notyet = 1;
    do {
	if (fread(&header, 1,
		  MIFI_TRACKHEADER_SIZE, x->s_fp) < MIFI_TRACKHEADER_SIZE)
	    goto nomoretracks;
	header.h_length = bifi_swap4(header.h_length);
	if (strncmp(header.h_type, "MTrk", 4))
	{
	    char buf[5];
	    strncpy(buf, header.h_type, 4);
	    buf[5] = '\0';
	    if (x->s_anapass)
		post("unknown chunk %s in midifile -- skipped", buf);
	}
	else if (header.h_length < MIFI_SHORTEST_EVENT)
	{
	    if (x->s_anapass) post("empty track in midifile -- skipped");
	}
	else notyet = 0;
	if (notyet && (skip = header.h_length) &&
	    fseek(x->s_fp, skip, SEEK_CUR) < 0)
	    goto nomoretracks;
    } while (notyet);

    x->s_track++;
    x->s_newtrack = 1;
    x->s_status = x->s_channel = 0;
    x->s_bytesleft = header.h_length;
    x->s_time = 0;

    return (1);
nomoretracks:
    if (x->s_track == 0)
	if (x->s_anapass) post("no valid miditracks");
    return (0);
}

/* public interface */

t_mifi_event *mifi_event_new(void)
{
    t_mifi_event *e = getbytes(sizeof(*e));
    if (e && !(e->e_data = getbytes(e->e_bufsize = MIFI_EVENT_NALLOC)))
    {
	freebytes(e, sizeof(*e));
	return (0);
    }
    return (e);
}

void mifi_event_free(t_mifi_event *e)
{
    freebytes(e->e_data, e->e_bufsize);
    freebytes(e, sizeof(*e));
}

int mifi_event_settext(t_mifi_event *e, int type, char *text)
{
    e->e_delay = 0;
    e->e_status = MIFI_EVENT_META;
    e->e_meta = type;
    e->e_length = strlen(text);
    if (squb_checksize(e, e->e_length + 1, 1) <= e->e_length)
    {
	e->e_length = 0;
	return (0);
    }
    strcpy(e->e_data, text);
    return (1);
}

void mifi_event_printmeta(t_mifi_event *e)
{
    static int isprintable[MIFI_META_MAXPRINTABLE+1] =
    {
#ifdef MIFI_DEBUG
	0, 1, 1, 1, 1, 1, 1, 1, 1, 1, 1, 1, 1, 1, 1, 1
#elif defined MIFI_VERBOSE
	0, 0, 1, 1, 1, 1, 1, 1
#endif
    };
    static char *printformat[MIFI_META_MAXPRINTABLE+1] =
    {
	"", "text: %s", "copyright: %s", "track name: %s",
	"instrument name: %s", "lyric: %s", "marker: %s", "cue point: %s"
    };
    if (e->e_meta <= MIFI_META_MAXPRINTABLE)
    {
	if (isprintable[e->e_meta] && printformat[e->e_meta])
	    post(printformat[e->e_meta], e->e_data);
    }
#ifdef MIFI_DEBUG  /* in verbose mode tempo printout done only after sorting */
    else if (e->e_meta == MIFI_META_TEMPO)
    {
	int tempo = bifi_swap4(*(uint32*)e->e_data);
	post("tempo %d after %d", tempo, e->e_delay);
    }
#endif
}

void mifi_stream_reset(t_mifi_stream *x)
{
    sq_reset(x);
    x->s_status = x->s_channel = 0;
    x->s_timecoef = sq_msecs2ticks(x, 0);
    x->s_bytesleft = 0;
}

t_mifi_stream *mifi_stream_new(void)
{
    t_mifi_stream *x = sq_new();
    if (x)
    {
	if (x->s_auxeve = mifi_event_new())
	{
	    x->s_hdtracks = 1;
	    x->s_alltracks = 0;
	    mifi_stream_reset(x);  /* LATER avoid calling sq_reset() twice */
	}
	else
	{
	    mifi_stream_free(x);
	    return (0);
	}
    }
    return (x);
}

void mifi_stream_free(t_mifi_stream *x)
{
    if (x->s_auxeve)
	mifi_event_free(x->s_auxeve);
    sq_free(x);
}

/* Open midifile for reading, parse the header.  May be used as t_mifi_stream
   allocator (if x is a null pointer), to be freed by mifi_read_end() or
   explicitly.

