+dnl Check for fully workin MMX intrinsics
+dnl We need support for -mmmx, we need <mmintrin.h>, and we also need a
+dnl working compiler (http://gcc.gnu.org/bugzilla/show_bug.cgi?id=23963)
+AC_CACHE_CHECK([if \$CC groks MMX intrinsics],
+ [ac_cv_c_mmx_intrinsics],
+ [CFLAGS="${CFLAGS_save} -O -mmmx"
+ AC_TRY_COMPILE([#include <mmintrin.h>
+ #include <stdint.h>
+ uint64_t frobzor;],
+ [__m64 a, b, c;
+ a = b = c = (__m64)frobzor;
+ a = _mm_slli_pi16(a, 3);
+ a = _mm_adds_pi16(a, b);
+ c = _mm_srli_pi16(c, 8);
+ c = _mm_slli_pi16(c, 3);
+ b = _mm_adds_pi16(b, c);
+ a = _mm_unpacklo_pi8(a, b);
+ frobzor = (uint64_t)a;],
+ [ac_cv_c_mmx_intrinsics=yes],
+ [ac_cv_c_mmx_intrinsics=no])])
+if test "${ac_cv_c_mmx_intrinsics}" != "no"; then
+ AC_DEFINE(HAVE_MMX_INTRINSICS, 1, Define if MMX intrinsics are available.)
+ VLC_ADD_CFLAGS([i420_rgb_mmx],[-mmmx])
+fi
+