/*	MikMod sound library
	(c) 1998, 1999 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: load_s3m.c,v 1.20 1999/02/08 07:24:10 miod Exp $

  Screamtracker (S3M) module loader

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

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

#include <string.h>

#include <mikmod_internals.h>

/*========== Module structure */

/* header */
typedef struct S3MHEADER {
	CHAR  songname[28];
	UBYTE t1a;
	UBYTE type;
	UBYTE unused1[2];
	UWORD ordnum;
	UWORD insnum;
	UWORD patnum;
	UWORD flags;
	UWORD tracker;
	UWORD fileformat;
	CHAR  scrm[4];
	UBYTE mastervol;
	UBYTE initspeed;
	UBYTE inittempo;
	UBYTE mastermult;
	UBYTE ultraclick;
	UBYTE pantable;
	UBYTE unused2[8];
	UWORD special;
	UBYTE channels[32];
} S3MHEADER;

/* sample information */
typedef struct S3MSAMPLE {
	UBYTE type;
	CHAR  filename[12];
	UBYTE memsegh;
	UWORD memsegl;
	ULONG length;
	ULONG loopbeg;
	ULONG loopend;
	UBYTE volume;
	UBYTE dsk;
	UBYTE pack;
	UBYTE flags;
	ULONG c2spd;
	UBYTE unused[12];
	CHAR  sampname[28];
	CHAR  scrs[4];
} S3MSAMPLE;

typedef struct S3MNOTE {
	UBYTE note,ins,vol,cmd,inf;
} S3MNOTE;

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

static S3MNOTE   *s3mbuf  = NULL; /* pointer to a complete S3M pattern */
static S3MHEADER *mh      = NULL;
static UWORD     *paraptr = NULL; /* parapointer array (see S3M docs) */

/* tracker identifiers */
#define NUMTRACKERS (5)
static CHAR* S3M_Version[NUMTRACKERS] = {
	"Screamtracker x.xx",
	"Imago Orpheus x.xx (S3M format)",
	"Impulse Tracker x.xx (S3M format)",
	"Unknown tracker x.xx (S3M format)",
	"Impulse Tracker 2.14p3 (S3M format)"
};
/* version number position in above array */
static int numeric[NUMTRACKERS-1]={14,14,16,16};

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

BOOL S3M_Test(void)
{
	UBYTE id[4];

	_mm_fseek(modreader,0x2c,SEEK_SET);
	if(!_mm_read_UBYTES(id,4,modreader)) return 0;
	if(!memcmp(id,"SCRM",4)) return 1;
	return 0;
}

BOOL S3M_Init(void)
{
	if(!(s3mbuf=(S3MNOTE*)_mm_malloc(32*64*sizeof(S3MNOTE)))) return 0;
	if(!(mh=(S3MHEADER*)_mm_malloc(sizeof(S3MHEADER)))) return 0;
	if(!(poslookup=(UBYTE*)_mm_malloc(sizeof(UBYTE)*256))) return 0;

	return 1;
}

void S3M_Cleanup(void)
{
	if(s3mbuf) free(s3mbuf);
	if(paraptr) free(paraptr);
	if(poslookup) free(poslookup);
	if(mh) free(mh);

	paraptr   = NULL;
	s3mbuf    = NULL;
	poslookup = NULL;
	mh        = NULL;
}

/* Because so many s3m files have 16 channels as the set number used, but really
   only use far less (usually 8 to 12 still), I had to make this function, which
   determines the number of channels that are actually USED by a pattern.

   For every channel that's used, it sets the appropriate array entry of the
   global variable 'remap'

   NOTE: You must first seek to the file location of the pattern before calling
         this procedure.

   Returns 1 on fail.                                                         */
static BOOL S3M_GetNumChannels(void)
{
	int row=0,flag,ch;

	while(row<64) {
		flag=_mm_read_UBYTE(modreader);

		if(_mm_eof(modreader)) {
			_mm_errno = MMERR_LOADING_PATTERN;
			return 1;
		}

		if(flag) {
			ch=flag&31;
			if(mh->channels[ch]<32) remap[ch] = 0;
			if(flag&32) {_mm_read_UBYTE(modreader);_mm_read_UBYTE(modreader);}
			if(flag&64) _mm_read_UBYTE(modreader);
			if(flag&128){_mm_read_UBYTE(modreader);_mm_read_UBYTE(modreader);}
		} else row++;
	}
	return 0;
}    

static BOOL S3M_ReadPattern(void)
{
	int row=0,flag,ch;
	S3MNOTE *n,dummy;

