> by 'not working' i mean i get undefined sub-rules and
> such as if i was getting file/stream type redirection
> instead of the shifts i want.
> as a result, i've ended up with exe blocks that look like:
>
> {
> $main::Instruction_upper = 0x440000
> | ($item[1] / 2048)
> | $item[4]
> | ($item[8] / 512)
> | ($item[10] * 16)
> | (($item[26] & 0x000010) / 16)
> | ($item[32] / 2)
> ;
> $main::Instruction_lower = 0x000000
> | ($item[14] * 2)
> | ($item[16] / 2048)
> | ($item[20] * 16)
> | ($item[22] / 128)
> | (($item[26] & 0x00000C) * 1048576)
> | (($item[28] & 0xC00000) / 16384)
> | (($item[28] & 0x000003) * 1024)
> | (($item[34] & 0xC00000) / 1024)
> | (($item[34] & 0x000003) * 16384)
> ;
> 1
> }
>
> it does what's desired, but from a maintenance point of view
> it is just not clear, without doing some math, what the
> various shifts are.
> not to mention the increased chances of a typo in these magic
> numbers!
>
> any ideas about where i've gone wrong in trying to use the
> bit shifts?
> or is this a bug in p::rd ?
Dunno about the cause of this. But the obvious solution is to put stuff like
this in a sub that you call. Frankly I would do that anyway. I find large
chunks of code intermingled with the grammer is difficult to grok. And by
using
$item{$name}
instead of
$item[$num]
your code would be much more resiliant to future changes, especially if you
do move stuff into subs.
Cheers,
yves
