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<title>Complex Type Example (libffi: the portable foreign function interface library)</title>
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<div class="subsection" id="Complex-Type-Example">
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<p>
Previous: <a href="Complex.html" accesskey="p" rel="prev">Complex Types</a>, Up: <a href="Types.html" accesskey="u" rel="up">Types</a> [<a href="Index.html" title="Index" rel="index">Index</a>]</p>
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<hr>
<span id="Complex-Type-Example-1"></span><h4 class="subsection">2.3.7 Complex Type Example</h4>
<p>This example demonstrates how to use complex types:
</p>
<div class="example">
<pre class="example">#include <stdio.h>
#include <ffi.h>
#include <complex.h>
void complex_fn(_Complex float cf,
_Complex double cd,
_Complex long double cld)
{
printf("cf=%f+%fi\ncd=%f+%fi\ncld=%f+%fi\n",
(float)creal (cf), (float)cimag (cf),
(float)creal (cd), (float)cimag (cd),
(float)creal (cld), (float)cimag (cld));
}
int main()
{
ffi_cif cif;
ffi_type *args[3];
void *values[3];
_Complex float cf;
_Complex double cd;
_Complex long double cld;
/* Initialize the argument info vectors */
args[0] = &ffi_type_complex_float;
args[1] = &ffi_type_complex_double;
args[2] = &ffi_type_complex_longdouble;
values[0] = &cf;
values[1] = &cd;
values[2] = &cld;
/* Initialize the cif */
if (ffi_prep_cif(&cif, FFI_DEFAULT_ABI, 3,
&ffi_type_void, args) == FFI_OK)
{
cf = 1.0 + 20.0 * I;
cd = 300.0 + 4000.0 * I;
cld = 50000.0 + 600000.0 * I;
/* Call the function */
ffi_call(&cif, (void (*)(void))complex_fn, 0, values);
}
return 0;
}
</pre></div>
<p>This is an example for defining a custom complex type descriptor
for compilers that support them:
</p>
<div class="example">
<pre class="example">/*
* This macro can be used to define new complex type descriptors
* in a platform independent way.
*
* name: Name of the new descriptor is ffi_type_complex_<name>.
* type: The C base type of the complex type.
*/
#define FFI_COMPLEX_TYPEDEF(name, type, ffitype) \
static ffi_type *ffi_elements_complex_##name [2] = { \
(ffi_type *)(&ffitype), NULL \
}; \
struct struct_align_complex_##name { \
char c; \
_Complex type x; \
}; \
ffi_type ffi_type_complex_##name = { \
sizeof(_Complex type), \
offsetof(struct struct_align_complex_##name, x), \
FFI_TYPE_COMPLEX, \
(ffi_type **)ffi_elements_complex_##name \
}
/* Define new complex type descriptors using the macro: */
/* ffi_type_complex_sint */
FFI_COMPLEX_TYPEDEF(sint, int, ffi_type_sint);
/* ffi_type_complex_uchar */
FFI_COMPLEX_TYPEDEF(uchar, unsigned char, ffi_type_uint8);
</pre></div>
<p>The new type descriptors can then be used like one of the built-in
type descriptors in the previous example.
</p>
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