64bit sized bigarrays support

[XVilka]

One of the good example is to use Bigarray mapped on top of the file, whose size can easily exceed the 32bit limits. It would be really useful in 2019 to have bigger bigarrays.

[nojb]

One of the good example is to use Bigarray mapped on top of the file, whose size can easily exceed the 32bit limits. It would be really useful in 2019 to have bigger bigarrays.

Which limit is this? I thought bigarrays did not have any hard-coded limit.

[XVilka]

@nojb for example Bigarray.Array1.get ba offset requires offset to be int, rather than int64, obviously limiting the size to 32bits.

[dbuenzli]

obviously limiting the size to 32bits.

To 30 bits to be precise. But then on a 32-bit machine addressing is limited to 32-bits anyways.

If you want to use large files on 32-bit machines you should use Unix.Largefile rather than mmaping them. Depending on the size of your platform's off_t type this may allow you to deal with files larger than what 30-bits allow.

[XVilka]

@dbuenzli well, I talk more about 64bit machines, since 32bit are quite rare these days.

P.S. Yes, of course 30 bits, you are right.

[nojb]

@dbuenzli well, I talk more about 64bit machines, since 32bit are quite rare these days.

An int in a 64bit machine is 63 bits wide, so it limits you to 62 bits of addressable memory. This is surely enough, right?

[dbuenzli]

Well but your indexing ints on a 64-bit machine are 62-bit then which should be sufficient for most needs.

[XVilka]

Oh, I misunderstood then. Thanks for the answers, closing this one.