ffi: fix more bugginess in struct bitfield allocation.

* ffi.c (make_ffi_type_struct): Fix incorrect shift
calculations, which are still being done from the
unit_offs byte rather than the correct offs byte where
the bitfield is actually placed. It is bit_offs which
has the correct bit offset of the bitfield relative
to offs.

1 files changed, 2 insertions, 2 deletions

diff --git a/ffi.c b/ffi.c
index 98d126ce..3c8a1c8c 100644
--- a/ffi.c
+++ b/ffi.c
@@ -2906,9 +2906,9 @@ static val make_ffi_type_struct(val syntax, val lisp_type,
       memb[i].offs = offs;
 
 #if HAVE_LITTLE_ENDIAN
-      mtft->shift = bits_alloc;
+      mtft->shift = bit_offs;
 #else
-      mtft->shift = bits_int - bits_alloc - bits;
+      mtft->shift = bits_int - bit_offs - bits;
 #endif
       if (bits == bits_int)
         mtft->mask = UINT_MAX;