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audacia/lib-src/portsmf/mfmidi.cpp

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/*
* Read a Standard MIDI File. Externally-assigned function pointers are
* called upon recognizing things in the file. See midifile(3).
*/
/*****************************************************************************
* Change Log
* Date | who : Change
*-----------+-----------------------------------------------------------------
* 2-Mar-92 | GWL : created changelog; MIDIFILE_ERROR to satisfy compiler
*****************************************************************************/
#include "stdio.h"
#include "mfmidi.h"
#include "string.h"
#include "assert.h"
#define MIDIFILE_ERROR -1
/* public stuff */
extern int abort_flag;
void Midifile_reader::midifile()
{
int ntrks;
midifile_error = 0;
ntrks = readheader();
if (midifile_error) return;
if (ntrks <= 0) {
mferror("No tracks!");
/* no need to return since midifile_error is set */
}
while (ntrks-- > 0 && !midifile_error) readtrack();
}
int Midifile_reader::readmt(const char *s, int skip)
/* read through the "MThd" or "MTrk" header string */
/* if skip == 1, we attempt to skip initial garbage. */
{
assert(strlen(s) == 4); // must be "MThd" or "MTrk"
int nread = 0;
char b[4];
char buff[32];
int c;
const char *errmsg = "expecting ";
retry:
while ( nread<4 ) {
c = Mf_getc();
if ( c == EOF ) {
errmsg = "EOF while expecting ";
goto err;
}
b[nread++] = c;
}
/* See if we found the 4 characters we're looking for */
if ( s[0]==b[0] && s[1]==b[1] && s[2]==b[2] && s[3]==b[3] )
return(0);
if ( skip ) {
/* If we are supposed to skip initial garbage, */
/* try again with the next character. */
b[0]=b[1];
b[1]=b[2];
b[2]=b[3];
nread = 3;
goto retry;
}
err:
#pragma warning(disable: 4996) // strcpy is safe since strings have known lengths
(void) strcpy(buff,errmsg);
(void) strcat(buff,s);
#pragma warning(default: 4996) // turn it back on
mferror(buff);
return(0);
}
int Midifile_reader::egetc()
/* read a single character and abort on EOF */
{
int c = Mf_getc();
if ( c == EOF ) {
mferror("premature EOF");
return EOF;
}
Mf_toberead--;
return(c);
}
int Midifile_reader::readheader()
/* read a header chunk */
{
int format, ntrks, division;
if ( readmt("MThd",Mf_skipinit) == EOF )
return(0);
Mf_toberead = read32bit();
if (midifile_error) return MIDIFILE_ERROR;
format = read16bit();
if (midifile_error) return MIDIFILE_ERROR;
ntrks = read16bit();
if (midifile_error) return MIDIFILE_ERROR;
division = read16bit();
if (midifile_error) return MIDIFILE_ERROR;
Mf_header(format,ntrks,division);
/* flush any extra stuff, in case the length of header is not 6 */
while ( Mf_toberead > 0 && !midifile_error)
(void) egetc();
return(ntrks);
}
void Midifile_reader::readtrack()
/* read a track chunk */
{
/* This array is indexed by the high half of a status byte. It's */
/* value is either the number of bytes needed (1 or 2) for a channel */
/* message, or 0 (meaning it's not a channel message). */
static int chantype[] = {
0, 0, 0, 0, 0, 0, 0, 0, /* 0x00 through 0x70 */
2, 2, 2, 2, 1, 1, 2, 0 /* 0x80 through 0xf0 */
};
long lookfor, lng;
int c, c1, type;
