{  Unit for general string manipulation ver 1992-01-22 }

UNIT strings;

INTERFACE

  FUNCTION val(s: string): int;
  FUNCTION str(n,base,digits: int; zeros: boolean; var res: string);
  FUNCTION decstr(n: int; var res: string);
  FUNCTION hexstr(n: int; var res: string);
  {
  FUNCTION append(var s1: string; s2: string);
  FUNCTION scan(source: string; var dest: string; var pos: int);
  FUNCTION uppercase(var s: string);
  FUNCTION pad(s: string; n: int; var res: string);
  }

IMPLEMENTATION


  FUNCTION digitVal(ch: char): int;
   var
     x : int;
  BEGIN
    if (ch >= '0') and (ch <= '9') then
       x := int(ch - '0') and 255;
    elsif (ch >= 'A') and (ch <= 'F') then
       x := 10 + int(ch - 'A') and 255;
    elsif (ch >= 'a') and (ch <= 'f') then
       x := 10 + int(ch - 'a') and 255;
    else
       x := 0;
    end;
    return x;
  END;


  { Convert decimal or hexadecimal string to int }

  FUNCTION val(s: string): int;
   var
     i,x,sum,base : int;
  BEGIN
     sum := 0;
     if s[1] = '$' then
        i := 2;
        base := 16;
     else
        i := 1;
        base := 10;
     end;
     while i <= length(s) loop
        sum := sum * base + digitVal(s[i]);
        inc(i);
     end loop;
     return sum;
  END val;

  const
    tab = "0123456789ABCDEF";

  { Convert n to number string using base and digits,
    skip leading zeros if zeros is false. }

  FUNCTION str(n,base,digits: int; zeros: boolean; var res: string);
   var
    b,i,x : int;
  BEGIN
    i := 1;
    if base > 16 then base := 16; end;
    if base < 2 then base := 2; end;
    b := 1;
    while digits > 1 loop
      b := b * base;
      dec(digits);
    end;
    while b > 0 loop
      x := n / b;
      if x > 0 then
         zeros := true;
      end;
      if zeros or (b = 1) then
         res[i] := tab[x+1];
      else
         res[i] := ' ';
      end; 
      inc(i);
      n := n mod b;
      b := b / base;
    end;
    length(res) := i-1;
  END str;


  { Convert int to decimal string }

  FUNCTION decstr(n: int; var res: string);
  BEGIN
    str(n,10,5,false,res);
  END;


  { Convert int to hexadecimal string }

  FUNCTION hexstr(n: int; var res: string);
  BEGIN
    str(n,16,4,true,res);
  END;

{
  FUNCTION append(var s1: string; s2: string);
   var
     i,j : int;
  BEGIN
    i := 1;
    j := length(s1) + 1;
    while (i <= length(s2)) and (j+1 < sizeof(string)) loop
       s1[j] := s2[i];
       inc(i);
       inc(j);
    end loop;
    length(s1) := j-1;
  END append;


  FUNCTION scan(source: string; var dest: string; var pos: int);
    var
      len,i : int;
  BEGIN
    len := length(source);
    while (pos <= len) and (source[pos] = ' ') loop
       inc(pos);
    end loop;
    i := 1;
    while (pos <= len) and (source[pos] <> ' ') loop
       dest[i] := source[pos];
       inc(i);
       inc(pos);
    end loop;
    length(dest) := i-1;
  END scan;


  FUNCTION uppercase(var s: string);
   var
     i   : int;
     ch  : char;
  BEGIN
    for i := 1 while i <= length(s) do inc(i) loop
       ch := s[i];
       if (ch >= 'a') and (ch <= 'z') then
          s[i] := ch + 'A' - 'a';
       end if;
    end loop;
  END uppercase;


  FUNCTION pad(s: string; n: int; var res: string);
   var
     i   : int;
  BEGIN
    for i := 1 while i <= n do inc(i) loop
        if i <= length(s) then
           res[i] := s[i];
        else 
           res[i] := ' ';
        end;
    end loop;
    length(res) := n;
  END pad;
}

BEGIN
END strings;