   Return value: null on error, else x if passed a valid pointer, else pointer
   to an allocated structure.
*/
t_mifi_stream *mifi_read_start(t_mifi_stream *x,
			       const char *filename, const char *dirname,
			       int complain)
{
    t_mifi_stream *result = x;
    t_bifi bifi;
    t_bifi *bp = &bifi;
    t_mifi_header header;
    long skip;

    bifi_new(bp, (char *)&header, MIFI_HEADER_SIZE);
    if (!bifi_read_start(bp, filename, dirname))
    {
	bifi_error_report(bp);
	bifi_free(bp);
	return (0);
    }
    if (strncmp(header.h_type, "MThd", 4))
	goto badheader;
    header.h_length = bifi_swap4(header.h_length);
    if (header.h_length < MIFI_HEADERDATA_SIZE)
	goto badheader;
    if (skip = header.h_length - MIFI_HEADERDATA_SIZE)
    {
	post("%ld extra bytes of midifile header -- skipped", skip);
	if (fseek(bp->b_fp, skip, SEEK_CUR) < 0)
	    goto badstart;
    }

    /* since we will tolerate other incompatibilities, now we can allocate */
    if (x) mifi_stream_reset(x);
    else
    {
	if (!(result = mifi_stream_new()))
	    goto badstart;
	result->s_autoalloc = 1;
    }
    result->s_fp = bp->b_fp;
    result->s_format = bifi_swap2(header.h_format);
    result->s_hdtracks = bifi_swap2(header.h_ntracks);
    result->s_nticks = bifi_swap2(header.h_division);
    if (result->s_nticks & 0x8000)
    {
	result->s_nframes = (result->s_nticks >> 8);
	result->s_nticks &= 0xff;
    }
    else result->s_nframes = 0;
    if (result->s_nticks == 0)
	goto badheader;

    return (result);
badheader:
    if (complain)
	post("`%s\' is not a valid midifile", filename);
badstart:
    if (result && !x) mifi_stream_free(result);
    bifi_free(bp);
    return (0);
}

int mifi_read_restart(t_mifi_stream *x)
{
    FILE *fp = x->s_fp;
    mifi_stream_reset(x);
    x->s_anapass = 0;
    x->s_fp = fp;
    return (fseek(fp, 0, SEEK_SET) ? 0 : 1);
}

/* Close midifile and free t_mifi_stream if it was allocated
   by mifi_read_start() */
void mifi_read_end(t_mifi_stream *x)
{
    if (x->s_fp) fclose(x->s_fp);
    if (x->s_autoalloc) mifi_stream_free(x);
}

/* Read next event from midifile.
   Return value: see #defines in mifi.h.
*/
int mifi_read_event(t_mifi_stream *x, t_mifi_event *e)
{
    uchar status, channel;
    uint32 length;

    x->s_newtrack = 0;
nextattempt:
    if (x->s_bytesleft < MIFI_SHORTEST_EVENT && !mifi_read_start_track(x))
	return (MIFI_READ_EOF);

    x->s_time += (e->e_delay = mifi_readvarlen(x));

    if ((status = mifi_getbyte(x)) < 0x80)
    {
	if (MIFI_IS_CHANNEL(x->s_status))
	{
	    e->e_data[0] = status;
	    e->e_length = 1;
	    status = x->s_status;
	    e->e_channel = x->s_channel;
	}
	else {
	    if (x->s_anapass)
		post("missing running status in midifile -- skip to end of track");
	    goto endoftrack;
	}
    }
    else e->e_length = 0;

