/*	MikMod sound library
	(c) 1998, 1999, 2000, 2001 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.
*/

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

  $Id$

  All routines dealing with the manipulation of UNITRK streams

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

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

#include "mikmod_internals.h"

#include <string.h>

/* Unibuffer chunk size */
#define BUFPAGE  128

UWORD unioperands[UNI_LAST]={
	0, /* not used */
	1, /* UNI_NOTE */
	1, /* UNI_INSTRUMENT */
	1, /* UNI_PTEFFECT0 */
	1, /* UNI_PTEFFECT1 */
	1, /* UNI_PTEFFECT2 */
	1, /* UNI_PTEFFECT3 */
	1, /* UNI_PTEFFECT4 */
	1, /* UNI_PTEFFECT5 */
	1, /* UNI_PTEFFECT6 */
	1, /* UNI_PTEFFECT7 */
	1, /* UNI_PTEFFECT8 */
	1, /* UNI_PTEFFECT9 */
	1, /* UNI_PTEFFECTA */
	1, /* UNI_PTEFFECTB */
	1, /* UNI_PTEFFECTC */
	1, /* UNI_PTEFFECTD */
	1, /* UNI_PTEFFECTE */
	1, /* UNI_PTEFFECTF */
	1, /* UNI_S3MEFFECTA */
	1, /* UNI_S3MEFFECTD */
	1, /* UNI_S3MEFFECTE */
	1, /* UNI_S3MEFFECTF */
	1, /* UNI_S3MEFFECTI */
	1, /* UNI_S3MEFFECTQ */
	1, /* UNI_S3MEFFECTR */
	1, /* UNI_S3MEFFECTT */
	1, /* UNI_S3MEFFECTU */
	0, /* UNI_KEYOFF */
	1, /* UNI_KEYFADE */
	2, /* UNI_VOLEFFECTS */
	1, /* UNI_XMEFFECT4 */
	1, /* UNI_XMEFFECT6 */
	1, /* UNI_XMEFFECTA */
	1, /* UNI_XMEFFECTE1 */
	1, /* UNI_XMEFFECTE2 */
	1, /* UNI_XMEFFECTEA */
	1, /* UNI_XMEFFECTEB */
	1, /* UNI_XMEFFECTG */
	1, /* UNI_XMEFFECTH */
	1, /* UNI_XMEFFECTL */
	1, /* UNI_XMEFFECTP */
	1, /* UNI_XMEFFECTX1 */
	1, /* UNI_XMEFFECTX2 */
	1, /* UNI_ITEFFECTG */
	1, /* UNI_ITEFFECTH */
	1, /* UNI_ITEFFECTI */
	1, /* UNI_ITEFFECTM */
	1, /* UNI_ITEFFECTN */
	1, /* UNI_ITEFFECTP */
	1, /* UNI_ITEFFECTT */
	1, /* UNI_ITEFFECTU */
	1, /* UNI_ITEFFECTW */
	1, /* UNI_ITEFFECTY */
	2, /* UNI_ITEFFECTZ */
	1, /* UNI_ITEFFECTS0 */
	2, /* UNI_ULTEFFECT9 */
	2, /* UNI_MEDSPEED */
	0, /* UNI_MEDEFFECTF1 */
	0, /* UNI_MEDEFFECTF2 */
	0, /* UNI_MEDEFFECTF3 */
	2, /* UNI_OKTARP */
};

/* Sparse description of the internal module format
   ------------------------------------------------

  A UNITRK stream is an array of bytes representing a single track of a pattern.
It's made up of 'repeat/length' bytes, opcodes and operands (sort of a assembly
language):

rrrlllll
[REP/LEN][OPCODE][OPERAND][OPCODE][OPERAND] [REP/LEN][OPCODE][OPERAND]..
^                                         ^ ^
|-------ROWS 0 - 0+REP of a track---------| |-------ROWS xx - xx+REP of a track...

  The rep/len byte contains the number of bytes in the current row, _including_
the length byte itself (So the LENGTH byte of row 0 in the previous example
would have a value of 5). This makes it easy to search through a stream for a
particular row. A track is concluded by a 0-value length byte.

  The upper 3 bits of the rep/len byte contain the number of times -1 this row
is repeated for this track. (so a value of 7 means this row is repeated 8 times)

  Opcodes can range from 1 to 255 but currently only opcodes 1 to 62 are being
used. Each opcode can have a different number of operands. You can find the
number of operands to a particular opcode by using the opcode as an index into
the 'unioperands' table.

