//================================================
//       L Z R W 1
//------------------------------------------------
//  copied from the net.
//          by....
//------------------------------------------------
// Modification by me
//
//    change fast_copy to the UNIX system  bcopy.
//    bcopy supposed to be faster.
//                                   E.C.Chang
//------------------------------------------------
//  sunos v4   use  <string.h>
//  the following are for solaris
#include<strings.h>


#ifndef __HUGE__
   #error Use HUGE memory model.
#endif


#define TRUE 1

#define UBYTE unsigned char /* Unsigned     byte (1 byte )        */
#define UWORD unsigned int  /* Unsigned     word (2 bytes)        */
#define ULONG unsigned long /* Unsigned longword (4 bytes)        */
#define FLAG_BYTES    4     /* Number of bytes used by copy flag. */
#define FLAG_COMPRESS 0     /* Signals that compression occurred. */
#define FLAG_COPY     1     /* Signals that a copyover occurred.  */
void fast_copy(p_src,p_dst,len) /* Fast copy routine.             */
UBYTE *p_src,*p_dst; {while (len--) *p_dst++=*p_src++;}

/******************************************************************************/

void lzrw1_compress(p_src_first,src_len,p_dst_first,p_dst_len)
/* Input  : Specify input block using p_src_first and src_len.          */
/* Input  : Point p_dst_first to the start of the output zone (OZ).     */
/* Input  : Point p_dst_len to a ULONG to receive the output length.    */
/* Input  : Input block and output zone must not overlap.               */
/* Output : Length of output block written to *p_dst_len.               */
/* Output : Output block in Mem[p_dst_first..p_dst_first+*p_dst_len-1]. */
/* Output : May write in OZ=Mem[p_dst_first..p_dst_first+src_len+256-1].*/
/* Output : Upon completion guaranteed *p_dst_len<=src_len+FLAG_BYTES.  */
UBYTE *p_src_first,*p_dst_first; ULONG src_len,*p_dst_len;
#define PS *p++!=*s++  /* Body of inner unrolled matching loop.         */
#define ITEMMAX 16     /* Maximum number of bytes in an expanded item.  */
{UBYTE *p_src=p_src_first,*p_dst=p_dst_first;
 UBYTE *p_src_post=p_src_first+src_len,*p_dst_post=p_dst_first+src_len;
 UBYTE *p_src_max1=p_src_post-ITEMMAX,*p_src_max16=p_src_post-16*ITEMMAX;
 UBYTE *hash[4096],*p_control; UWORD control=0,control_bits=0;
 *p_dst=FLAG_COMPRESS; p_dst+=FLAG_BYTES; p_control=p_dst; p_dst+=2;
 while (TRUE)
   {UBYTE *p,*s; UWORD unroll=16,len,index; ULONG offset;
    if (p_dst>p_dst_post) goto overrun;
    if (p_src>p_src_max16)
      {unroll=1;
       if (p_src>p_src_max1)
         {if (p_src==p_src_post) break; goto literal;}}
    begin_unrolled_loop:
       index=((40543*((((p_src[0]<<4)^p_src[1])<<4)^p_src[2]))>>4) & 0xFFF;
       p=hash[index]; hash[index]=s=p_src; offset=s-p;
       if (offset>4095 || p<p_src_first || offset==0 || PS || PS || PS)
         {literal: *p_dst++=*p_src++; control>>=1; control_bits++;}
       else
         {PS || PS || PS || PS || PS || PS || PS ||
          PS || PS || PS || PS || PS || PS || s++; len=s-p_src-1;
          *p_dst++=((offset&0xF00)>>4)+(len-1); *p_dst++=offset&0xFF;
          p_src+=len; control=(control>>1)|0x8000; control_bits++;}
    end_unrolled_loop: if (--unroll) goto begin_unrolled_loop;
    if (control_bits==16)
      {*p_control=control&0xFF; *(p_control+1)=control>>8;
       p_control=p_dst; p_dst+=2; control=control_bits=0;}
   }
 control>>=16-control_bits;
 *p_control++=control&0xFF; *p_control++=control>>8;
 if (p_control==p_dst) p_dst-=2;
 *p_dst_len=p_dst-p_dst_first;
 return;
 overrun: bcopy(p_src_first,p_dst_first+FLAG_BYTES,src_len);
          *p_dst_first=FLAG_COPY; *p_dst_len=src_len+FLAG_BYTES;
}

/******************************************************************************/

void lzrw1_decompress(p_src_first,src_len,p_dst_first,p_dst_len)
/* Input  : Specify input block using p_src_first and src_len.          */
/* Input  : Point p_dst_first to the start of the output zone.          */
/* Input  : Point p_dst_len to a ULONG to receive the output length.    */
/* Input  : Input block and output zone must not overlap. User knows    */
/* Input  : upperbound on output block length from earlier compression. */
/* Input  : In any case, maximum expansion possible is eight times.     */
/* Output : Length of output block written to *p_dst_len.               */
/* Output : Output block in Mem[p_dst_first..p_dst_first+*p_dst_len-1]. */
/* Output : Writes only  in Mem[p_dst_first..p_dst_first+*p_dst_len-1]. */
UBYTE *p_src_first, *p_dst_first; ULONG src_len, *p_dst_len;
{UWORD controlbits=0, control;
 UBYTE *p_src=p_src_first+FLAG_BYTES, *p_dst=p_dst_first,
       *p_src_post=p_src_first+src_len;
 if (*p_src_first==FLAG_COPY)
   {bcopy(p_src_first+FLAG_BYTES,p_dst_first,src_len-FLAG_BYTES);
    *p_dst_len=src_len-FLAG_BYTES; return;}
 while (p_src!=p_src_post)
   {if (controlbits==0)
      {control=*p_src++; control|=(*p_src++)<<8; controlbits=16;}
    if (control&1)
      {UWORD offset,len; UBYTE *p;
       offset=(*p_src&0xF0)<<4; len=1+(*p_src++&0xF);
       offset+=*p_src++&0xFF; p=p_dst-offset;
       while (len--) *p_dst++=*p++;}
    else
       *p_dst++=*p_src++;
    control>>=1; controlbits--;
   }
 *p_dst_len=p_dst-p_dst_first;
}

/******************************************************************************/
/*                          End of LZRW1.C                                    */
/******************************************************************************/