akr	2010-05-12 22:23:20 +0900 (Wed, 12 May 2010)

  New Revision: 27759

  http://svn.ruby-lang.org/cgi-bin/viewvc.cgi?view=rev&revision=27759

  Log:
    * time.c (rb_big_abs_find_minbit): use ffs().
    
    * configure.in: check ffs().
    
    * missing/ffs.c: new file.
    
    * include/ruby/missing.h (ffs): declared.

  Added files:
    trunk/missing/ffs.c
  Modified files:
    trunk/ChangeLog
    trunk/configure.in
    trunk/include/ruby/missing.h
    trunk/time.c

Index: time.c
===================================================================
--- time.c	(revision 27758)
+++ time.c	(revision 27759)
@@ -345,7 +345,7 @@
         return Qnil;
     res = mul(LONG2NUM(i), INT2FIX(SIZEOF_BDIGITS * CHAR_BIT));
     d = ds[i];
-    res = add(res, LONG2FIX(bdigit_find_maxbit(d & (~d+1))));
+    res = add(res, LONG2FIX(ffs(d)-1));
     return res;
 }
 
Index: include/ruby/missing.h
===================================================================
--- include/ruby/missing.h	(revision 27758)
+++ include/ruby/missing.h	(revision 27759)
@@ -159,6 +159,10 @@
 RUBY_EXTERN size_t strlcat(char *, const char*, size_t);
 #endif
 
+#ifndef HAVE_FFS
+RUBY_EXTERN int ffs(int);
+#endif
+
 #if defined(__cplusplus)
 #if 0
 { /* satisfy cc-mode */
Index: configure.in
===================================================================
--- configure.in	(revision 27758)
+++ configure.in	(revision 27759)
@@ -1117,7 +1117,7 @@
 AC_REPLACE_FUNCS(dup2 memmove strerror\
 		 strchr strstr crypt flock\
 		 isnan finite isinf hypot acosh erf tgamma lgamma_r cbrt \
-                 strlcpy strlcat)
+                 strlcpy strlcat ffs)
 AC_CACHE_CHECK(for signbit, rb_cv_have_signbit,
   [AC_TRY_LINK([
 #include <math.h>
Index: ChangeLog
===================================================================
--- ChangeLog	(revision 27758)
+++ ChangeLog	(revision 27759)
@@ -1,3 +1,13 @@
+Wed May 12 22:22:05 2010  Tanaka Akira  <akr@f...>
+
+	* time.c (rb_big_abs_find_minbit): use ffs().
+
+	* configure.in: check ffs().
+
+	* missing/ffs.c: new file.
+
+	* include/ruby/missing.h (ffs): declared.
+
 Wed May 12 16:43:12 2010  Nobuyoshi Nakada  <nobu@r...>
 
 	* numeric.c (flo_to_s): fixed broken output including nuls.
Index: missing/ffs.c
===================================================================
--- missing/ffs.c	(revision 0)
+++ missing/ffs.c	(revision 27759)
@@ -0,0 +1,47 @@
+/* ffs.c - find first set bit */
+/* ffs() is defined by POSIX. */
+
+#include "ruby.h"
+
+int ffs(int arg)
+{
+    unsigned int x = (unsigned int)arg;
+    int r = 0;
+
+    if (x == 0)
+        return 0;
+
+#if 32 < SIZEOF_INT * CHAR_BIT
+    if ((x & 0xffffffff) == 0) {
+        x >>= 32;
+        r += 32;
+    }
+#endif
+
+    if ((x & 0xffff) == 0) {
+        x >>= 16;
+        r += 16;
+    }
+
+    if ((x & 0xff) == 0) {
+        x >>= 8;
+        r += 8;
+    }
+
+    if ((x & 0xf) == 0) {
+        x >>= 4;
+        r += 4;
+    }
+
+    if ((x & 0x3) == 0) {
+        x >>= 2;
+        r += 2;
+    }
+
+    if ((x & 0x1) == 0) {
+        x >>= 1;
+        r += 1;
+    }
+
+    return r;
+}

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