[LispM-Hackers] hello

[Tim Moore]

I just came across this project and can't ever resist a good hack.  I have
a lot of coals in the Lisp fires and can't commit to really diving into
this project, but I do have a lot of Lisp system/compiler experience and
would love to help out on a low level, perhaps implementing some macro
instructions.

So, here's a question about what I suspect is a bug.  In memobj.cc we
have:


e3s32 memFix::value(void) const
{
  e3Word me = readMe();

  e3u8  sign_bit = me.selectBitsPPSS(24, 1);
  e3u32 magnitude = me.selectBitsPPSS(0, 24);
  e3s32 signed_magnitude = magnitude;

  if (sign_bit)
    {
      signed_magnitude *= -1;	// Probably should just set sign bit.
    }

  return(signed_magnitude);
}

But a fixnum is in two's complement, right?  I suspect this should be
something like:

e3s32 val = me.getBits();
return (val << 7) >> 7;

Comments?

Tim