*/

/*========== Reading routines */

static	UBYTE *rowstart; /* startadress of a row */
static	UBYTE *rowend;   /* endaddress of a row (exclusive) */
static	UBYTE *rowpc;    /* current unimod(tm) programcounter */

static	UBYTE lastbyte;  /* for UniSkipOpcode() */

void UniSetRow(UBYTE* t)
{
	rowstart = t;
	rowpc    = rowstart;
	rowend   = t?rowstart+(*(rowpc++)&0x1f):t;
}

UBYTE UniGetByte(void)
{
	return lastbyte = (rowpc<rowend)?*(rowpc++):0;
}

UWORD UniGetWord(void)
{
	return ((UWORD)UniGetByte()<<8)|UniGetByte();
}

void UniSkipOpcode(void)
{
	if (lastbyte < UNI_LAST) {
		UWORD t = unioperands[lastbyte];

		while (t--)
			UniGetByte();
	}
}

/* Finds the address of row number 'row' in the UniMod(tm) stream 't' returns
   NULL if the row can't be found. */
UBYTE *UniFindRow(UBYTE* t,UWORD row)
{
	UBYTE c,l;

	if(t)
		while(1) {
			c = *t;             /* get rep/len byte */
			if(!c) return NULL; /* zero ? -> end of track.. */
			l = (c>>5)+1;       /* extract repeat value */
			if(l>row) break;    /* reached wanted row? -> return pointer */
			row -= l;           /* haven't reached row yet.. update row */
			t += c&0x1f;        /* point t to the next row */
		}
	return t;
}

/*========== Writing routines */

static	UBYTE *unibuf; /* pointer to the temporary unitrk buffer */
static	UWORD unimax;  /* buffer size */

static	UWORD unipc;   /* buffer cursor */
static	UWORD unitt;   /* current row index */
static	UWORD lastp;   /* previous row index */

/* Resets index-pointers to create a new track. */
void UniReset(void)
{
	unitt     = 0;   /* reset index to rep/len byte */
	unipc     = 1;   /* first opcode will be written to index 1 */
	lastp     = 0;   /* no previous row yet */
	unibuf[0] = 0;   /* clear rep/len byte */
}

/* Expands the buffer */
static BOOL UniExpand(int wanted)
{
	if ((unipc+wanted)>=unimax) {
		UBYTE *newbuf;

		/* Expand the buffer by BUFPAGE bytes */
		newbuf=(UBYTE*)MikMod_realloc(unibuf,(unimax+BUFPAGE)*sizeof(UBYTE));

		/* Check if realloc succeeded */
		if(newbuf) {
			unibuf = newbuf;
			unimax+=BUFPAGE;
			return 1;
		} else 
			return 0;
	}
	return 1;
}

/* Appends one byte of data to the current row of a track. */
void UniWriteByte(UBYTE data)
{
	if (UniExpand(1))
		/* write byte to current position and update */
		unibuf[unipc++]=data;
}

void UniWriteWord(UWORD data)
{
	if (UniExpand(2)) {
		unibuf[unipc++]=data>>8;
		unibuf[unipc++]=data&0xff;
	}
}

static BOOL MyCmp(UBYTE* a,UBYTE* b,UWORD l)
{
	UWORD t;

	for(t=0;t<l;t++)
		if(*(a++)!=*(b++)) return 0;
	return 1;
}

/* Closes the current row of a unitrk stream (updates the rep/len byte) and sets
   pointers to start a new row. */
void UniNewline(void)
{
	UWORD n,l,len;

	n = (unibuf[lastp]>>5)+1;     /* repeat of previous row */
	l = (unibuf[lastp]&0x1f);     /* length of previous row */

	len = unipc-unitt;            /* length of current row */

	/* Now, check if the previous and the current row are identical.. when they
	   are, just increase the repeat field of the previous row */
	if(n<8 && len==l && MyCmp(&unibuf[lastp+1],&unibuf[unitt+1],len-1)) {
		unibuf[lastp]+=0x20;
		unipc = unitt+1;
	} else {
		if (UniExpand(unitt-unipc)) {
			/* current and previous row aren't equal... update the pointers */
			unibuf[unitt] = len;
			lastp = unitt;
			unitt = unipc++;
		}
	}
}

/* Terminates the current unitrk stream and returns a pointer to a copy of the
   stream. */
UBYTE* UniDup(void)
{
	UBYTE *d;

	if (!UniExpand(unitt-unipc)) return NULL;
	unibuf[unitt] = 0;

	if(!(d=(UBYTE *)MikMod_malloc(unipc))) return NULL;
	memcpy(d,unibuf,unipc);

	return d;
}

BOOL UniInit(void)
{
	unimax = BUFPAGE;

	if(!(unibuf=(UBYTE*)MikMod_malloc(unimax*sizeof(UBYTE)))) return 0;
	return 1;
}

void UniCleanup(void)
{
	if(unibuf) MikMod_free(unibuf);
	unibuf = NULL;
}

/* ex:set ts=4: */