Better blackbox operation for vindex

[BosJ]

Solves wrong integer initialization when an integer is used as array-index, it is by default initialized as "Integer 'LOW" (-1). The simulator (Questa Sim) reports after a few delta cycles: Fatal error #_#_vindex_integer at <file>

[
{ "BlackBox" :
    { "name"      : "CLaSH.Sized.Vector.vindex_integer"
    , "templateD" :
"~SYM[0]_vindex_integer : block
  signal ~SYM[1] : ~TYP[1];
begin
  ~SYM[1] <= ~ARG[1];
  -- pragma translate_off
  ~SYM[2]_proc : process (~SYM[1],~ARG[2]) is
  begin
    if ~ARG[2] < 0 then
       ~RESULT <= ~SYM[1](0);
    else
    -- pragma translate_on
    ~RESULT <= ~SYM[1](~ARG[2]);
    -- pragma translate_off
    end if;
  end process;
  -- pragma translate_on
end block;"
    }
  }
]

EDIT: the above goes still wrong with constants in the second argument, maybe the code below is better?

[
{ "BlackBox" :
    { "name"      : "CLaSH.Sized.Vector.vindex_integer"
    , "templateD" :
"~SYM[0]_vindex_integer : block
  signal ~SYM[1] : ~TYP[1];
  signal ~SYM[2] : ~TYP[2] := 0;
begin
  ~SYM[1] <= ~ARG[1];
  ~SYM[2] <= ~ARG[2];
  -- pragma translate_off
  ~SYM[2]_proc : process (~SYM[1],~SYM[2]) is
  begin
    if ~ARG[2] < 0 then
       ~RESULT <= ~SYM[1](0);
    else
    -- pragma translate_on
    ~RESULT <= ~SYM[1](~SYM[2]);
    -- pragma translate_off
    end if;
  end process;
  -- pragma translate_on
end block;"
    }
  }
]

[christiaanb]

You are indeed right that constants might end up in the sensitivity list with the old version. Here is the final improvement that I made, although I still have to actually test it:

[ { "BlackBox" :
    { "name"      : "CLaSH.Sized.Vector.vindex_integer"
    , "templateD" :
"~SYM[0]_vindex_integer : block
  signal ~SYM[1] : ~TYP[1];
  signal ~SYM[2] : ~TYP[2];
begin
  ~SYM[1] <= ~ARG[1];
  ~SYM[2] <= ~ARG[2];
  -- pragma translate_off
  process (~SYM[1],~SYM[2])
  begin
    if ~SYM[2] < ~SYM[1]'low or ~SYM[2] > ~SYM[1]'high then
      assert true report (\"Index: \" & integer'image(~SYM[2]) & \" is out of bounds:\" & integer'image(~SYM[1]'low) & \"-\" & integer'image(~SYM[1]'high)) severity warning;
      ~RESULT <= ~DEFAULTO;
    else
    -- pragma translate_on
      ~RESULT <= ~SYM[1](~SYM[2]);
    -- pragma translate_off
    end if;
  end process;
  -- pragma translate_on
end block;"
    }
  }
, { "BlackBox" :
    { "name"      : "CLaSH.Sized.Vector.vreplace_integer"
    , "templateD" :
"~SYM[0]_vreplace_integer : block
  signal ~SYM[1] : ~TYP[1];
  signal ~SYM[2] : ~TYP[2];
  signal ~SYM[3] : ~TYP[3];
begin
  ~SYM[1] <= ~ARG[1];
  ~SYM[2] <= ~ARG[2];
  ~SYM[3] <= ~ARG[3];
  process(~SYM[1],~SYM[2],~SYM[3])
    variable ~SYM[4] : ~TYP[1];
  begin
    ~SYM[4] := ~SYM[1];
    -- pragma translate_off
    if ~SYM[2] < ~SYM[4]'low or ~SYM[2] > ~SYM[4]'high then
      assert true report (\"Index: \" & integer'image(~SYM[2]) & \" is out of bounds:\" & integer'image(~SYM[1]'low) & \"-\" & integer'image(~SYM[1]'high)) severity warning;
    else
      -- pragma translate_on
      ~SYM[4](~SYM[2]) := ~SYM[3];
      -- pragma translate_off
    end if;
    -- pragma translate_on
    ~RESULT <= ~SYM[4];
  end process;
end block;"
    }
  }
]