/*	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.
*/

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

  $Id$

  Generic MOD loader (Protracker, StarTracker, FastTracker, etc)

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

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

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

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

#include "mikmod_internals.h"
#include "mikmod_ctype.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[31];		/* all sampleinfo */
	UBYTE songlength;			/* number of patterns used */
	UBYTE magic1;				/* should be 127 */
	UBYTE positions[128];		/* which pattern to play at pos */
	UBYTE magic2[4];			/* string "M.K." or "FLT4" or "FLT8" */
} MODULEHEADER;

typedef struct MODTYPE {
	CHAR id[5];
	UBYTE channels;
	CHAR *name;
} MODTYPE;

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

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

#define MODULEHEADERSIZE 0x438

static CHAR protracker[] = "Protracker";
static CHAR startrekker[] = "Startrekker";
static CHAR fasttracker[] = "Fasttracker";
static CHAR octalyser[] = "Octalyser";
static CHAR oktalyzer[] = "Oktalyzer";
static CHAR taketracker[] = "TakeTracker";
static CHAR digitaltracker[] = "Digital Tracker MOD";
static CHAR orpheus[] = "Imago Orpheus (MOD format)";
static CHAR modsgrave[] = "Mod's Grave";
static CHAR unknown[] = "Unknown tracker MOD";

static MODULEHEADER *mh = NULL;
static MODNOTE *patbuf = NULL;
static int modtype, trekker;

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

/* given the module ID, determine the number of channels and the tracker
   description ; also alters modtype */
static BOOL MOD_CheckType(UBYTE *id, UBYTE *numchn, CHAR **descr)
{
	modtype = trekker = 0;

	/* Protracker and variants */
	if ((!memcmp(id, "M.K.", 4)) || (!memcmp(id, "M!K!", 4)) || (!memcmp(id, "M&K!", 4))) {
		*descr = protracker;
		modtype = 0;
		*numchn = 4;
		return 1;
	}

	/* Star Tracker */
	if (((!memcmp(id, "FLT", 3)) || (!memcmp(id, "EXO", 3))) &&
		(mik_isdigit(id[3]))) {
		*descr = startrekker;
		modtype = trekker = 1;
		*numchn = id[3] - '0';
		if (*numchn == 4 || *numchn == 8)
			return 1;
#ifdef MIKMOD_DEBUG
		else
			fprintf(stderr, "\rUnknown FLT%d module type\n", *numchn);
#endif
		return 0;
	}

	/* Oktalyzer (Amiga) */
	if (!memcmp(id, "OKTA", 4)) {
		*descr = oktalyzer;
		modtype = 1;
		*numchn = 8;
		return 1;
	}

	/* Octalyser (Atari) */
	if (!memcmp(id, "CD81", 4) || !memcmp(id, "CD61", 4)) {
		*descr = octalyser;
		modtype = 1;
		*numchn = id[2] - '0';
		return 1;
	}

	/* Fasttracker */
	if ((!memcmp(id + 1, "CHN", 3)) && (mik_isdigit(id[0]))) {
		*descr = fasttracker;
		modtype = 1;
		*numchn = id[0] - '0';
		return 1;
	}
	/* Fasttracker or Taketracker */
	if (((!memcmp(id + 2, "CH", 2)) || (!memcmp(id + 2, "CN", 2)))
		&& (mik_isdigit(id[0])) && (mik_isdigit(id[1]))) {
		if (id[3] == 'H') {
			*descr = fasttracker;
			modtype = 2;		/* this can also be Imago Orpheus */
		} else {
			*descr = taketracker;
			modtype = 1;
		}
		*numchn = (id[0] - '0') * 10 + (id[1] - '0');
		return 1;
	}
	/* Taketracker */
	if (!memcmp(id, "TDZ", 3) && (id[3] >= '1' && id[3] <= '3')) {
		*descr = taketracker;
		*numchn = (id[3] - '0');
		return 1;
	}