    /* channel message */
    if (status < 0xf0)
    {
	if (e->e_length == 0)
	{
	    e->e_data[0] = mifi_getbyte(x);
	    e->e_length = 1;
	    x->s_status = status & 0xf0;
	    x->s_channel = e->e_channel = status & 0x0f;
	    status = x->s_status;
	}
	if (!MIFI_ONE_DATABYTE(status))
	{
	    e->e_data[1] = mifi_getbyte(x);
	    e->e_length = 2;
	}
    }

    /* system exclusive */
    else if (status == MIFI_SYSEX_FIRST || status == MIFI_SYSEX_NEXT)
    {
	/* LATER choose the right way --
	   do we really need all those huge bulk dumps? */
	length = mifi_readvarlen(x);
	if (squb_checksize(e, length, 1) < length)
	{
	    if (mifi_skipbytes(x, length) < 0)
		return (MIFI_READ_FATAL);
	    goto nextattempt;
	}
	if (mifi_readbytes(x, e->e_data, length) != length)
	    return (MIFI_READ_FATAL);
	e->e_length = length;
#ifdef MIFI_VERBOSE
	if (x->s_anapass) post("got %d bytes of sysex", length);
#endif
    }

    /* meta-event */
    else if (status == MIFI_EVENT_META)
    {
	e->e_meta = mifi_getbyte(x);
	length = mifi_readvarlen(x);
	if (e->e_meta > 127)
	{
	    /* try to skip corrupted meta-event (quietly) */
#ifdef MIFI_VERBOSE
	    if (x->s_anapass) post("bad meta: %d > 127", e->e_meta);
#endif
	    if (mifi_skipbytes(x, length) < 0)
		return (MIFI_READ_FATAL);
	    goto nextattempt;
	}
	switch (e->e_meta)
	{
	case MIFI_META_EOT:
	    if (length)
	    {
		/* corrupted eot: ignore and skip to the real end of track */
#ifdef MIFI_VERBOSE
		if (x->s_anapass) post("corrupted eot, length %d", length);
#endif
		goto endoftrack;
	    }
	    break;
	case MIFI_META_TEMPO:
	    if (length != 3)
	    {
		if (x->s_anapass)
		    post("corrupted event in midifile -- skip to end of track");
		goto endoftrack;
	    }
	    if (mifi_readbytes(x, e->e_data+1, 3) != 3)
		return (MIFI_READ_FATAL);
	    e->e_data[0] = 0;
	    x->s_tempo = bifi_swap4(*(uint32*)e->e_data);
	    break;
	default:
	    if (squb_checksize(e, length + 1, 1) <= length)
	    {
		if (mifi_skipbytes(x, length) < 0)
		    return (MIFI_READ_FATAL);
		goto nextattempt;
	    }
	    if (mifi_readbytes(x, e->e_data, length) != length)
		return (MIFI_READ_FATAL);
	    e->e_length = length;
	    if (e->e_meta && e->e_meta <= MIFI_META_MAXPRINTABLE)
		e->e_data[length] = '\0';  /* text meta-event nultermination */
	}
    }
    else {
	if (x->s_anapass)
	    post("unknown event type in midifile -- skip to end of track");
	goto endoftrack;
    }

    return ((e->e_status = status) == MIFI_EVENT_META ? e->e_meta : status);

endoftrack:
    if (mifi_skipbytes(x, x->s_bytesleft) < 0)
	return (MIFI_READ_FATAL);
    return (MIFI_READ_SKIP);
}

/* Gather statistics (nevents, ntracks, ntempi), pick track names, and
   allocate the maps.  To be called in the first pass of reading.
*/
/* LATER consider optional reading of nonchannel events */
int mifi_read_analyse(t_mifi_stream *x)
{
    t_mifi_event *evp = x->s_auxeve;
    int evtype, result = MIFI_READ_FATAL;
    int isnewtrack = 0;
    int i;
    char tnamebuf[MAXPDSTRING];
    t_symbol *tnamesym = 0;
    t_squack *trp = 0;

