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This example demonstrates how to use complex types:
#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; }
This is an example for defining a custom complex type descriptor for compilers that support them:
/* * 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);
The new type descriptors can then be used like one of the built-in type descriptors in the previous example.