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/*	MikMod sound library
	(c) 1998, 1999, 2000, 2001, 2002 Miodrag Vallat and others - see file
	AUTHORS for complete list.

	This library is free software; you can redistribute it and/or modify
	it under the terms of the GNU Library General Public License as
	published by the Free Software Foundation; either version 2 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 Library General Public License for more details.

	You should have received a copy of the GNU Library General Public
	License along with this library; if not, write to the Free Software
	Foundation, Inc., 59 Temple Place - Suite 330, Boston, MA
	02111-1307, USA.
*/

/*==============================================================================

  $Id$

  15 instrument MOD loader
  Also supports Ultimate Sound Tracker (old M15 format)

==============================================================================*/

#ifdef HAVE_CONFIG_H
#include "config.h"
#endif

#ifdef HAVE_UNISTD_H
#include <unistd.h>
#endif

#include <ctype.h>
#include <stdio.h>
#ifdef HAVE_MEMORY_H
#include <memory.h>
#endif
#include <string.h>

#include "mikmod_internals.h"

#ifdef SUNOS
extern int fprintf(FILE *, const char *, ...);
#endif

/*========== Module Structure */

typedef struct MSAMPINFO {
	CHAR  samplename[23];	/* 22 in module, 23 in memory */
	UWORD length;
	UBYTE finetune;
	UBYTE volume;
	UWORD reppos;
	UWORD replen;
} MSAMPINFO;

typedef struct MODULEHEADER {
	CHAR      songname[21];		/* the songname.., 20 in module, 21 in memory */
	MSAMPINFO samples[15];		/* all sampleinfo */
	UBYTE     songlength;		/* number of patterns used */
	UBYTE     magic1;       	/* should be 127 */
	UBYTE     positions[128];	/* which pattern to play at pos */
} MODULEHEADER;

typedef struct MODNOTE {
	UBYTE a,b,c,d;
} MODNOTE;

/*========== Loader variables */

static MODULEHEADER *mh = NULL;
static MODNOTE *patbuf = NULL;
static int ust_loader = 0;		/* if TRUE, load as an ust module. */

/* known file formats which can confuse the loader */
#define REJECT 2
static const char *signatures[REJECT]={
	"CAKEWALK",	/* cakewalk midi files */
	"SZDD"		/* Microsoft compressed files */
};
static const int siglen[REJECT]={8,4};

/*========== Loader code */

static int LoadModuleHeader(MODULEHEADER *h)
{
	int t,u;

	_mm_read_string(h->songname,20,modreader);

	/* sanity check : title should contain printable characters and a bunch
	   of null chars */
	for(t=0;t<20;t++)
		if((h->songname[t])&&(h->songname[t]<32)) return 0;
	for(t=0;(h->songname[t])&&(t<20);t++);
	if(t<20) for(;t<20;t++) if(h->songname[t]) return 0;

	for(t=0;t<15;t++) {
		MSAMPINFO *s=&h->samples[t];

		_mm_read_string(s->samplename,22,modreader);
		s->length   =_mm_read_M_UWORD(modreader);
		s->finetune =_mm_read_UBYTE(modreader);
		s->volume   =_mm_read_UBYTE(modreader);
		s->reppos   =_mm_read_M_UWORD(modreader);
		s->replen   =_mm_read_M_UWORD(modreader);

		/* sanity check : sample title should contain printable characters and
		   a bunch of null chars */
		for(u=0;u<20;u++)
			if((s->samplename[u])&&(s->samplename[u]</*32*/14)) return 0;
		for(u=0;(s->samplename[u])&&(u<20);u++);
		if(u<20) for(;u<20;u++) if(s->samplename[u]) return 0;

		/* sanity check : finetune values */
		if(s->finetune>>4) return 0;
	}

	h->songlength  =_mm_read_UBYTE(modreader);
	h->magic1      =_mm_read_UBYTE(modreader);	/* should be 127 */

