[+cc [email protected]] On Sat, Oct 18, 2014 at 5:09 AM, [email protected] <[email protected]> wrote: >> I think a neat way to use a C library from an ocamljava-compiled >> program would be to have a Java "backend" for Jeremy Yallop's >> ctypes (https://github.com/ocamllabs/ocaml-ctypes). I never had >> the time to implement that, but toyed with this idea and think the >> best way to implement it would be to go through JNA >> (https://github.com/twall/jna) rather than JNI. JNA includes a >> "dlopen"-like mechanism, and automatically maps simple types from >> Java to C. My knowledge of ctypes is quite limited, but I see no >> showstopper.
On 18/10/2014, Kenneth Adam Miller <[email protected]> wrote: > Precisely! ocaml-ctypes is exactly what's being used by the library > that I'm porting to call into C sub libraries. It would be really > sweet if the ocamljava compiler could detect the ocaml-ctypes and > generate these mappings automatically. This would eliminate a lot of > error prone code, since C code tends to interpret data raw at some > point... How might I got about writing this to boot? I'm moderately > new to ocaml, lacking deep expertise in it, but I'm an aggressive > learner. Please explain the best path forward, I want to create a > robust and reusable solution. OCaml-Java support is on the wish list for ctypes https://github.com/ocamllabs/ocaml-ctypes/issues/13 but we don't have the resources to implement it at present. Adding support would mostly likely only involve changing ctypes itself, not OCaml-Java, and is likely to involve writing OCaml-Java implementations of the following components: (1) memory access, i.e. functions for allocating blocks, for reading and writing scalar values to arbitrary addresses, and for viewing C objects as bigarrays: https://github.com/ocamllabs/ocaml-ctypes/blob/master/src/ctypes/memory_stubs.ml https://github.com/ocamllabs/ocaml-ctypes/blob/master/src/ctypes/bigarray_stubs.ml (2) functions for printing primitive (scalar) values: https://github.com/ocamllabs/ocaml-ctypes/blob/master/src/ctypes/value_printing_stubs.ml (3) implementations of signed and unsigned integer types of various sizes: https://github.com/ocamllabs/ocaml-ctypes/blob/master/src/ctypes/signed.ml https://github.com/ocamllabs/ocaml-ctypes/blob/master/src/ctypes/unsigned.ml (4) functions for converting between OCaml and C string representations https://github.com/ocamllabs/ocaml-ctypes/blob/master/src/ctypes/std_view_stubs.ml plus one of the following approaches for calling functions (a) a "dynamic" approach, which resolves symbols and constructs call frames at runtime, like the ctypes Foreign module. This involves two components: a dynamic loading interface along the following lines https://github.com/ocamllabs/ocaml-ctypes/blob/master/src/ctypes-foreign-base/dl.mli and primitives for dynamically constructing and making calls: https://github.com/ocamllabs/ocaml-ctypes/blob/master/src/ctypes-foreign-base/ffi_stubs.ml (b) a "static" approach, which generates code to be compiled by the standard toolchain: https://github.com/ocamllabs/ocaml-ctypes/blob/master/src/cstubs/cstubs.mli Note that most of the links above are to internal Ctypes modules, not to the interface, which I'd expect to remain largely unchanged. As Xavier suggests, JNA may be a good starting point for some or all of the above. If someone would like to look at adding OCaml-Java support, please feel free to ask questions, either on the GitHub issue tracker, or on the ctypes mailing list. Jeremy. _______________________________________________ Ctypes mailing list [email protected] http://lists.ocaml.org/listinfo/ctypes
