#include <stdio.h>
#if defined(DOS) | defined(NT)
#include <malloc.h>
#endif

struct Item {struct Item *Next; unsigned char *Value;}
 *Olditem=NULL, *Newitem=NULL, *T_Olditem, *T_Newitem;

char *Oldfile, *Newfile, *Listfile, Buffer[513];

int Binary=0, Oldline, Newline, T_Oldline, T_Newline, I, Inserted, Deleted,
 Howfar, Done, Oldread=0, Newread=0, E_Count=2;

FILE *Old, *New, *List;

struct Item *Read_Old()
{int I;
 struct Item *Temp;
 if (fgets(Buffer,512,Old)!=NULL)
 {I=strlen(Buffer);
  if (I==0||Buffer[I-1]!='\n')
  {Buffer[I]='\n';
   Buffer[I+1]=0;
  }
  if ((Temp=(struct Item *)malloc(sizeof(struct Item)))==NULL)
    Fatalerror("Out of memory");
  Temp->Next=NULL;
  if ((Temp->Value=malloc(I=strlen(Buffer)+1))==NULL)
   Fatalerror("Out of Memory");
  memcpy(Temp->Value,Buffer,I);
  return Temp;
 } else
 {Oldread=1;
  return NULL;
 }
}

struct Item *Read_New()
{int I;
 struct Item *Temp;
 if (fgets(Buffer,512,New)!=NULL)
 {I=strlen(Buffer);
  if (I==0||Buffer[I-1]!='\n')
  {Buffer[I]='\n';
   Buffer[I+1]=0;
  }
  if ((Temp=(struct Item *)malloc(sizeof(struct Item)))==NULL)
    Fatalerror("Out of memory");
  Temp->Next=NULL;
  if ((Temp->Value=malloc(I=strlen(Buffer)+1))==NULL)
   Fatalerror("Out of Memory");
  memcpy(Temp->Value,Buffer,I);
  return Temp;
 } else
 {Newread=1;
  return NULL;
 }
}

main(Argc,Argv)
int Argc;
char *Argv[];
{Oldfile=Newfile=NULL;
 Get_Arg(Argc,Argv);
 Newline=Oldline=1;
 Olditem=Read_Old();
 Newitem=Read_New();
 while (Olditem!=NULL||Newitem!=NULL)
 {if (Olditem!=NULL&&Newitem!=NULL&&strcmp(Olditem->Value,Newitem->Value)==0)
  {T_Newitem=Newitem;
   T_Olditem=Olditem;
   Newitem=Newitem->Next;
   Olditem=Olditem->Next;
   free(T_Newitem->Value);
   free(T_Olditem->Value);
   free(T_Newitem);
   free(T_Olditem);
   Oldline++;
   Newline++;
  } else
   Find_Change();
  if (Olditem==NULL&&!Oldread)
   Olditem=Read_Old();
  if (Newitem==NULL&&!Newread)
   Newitem=Read_New();
 }
 fclose(Old);
 fclose(New);
 fclose(List);
}

Get_Arg(Argc,Argv)
int Argc;
char *Argv[];
{char *P;
 for (I=1;I<Argc;I++)
 {if ((P=Argv[I])[0]=='-')
  {if (P[1]=='b'||P[1]=='B'&&P[2]==0)
    Binary=1; else
   if (P[1]=='a'||P[1]=='A'&&P[2]==0)
    Binary=0; else
   if (P[1]>='0'&&P[1]<='9')
   {int I=1;
    E_Count=0;
    while (P[I]!=0)
    {E_Count=E_Count*10+P[I]-'0';
     I++;
    }
   }
  } else
  if (Oldfile==NULL)
   Oldfile=Argv[I]; else
  if (Newfile==NULL)
   Newfile=Argv[I]; else
  if (Listfile==NULL)
   Listfile=Argv[I]; else
   Fatalerror("Too many file arguments");
 }
 if (Oldfile==NULL)
 {puts("");
  puts("Dif:  Create a differences file from an old and a new file");
  puts("Dif {-<N>} <Old file> <New file> {<Differences file>}");
  puts("");
  puts("Merg: Create a new file from an old file and a differences file");
  puts("Merg <Old file> <New file> {<Differences file>}");
  puts("");
  puts("Clist: Create a file containing unchanged, deleted and inserted lines");
  puts("Clist {-<N>} <Old File> <New file> {<Listing file>}");
  puts("");
  puts("N is the number of lines that must be the same for a match (default 2)");
#if defined(VMS)
  exit();
#endif
#if defined(DOS) | defined(NT)
  _exit(0);
#endif
 }
 if (Listfile==NULL)
  Listfile="CON";
 if ((Old=fopen(Oldfile,"r"))==NULL)
  Fatalerror("Could not find old file");
 if ((New=fopen(Newfile,"r"))==NULL)
  Fatalerror("Could not find new file");
#if defined(VMS)
 if ((List=fopen(Listfile,"w","fop=tef","rat=cr","rfm=var"))==NULL)
#endif
#if defined(DOS) | defined(NT)
 if ((List=fopen(Listfile,"w"))==NULL)
#endif
  Fatalerror("Could not dreate differences file");
}