    *tnamebuf = '\0';
    x->s_alltracks = x->s_ntracks = 0;
    x->s_nevents = 0;
    x->s_ntempi = 0;

    while ((evtype = mifi_read_event(x, evp)) >= MIFI_READ_SKIP)
    {
	if (evtype == MIFI_READ_SKIP)
	    continue;
	if (x->s_newtrack)
	{
#ifdef MIFI_VERBOSE
	    post("track %d", x->s_track);
#endif
	    isnewtrack = 1;
	    *tnamebuf = '\0';
	    tnamesym = 0;  /* set to nonzero for nonempty tracks only */
	}
	if (MIFI_IS_CHANNEL(evtype))
	{
	    if (isnewtrack)
	    {
		isnewtrack = 0;
		x->s_alltracks++;
		if (!(trp = squax_add(x)))
		    goto anafail;
		if (*tnamebuf)
		{
		    tnamesym = trp->tr_name = gensym(tnamebuf);
#ifdef MIFI_DEBUG
		    post("nonempty track name %s", tnamesym->s_name);
#endif
		}
		else tnamesym = trp->tr_name = &s_;
	    }
	    x->s_nevents++;
	}
	else if (evtype < 0x80)
	{
	    mifi_event_printmeta(evp);
	    if (evtype == MIFI_META_TEMPO)
		x->s_ntempi++;
	    else if (evtype == MIFI_META_TRACKNAME)
	    {
		char *p1 = evp->e_data;
		if (*p1 &&
		    !*tnamebuf) /* take the first one */
		{
		    while (*p1 == ' ') p1++;
		    if (*p1)
		    {
			char *p2 = evp->e_data + evp->e_length - 1;
			while (p2 > p1 && *p2 == ' ') *p2-- = '\0';
			p2 = p1;
			do if (*p2 == ' ' || *p2 == ',' || *p2 == ';')
			    *p2 = '-';
			while (*++p2);
			if (tnamesym == &s_)
			{  /* trackname after channel-event */
			    if (trp)  /* redundant check */
				tnamesym = trp->tr_name = gensym(p1);
			}
			else strcpy(tnamebuf, p1);
		    }
		}
	    }
	}
    }
    if (evtype != MIFI_READ_EOF)
	goto anafail;

    i = x->s_ntracks;
    while (--i >= 0)
    {
	if (!x->s_track_name(i) || x->s_track_name(i) == &s_)
	{
	    sprintf(tnamebuf, "%d-track", i);
	    x->s_track_name(i) = gensym(tnamebuf);
	}
    }

    /* now (re)allocate the buffers */
    if (squb_checksize(x->s_mytempi,
		       x->s_ntempi, sizeof(t_squmpo)) < x->s_ntempi)
	goto anafail;
    x->s_track_nevents(0) = 0;
    x->s_track_nevents(x->s_ntracks) = x->s_nevents;  /* guard point */

    result = evtype;
anafail:
    return (result);
}

/* To be called in second pass of reading */
/* LATER do not trust analysis: in case of inconsistency give up or checksize */
int mifi_read_doit(t_mifi_stream *x)
{
    t_mifi_event *evp = x->s_auxeve;
    t_squiter *it = x->s_myiter;
    t_squiter_seekhook seekhook = squiter_seekhook(it);
    t_squiter_incrhook incrhook = squiter_incrhook(it);
    t_squiter_setevehook evehook = squiter_setevehook(it);
    t_squiter_settimhook timhook = squiter_settimhook(it);
    t_squiter_settarhook tarhook = squiter_settarhook(it);
    int evtype, result = MIFI_READ_FATAL;
    int nevents = x->s_nevents;  /* three proxies... */
    int ntracks = x->s_ntracks;
    int ntempi = x->s_ntempi;
    int trackno = 0;
    t_symbol *trackname = 0;
    int isnewtrack = 0;
    t_squmpo *tp = x->s_tempomap;

