+#### NEON optimisations ####
+AC_ARG_ENABLE([neon-opt],
+ AS_HELP_STRING([--enable-neon-opt], [Enable NEON optimisations on ARM CPUs that support it]))
+
+AS_IF([test "x$enable_neon_opt" != "xno"],
+ [save_CFLAGS="$CFLAGS"; CFLAGS="-mfpu=neon $CFLAGS"
+ AC_COMPILE_IFELSE(
+ [AC_LANG_PROGRAM([[#include <arm_neon.h>]], [])],
+ [
+ HAVE_NEON=1
+ NEON_CFLAGS="-mfpu=neon"
+ ],
+ [
+ HAVE_NEON=0
+ NEON_CFLAGS=
+ ])
+ CFLAGS="$save_CFLAGS"
+ ],
+ [HAVE_NEON=0])
+
+AS_IF([test "x$enable_neon_opt" = "xyes" && test "x$HAVE_NEON" = "x0"],
+ [AC_MSG_ERROR([*** Compiler does not support -mfpu=neon or CFLAGS override -mfpu])])
+
+AC_SUBST(HAVE_NEON)
+AC_SUBST(NEON_CFLAGS)
+AM_CONDITIONAL([HAVE_NEON], [test "x$HAVE_NEON" = x1])
+AS_IF([test "x$HAVE_NEON" = "x1"], AC_DEFINE([HAVE_NEON], 1, [Have NEON support?]))
+