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// this is not a code to be separately compiled!
// instead, it is included in mhmt-depack.c several times and depends on existing at include moment #define's to generate some compiling code
//
// // example defines:
//#define DPK_CHECK // check input stream for consistency
//#define DPK_DEPACK // do depacking
//#define DPK_REPERR // report errors via printf
{
ULONG check
;
ULONG byte
,bits
,bitlen
;
LONG disp
;
ULONG length
;
ULONG stop
;
ULONG success
= 1;
// rewind input stream
//
check
= depack_getbyte
(DEPACK_GETBYTE_REWIND
);
#ifdef DPK_CHECK
if( 0xFFFFFFFF == check
)
{
#ifdef DPK_REPERR
printf("mhmt-depack-megalz.c:{} - Can't rewind input stream!\n");
#endif
return 0;
}
#endif
// first byte of input stream goes to the output unchanged
//
byte
= depack_getbyte
(DEPACK_GETBYTE_NEXT
);
#ifdef DPK_CHECK
if( 0xFFFFFFFF == byte
)
{
NO_BYTE
:
#ifdef DPK_REPERR
printf("mhmt-depack-megalz.c:{} - Can't get byte from input stream!\n");
#endif
return 0;
}
#endif
#ifdef DPK_DEPACK
success
= success
&& depack_outbyte
( (UBYTE
)(0x00FF&byte
), DEPACK_OUTBYTE_ADD
);
#endif
#ifdef DPK_CHECK
#ifdef DPK_REPERR
#endif
#endif
// next is byte to the bitstream
//
check
= depack_getbits
(8,DEPACK_GETBITS_FORCE
);
#ifdef DPK_CHECK
if( 0xFFFFFFFF == check
)
{
NO_BITS
:
#ifdef DPK_REPERR
printf("mhmt-depack-megalz.c:{} - Can't get bits from input stream!\n");
#endif
return 0;
}
#endif
// now normal depacking loop
//
stop
= 0;
while( (!stop
) && success
)
{
bits
= depack_getbits
(1,DEPACK_GETBITS_NEXT
);
#ifdef DPK_CHECK
if( 0xFFFFFFFF == bits
) goto NO_BITS
;
#endif
if( 1&bits
) // %1<byte>
{
byte
= depack_getbyte
(DEPACK_GETBYTE_NEXT
);
#ifdef DPK_CHECK
if( 0xFFFFFFFF == byte
) goto NO_BYTE
;
#endif
#ifdef DPK_DEPACK
success
= success
&& depack_outbyte
( (UBYTE
)(0x00FF&byte
), DEPACK_OUTBYTE_ADD
);
#endif
}
else // %0xx
{
bits
= depack_getbits
(2,DEPACK_GETBITS_NEXT
);
#ifdef DPK_CHECK
if( 0xFFFFFFFF == bits
) goto NO_BITS
;
#endif
switch( 0x03 & bits
)
{
case 0x00: // %000xxx
bits
= depack_getbits
(3,DEPACK_GETBITS_NEXT
);
#ifdef DPK_CHECK
if( 0xFFFFFFFF == bits
) goto NO_BITS
;
#endif
disp
= (-8) | (bits
&0x07); // FFFFFFF8..FFFFFFFF (-8..-1)
#ifdef DPK_CHECK
if( (ULONG
)(-disp
) > wrk.
maxwin )
{
WRONG_DISP
:
#ifdef DPK_REPERR
printf("mhmt-depack-megalz.c:{} - Wrong lookback displacement of %d, greater than maxwin\n",(-disp
) );
#endif
return 0;
}
#endif
#ifdef DPK_DEPACK
success
= success
&& depack_repeat
(disp
,1);
#endif
break;
case 0x01: // %001
byte
= depack_getbyte
(DEPACK_GETBYTE_NEXT
);
#ifdef DPK_CHECK
if( 0xFFFFFFFF == byte
) goto NO_BYTE
;
#endif
disp
= (-256) | (0x00FF&byte
); // -1..-256
#ifdef DPK_CHECK
if( (ULONG
)(-disp
) > wrk.
maxwin ) goto WRONG_DISP
;
#endif
#ifdef DPK_DEPACK
success
= success
&& depack_repeat
(disp
,2);
#endif
break;
case 0x02: // %010
length
= 3;
FAR_DISP
:
bits
= depack_getbits
(1,DEPACK_GETBITS_NEXT
);
#ifdef DPK_CHECK
if( 0xFFFFFFFF == bits
) goto NO_BITS
;
#endif
if( !(1&bits
) ) // -1..-256
{
byte
= depack_getbyte
(DEPACK_GETBYTE_NEXT
);
#ifdef DPK_CHECK
if( 0xFFFFFFFF == byte
) goto NO_BYTE
;
#endif
disp
= (-256) | (0x00FF&byte
); // -1..-256
#ifdef DPK_CHECK
if( (ULONG
)(-disp
) > wrk.
maxwin ) goto WRONG_DISP
;
#endif
#ifdef DPK_DEPACK
success
= success
&& depack_repeat
(disp
,length
);
#endif
}
else // -257..-4352
{
bits
= depack_getbits
(4,DEPACK_GETBITS_NEXT
);
#ifdef DPK_CHECK
if( 0xFFFFFFFF == bits
) goto NO_BITS
;
#endif
byte
= depack_getbyte
(DEPACK_GETBYTE_NEXT
);
#ifdef DPK_CHECK
if( 0xFFFFFFFF == byte
) goto NO_BYTE
;
#endif
disp
= ( ((-16)|(15&bits
)) - 1 )*0x100 + byte
;
#ifdef DPK_CHECK
if( (ULONG
)(-disp
) > wrk.
maxwin ) goto WRONG_DISP
;
#endif
#ifdef DPK_DEPACK
success
= success
&& depack_repeat
(disp
,length
);
#endif
}
break;
case 0x03: // %011 - variable length
bitlen
= 0;
do
{
bits
= depack_getbits
(1,DEPACK_GETBITS_NEXT
);
#ifdef DPK_CHECK
if( 0xFFFFFFFF == bits
) goto NO_BITS
;
#endif
bitlen
++;
} while ( !(1&bits
) );
if( bitlen
==9 ) // happy final! WARNING: does not check whether there is remaining of input stream left unused!
{
stop
= 1;
break; // exit switch(){}
}
#ifdef DPK_CHECK
if( bitlen
>7 )
{
#ifdef DPK_REPERR
printf("mhmt-depack-megalz.c:{} - Wrong LZ code\n");
#endif
return 0;
}
#endif
bits
= depack_getbits
(bitlen
,DEPACK_GETBITS_NEXT
);
#ifdef DPK_CHECK
if( 0xFFFFFFFF == bits
) goto NO_BITS
;
#endif
length
= 2 + (1<<bitlen
) + ( bits
& ((1<<bitlen
)-1) );
#ifdef DPK_CHECK
if( length
>255 )
{
#ifdef DPK_REPERR
printf("mhmt-depack-megalz.c:{} - Wrong LZ code\n");
#endif
return 0;
}
#endif
goto FAR_DISP
;
break;
}
}
}
return success
;
}