Change float representation in mrb binary files.

From human readable (ASCII) string representation to binary dump of
IEEE754 in little endian.

include/mruby/endian.h

@@ -0,0 +1,44 @@
+/**
+** @file mruby/endian.h - detect endian-ness
+**
+** See Copyright Notice in mruby.h
+*/
+
+#ifndef MRUBY_ENDIAN_H
+#define MRUBY_ENDIAN_H
+
+#include <limits.h>
+
+MRB_BEGIN_DECL
+
+#if !defined(BYTE_ORDER) && defined(__BYTE_ORDER__)
+# define BYTE_ORDER __BYTE_ORDER__
+#endif
+#if !defined(BIG_ENDIAN) && defined(__ORDER_BIG_ENDIAN__)
+# define BIG_ENDIAN __ORDER_BIG_ENDIAN__
+#endif
+#if !defined(LITTLE_ENDIAN) && defined(__ORDER_LITTLE_ENDIAN__)
+# define LITTLE_ENDIAN __ORDER_LITTLE_ENDIAN__
+#endif
+
+#ifdef BYTE_ORDER
+# if BYTE_ORDER == BIG_ENDIAN
+#  define littleendian 0
+# elif BYTE_ORDER == LITTLE_ENDIAN
+#  define littleendian 1
+# endif
+#endif
+#ifndef littleendian
+/* can't distinguish endian in compile time */
+static inline int
+check_little_endian(void)
+{
+  unsigned int n = 1;
+  return (*(unsigned char *)&n == 1);
+}
+#  define littleendian check_little_endian()
+#endif
+
+MRB_END_DECL
+
+#endif  /* MRUBY_ENDIAN_H */