Find_Change()
{Howfar=0;
 Done=0;
 while (!Done)
 {Howfar++;
  Inserted=Howfar;
  for (Deleted=0;Deleted<=Howfar&&!Done;Deleted++)
  {T_Oldline=Oldline;
   T_Newline=Newline;
   T_Olditem=Olditem;
   T_Newitem=Newitem;
   while (T_Olditem!=NULL&&T_Oldline-Oldline<Deleted)
   {if (T_Olditem->Next==NULL&&!Oldread)
     T_Olditem->Next=Read_Old();
    T_Olditem=T_Olditem->Next;
    T_Oldline++;
   }
   while (T_Newitem!=NULL&&T_Newline-Newline<Inserted)
   {if (T_Newitem->Next==NULL&&!Newread)
     T_Newitem->Next=Read_New();
    T_Newitem=T_Newitem->Next;
    T_Newline++;
   }
   if (T_Olditem==NULL||T_Newitem==NULL)
   {if (T_Olditem==NULL&&Inserted!=0)
     Done=1; else
    if (T_Newitem==NULL&&Deleted!=0)
     Done=1;
   } else
   if (strcmp(T_Newitem->Value,T_Olditem->Value)==0)
   {int I=1;
    while (1)
    {if (I++==E_Count||T_Olditem==NULL||T_Newitem==NULL)
     {Done=1;
      break;
     }
     if (T_Newitem->Next==NULL&&!Newread)
      T_Newitem->Next=Read_New();
     if (T_Olditem->Next==NULL&&!Oldread)
      T_Olditem->Next=Read_Old();
     if (T_Newitem->Next!=NULL&&T_Olditem->Next!=NULL)
     if (strcmp(T_Newitem->Next->Value,T_Olditem->Next->Value)==0)
     {T_Olditem=T_Olditem->Next;
      T_Newitem=T_Newitem->Next;
     } else
      break;
    }
   }
  }
  if (!Done)
  {Deleted=Howfar;
   for (Inserted=0;Inserted<=Howfar&&!Done;Inserted++)
   {T_Oldline=Oldline;
    T_Newline=Newline;
    T_Olditem=Olditem;
    T_Newitem=Newitem;
    while (T_Olditem!=NULL&&T_Oldline-Oldline<Deleted)
    {if (T_Olditem->Next==NULL&&!Oldread)
      T_Olditem->Next=Read_Old();
     T_Olditem=T_Olditem->Next;
     T_Oldline++;
    }
    while (T_Newitem!=NULL&&T_Newline-Newline<Inserted)
    {if (T_Newitem->Next==NULL&&!Newread)
      T_Newitem->Next=Read_New();
     T_Newitem=T_Newitem->Next;
     T_Newline++;
    }
    if (T_Olditem==NULL||T_Newitem==NULL)
    {if (T_Olditem==NULL&&Inserted!=0)
      Done=1; else
     if (T_Newitem==NULL&&Deleted!=0)
      Done=1;
    } else
    if (strcmp(T_Newitem->Value,T_Olditem->Value)==0)
    {int I=1;
     while (1)
     {if (I++==E_Count||T_Olditem==NULL||T_Newitem==NULL)
      {Done=1;
       break;
      }
      if (T_Newitem->Next==NULL&&!Newread)
       T_Newitem->Next=Read_New();
      if (T_Olditem->Next==NULL&&!Oldread)
       T_Olditem->Next=Read_Old();
      if (T_Newitem->Next!=NULL&&T_Olditem->Next!=NULL)
      if (strcmp(T_Newitem->Next->Value,T_Olditem->Next->Value)==0)
      {T_Olditem=T_Olditem->Next;
       T_Newitem=T_Newitem->Next;
      } else
       break;
     }
    }
   }
  }
 }
 while (Oldline!=T_Oldline)
 {fprintf(List,"d%d:%s",Oldline,Olditem->Value);
  T_Olditem=Olditem;
  Olditem=Olditem->Next;
  Oldline++;
  free(T_Olditem->Value);
  free(T_Olditem);
 }
 while (Newline!=T_Newline)
 {fprintf(List,"i%d:%s",Newline,Newitem->Value);
  T_Newitem=Newitem;
  Newitem=Newitem->Next;
  Newline++;
  free(T_Newitem->Value);
  free(T_Newitem);
 }
}

Fatalerror(S)
char *S;
{printf(S);
 _exit(1);
}

#if defined(VMS)
memcpy(D,S,C)
char *D, *S;
int C;
{while (C--)
 (*D++)=(*S++);
}
#endif