	/* sanity check : no more than 128 positions, restart position in range */
	if((!h->songlength)||(h->songlength>128)) return 0;
	/* values encountered so far are 0x6a and 0x78 */
	if(((h->magic1&0xf8)!=0x78)&&(h->magic1!=0x6a)&&(h->magic1>h->songlength)) return 0;

	_mm_read_UBYTES(h->positions,128,modreader);

	/* sanity check : pattern range is 0..63 */
	for(t=0;t<128;t++)
		if(h->positions[t]>63) return 0;

	return(!_mm_eof(modreader));
}

/* Checks the patterns in the modfile for UST / 15-inst indications.
   For example, if an effect 3xx is found, it is assumed that the song
   is 15-inst.  If a 1xx effect has dat greater than 0x20, it is UST.

   Returns:  0 indecisive; 1 = UST; 2 = 15-inst                               */
static int CheckPatternType(int numpat)
{
	unsigned int t;
	UBYTE eff, dat;

	for(t=0;t<numpat*(64U*4);t++) {
		/* Load the pattern into the temp buffer and scan it */
		_mm_skip_BYTE(modreader);_mm_skip_BYTE(modreader);
		eff = _mm_read_UBYTE(modreader);
		dat = _mm_read_UBYTE(modreader);

		switch(eff) {
			case 1:
				if(dat>0x1f) return 1;
				if(dat<0x3)  return 2;
				break;
			case 2:
				if(dat>0x1f) return 1;
				return 2;
			case 3:
				if (dat) return 2;
				break;
			default:
				return 2;
		}
	}
	return 0;
}

static int M15_Test(void)
{
	int t, numpat;
	MODULEHEADER h;

	ust_loader = 0;
	memset(&h, 0, sizeof(MODULEHEADER));
	if(!LoadModuleHeader(&h)) return 0;

	/* reject other file types */
	for(t=0;t<REJECT;t++)
		if(!memcmp(h.songname,signatures[t],siglen[t])) return 0;

	if(h.magic1>127) return 0;
	if((!h.songlength)||(h.songlength>h.magic1)) return 0;

	for(t=0;t<15;t++) {
		/* all finetunes should be zero */
		if(h.samples[t].finetune) return 0;

		/* all volumes should be <= 64 */
		if(h.samples[t].volume>64) return 0;

		/* all instrument names should begin with s, st-, or a number */
		if((h.samples[t].samplename[0]=='s')||
		   (h.samples[t].samplename[0]=='S')) {
			if((memcmp(h.samples[t].samplename,"st-",3)) &&
			   (memcmp(h.samples[t].samplename,"ST-",3)) &&
			   (*h.samples[t].samplename))
				ust_loader = 1;
		} else
		  if(!isdigit((int)h.samples[t].samplename[0]))
				ust_loader = 1;

		if(h.samples[t].length>4999||h.samples[t].reppos>9999) {
			ust_loader = 0;
			if(h.samples[t].length>32768) return 0;
		}

		/* if loop information is incorrect as words, but correct as bytes,
		   this is likely to be an ust-style module */
		if((h.samples[t].reppos+h.samples[t].replen>h.samples[t].length)&&
		   (h.samples[t].reppos+h.samples[t].replen<(h.samples[t].length<<1))) {
			ust_loader = 1;
			return 1;
		}

		if(!ust_loader) return 1;
	}

	for(numpat=0,t=0;t<h.songlength;t++)
		if(h.positions[t]>numpat)
			numpat = h.positions[t];
	numpat++;
	switch(CheckPatternType(numpat)) {
		case 0:   /* indecisive, so check more clues... */
			break;
		case 1:
			ust_loader = 1;
			break;
		case 2:
			ust_loader = 0;
			break;
	}
	return 1;
}

static int M15_Init(void)
{
	if(!(mh=(MODULEHEADER*)MikMod_calloc(1,sizeof(MODULEHEADER)))) return 0;
	return 1;
}

static void M15_Cleanup(void)
{
	MikMod_free(mh);
	MikMod_free(patbuf);
	mh=NULL;
	patbuf=NULL;
}

