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To: libffi-discuss@sourceware.org
From: =?UTF-8?Q?St=c3=a9phane_Glondu?= <steph@glondu.net>
Subject: Function returning uint16
Message-ID: <5762BFD6.1020704@glondu.net>
Date: Thu, 16 Jun 2016 15:04:00 -0000
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Hello,

I am trying to debug

   https://github.com/ocamllabs/ocaml-ctypes/issues/404

and I realized that the following code (on amd64):

#include <stdio.h>
#include <stdint.h>
#include <ffi.h>

uint16_t retrieve() {
   return 0x4242;
}

int main() {
   uint16_t r[2] = { 0xdead, 0xbeef };
   ffi_cif cif;
   printf("r = {%x, %x}\n", r[0], r[1]);
   ffi_prep_cif(&cif, FFI_DEFAULT_ABI, 0, &ffi_type_uint16, NULL);
   ffi_call(&cif, FFI_FN(retrieve), &r[0], NULL);
   printf("r = {%x, %x}\n", r[0], r[1]);
   return 0;
}

returns:

r = {dead, beef}
r = {4242, 0}

Is that expected? I don't expect r[1] to be overwritten...


Cheers,

-- 
Stéphane