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Re: ffi helper
Re: ffi helper
Mon, 13 Mar 2017 17:53:59 -0700
> On Mar 8, 2017, at 6:06 PM, Matt Wette <address@hidden> wrote:
> I’m now working on a FFI helper based on the nyacc C99 parser.
So, like, I think what might be useful is something that will convert a dot-h
file to a spec file, with certain assumptions about function signatures (e.g.,
if passing a pointer to int, then the scheme implementation is a (system
foreign) int*, or maybe a boxed integer).
Then the spec is compiled, in a machine-dependent manner to deal with type
sizes and alignment, to a .go file which provides scheme-callable functions.
I’m not sure the output of the dot-H reader can be machine independent, given
all the spaghetti code that typically exists in /usr/include. It may be worth
a try, later.
Also, the module should support structures. The bytestructures package looks
Enums should be provided also.
CPP constants (aka #define’s) should be supported.
Do CPP macros with arguments need to be supported? This is not just
converting to functions, because CPP macros do not recurse (e.g., `#define
sqrt(F) sqrt(fabs(F))’ is perfectly legal C).
Some other tidbits:
The nyacc c99 module provides a few neat functions to support this. One is
expand-typerefs (was expand-decl-typerefs). This will convert an sxml
typedef const int (*foo_t)(int a, double b);
extern foo_t fctns;
into one of
extern const int (*fctns)(int a, double b);
Another function, udecl->mspec, helps with the conversion as follows. Consider
double x; /* state vector */
The c99 parser, followed by tree->udict, followed by cadr will turn the above
(type-spec (float-type "double")))
(array-of (ident "x") (p-expr (fixed "10"))))
(comment " state vector “))
And “udecl->mspec/comm” will convert the above into
" state vector "
I am in the process of cleaning up the above in order to convert some function