Simple header file with defintions:


void sunpos(double d, double *L, double *M, double *ra, double *decl, double *rad);

In PHP, load definitions and call:


<?php
$ffi = FFI::load(__DIR__ . '/astro.h');

$dayNr = (time() - 946598400) / 86400.0;

$L    = FFI::new('double');
$M    = FFI::new('double');
$ra   = FFI::new('double');
$decl = FFI::new('double');
$rad  = FFI::new('double');

$ffi->sunpos(
    $dayNr,
    FFI::addr($L), FFI::addr($M), FFI::addr($ra), FFI::addr($decl), FFI::addr($rad)
);