    if (!it || !seekhook(it, 0))
	goto readfailed;

    while ((evtype = mifi_read_event(x, evp)) >= MIFI_READ_SKIP)
    {
	if (evtype == MIFI_READ_SKIP)
	    continue;
	if (x->s_newtrack)
	    isnewtrack = 1;
	if (MIFI_IS_CHANNEL(evtype))
	{
	    int ret;
	    if (isnewtrack)
	    {
		isnewtrack = 0;
		trackname = x->s_track_name(trackno);
		trackno++;
		if (!trackname || trackname == &s_)
		{
		    bug("mifi_read_doit: empty track name");
		    trackname = gensym("bug-track");
		}
	    }
	    x->s_track_nevents(trackno)++;
	    if (ret = squiter_inrange(it))
	    {
		evehook(it, (t_squeve *)evp, &ret);
		/* We store onset times instead of delta times, because:
		   1) some deltas may represent delays since nonchannel events;
		   2) we'll need onsets while merging the tracks. */
		if (ret) timhook(it, (t_float)x->s_time, &ret);
		if (ret) tarhook(it, trackname, &ret);
	    }
	    if (ret) incrhook(it);
	    else
		goto readfailed;
	}
	else if (evtype < 0x80)
	{
	    if (evtype == MIFI_META_TEMPO)
	    {
		tp->te_onset = x->s_time;
		tp->te_value = x->s_tempo;
		tp++;
	    }
	}
    }
    if (evtype != MIFI_READ_EOF)
	goto readfailed;

    result = evtype;
readfailed:
    return (result);
}

/* Open midifile for saving, write the header.  May be used as t_mifi_stream
   allocator (if x is a null pointer), to be freed by mifi_write_end() or
   explicitly.

   Return value: null on error, else x if passed a valid pointer, else pointer
   to allocated structure.
*/
t_mifi_stream *mifi_write_start(t_mifi_stream *x,
				const char *filename, const char *dirname)
{
    t_mifi_stream *result = x;
    t_bifi bifi;
    t_bifi *bp = &bifi;
    t_mifi_header header;

    /* this must precede bifi_swap() calls */
    bifi_new(bp, (char *)&header, MIFI_HEADER_SIZE);

    if (x->s_format == 0)
    {
	if (x->s_ntracks != 1)
	    goto startfailure;  /* LATER replace with a warning only? */
#ifdef MIFI_VERBOSE
	post("writing singletrack midifile %s", filename);
#endif
    }
#ifdef MIFI_VERBOSE
    else post("writing midifile %s (%d tracks)", filename, x->s_ntracks);
#endif

    strncpy(header.h_type, "MThd", 4);
    header.h_length = bifi_swap4(MIFI_HEADERDATA_SIZE);
    if (x)
    {
	if (!x->s_hdtracks || !x->s_nticks)
	    goto startfailure;
	header.h_format = bifi_swap2(x->s_format);
	header.h_ntracks = bifi_swap2(x->s_hdtracks);
	if (x->s_nframes)
	    header.h_division = ((x->s_nframes << 8) | x->s_nticks) | 0x8000;
	else
	    header.h_division = x->s_nticks & 0x7fff;
	header.h_division = bifi_swap2(header.h_division);
    }
    else {
	header.h_format = 0;
	header.h_ntracks = bifi_swap2(1);
	header.h_division = bifi_swap2(192);  /* LATER parametrize this somehow */
    }

    if (!bifi_write_start(bp, filename, dirname))
    {
	bifi_error_report(bp);
	bifi_free(bp);
	return (0);
    }

    if (x) mifi_stream_reset(x);
    else
    {
	if (!(result = mifi_stream_new()))
	    goto startfailure;
	result->s_autoalloc = 1;
    }
    result->s_fp = bp->b_fp;
    result->s_track = 0;

    return (result);
startfailure:
    if (result && !x) mifi_stream_free(result);
    bifi_free(bp);
    return (0);
}

