Cope with big endian float word order on little endian machines

diff --git a/aclocal.m4 b/aclocal.m4
index 619d414..9d1e1ca 100644 (file)
--- a/aclocal.m4
+++ b/aclocal.m4
@@ -4,6 +4,33 @@
 # ensure we don't clash with any pre-supplied autoconf ones.
 
 
+# FPTOOLS_FLOAT_WORD_ORDER_BIGENDIAN
+# ----------------------------------
+# Little endian Arm on Linux with some ABIs has big endian word order
+# in doubles. Define FLOAT_WORDS_BIGENDIAN if this is the case.
+AC_DEFUN([FPTOOLS_FLOAT_WORD_ORDER_BIGENDIAN],
+  [AC_CACHE_CHECK([whether float word order is big endian], [fptools_cv_float_word_order_bigendian],
+    [AC_COMPILE_IFELSE(
+      [AC_LANG_PROGRAM(
+        [#include <endian.h>],
+        [#if defined(__FLOAT_WORD_ORDER) && __FLOAT_WORD_ORDER == BIG_ENDIAN
+             return 0;
+         #else
+             not float word order big endian
+         #endif]
+      )],
+      [fptools_cv_float_word_order_bigendian=yes],
+      [fptools_cv_float_word_order_bigendian=no])
+    ])
+  case $fptools_cv_float_word_order_bigendian in
+      yes)
+          AC_DEFINE([FLOAT_WORDS_BIGENDIAN], 1,
+          [Define to 1 if your processor stores words of floats with
+           the most significant byte first]) ;;
+  esac
+])
+
+
 # FP_EVAL_STDERR(COMMAND)
 # -----------------------
 # Eval COMMAND, save its stderr (without lines resulting from shell tracing)

diff --git a/configure.ac b/configure.ac
index 37bf318..1d28aa8 100644 (file)
--- a/configure.ac
+++ b/configure.ac
@@ -1136,6 +1136,7 @@ AC_C_CONST
 
 dnl ** are we big endian?
 AC_C_BIGENDIAN
+FPTOOLS_FLOAT_WORD_ORDER_BIGENDIAN
 
 dnl ** check for leading underscores in symbol names
 FP_LEADING_UNDERSCORE

diff --git a/rts/StgPrimFloat.c b/rts/StgPrimFloat.c
index 5bd6aeb..9521094 100644 (file)
--- a/rts/StgPrimFloat.c
+++ b/rts/StgPrimFloat.c
@@ -48,7 +48,7 @@
 #define FMSBIT   0x80000000
 #endif
 
-#ifdef WORDS_BIGENDIAN
+#if defined(WORDS_BIGENDIAN) || defined(FLOAT_WORDS_BIGENDIAN)
 #define L 1
 #define H 0
 #else
@@ -307,11 +307,18 @@ union stg_ieee754_dbl
        unsigned int mantissa0:20;
        unsigned int mantissa1:32;
 #else
+#if FLOAT_WORDS_BIGENDIAN
+       unsigned int mantissa0:20;
+       unsigned int exponent:11;
+       unsigned int negative:1;
+       unsigned int mantissa1:32;
+#else
        unsigned int mantissa1:32;
        unsigned int mantissa0:20;
        unsigned int exponent:11;
        unsigned int negative:1;
 #endif
+#endif
    } ieee;
     /* This format makes it easier to see if a NaN is a signalling NaN.  */
    struct {
@@ -323,12 +330,20 @@ union stg_ieee754_dbl
        unsigned int mantissa0:19;
        unsigned int mantissa1:32;
 #else
+#if FLOAT_WORDS_BIGENDIAN
+       unsigned int mantissa0:19;
+       unsigned int quiet_nan:1;
+       unsigned int exponent:11;
+       unsigned int negative:1;
+       unsigned int mantissa1:32;
+#else
        unsigned int mantissa1:32;
        unsigned int mantissa0:19;
        unsigned int quiet_nan:1;
        unsigned int exponent:11;
        unsigned int negative:1;
 #endif
+#endif
    } ieee_nan;
 };