	/* clear pattern data */
	memset(s3mbuf,255,32*64*sizeof(S3MNOTE));

	while(row<64) {
		flag=_mm_read_UBYTE(modreader);

		if(_mm_eof(modreader)) {
			_mm_errno = MMERR_LOADING_PATTERN;
			return 0;
		}

		if(flag) {
			ch=remap[flag&31];

			if(ch!=-1)
				n=&s3mbuf[(64U*ch)+row];
			else
				n=&dummy;

			if(flag&32) {
				n->note=_mm_read_UBYTE(modreader);
				n->ins=_mm_read_UBYTE(modreader);
			}
			if(flag&64)
				n->vol=_mm_read_UBYTE(modreader);
			if(flag&128) {
				n->cmd=_mm_read_UBYTE(modreader);
				n->inf=_mm_read_UBYTE(modreader);
			}
		} else row++;
	}
	return 1;
}

static UBYTE* S3M_ConvertTrack(S3MNOTE* tr)
{
	int t;

	UniReset();
	for(t=0;t<64;t++) {
		UBYTE note,ins,vol;

		note=tr[t].note;
		ins=tr[t].ins;
		vol=tr[t].vol;

		if((ins)&&(ins!=255)) UniInstrument(ins-1);
		if(note!=255) {
			if(note==254) UniPTEffect(0xc,0);	/* note cut command */
			else UniNote(((note>>4)*OCTAVE)+(note&0xf));	/* normal note */
		}
		if(vol<255) UniPTEffect(0xc,vol);

		S3MIT_ProcessCmd(tr[t].cmd,tr[t].inf,1);
		UniNewline();
	}
	return UniDup();
}

BOOL S3M_Load(BOOL curious)
{
	int t,u,track = 0;
	SAMPLE *q;
	UBYTE pan[32];

	/* try to read module header */
	_mm_read_string(mh->songname,28,modreader);
	mh->t1a         =_mm_read_UBYTE(modreader);
	mh->type        =_mm_read_UBYTE(modreader);
	_mm_read_UBYTES(mh->unused1,2,modreader);
	mh->ordnum      =_mm_read_I_UWORD(modreader);
	mh->insnum      =_mm_read_I_UWORD(modreader);
	mh->patnum      =_mm_read_I_UWORD(modreader);
	mh->flags       =_mm_read_I_UWORD(modreader);
	mh->tracker     =_mm_read_I_UWORD(modreader);
	mh->fileformat  =_mm_read_I_UWORD(modreader);
	_mm_read_string(mh->scrm,4,modreader);
	mh->mastervol   =_mm_read_UBYTE(modreader);
	mh->initspeed   =_mm_read_UBYTE(modreader);
	mh->inittempo   =_mm_read_UBYTE(modreader);
	mh->mastermult  =_mm_read_UBYTE(modreader);
	mh->ultraclick  =_mm_read_UBYTE(modreader);
	mh->pantable    =_mm_read_UBYTE(modreader);
	_mm_read_UBYTES(mh->unused2,8,modreader);
	mh->special     =_mm_read_I_UWORD(modreader);
	_mm_read_UBYTES(mh->channels,32,modreader);

	if(_mm_eof(modreader)) {
		_mm_errno = MMERR_LOADING_HEADER;
		return 0;
	}

	/* set module variables */
	of.songname    = DupStr(mh->songname,28,0);
	of.numpat      = mh->patnum;
	of.reppos      = 0;
	of.numins      = of.numsmp = mh->insnum;
	of.initspeed   = mh->initspeed;
	of.inittempo   = mh->inittempo;
	of.initvolume  = mh->mastervol<<1;
	if((mh->tracker==0x1300)||(mh->flags&64))
		of.flags|=UF_S3MSLIDES;

	/* read the order data */
	if(!AllocPositions(mh->ordnum)) return 0;
	for(t=0;t<mh->ordnum;t++)
		of.positions[t]=_mm_read_UBYTE(modreader);

	of.numpos=0;poslookupcnt=mh->ordnum;
	for(t=0;t<mh->ordnum;t++) {
		of.positions[of.numpos]=of.positions[t];
		poslookup[t]=of.numpos;	/* bug fix for freaky S3Ms */
		if(of.positions[t]<254) of.numpos++;        
		else
		  /* special end of song pattern */
		  if((of.positions[t]==255)&&(!curious)) break;
	}

	if(!(paraptr=(UWORD*)_mm_malloc((of.numins+of.numpat)*sizeof(UWORD))))
		return 0;

	/* read the instrument+pattern parapointers */
	_mm_read_I_UWORDS(paraptr,of.numins+of.numpat,modreader);

	if(mh->pantable==252) {
		/* read the panning table (ST 3.2 addition.  See below for further
		   portions of channel panning [past reampper]). */
		_mm_read_UBYTES(pan,32,modreader);
	}

	if(_mm_eof(modreader)) {
		_mm_errno = MMERR_LOADING_HEADER;
		return 0;
	}

	/* load samples */
	if(!AllocSamples()) return 0;
	q = of.samples;
	for(t=0;t<of.numins;t++) {
		S3MSAMPLE s;

