Glynn Clements wrote:
Markus Metz wrote:
AFAIKT, r38992 Vect_get_num return long has no effect because the number
of features (for each type) is stored as plus_t which is int. If you
want to prepare the vector libs to support more than INT_MAX objects, I
would suggest to use
plus_t Vect_get_num_primitives(const struct Map_info *, int);
etc and then think about what type is appropriate for plus_t.
I would suggest *not* to use long because long is the same like int on
32 bit (4 bytes) and the same like long long int on 64 bit (8 bytes),
i.e. a vector written with 64 bit may not be readable with 32 bit which
is against all the efforts to keep the vector format independent of
platform/architecture/compiler. Some unsigned integer type should work,
else some checks would be needed similar to what Glynn recently
implemented to get an integer type of size 8 in port_init.c. E.g. use
long if possible else use long long if possible else fatal error, no
integer of size 8 available (or is there something else that could have
a size of 8 ?).
#ifdef HAVE_LONG_LONG_INT
typedef long long longest;
#else
typedef long longest;
#endif
?
If you're desperate for more than 32 bits, an IEEE "double" can
represent integers between -2^53 and 2^53 exactly, but this is likely
to be more trouble than it's worth (you have to be careful with
division, you can't use a double as an array index, you can't use
shifts or bitwise operators, ...).
IMHO, we should first make sure that the vector libs support up to
INT_MAX (2^31 - 1) features. Vector libs LFS was a first step, and
unless there is a revolutionary new hardware concept in the near future
with huge amounts of RAM and much higher processing speed, building
topology for so many features will take a long long time, particularly
in case of areas. One solution would be to increase the speed and
decrease the memory requirements of topology building, and I think more
brains should be put to that task before increasing the number of
supported features, i.e. changing plus_t from a 32-bit integer type to a
64-bit integer type.
Markus M
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