🚀 go-pugleaf

meissner@osf.org (Michael Meissner) writes:
: In article <1992Jul20.210212.2935@cognos.com> jimp@cognos.com (Jim
: Patterson) writes:
: 
: | I don't know of any way to do this that's guaranteed to work, but it
: | can be done for any compiler where casting a pointer to an int
: 
: Of course, if you ever want your code to run on Alpha, you had better
: cast the pointer to LONG and not INT.  On them new fangled 64-bit
: alpha's, ints are 32 bits, longs are 64 bits, and pointers are 64
: bits.

No, it doesn't matter. Only the low-order few bits are relevant in the
(int)-cast version of the pointer, since it's just used to determine
the amount of "unalignment", which is used to build an adjustment to
add to the original pointer. I believe it will even work on an AS/400,
where pointers are 16 bytes but there is no integer datatype larger
than 4 bytes in length. (On the AS/400, casting a pointer to an int
returns the offset but drops the segment info etc., but the algorithm
is only interested in the offset anyways so doesn't care). The only
really troublesome cases are where the alignment size is not a power
of two, but fortunately such machines are becoming increasingly rare.
-- 
Jim Patterson                  Cognos Incorporated
Sr Consulting Engineer         P.O. BOX 9707
UUNET:jimp@cognos.COM          3755 Riverside Drive
PHONE:(613)738-1338 x3385      Ottawa, Ont  K1G 3Z4