int sysexcontinue = 0; /* 1 if last message was an unfinished sysex */
int running = 0; /* 1 when running status used */
int status = 0; /* (possibly running) status byte */
int needed;
if ( readmt("MTrk",0) == EOF )
return;
Mf_toberead = read32bit();
if (midifile_error) return;
Mf_currtime = 0L;
Mf_starttrack();
while ( Mf_toberead > 0 ) {
Mf_currtime += readvarinum(); /* delta time */
if (midifile_error) return;
c = egetc();
if (midifile_error) return;
if ( sysexcontinue && c != 0xf7 ) {
mferror("didn't find expected continuation of a sysex");
return;
}
if ( (c & 0x80) == 0 ) { /* running status? */
if ( status == 0 ) {
mferror("unexpected running status");
return;
}
running = 1;
} else {
status = c;
running = 0;
}
needed = chantype[ (status>>4) & 0xf ];
if ( needed ) { /* ie. is it a channel message? */
if ( running )
c1 = c;
else {
c1 = egetc();
if (midifile_error) return;
}
chanmessage( status, c1, (needed>1) ? egetc() : 0 );
if (midifile_error) return;
continue;;
}
switch ( c ) {
case 0xff: /* meta event */
type = egetc();
if (midifile_error) return;
/* watch out - Don't combine the next 2 statements */
lng = readvarinum();
if (midifile_error) return;
lookfor = Mf_toberead - lng;
msginit();
while ( Mf_toberead > lookfor ) {
unsigned char c = egetc();
if (midifile_error) return;
msgadd(c);
}
metaevent(type);
break;
case 0xf0: /* start of system exclusive */
/* watch out - Don't combine the next 2 statements */
lng = readvarinum();
if (midifile_error) return;
lookfor = Mf_toberead - lng;
msginit();
msgadd(0xf0);
while ( Mf_toberead > lookfor ) {
c = egetc();
if (midifile_error) return;
msgadd(c);
}
if ( c==0xf7 || Mf_nomerge==0 )
sysex();
else
sysexcontinue = 1; /* merge into next msg */
break;
case 0xf7: /* sysex continuation or arbitrary stuff */
/* watch out - Don't combine the next 2 statements */
lng = readvarinum();
if (midifile_error) return;
lookfor = Mf_toberead - lng;
if ( ! sysexcontinue )
msginit();
while ( Mf_toberead > lookfor ) {
c = egetc();
if (midifile_error) return;
msgadd(c);
}
if ( ! sysexcontinue ) {
Mf_arbitrary(msgleng(), msg());
}
else if ( c == 0xf7 ) {
sysex();
sysexcontinue = 0;
}
break;
default:
badbyte(c);
break;
}
}
Mf_endtrack();
return;
}
void Midifile_reader::badbyte(int c)
{
char buff[32];
#pragma warning(disable: 4996) // safe in this case
(void) sprintf(buff,"unexpected byte: 0x%02x",c);
#pragma warning(default: 4996)
mferror(buff);
}
void Midifile_reader::metaevent(int type)
{
int leng = msgleng();
// made this unsigned to avoid sign extend
unsigned char *m = msg();
switch ( type ) {
case 0x00:
Mf_seqnum(to16bit(m[0],m[1]));
break;
case 0x01: /* Text event */
case 0x02: /* Copyright notice */
case 0x03: /* Sequence/Track name */
case 0x04: /* Instrument name */
case 0x05: /* Lyric */
case 0x06: /* Marker */
case 0x07: /* Cue point */
case 0x08:
case 0x09:
case 0x0a:
case 0x0b:
case 0x0c:
case 0x0d:
case 0x0e:
case 0x0f:
/* These are all text events */
Mf_text(type,leng,m);
break;
case 0x20:
Mf_chanprefix(m[0]);
break;
case 0x21:
Mf_portprefix(m[0]);
break;
case 0x2f: /* End of Track */
Mf_eot();
break;
case 0x51: /* Set tempo */
Mf_tempo(to32bit(0,m[0],m[1],m[2]));
break;
case 0x54:
Mf_smpte(m[0],m[1],m[2],m[3],m[4]);
break;
