Mapping questions

[Julien Nicoulaud]

Hi all,

I'm thinking of using HawtJNI to write a Java wrapper for an existing C library. I have a few questions regarding type mappings:

Non-struct typedefs

How do I map something like that ?

typedef long my_long;

Unions

Is union type supported ?

Enums

The library defines enums, used by ordinal:

enum {

  FOO,

  BAR

};

typedef struct my_struct {

  int enum_value;

}

Is there an smart way to handle this with HawtJNI ?

Disable statistics code generation ?

Last thing, I see HawtJNI inserts some pre/post method call code in the generated code, I guess this is for the statistics feature. Is it possible to disable it (for performance reasons) ?

Regards,

Julien

[Hiram Chirino]

On Sun, Jul 7, 2013 at 4:01 PM, Julien Nicoulaud
<julien.n...@gmail.com> wrote:
> Hi all,
>
> I'm thinking of using HawtJNI to write a Java wrapper for an existing C
> library. I have a few questions regarding type mappings:
>
> Non-struct typedefs
>
> How do I map something like that ?
>
> typedef long my_long;
>

Just map it to a long and optionally cast to a my_long. For example:

@JniArg(cast="my_long") long arg1

>
> Unions
>
> Is union type supported ?

There is no class mapping that can nicely represent a union in java.
Just define multiple structs and memcpy the memory to the struct that
has the layout that you need.

>
> Enums
>
> The library defines enums, used by ordinal:
>
> enum {
> FOO,
> BAR
> };
>
> typedef struct my_struct {
> int enum_value;
> }
>
>
> Is there an smart way to handle this with HawtJNI ?
>

The best you can do is to load the ordinal constants.
See: http://hawtjni.fusesource.org/documentation/developer-guide.html#platform-constants

> Disable statistics code generation ?
>
> Last thing, I see HawtJNI inserts some pre/post method call code in the
> generated code, I guess this is for the statistics feature. Is it possible
> to disable it (for performance reasons) ?

Not currently. Feel free to send in a pull request that adds an
option to disable that part of the code generation.

>
> Regards,
> Julien
>
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--
Hiram Chirino

Engineering | Red Hat, Inc.

hchi...@redhat.com | fusesource.com | redhat.com

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