Unbreak floating point on middle-endian machines.

On some ARMs (and maybe other platforms), doubles are stored with the
the two 32-bit words reversed with respect to more common
architectures.

The symptom is this:

> io_lib:write(1.0).
"0.000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000005299808824"

Detect that and account for it when decoding floats.

8 files changed, 63 insertions, 1 deletions

diff --git a/xcomp/README.md b/xcomp/README.md
index 2d79107283..98e71d5962 100644
--- a/xcomp/README.md
+++ b/xcomp/README.md
@@ -430,6 +430,14 @@ When a variable has been set, no warning will be issued.
     `configure` will fail unless this variable is set. Since no default
     value is used, `configure` will try to figure this out automatically.
 
+*   `erl_xcomp_double_middle` - `yes|no`. No default. If `yes`, the
+    target system must have doubles in "middle-endian" format. If
+    `no`, it has "regular" endianness. This can often be automatically
+    detected, but not always. If not automatically detected,
+    `configure` will fail unless this variable is set. Since no
+    default value is used, `configure` will try to figure this out
+    automatically.
+
 *   `erl_xcomp_clock_gettime_cpu_time` - `yes|no`. Defaults to `no`. If `yes`,
     the target system must have a working `clock_gettime()` implementation
     that can be used for retrieving process CPU time.
diff --git a/xcomp/erl-xcomp-TileraMDE2.0-tilepro.conf b/xcomp/erl-xcomp-TileraMDE2.0-tilepro.conf
index f9fff0fa8e..287cb787d9 100644
--- a/xcomp/erl-xcomp-TileraMDE2.0-tilepro.conf
+++ b/xcomp/erl-xcomp-TileraMDE2.0-tilepro.conf
@@ -187,6 +187,15 @@ erl_xcomp_sysroot="$TILERA_ROOT/tile"
 #   value is used, `configure' will try to figure this out automatically.
 #erl_xcomp_bigendian=
 
+# * `erl_xcomp_double_middle_endian` - `yes|no`. No default. If `yes`, the
+#   target system must have doubles in "middle-endian" format. If
+#   `no`, it has "regular" endianness. This can often be automatically
+#   detected, but not always. If not automatically detected,
+#   `configure` will fail unless this variable is set. Since no
+#   default value is used, `configure` will try to figure this out
+#   automatically.
+#erl_xcomp_double_middle_endian
+
 # * `erl_xcomp_clock_gettime_cpu_time' - `yes|no'. Defaults to `no'. If `yes',
 #   the target system must have a working `clock_gettime()' implementation
 #   that can be used for retrieving process CPU time.
diff --git a/xcomp/erl-xcomp-avr32-atmel-linux-gnu.conf b/xcomp/erl-xcomp-avr32-atmel-linux-gnu.conf
index 31f5306c1a..9e553e6217 100644
--- a/xcomp/erl-xcomp-avr32-atmel-linux-gnu.conf
+++ b/xcomp/erl-xcomp-avr32-atmel-linux-gnu.conf
@@ -190,6 +190,15 @@ erl_xcomp_sysroot="$ATMEL_SYSROOT_AVR32"
 #   value is used, `configure' will try to figure this out automatically.
 #erl_xcomp_bigendian=
 
+# * `erl_xcomp_double_middle_endian` - `yes|no`. No default. If `yes`, the
+#   target system must have doubles in "middle-endian" format. If
+#   `no`, it has "regular" endianness. This can often be automatically
+#   detected, but not always. If not automatically detected,
+#   `configure` will fail unless this variable is set. Since no
+#   default value is used, `configure` will try to figure this out
+#   automatically.
+#erl_xcomp_double_middle_endian
+
 # * `erl_xcomp_clock_gettime_cpu_time' - `yes|no'. Defaults to `no'. If `yes',
 #   the target system must have a working `clock_gettime()' implementation
 #   that can be used for retrieving process CPU time.
diff --git a/xcomp/erl-xcomp-mips-linux.conf b/xcomp/erl-xcomp-mips-linux.conf
index 3ac057bb4c..2195b7d6e9 100644
--- a/xcomp/erl-xcomp-mips-linux.conf
+++ b/xcomp/erl-xcomp-mips-linux.conf
@@ -187,6 +187,15 @@ CFLAGS=-Os
 #   value is used, `configure' will try to figure this out automatically.
 #erl_xcomp_bigendian=
 
+# * `erl_xcomp_double_middle_endian` - `yes|no`. No default. If `yes`, the
+#   target system must have doubles in "middle-endian" format. If
+#   `no`, it has "regular" endianness. This can often be automatically
+#   detected, but not always. If not automatically detected,
+#   `configure` will fail unless this variable is set. Since no
+#   default value is used, `configure` will try to figure this out
+#   automatically.
+#erl_xcomp_double_middle_endian
+
 # * `erl_xcomp_clock_gettime_cpu_time' - `yes|no'. Defaults to `no'. If `yes',
 #   the target system must have a working `clock_gettime()' implementation
 #   that can be used for retrieving process CPU time.
diff --git a/xcomp/erl-xcomp-vars.sh b/xcomp/erl-xcomp-vars.sh
index d9972eb3db..168b25262a 100644
--- a/xcomp/erl-xcomp-vars.sh
+++ b/xcomp/erl-xcomp-vars.sh
@@ -26,4 +26,4 @@
 #    and precious variables in $ERL_TOP/erts/aclocal.m4.
 #
 
