From d4210ef902a2e6bbe43dfec9e52b683d4f46c0d3 Mon Sep 17 00:00:00 2001
From: gbeauche <>
Date: Fri, 27 Jan 2006 23:48:08 +0000
Subject: [PATCH] Check whether compiler supports byte bit-fields. If so, we
 can enable slirp emulation code since it pure C+sockets code.

---
 SheepShaver/src/Unix/configure.ac | 39 +++++++++++++++++++++++++++++--
 1 file changed, 37 insertions(+), 2 deletions(-)

diff --git a/SheepShaver/src/Unix/configure.ac b/SheepShaver/src/Unix/configure.ac
index 4714e933..5a4f5c7a 100644
--- a/SheepShaver/src/Unix/configure.ac
+++ b/SheepShaver/src/Unix/configure.ac
@@ -456,6 +456,36 @@ if [[ "$ac_cv_nonblocking_io" = "FIONBIO" ]]; then
   AC_DEFINE(USE_FIONBIO, 1, [Define if BSD-style non-blocking I/O is to be used])
 fi
 
+dnl Check whether compiler supports byte bit-fields
+AC_CACHE_CHECK([whether compiler supports byte bit-fields],
+  ac_cv_have_byte_bitfields, [
+  AC_LANG_SAVE
+  AC_LANG_CPLUSPLUS
+  AC_TRY_RUN([
+    struct A {
+      unsigned char b1:4;
+      unsigned char b2:4;
+      unsigned char c;
+      unsigned short s;
+      unsigned char a[4];
+    };
+
+    int main(void) {
+      A a;
+      return ! (sizeof(A) == 8 && &a.c == ((unsigned char *)&a + 1));
+    }],
+    [ac_cv_have_byte_bitfields=yes],
+    [ac_cv_have_byte_bitfields=no],
+    dnl When cross-compiling, assume only GCC supports this
+    [if [[ "$GCC" = "yes" ]]; then
+      ac_cv_have_byte_bitfields="guessing yes"
+    else
+      ac_cv_have_byte_bitfields="guessing no"
+    fi]
+    )
+  AC_LANG_RESTORE
+])
+
 dnl AC_CHECK_FRAMEWORK($1=NAME, $2=INCLUDES)
 AC_DEFUN(AC_CHECK_FRAMEWORK, [
   AS_VAR_PUSHDEF([ac_Framework], [ac_cv_framework_$1])dnl
@@ -517,7 +547,6 @@ darwin*)
   fi
   ;;
 irix*)
-  ETHERSRC=ether_unix.cpp
   AUDIOSRC=Irix/audio_irix.cpp
   LIBS="$LIBS -laudio"
   WANT_ESD=no
@@ -536,7 +565,13 @@ irix*)
 esac
 
 dnl Is the slirp library supported?
-if [[ "x$ETHERSRC" = "xether_unix.cpp" ]]; then
+case "$ac_cv_have_byte_bitfields" in
+yes|"guessing yes")
+  CAN_SLIRP=yes
+  ETHERSRC=ether_unix.cpp
+  ;;
+esac
+if [[ -n "$CAN_SLIRP" ]]; then
   AC_DEFINE(HAVE_SLIRP, 1, [Define if slirp library is supported])
   SLIRP_SRCS="\
     ../slirp/bootp.c     ../slirp/ip_output.c  ../slirp/tcp_input.c  \