[libiberty and gdb] floatformat_is_valid

[Daniel Jacobowitz]

On Mon, Sep 15, 2003 at 04:54:17PM -0400, Andrew Cagney wrote:
> >+/* Return non-zero iff the data at FROM is a valid number in format FMT.  
> >*/
> >+
> >+int
> >+floatformat_is_valid (fmt, from)
> >+     const struct floatformat *fmt;
> >+     char *from;
> >+{
> 
> Shouldn't this be a new virtual method in floatformat?

Floatformats don't have any virtual methods right now; if you want to
add them, be my guest.  Besides, this is more in line with the
libiberty policy of backwards compatibility, since it does not change
the structure layout.

> 
> >+  if (fmt == &floatformat_i387_ext)
> >+    {
> >+      /* In the i387 double-extended format, if the exponent is all
> >+	 ones, then the integer bit must be set.  If the exponent
> >+	 is neither 0 nor ~0, the intbit must also be set.  Only
> >+	 if the exponent is zero can it be zero, and then it must
> >+	 be zero.  */
> >+      unsigned int exponent, int_bit;
> >+      unsigned char *ufrom = (unsigned char *) from;
> >+
> >+      exponent = get_field (ufrom, fmt->byteorder, fmt->totalsize,
> >+			    fmt->exp_start, fmt->exp_len);
> >+      int_bit = get_field (ufrom, fmt->byteorder, fmt->totalsize,
> >+			   fmt->man_start, 1);
> >+
> >+      if ((exponent == 0) != (int_bit == 0))
> >+	return 0;
> >+      else
> >+	return 1;
> >+    }
> >+
> >+  /* Other formats with invalid representations should be added
> >+     here.  */
> >+  return 1;
> > }
> 
> Andrew
> 
> 
> 

-- 
Daniel Jacobowitz
MontaVista Software                         Debian GNU/Linux Developer