Goto?!? (was Re: A89: fwrite bug located (and a bugfix))

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Goto?!? (was Re: A89: fwrite bug located (and a bugfix))


> #undef fread // this will cancel old definition from stdio.h
> unsigned fread(void *ptr,unsigned size,unsigned n,FILE *f)
> {
>   unsigned i,j;
>   int saveflags=f->flags;
>   f->flags|=_F_BIN;
>   for(i=0;i<n;i++)
>     for(j=0;j<size;j++)
>       if((*(unsigned char*)ptr++=fgetc(f))<0) goto exit;
> exit:
>   f->flags=saveflags;
>   return i;
> }

Somebody PLEASE tell me why you're using _GOTO_ there before Wing and I die
of laughter?!?

Geez, you're breaking the ultimate C taboo here - the only accepted use of
goto involves breaking out of nested loops with faster/smaller code, but
that doesn't apply in this instance - I can do it without goto, and I bet
it'll generate the same code.

Why not use the following code?  I think this meets all conditions, is
anyone smart enough to check and see?

It's a question of whether or not this will generate the same code - a good
test of how smart GCC is.  Can it optimize this code into the equivalent
goto'd form, without using a dreaded goto? hmmm. . .

#undef fread // this will cancel old definition from stdio.h
unsigned fread(void *ptr,unsigned size,unsigned n,FILE *f)
{
  unsigned i=0,j=0;
  int saveflags=f->flags;
  f->flags|=_F_BIN;
  while (i++<n && (*(unsigned char*)ptr++=fgetc(f))>=0)
    while (j++<size && (*(unsigned char*)ptr++=fgetc(f))>=0)
      continue;
  f->flags=saveflags;
  return i;
}

As confusing as this is - it could probably use some extra parentheses - I'm
nearly sure it works.  Can anyone find out if GCC is good enough to have
this output the proper code???

    -Scott
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