-erl_xcomp_vars="erl_xcomp_sysroot erl_xcomp_isysroot erl_xcomp_bigendian erl_xcomp_linux_clock_gettime_correction erl_xcomp_linux_nptl erl_xcomp_linux_usable_sigusrx erl_xcomp_linux_usable_sigaltstack erl_xcomp_poll erl_xcomp_kqueue erl_xcomp_putenv_copy erl_xcomp_reliable_fpe erl_xcomp_getaddrinfo erl_xcomp_gethrvtime_procfs_ioctl erl_xcomp_clock_gettime_cpu_time erl_xcomp_after_morecore_hook erl_xcomp_dlsym_brk_wrappers"
+erl_xcomp_vars="erl_xcomp_sysroot erl_xcomp_isysroot erl_xcomp_bigendian erl_xcomp_double_middle_endian erl_xcomp_linux_clock_gettime_correction erl_xcomp_linux_nptl erl_xcomp_linux_usable_sigusrx erl_xcomp_linux_usable_sigaltstack erl_xcomp_poll erl_xcomp_kqueue erl_xcomp_putenv_copy erl_xcomp_reliable_fpe erl_xcomp_getaddrinfo erl_xcomp_gethrvtime_procfs_ioctl erl_xcomp_clock_gettime_cpu_time erl_xcomp_after_morecore_hook erl_xcomp_dlsym_brk_wrappers"
diff --git a/xcomp/erl-xcomp-vxworks_ppc32.conf b/xcomp/erl-xcomp-vxworks_ppc32.conf
index ed8305ea93..bea4b3e374 100644
--- a/xcomp/erl-xcomp-vxworks_ppc32.conf
+++ b/xcomp/erl-xcomp-vxworks_ppc32.conf
@@ -187,6 +187,15 @@ AR="$WIND_BASE/gnu/3.4.4-vxworks-6.3/$WIND_HOST_TYPE/bin/arppc"
 #   value is used, `configure' will try to figure this out automatically.
 erl_xcomp_bigendian=yes
 
+# * `erl_xcomp_double_middle_endian` - `yes|no`. No default. If `yes`, the
+#   target system must have doubles in "middle-endian" format. If
+#   `no`, it has "regular" endianness. This can often be automatically
+#   detected, but not always. If not automatically detected,
+#   `configure` will fail unless this variable is set. Since no
+#   default value is used, `configure` will try to figure this out
+#   automatically.
+#erl_xcomp_double_middle_endian
+
 # * `erl_xcomp_clock_gettime_cpu_time' - `yes|no'. Defaults to `no'. If `yes',
 #   the target system must have a working `clock_gettime()' implementation
 #   that can be used for retrieving process CPU time.
diff --git a/xcomp/erl-xcomp-x86_64-saf-linux-gnu.conf b/xcomp/erl-xcomp-x86_64-saf-linux-gnu.conf
index f645ddbd96..de9118ae30 100644
--- a/xcomp/erl-xcomp-x86_64-saf-linux-gnu.conf
+++ b/xcomp/erl-xcomp-x86_64-saf-linux-gnu.conf
@@ -187,6 +187,15 @@ erl_xcomp_after_morecore_hook=yes
 #   value is used, `configure' will try to figure this out automatically.
 #erl_xcomp_bigendian=
 
+# * `erl_xcomp_double_middle_endian` - `yes|no`. No default. If `yes`, the
+#   target system must have doubles in "middle-endian" format. If
+#   `no`, it has "regular" endianness. This can often be automatically
+#   detected, but not always. If not automatically detected,
+#   `configure` will fail unless this variable is set. Since no
+#   default value is used, `configure` will try to figure this out
+#   automatically.
+#erl_xcomp_double_middle_endian
+
 # * `erl_xcomp_clock_gettime_cpu_time' - `yes|no'. Defaults to `no'. If `yes',
 #   the target system must have a working `clock_gettime()' implementation
 #   that can be used for retrieving process CPU time.
diff --git a/xcomp/erl-xcomp.conf.template b/xcomp/erl-xcomp.conf.template
index eb331ffe92..c215f0fb13 100644
--- a/xcomp/erl-xcomp.conf.template
+++ b/xcomp/erl-xcomp.conf.template
@@ -187,6 +187,15 @@
 #   value is used, `configure' will try to figure this out automatically.
 #erl_xcomp_bigendian=
 
+# * `erl_xcomp_double_middle` - `yes|no`. No default. If `yes`, the
+#   target system must have doubles in "middle-endian" format. If
+#   `no`, it has "regular" endianness. This can often be automatically
+#   detected, but not always. If not automatically detected,
+#   `configure` will fail unless this variable is set. Since no
+#   default value is used, `configure` will try to figure this out
+#   automatically.
+#erl_xcomp_double_middle_endian
+
 # * `erl_xcomp_clock_gettime_cpu_time' - `yes|no'. Defaults to `no'. If `yes',
 #   the target system must have a working `clock_gettime()' implementation
 #   that can be used for retrieving process CPU time.