/*----------------------------------------------------------------------------
  Radical Dreamers(R) script decompression

  written by  Maximilian Rehkopf <ikari@gmx.net>
  following given specs by  Steve Demeter <overman@acorn.net>,
  which have been partially corrected.
  status: working flawlessly according to given specs.
  input : raw dump of RD text segment as file "text",
          beginning w/ a stub
  output: decompressed dump of input file as file "text.dec"
  target: DOS real / protected
          32-bit protected mode compiling recommended
          ANSI-C compatible code
----------------------------------------------------------------------------*/

#include <stdio.h>
#include <stdlib.h>

char *dcpb;
FILE *in,*out;
long flen,foff;
long decsize=0;
long decptr=0;
unsigned char c1;       // stub (a), (b)
unsigned char c2,c3;    // stub (c), (d)
unsigned char sl,ssl;   // stringlength, substringlength
unsigned short jmp;     // jump value

unsigned char cs[31],css[11]; // string, substring
void main()
{
    in=fopen("text","rb");
    out=fopen("text.dec","wb");
    foff=0;
    fseek(in,0,SEEK_END);
    flen=ftell(in);
    fseek(in,0,SEEK_SET);
    while(foff<flen)
    {
        c1=getc(in);
        c2=getc(in);
        c3=getc(in);
        foff+=3;
        sl=c1>>3;
        ssl=4+(c1&7);   // This is the line I got wrong previously!
        jmp=c2+(c3<<8);
        decsize+=(sl+(jmp?ssl:0));
        printf("[%05X] stub 0x%02X%02X%02X : SL: %02X  SSL: %02X  JMP: %04X  dec: %04lX\n",ftell(in)-3,c1,
c2,c3,sl,ssl,jmp,decsize);
//        getch();
        if(sl)fseek(in,sl,SEEK_CUR);
        foff+=sl;
    }
    printf("decompressed size: %lu\n",decsize);
    foff=0;
    dcpb=malloc(decsize+4096);
    fseek(in,0,SEEK_SET);
    while(foff<flen)
    {
        c1=getc(in);
        c2=getc(in);
        c3=getc(in);
        foff+=3;
        sl=c1>>3;
        ssl=4+(c1&7);   // And here, once again!
        jmp=c2+(c3<<8);
//        printf("Stub info: SL: %02X  SSL: %02X  JMP: %04X. committing process...\n",sl,ssl,jmp);
//        getch();
        if(jmp && (jmp<=(decptr))) //just to prevent exceptions
                                   //(negative memory offsets are no good ^^)
        {
            memcpy(css,dcpb+(decptr-jmp),ssl);
            memcpy(dcpb+decptr,css,ssl);
            decptr+=ssl;
        }
        if(sl)
        {
            fread(cs,sl,1,in);
            memcpy(dcpb+decptr,cs,sl);
            foff+=sl;
            decptr+=sl;
        }
    }
    fwrite(dcpb,decsize,1,out);
    fclose(out);
    fclose(in);
    free(dcpb);
}