* missing/signbit.c: added.

git-svn-id: svn+ssh://ci.ruby-lang.org/ruby/trunk@26871 b2dd03c8-39d4-4d8f-98ff-823fe69b080e

ChangeLog

@@ -1,3 +1,7 @@
+Thu Mar 11 12:14:17 2010  Nobuyoshi Nakada  <nobu@ruby-lang.org>
+
+	* missing/signbit.c: added.
+
 Thu Mar 11 11:16:33 2010  Nobuyoshi Nakada  <nobu@ruby-lang.org>
 
 	* configure.in: check if target_archs has changed.

configure.in

@@ -1114,7 +1114,7 @@ AS_CASE([$rb_cv_broken_glibc_ia64_erfc],[yes],[ac_cv_func_erf=no])
 AS_CASE(["$target_os"],[mingw*],[],[AC_REPLACE_FUNCS(vsnprintf)])
 AC_REPLACE_FUNCS(dup2 memmove strerror\
 		 strchr strstr crypt flock\
-		 isnan finite isinf hypot acosh erf tgamma lgamma_r cbrt \
+		 isnan finite isinf hypot acosh erf tgamma lgamma_r cbrt signbit \
                  strlcpy strlcat)
 AC_CHECK_FUNCS(fmod killpg wait4 waitpid fork spawnv syscall chroot getcwd eaccess\
 	      truncate ftruncate chsize times utimes utimensat fcntl lockf lstat\
@@ -1124,7 +1124,7 @@ AC_CHECK_FUNCS(fmod killpg wait4 waitpid fork spawnv syscall chroot getcwd eacce
 	      getpgrp setpgrp getpgid setpgid initgroups getgroups setgroups\
 	      getpriority getrlimit setrlimit sysconf \
 	      dlopen sigprocmask sigaction sigsetjmp _setjmp _longjmp snprintf\
-	      setsid telldir seekdir fchmod cosh sinh tanh log2 round signbit\
+	      setsid telldir seekdir fchmod cosh sinh tanh log2 round\
 	      setuid setgid daemon select_large_fdset setenv unsetenv\
               mktime timegm gmtime_r clock_gettime gettimeofday\
               pread sendfile shutdown sigaltstack)

missing/signbit.c

@@ -0,0 +1,19 @@
+#include <limits.h>
+#include "ruby.h"
+
+int
+signbit(double x)
+{
+    enum {double_per_long = sizeof(double) / sizeof(long)};
+    enum {long_msb = sizeof(long) * CHAR_BIT - 1};
+    union {double d; unsigned long i[double_per_long];} u;
+    unsigned long l;
+
+    u.d = x;
+#ifdef WORDS_BIGENDIAN
+    l = u.i[0];
+#else
+    l = u.i[double_per_long - 1];
+#endif
+    return (int)(l >> long_msb);
+}