		/* seek to instrument position */
		_mm_fseek(modreader,((long)paraptr[t])<<4,SEEK_SET);
		/* and load sample info */
		s.type      =_mm_read_UBYTE(modreader);
		_mm_read_string(s.filename,12,modreader);
		s.memsegh   =_mm_read_UBYTE(modreader);
		s.memsegl   =_mm_read_I_UWORD(modreader);
		s.length    =_mm_read_I_ULONG(modreader);
		s.loopbeg   =_mm_read_I_ULONG(modreader);
		s.loopend   =_mm_read_I_ULONG(modreader);
		s.volume    =_mm_read_UBYTE(modreader);
		s.dsk       =_mm_read_UBYTE(modreader);
		s.pack      =_mm_read_UBYTE(modreader);
		s.flags     =_mm_read_UBYTE(modreader);
		s.c2spd     =_mm_read_I_ULONG(modreader);
		_mm_read_UBYTES(s.unused,12,modreader);
		_mm_read_string(s.sampname,28,modreader);
		_mm_read_string(s.scrs,4,modreader);

		if(_mm_eof(modreader)) {
			_mm_errno = MMERR_LOADING_SAMPLEINFO;
			return 0;
		}

		q->samplename = DupStr(s.sampname,28,0);
		q->speed      = s.c2spd;
		q->length     = s.length;
		q->loopstart  = s.loopbeg;
		q->loopend    = s.loopend;
		q->volume     = s.volume;
		q->seekpos    = (((long)s.memsegh)<<16|s.memsegl)<<4;

		if(s.flags&1) q->flags |= SF_LOOP;
		if(s.flags&4) q->flags |= SF_16BITS;
		if(mh->fileformat==1) q->flags |= SF_SIGNED;

		/* don't load sample if it doesn't have the SCRS tag */
		if(memcmp(s.scrs,"SCRS",4)) q->length = 0;

		q++;
	}

	/* determine the number of channels actually used. */
	of.numchn = 0;
	memset(remap,-1,32*sizeof(UBYTE));
	for(t=0;t<of.numpat;t++) {
		/* seek to pattern position (+2 skip pattern length) */
		_mm_fseek(modreader,(long)((paraptr[of.numins+t])<<4)+2,SEEK_SET);
		if(S3M_GetNumChannels()) return 0;
	}
	/* only Imago Orpheus creates S3M with more than 16 channels */
	if((of.numchn>16)&&(mh->tracker>>12!=2)) {
		_mm_errno=MMERR_LOADING_HEADER;
		return 0;
	}

	/* then we can decide the module type */
	t=mh->tracker>>12;
	if((!t)||(t>3)) t=NUMTRACKERS-1; /* unknown tracker */
	if(mh->tracker>=0x3216)
		t=NUMTRACKERS; /* IT 2.14p3 */
	else
	  if(mh->tracker==0x3215)
		mh->tracker=0x3214; /* lie about IT 2.14p1 or p2, report 2.14 */
	of.modtype = strdup(S3M_Version[t-1]);
	if(t!=NUMTRACKERS) {
		of.modtype[numeric[t-1]] = ((mh->tracker>>8) &0xf)+'0';
		of.modtype[numeric[t-1]+2] = ((mh->tracker>>4)&0xf)+'0';
		of.modtype[numeric[t-1]+3] = ((mh->tracker)&0xf)+'0';
	}

	/* build the remap array  */
	for(t=0;t<32;t++)
		if(!remap[t]) 
			remap[t]=of.numchn++;

	/* set panning positions after building remap chart! */
	for(t=0;t<32;t++) 
		if((mh->channels[t]<32)&&(remap[t]!=-1)) {
			if(mh->channels[t]<8)
				of.panning[remap[t]]=0x20;	/* 0x30 = std s3m val */
			else
				of.panning[remap[t]]=0xd0;	/* 0xc0 = std s3m val */
		}
	if(mh->pantable==252)
		/* set panning positions according to panning table (new for st3.2) */
		for(t=0;t<32;t++)
			if((pan[t]&0x20)&&(mh->channels[t]<32)&&(remap[t]!=-1))
				of.panning[remap[t]]=(pan[t]&0xf)<<4;

	/* load pattern info */
	of.numtrk=of.numpat*of.numchn;
	if(!AllocTracks()) return 0;
	if(!AllocPatterns()) return 0;

	for(t=0;t<of.numpat;t++) {
		/* seek to pattern position (+2 skip pattern length) */
		_mm_fseek(modreader,(((long)paraptr[of.numins+t])<<4)+2,SEEK_SET);
		if(!S3M_ReadPattern()) return 0;
		for(u=0;u<of.numchn;u++)
			if(!(of.tracks[track++]=S3M_ConvertTrack(&s3mbuf[u*64]))) return 0;
	}

	return 1;
}

CHAR *S3M_LoadTitle(void)
{
	CHAR s[28];

	_mm_fseek(modreader,0,SEEK_SET);
	if(!_mm_read_UBYTES(s,28,modreader)) return NULL;

	return(DupStr(s,28,0));
}

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

MLOADER load_s3m={
	NULL,
	"S3M",
	"S3M loader v1.0",
	S3M_Init,
	S3M_Test,
	S3M_Load,
	S3M_Cleanup,
	S3M_LoadTitle
};