/* Close midifile, free t_mifi_stream if it was allocated
   by mifi_write_start(). */
void mifi_write_end(t_mifi_stream *x)
{
    if (x->s_autoalloc)
    {
	/* LATER adjust ntracks field in a file header, but do so only if
	   a stream was autoallocated -- number of tracks must be known
	   before calling mifi_write_start() for a preexisting stream. */
    }
    if (x->s_fp) fclose(x->s_fp);
    if (x->s_autoalloc) mifi_stream_free(x);
}

int mifi_write_start_track(t_mifi_stream *x)
{
    t_mifi_trackheader header;
    /* LATER check if (x->s_track < x->s_hdtracks)... after some thinking */
    strncpy(header.h_type, "MTrk", 4);
    header.h_length = 0;
    x->s_trackid = x->s_track_id(x->s_track);
    x->s_track++;
    x->s_newtrack = 1;
    x->s_status = x->s_channel = 0;
    x->s_bytesleft = 0;
    x->s_time = 0;
    if (fwrite(&header, 1,
	       MIFI_TRACKHEADER_SIZE, x->s_fp) != MIFI_TRACKHEADER_SIZE)
    {
	post("unable to write midifile header");
	return (0);
    }
    return (1);
}

/* append eot meta and update length field in a track header */
int mifi_write_adjust_track(t_mifi_stream *x, uint32 eotdelay)
{
    t_mifi_event *evp = x->s_auxeve;
    long skip;
    uint32 length;
    evp->e_delay = eotdelay;
    evp->e_status = MIFI_EVENT_META;
    evp->e_meta = MIFI_META_EOT;
    evp->e_length = 0;
    if (!mifi_write_event(x, evp))
	return (0);
    skip = x->s_bytesleft + 4;
    length = bifi_swap4(x->s_bytesleft);
#ifdef MIFI_DEBUG
    post("adjusting track size to %d", x->s_bytesleft);
#endif
    /* LATER add sanity check (compare to saved filepos) */
    if (skip > 4 &&
	fseek(x->s_fp, -skip, SEEK_CUR) < 0 ||
	fwrite(&length, 1, 4, x->s_fp) != 4 ||
	fseek(x->s_fp, 0, SEEK_END) < 0)
    {
	post("unable to adjust length field in midifile track header (length %d)",
	     x->s_bytesleft);
	return (0);
    }
    return (1);
}

/* LATER analyse shrinking effect caused by truncation */
int mifi_write_event(t_mifi_stream *x, t_mifi_event *e)
{
    uchar buf[3], *ptr = buf;
    size_t size = mifi_writevarlen(x, e->e_delay);
    if (!size)
	return (0);
    x->s_bytesleft += size;
    if (MIFI_IS_CHANNEL(e->e_status))
    {
	if ((*ptr = e->e_status | e->e_channel) == x->s_status)
	    size = 1;
	else {
	    x->s_status = *ptr++;
	    size = 2;
	}
	*ptr++ = e->e_data[0];
	if (!MIFI_ONE_DATABYTE(e->e_status))
	{
	    *ptr = e->e_data[1];
	    size++;
	}
	ptr = buf;
    }
    else if (e->e_status == MIFI_EVENT_META)
    {
	x->s_status = 0;  /* sysex and meta-events cancel any running status */
	buf[0] = e->e_status;
	buf[1] = e->e_meta;
	if (fwrite(buf, 1, 2, x->s_fp) != 2)
	    return (0);
	x->s_bytesleft += 2;
	size = mifi_writevarlen(x, (uint32)(e->e_length));
	if (!size)
	    return (0);
	x->s_bytesleft += size;
	size = e->e_length;
	ptr = e->e_data;
    }
    else return (0);
    if (fwrite(ptr, 1, size, x->s_fp) != size)
	return (0);
    x->s_bytesleft += size;
    return (1);
}