/*
Old (amiga) noteinfo:

 _____byte 1_____   byte2_    _____byte 3_____   byte4_
/                \ /      \  /                \ /      \
0000          0000-00000000  0000          0000-00000000

Upper four    12 bits for    Lower four    Effect command.
bits of sam-  note period.   bits of sam-
ple number.                  ple number.
*/

static UBYTE M15_ConvertNote(MODNOTE* n, UBYTE lasteffect)
{
	UBYTE instrument,effect,effdat,note;
	UWORD period;
	UBYTE lastnote=0;

	/* decode the 4 bytes that make up a single note */
	instrument = n->c>>4;
	period     = (((UWORD)n->a&0xf)<<8)+n->b;
	effect     = n->c&0xf;
	effdat     = n->d;

	/* Convert the period to a note number */
	note=0;
	if(period) {
		for(note=0;note<7*OCTAVE;note++)
			if(period>=npertab[note]) break;
		if(note==7*OCTAVE) note=0;
		else note++;
	}

	if(instrument) {
		/* if instrument does not exist, note cut */
		if((instrument>15)||(!mh->samples[instrument-1].length)) {
			UniPTEffect(0xc,0);
			if(effect==0xc) effect=effdat=0;
		} else {
			/* if we had a note, then change instrument... */
			if(note)
				UniInstrument(instrument-1);
			/* ...otherwise, only adjust volume... */
			else {
				/* ...unless an effect was specified, which forces a new note
				   to be played */
				if(effect||effdat) {
					UniInstrument(instrument-1);
					note=lastnote;
				} else
					UniPTEffect(0xc,mh->samples[instrument-1].volume&0x7f);
			}
		}
	}
	if(note) {
		UniNote(note+2*OCTAVE-1);
		lastnote=note;
	}

	/* Convert pattern jump from Dec to Hex */
	if(effect == 0xd)
		effdat=(((effdat&0xf0)>>4)*10)+(effdat&0xf);

	/* Volume slide, up has priority */
	if((effect==0xa)&&(effdat&0xf)&&(effdat&0xf0))
		effdat&=0xf0;

	/* Handle ``heavy'' volumes correctly */
	if ((effect == 0xc) && (effdat > 0x40))
		effdat = 0x40;

	if(ust_loader) {
		switch(effect) {
			case 0:
			case 3:
				break;
			case 1:
				UniPTEffect(0,effdat);
				break;
			case 2:
				if(effdat&0xf) UniPTEffect(1,effdat&0xf);
				else if(effdat>>2)  UniPTEffect(2,effdat>>2);
				break;
			default:
				UniPTEffect(effect,effdat);
				break;
		}
	} else {
		/* An isolated 100, 200 or 300 effect should be ignored (no
		   "standalone" porta memory in mod files). However, a sequence
		   such as 1XX, 100, 100, 100 is fine. */
		if ((!effdat) && ((effect == 1)||(effect == 2)||(effect ==3)) &&
			(lasteffect < 0x10) && (effect != lasteffect))
			effect = 0;

		UniPTEffect(effect,effdat);
	}
	if (effect == 8)
		of.flags |= UF_PANNING;

	return effect;
}

static UBYTE *M15_ConvertTrack(MODNOTE* n)
{
	int t;
	UBYTE lasteffect = 0x10;	/* non existant effect */

	UniReset();
	for(t=0;t<64;t++) {
		lasteffect = M15_ConvertNote(n,lasteffect);
		UniNewline();
		n+=4;
	}
	return UniDup();
}

/* Loads all patterns of a modfile and converts them into the 3 byte format. */
static int M15_LoadPatterns(void)
{
	unsigned int t,s,tracks=0;

	if(!AllocPatterns()) return 0;
	if(!AllocTracks()) return 0;

