/
munitrk.c
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/*
Name:
MUNITRK.C
Description:
All routines dealing with the manipulation of UNITRK(tm) streams
Portability:
All systems - all compilers
*/
#include <string.h>
#include "mikmod.h"
#define BUFPAGE 128 /* smallest unibuffer size */
#define TRESHOLD 16
UWORD unioperands[256] =
{ 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_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_ITEFFECTU */
1, /* UNI_ITEFFECTW */
1, /* UNI_ITEFFECTY */
1 /* UNI_ITEFFECTS0 */
};
/* unibuffer is increased by BUFPAGE */
/* bytes when unipc reaches unimax-TRESHOLD */
/*
Ok.. I'll try to explain the new internal module format.. so here it goes:
The UNITRK(tm) 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 45 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.
*/
/***************************************************************************
>>>>>>>>>>> Next are the routines for reading a UNITRK stream: <<<<<<<<<<<<<
***************************************************************************/
static UBYTE *rowstart; /* startadress of a row */
static UBYTE *rowend; /* endaddress of a row (exclusive) */
static UBYTE *rowpc; /* current unimod(tm) programcounter */
void UniSetRow(UBYTE *t)
{
rowstart = t;
rowpc = rowstart;
rowend = rowstart+(*(rowpc++)&0x1f);
}
UBYTE UniGetByte(void)
{
return (rowpc<rowend) ? *(rowpc++) : 0;
}
void UniSkipOpcode(UBYTE op)
{
UWORD t = unioperands[op];
while(t--) UniGetByte();
}
UBYTE *UniFindRow(UBYTE *t, UWORD row)
/* Finds the address of row number 'row' in the UniMod(tm) stream 't' */
/* returns NULL if the row can't be found. */
{
UBYTE c,l;
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;
}
/***************************************************************************
>>>>>>>>>>> Next are the routines for CREATING UNITRK streams: <<<<<<<<<<<<<
***************************************************************************/
static UBYTE *unibuf; /* pointer to the temporary unitrk buffer */
static UWORD unimax; /* maximum number of bytes to be written to this buffer */
static UWORD unipc; /* index in the buffer where next opcode will be written */
static UWORD unitt; /* holds index of the rep/len byte of a row */
static UWORD lastp; /* holds index to the previous row (needed for compressing) */
void UniReset(void)
/* Resets index-pointers to create a new track. */
{
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 */
}
void UniWrite(UBYTE data)
/* Appends one byte of data to the current row of a track. */
{
/* write byte to current position and update */
unibuf[unipc++] = data;
/* Check if we've reached the end of the buffer */
if(unipc > (unimax-TRESHOLD))
{ UBYTE *newbuf;
/* We've reached the end of the buffer, so expand */
/* the buffer by BUFPAGE bytes */
newbuf = (UBYTE *)realloc(unibuf, unimax+BUFPAGE);
/* Check if realloc succeeded */
if(newbuf!=NULL)
{ unibuf = newbuf;
unimax+=BUFPAGE;
} else
{ /* realloc failed, so decrease unipc so we won't write beyond */
/* the end of the buffer.. I don't report the out-of-memory */
/* here; the UniDup() will fail anyway so that's where the */
/* loader sees that something went wrong */
unipc--;
}
}
}
BOOL MyCmp(UBYTE *a, UBYTE *b, UWORD l)
{
UWORD t;
for(t=0; t<l; t++)
if(*(a++) != *(b++)) return 0;
return 1;
}
void UniNewline(void)
/* Closes the current row of a unitrk stream (updates the rep/len byte) */
/* and sets pointers to start a new row. */
{
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
{ /* current and previous row aren't equal.. so just update the pointers */
unibuf[unitt] = len;
lastp = unitt;
unitt = unipc;
unipc++;
}
}
UBYTE *UniDup(void)
/* Terminates the current unitrk stream and returns a pointer */
/* to a copy of the stream. */
{
UBYTE *d;
unibuf[unitt] = 0;
if((d=(UBYTE *)_mm_malloc(unipc))==NULL) return NULL;
memcpy(d,unibuf,unipc);
return d;
}
UWORD TrkLen(UBYTE *t)
/* Determines the length (in rows) of a unitrk stream 't' */
{
UWORD len = 0;
UBYTE c;
while(c = *t & 0x1f)
{ len += c;
t += c;
}
len++;
return len;
}
BOOL UniInit(void)
{
unimax = BUFPAGE;
if(!(unibuf=(UBYTE *)_mm_malloc(unimax))) return 0;
return 1;
}
void UniCleanup(void)
{
if(unibuf!=NULL) free(unibuf);
unibuf = NULL;
}