	/* Digital Tracker */
	if (!memcmp(id, "FA0", 3) && (id[3] == '4' || id[3] == '6' || id[3] == '8')) {
		*descr = digitaltracker;
		*numchn = (id[3] - '0');
		return 1;
	}

	/* Standard 4-channel MODs with unusual IDs. */
	if (!memcmp(id, "LARD", 4)		/* judgement_day_gvine.mod */
		|| !memcmp(id, "NSMS", 4)) {	/* kingdomofpleasure.mod */
		*descr = unknown;
		*numchn = 4;
		return 1;
	}

	return 0;
}

static BOOL MOD_Test(void)
{
	UBYTE id[4], numchn;
	CHAR *descr;

	_mm_fseek(modreader, MODULEHEADERSIZE, SEEK_SET);
	if (!_mm_read_UBYTES(id, 4, modreader))
		return 0;

	if (MOD_CheckType(id, &numchn, &descr))
		return 1;

	return 0;
}

static BOOL MOD_Init(void)
{
	if (!(mh = (MODULEHEADER *)MikMod_malloc(sizeof(MODULEHEADER))))
		return 0;
	return 1;
}

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

	/* extract the various information from the 4 bytes that make up a note */
	instrument = (n->a & 0x10) | (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 > 31) || (!mh->samples[instrument - 1].length)) {
			UniPTEffect(0xc, 0);
			if (effect == 0xc)
				effect = effdat = 0;
		} else {
			/* Protracker handling */
			if (!modtype) {
				/* 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);
				}
			} else {
				/* Fasttracker handling */
				UniInstrument(instrument - 1);
				if (!note)
					note = lastnote;
			}
		}
	}
	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;

	/* 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 *ConvertTrack(MODNOTE *n, int numchn)
{
	int t;
	UBYTE lasteffect = 0x10;	/* non existant effect */

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

/* Loads all patterns of a modfile and converts them into the 3 byte format. */
static BOOL ML_LoadPatterns(void)
{
	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 * of.numchn, sizeof(MODNOTE))))
		return 0;

	if (trekker && of.numchn == 8) {
		/* Startrekker module dual pattern */
		for (t = 0; t < of.numpat; t++) {
			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++] = ConvertTrack(patbuf + s, 4)))
					return 0;
			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++] = ConvertTrack(patbuf + s, 4)))
					return 0;
		}
	} else {
		/* Generic module pattern */
		for (t = 0; t < of.numpat; t++) {
			/* Load the pattern into the temp buffer and convert it */
			for (s = 0; s < (64U * of.numchn); 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 < of.numchn; s++)
				if (!(of.tracks[tracks++] = ConvertTrack(patbuf + s, of.numchn)))
					return 0;
		}
	}
	return 1;
}

static BOOL MOD_Load(BOOL curious)
{
	int t, scan;
	SAMPLE *q;
	MSAMPINFO *s;
	CHAR *descr;
	BOOL maybewow = 1;
	ULONG samplelength = 0;
	ULONG filelength;
	ULONG pos;
	char adpcm[5];

	pos = _mm_ftell(modreader);
	_mm_fseek(modreader, 0, SEEK_END);
	filelength = _mm_ftell(modreader);
	_mm_fseek(modreader, pos, SEEK_SET);

	/* try to read module header */
	_mm_read_string((CHAR *)mh->songname, 20, modreader);
	mh->songname[20] = 0;		/* just in case */

	for (t = 0; t < 31; t++) {
		s = &mh->samples[t];
		_mm_read_string(s->samplename, 22, modreader);
		s->samplename[22] = 0;	/* just in case */
		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);
		/* Mod's Grave .WOW files are converted from .669 and thus
		   do not have sample finetune or volume. */
		samplelength += (ULONG)s->length << 1;
		if (s->length && (s->finetune != 0x00 || s->volume != 0x40))
			maybewow = 0;
	}

	mh->songlength = _mm_read_UBYTE(modreader);

	/* this fixes mods which declare more than 128 positions.
	 * eg: beatwave.mod */
	if (mh->songlength > 128) { mh->songlength = 128; }

	mh->magic1 = _mm_read_UBYTE(modreader);
	_mm_read_UBYTES(mh->positions, 128, modreader);
	_mm_read_UBYTES(mh->magic2, 4, modreader);