	/* Allocate temporary buffer for loading and converting the patterns */
	if(!(patbuf=(MODNOTE*)MikMod_calloc(64U*4,sizeof(MODNOTE)))) return 0;

	for(t=0;t<of.numpat;t++) {
		/* Load the pattern into the temp buffer and convert it */
		for(s=0;s<(64U*4);s++) {
			patbuf[s].a=_mm_read_UBYTE(modreader);
			patbuf[s].b=_mm_read_UBYTE(modreader);
			patbuf[s].c=_mm_read_UBYTE(modreader);
			patbuf[s].d=_mm_read_UBYTE(modreader);
		}

		for(s=0;s<4;s++)
			if(!(of.tracks[tracks++]=M15_ConvertTrack(patbuf+s))) return 0;
	}
	return 1;
}

static int M15_Load(int curious)
{
	unsigned int t,scan;
	SAMPLE *q;
	MSAMPINFO *s;
	(void)curious;

	/* try to read module header */
	if(!LoadModuleHeader(mh)) {
		_mm_errno = MMERR_LOADING_HEADER;
		return 0;
	}

	if(ust_loader)
		of.modtype = MikMod_strdup("Ultimate Soundtracker");
	else
		of.modtype = MikMod_strdup("Soundtracker");

	/* set module variables */
	of.initspeed = 6;
	of.inittempo = 125;
	of.numchn    = 4;
	of.songname  = DupStr(mh->songname,21,1);
	of.numpos    = mh->songlength;
	of.reppos    = 0;

	/* Count the number of patterns */
	of.numpat = 0;
	for(t=0;t<of.numpos;t++)
		if(mh->positions[t]>of.numpat)
			of.numpat=mh->positions[t];
	/* since some old modules embed extra patterns, we have to check the
	   whole list to get the samples' file offsets right - however we can find
	   garbage here, so check carefully */
	scan=1;
	for(t=of.numpos;t<128;t++)
		if(mh->positions[t]>=0x80) scan=0;
	if (scan)
		for(t=of.numpos;t<128;t++) {
			if(mh->positions[t]>of.numpat)
				of.numpat=mh->positions[t];
			if((curious)&&(mh->positions[t])) of.numpos=t+1;
		}
	of.numpat++;
	of.numtrk = of.numpat*of.numchn;

	if(!AllocPositions(of.numpos)) return 0;
	for(t=0;t<of.numpos;t++)
		of.positions[t]=mh->positions[t];

	/* Finally, init the sampleinfo structures */
	of.numins=of.numsmp=15;
	if(!AllocSamples()) return 0;

	s = mh->samples;
	q = of.samples;

	for(t=0;t<of.numins;t++) {
		/* convert the samplename */
		q->samplename = DupStr(s->samplename,23,1);

		/* init the sampleinfo variables and convert the size pointers */
		q->speed     = finetune[s->finetune&0xf];
		q->volume    = s->volume;
		if(ust_loader)
			q->loopstart = s->reppos;
		else
			q->loopstart = s->reppos<<1;
		q->loopend   = q->loopstart+(s->replen<<1);
		q->length    = s->length<<1;

		q->flags = SF_SIGNED;
		if(ust_loader) q->flags |= SF_UST_LOOP;
		if(s->replen>2) q->flags |= SF_LOOP;

		s++;
		q++;
	}

	if(!M15_LoadPatterns()) return 0;
	ust_loader = 0;

	return 1;
}

static CHAR *M15_LoadTitle(void)
{
	CHAR s[21];

	_mm_fseek(modreader,0,SEEK_SET);
	if(!_mm_read_UBYTES(s,20,modreader)) return NULL;
	s[20]=0;	/* just in case */
	return(DupStr(s,21,1));
}

/*========== Loader information */

MIKMODAPI MLOADER load_m15={
	NULL,
	"15-instrument module",
	"MOD (15 instrument)",
	M15_Init,
	M15_Test,
	M15_Load,
	M15_Cleanup,
	M15_LoadTitle
};

/* ex:set ts=4: */