From: Ben Pfaff <blp@gnu.org>
Date: Wed, 15 Aug 2007 03:37:54 +0000 (+0000)
Subject: * lib/count-one-bits.h: Add comments.  (From Bruno Haible.)
X-Git-Url: https://pintos-os.org/cgi-bin/gitweb.cgi?a=commitdiff_plain;h=6684d992bfedd21bf8dea1fbb52392c1d7c8159b;p=pspp

* lib/count-one-bits.h: Add comments.  (From Bruno Haible.)

* lib/count-one-bits.h: Don't include <limits.h>; no longer needed
given the changes below.
(COUNT_ONE_BITS): Use 'verify' rather than 'verify_true'.  Work
even on hosts that have padding bits beyond the supported 64.
(From Paul Eggert.)
---

diff --git a/ChangeLog b/ChangeLog
index 38652ba833..db8ece63b8 100644
--- a/ChangeLog
+++ b/ChangeLog
@@ -1,3 +1,14 @@
+2007-08-14  Ben Pfaff  <blp@gnu.org>
+
+	* lib/count-one-bits.h: Add comments.  From Bruno Haible.
+
+2007-08-14  Paul Eggert  <eggert@cs.ucla.edu>
+
+	* lib/count-one-bits.h: Don't include <limits.h>; no longer needed
+	given the changes below.
+	(COUNT_ONE_BITS): Use 'verify' rather than 'verify_true'.  Work
+	even on hosts that have padding bits beyond the supported 64.
+
 2007-08-10  Paul Eggert  <eggert@cs.ucla.edu>
 
 	* NEWS: In xstrtol, remove STRTOL_FATAL_ERROR and add xstrtol_fatal.
diff --git a/lib/count-one-bits.h b/lib/count-one-bits.h
index 7553bec4ec..e4a477b19d 100644
--- a/lib/count-one-bits.h
+++ b/lib/count-one-bits.h
@@ -20,19 +20,21 @@
 #ifndef COUNT_ONE_BITS_H
 # define COUNT_ONE_BITS_H 1
 
-#include <limits.h>
 #include <stdlib.h>
 #include "verify.h"
 
+/* Expand the code which computes the number of 1-bits of the local
+   variable 'x' of type TYPE (an unsigned integer type) and returns it
+   from the current function.  */
 #if __GNUC__ > 3 || (__GNUC__ == 3 && __GNUC_MINOR >= 4)
 #define COUNT_ONE_BITS(BUILTIN, TYPE)              \
         return BUILTIN (x);
 #else
-#define COUNT_ONE_BITS(BUILTIN, TYPE)                           \
-        int count = count_one_bits_32 (x);                      \
-        if (CHAR_BIT * sizeof (TYPE) > 32)                      \
-          count += count_one_bits_32 (x >> 31 >> 1);            \
-        (void) verify_true (CHAR_BIT * sizeof (TYPE) <= 64);    \
+#define COUNT_ONE_BITS(BUILTIN, TYPE)                                       \
+        verify ((TYPE) -1 >> 31 >> 31 <= 3); /* TYPE has at most 64 bits */ \
+        int count = count_one_bits_32 (x);                                  \
+        if (1 < (TYPE) -1 >> 31) /* TYPE has more than 32 bits? */          \
+          count += count_one_bits_32 (x >> 31 >> 1);                        \
         return count;
 
 /* Compute and return the the number of 1-bits set in the least