	/* Mod's Grave .WOW files always use 0x00 for the "restart" byte. */
	if (mh->magic1 != 0x00)
		maybewow = 0;

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

	/* set module variables */
	of.initspeed = 6;
	of.inittempo = 125;
	if (!(MOD_CheckType(mh->magic2, &of.numchn, &descr))) {
		_mm_errno = MMERR_NOT_A_MODULE;
		return 0;
	}
	if (descr == digitaltracker) {
		/* Digital Tracker FA0x modules add four extra bytes after the
		 * magic. These don't seem to have ever been used for their
		 * intended purpose (rows per pattern and sample bits/rate). */
		_mm_read_M_ULONG(modreader);
	}
	if (trekker && of.numchn == 8)
		for (t = 0; t < 128; t++)
			/* if module pretends to be FLT8, yet the order table
			   contains odd numbers, chances are it's a lying FLT4... */
			if (mh->positions[t] & 1) {
				of.numchn = 4;
				break;
			}
	if (trekker && of.numchn == 8)
		for (t = 0; t < 128; t++)
			mh->positions[t] >>= 1;

	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++;

	/* Mod's Grave .WOW files have an M.K. signature but they're actually 8 channel.
	   The only way to distinguish them from a 4-channel M.K. file is to check the
	   length of the .MOD against the expected length of a .WOW file with the same
	   number of patterns as this file. To make things harder, Mod's Grave occasionally
	   adds an extra byte to .WOW files and sometimes .MOD authors pad their files.
	   Prior checks for WOW behavior should help eliminate false positives here.

	   Also note the length check relies on counting samples with a length word=1 to work. */
	if (modtype == 0 && maybewow == 1) {
		ULONG wowlength = MODULEHEADERSIZE + 4 + samplelength + of.numpat * (64 * 4 * 8);
		if ((filelength & ~1) == wowlength) {
			modtype = 1;
			descr = modsgrave;
			of.numchn = 8;
		}
	}

	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];

	if (!ML_LoadPatterns())
		return 0;

	/* Finally, init the sampleinfo structures  */
	of.numins = of.numsmp = 31;
	if (!AllocSamples())
		return 0;
	s = mh->samples;
	q = of.samples;
	pos = _mm_ftell(modreader);
	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 & 0x7f;
		q->loopstart = (ULONG)s->reppos << 1;
		q->loopend = q->loopstart + ((ULONG)s->replen << 1);
		q->length = (ULONG)s->length << 1;
		q->flags = SF_SIGNED;
		/* Imago Orpheus creates MODs with 16 bit samples, check */
		if ((modtype == 2) && (s->volume & 0x80)) {
			q->flags |= SF_16BITS;
			descr = orpheus;
		}
		if (s->replen > 2)
			q->flags |= SF_LOOP;

		q->seekpos = pos;
		/* Test for MODPlugin ADPCM. These are indicated by "ADPCM"
		 * embedded at the start of each sample's data. :( */
		memset(adpcm, 0, sizeof(adpcm));
		_mm_read_UBYTES(adpcm, 5, modreader);
		if (!memcmp(adpcm, "ADPCM", 5)) {
			q->flags |= SF_ADPCM4;
			q->seekpos += 5;
			/* Stored half-length, plus a 16 byte table. */
			pos += s->length + 16 + 5;
			_mm_fseek(modreader, s->length + 16, SEEK_CUR);
		} else {
			pos += q->length;
			_mm_fseek(modreader, q->length - 5, SEEK_CUR);
		}

		s++;
		q++;
	}

	of.modtype = MikMod_strdup(descr);

	return 1;
}

static CHAR *MOD_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_mod = {
	NULL,
	"Standard module",
	"MOD (31 instruments)",
	MOD_Init,
	MOD_Test,
	MOD_Load,
	MOD_Cleanup,
	MOD_LoadTitle
};

/* ex:set ts=4: */