case 0x58:
Mf_timesig(m[0],m[1],m[2],m[3]);
break;
case 0x59:
Mf_keysig(m[0],m[1]);
break;
case 0x7f:
Mf_sqspecific(leng,m);
break;
default:
Mf_metamisc(type,leng,m);
}
}
void Midifile_reader::sysex()
{
Mf_sysex(msgleng(), msg());
}
void Midifile_reader::chanmessage(int status, int c1, int c2)
{
int chan = status & 0xf;
switch ( status & 0xf0 ) {
case NOTEOFF:
Mf_off(chan,c1,c2);
break;
case NOTEON:
Mf_on(chan,c1,c2);
break;
case PRESSURE:
Mf_pressure(chan,c1,c2);
break;
case CONTROLLER:
Mf_controller(chan,c1,c2);
break;
case PITCHBEND:
Mf_pitchbend(chan,c1,c2);
break;
case PROGRAM:
Mf_program(chan,c1);
break;
case CHANPRESSURE:
Mf_chanpressure(chan,c1);
break;
}
}
/* readvarinum - read a varying-length number, and return the */
/* number of characters it took. */
long Midifile_reader::readvarinum()
{
long value;
int c;
c = egetc();
if (midifile_error) return 0;
value = (long) c;
if ( c & 0x80 ) {
value &= 0x7f;
do {
c = egetc();
if (midifile_error) return 0;
value = (value << 7) + (c & 0x7f);
} while (c & 0x80);
}
return (value);
}
long Midifile_reader::to32bit(int c1, int c2, int c3, int c4)
{
long value = 0L;
value = (c1 & 0xff);
value = (value<<8) + (c2 & 0xff);
value = (value<<8) + (c3 & 0xff);
value = (value<<8) + (c4 & 0xff);
return (value);
}
int Midifile_reader::to16bit(int c1, int c2)
{
return ((c1 & 0xff ) << 8) + (c2 & 0xff);
}
long Midifile_reader::read32bit()
{
int c1, c2, c3, c4;
c1 = egetc(); if (midifile_error) return 0;
c2 = egetc(); if (midifile_error) return 0;
c3 = egetc(); if (midifile_error) return 0;
c4 = egetc(); if (midifile_error) return 0;
return to32bit(c1,c2,c3,c4);
}
int Midifile_reader::read16bit()
{
int c1, c2;
c1 = egetc(); if (midifile_error) return 0;
c2 = egetc(); if (midifile_error) return 0;
return to16bit(c1,c2);
}
void Midifile_reader::mferror(const char *s)
{
Mf_error(s);
midifile_error = 1;
}
/* The code below allows collection of a system exclusive message of */
/* arbitrary length. The Msgbuff is expanded as necessary. The only */
/* visible data/routines are msginit(), msgadd(), msg(), msgleng(). */
#define MSGINCREMENT 128
Midifile_reader::Midifile_reader()
{
Mf_nomerge = 0;
Mf_currtime = 0L;
Mf_skipinit = 0;
Mf_toberead = 0;
Msgbuff = 0; /* message buffer */
Msgsize = 0; /* Size of currently allocated Msg */
Msgindex = 0; /* index of next available location in Msg */
}
void Midifile_reader::finalize()
{
if (Msgbuff) Mf_free(Msgbuff, Msgsize);
Msgbuff = NULL;
}
void Midifile_reader::msginit()
{
Msgindex = 0;
}
unsigned char *Midifile_reader::msg()
{
return(Msgbuff);
}
int Midifile_reader::msgleng()
{
return(Msgindex);
}
void Midifile_reader::msgadd(int c)
{
/* If necessary, allocate larger message buffer. */
if ( Msgindex >= Msgsize )
msgenlarge();
Msgbuff[Msgindex++] = c;
}
void Midifile_reader::msgenlarge()
{
unsigned char *newmess;
unsigned char *oldmess = Msgbuff;
int oldleng = Msgsize;
Msgsize += MSGINCREMENT;
newmess = (unsigned char *) Mf_malloc((sizeof(unsigned char) * Msgsize) );
/* copy old message into larger new one */
if ( oldmess != 0 ) {
memcpy(newmess, oldmess, oldleng);
Mf_free(oldmess, oldleng);
}
Msgbuff = newmess;
}
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