[PATCH] portability: don't assume 8-bit bytes.

[Joel E. Denny]

I pushed these to master and branch-2.5.  I'm not sure how concerned we 
are with platforms where CHAR_BIT != 8, but this at least makes the 
semantics of the code a little more obvious, I think.

>From 175620d3c65209ce72e451bd75756f6bb67e33a1 Mon Sep 17 00:00:00 2001
From: Joel E. Denny <address@hidden>
Date: Fri, 16 Oct 2009 19:20:43 -0400
Subject: [PATCH] portability: don't assume 8-bit bytes.

That is, use CHAR_BIT and UCHAR_MAX instead of 8 and 0xff.
* src/Sbitset.h (Sbitset__nbytes): Here.
(Sbitset__byteAddress): Here.
(Sbitset__bit_mask): Here.
(Sbitset__last_byte_mask): Here.
(Sbitset__ones): Here.
(SBITSET__FOR_EACH): Here.
---
 ChangeLog     |   11 +++++++++++
 src/Sbitset.h |   18 +++++++++++-------
 2 files changed, 22 insertions(+), 7 deletions(-)

diff --git a/ChangeLog b/ChangeLog
index a0e138d..f281abb 100644
--- a/ChangeLog
+++ b/ChangeLog
@@ -1,3 +1,14 @@
+2009-10-16  Joel E. Denny  <address@hidden>
+
+       portability: don't assume 8-bit bytes.
+       That is, use CHAR_BIT and UCHAR_MAX instead of 8 and 0xff.
+       * src/Sbitset.h (Sbitset__nbytes): Here.
+       (Sbitset__byteAddress): Here.
+       (Sbitset__bit_mask): Here.
+       (Sbitset__last_byte_mask): Here.
+       (Sbitset__ones): Here.
+       (SBITSET__FOR_EACH): Here.
+
 2009-10-11  Joel E. Denny  <address@hidden>
 
        portability: use va_start and va_end in the same function.
diff --git a/src/Sbitset.h b/src/Sbitset.h
index a025040..0d0aabf 100644
--- a/src/Sbitset.h
+++ b/src/Sbitset.h
@@ -24,10 +24,14 @@ typedef char *Sbitset;
 typedef size_t Sbitset__Index;
 #define SBITSET__INDEX__CONVERSION_SPEC "zu"
 
-#define Sbitset__nbytes(NBITS)            (((NBITS)+7)/8)
-#define Sbitset__byteAddress(SELF, INDEX) (((SELF) + (INDEX)/8))
-#define Sbitset__bit_mask(INDEX)          (0x1 << (7 - (INDEX)%8))
-#define Sbitset__last_byte_mask(NBITS)    (0xff << (7 - ((NBITS)-1)%8))
+#define Sbitset__nbytes(NBITS) \
+  (((NBITS) + CHAR_BIT - 1) / CHAR_BIT)
+#define Sbitset__byteAddress(SELF, INDEX) \
+  (((SELF) + (INDEX) / CHAR_BIT))
+#define Sbitset__bit_mask(INDEX) \
+  (1 << (CHAR_BIT - 1 - (INDEX) % CHAR_BIT))
+#define Sbitset__last_byte_mask(NBITS) \
+  (UCHAR_MAX << (CHAR_BIT - 1 - ((NBITS) - 1) % CHAR_BIT))
 
 /* nbits must not be 0.  */
 Sbitset Sbitset__new (Sbitset__Index nbits);
@@ -63,7 +67,7 @@ do {                                                          
                \
 /* NBITS is the size of the bitset.  More than NBITS bits might be set.  */
 #define Sbitset__ones(SELF, NBITS)                                            \
 do {                                                                          \
-  memset (SELF, 0xff, Sbitset__nbytes (NBITS));                               \
+  memset (SELF, UCHAR_MAX, Sbitset__nbytes (NBITS));                          \
 } while(0)
 
 /* NBITS is the size of every bitset.  More than NBITS bits might be set.  */
@@ -80,8 +84,8 @@ do {                                                          
                \
 #define SBITSET__FOR_EACH(SELF, NBITS, ITER, INDEX)                           \
   for ((ITER) = (SELF); (ITER) < (SELF) + Sbitset__nbytes (NBITS); ++(ITER))  \
     if (*(ITER) != 0)                                                         \
-      for ((INDEX) = ((ITER)-(SELF))*8;                                       \
-           (INDEX) < (NBITS) && (SELF)+(INDEX)/8 < (ITER)+1;                  \
+      for ((INDEX) = ((ITER)-(SELF))*CHAR_BIT;                                \
+           (INDEX) < (NBITS) && (SELF)+(INDEX)/CHAR_BIT < (ITER)+1;           \
            ++(INDEX))                                                         \
         if (((*ITER) & Sbitset__bit_mask (INDEX)) != 0)
 
-- 
1.5.4.3


>From 5297ebb3bcdf4f957bdab9c5535c2c9c47f7dc07 Mon Sep 17 00:00:00 2001
From: Joel E. Denny <address@hidden>
Date: Fri, 16 Oct 2009 19:27:12 -0400
Subject: [PATCH] cleanup.

* src/Sbitset.c (Sbitset__new_on_obstack): Use Sbitset instead
of char*.
(Sbitset__isEmpty): Use Sbitset instead of char*.
* src/Sbitset.h (Sbitset): Make it a pointer to unsigned char
instead of char.  This helps to avoid casting errors.
(Sbitset__or): Use Sbitset instead of char*.
---
 ChangeLog     |   10 ++++++++++
 src/Sbitset.c |    8 ++++----
 src/Sbitset.h |   10 +++++-----
 3 files changed, 19 insertions(+), 9 deletions(-)

diff --git a/ChangeLog b/ChangeLog
index f281abb..b1425e3 100644
--- a/ChangeLog
+++ b/ChangeLog
@@ -1,5 +1,15 @@
 2009-10-16  Joel E. Denny  <address@hidden>
 
+       cleanup.
+       * src/Sbitset.c (Sbitset__new_on_obstack): Use Sbitset instead
+       of char*.
+       (Sbitset__isEmpty): Use Sbitset instead of char*.
+       * src/Sbitset.h (Sbitset): Make it a pointer to unsigned char
+       instead of char.  This helps to avoid casting errors.
+       (Sbitset__or): Use Sbitset instead of char*.
+
+2009-10-16  Joel E. Denny  <address@hidden>
+
        portability: don't assume 8-bit bytes.
        That is, use CHAR_BIT and UCHAR_MAX instead of 8 and 0xff.
        * src/Sbitset.h (Sbitset__nbytes): Here.
diff --git a/src/Sbitset.c b/src/Sbitset.c
index af8600b..742b565 100644
--- a/src/Sbitset.c
+++ b/src/Sbitset.c
@@ -33,9 +33,9 @@ Sbitset__new (Sbitset__Index nbits)
 Sbitset
 Sbitset__new_on_obstack (Sbitset__Index nbits, struct obstack *obstackp)
 {
-  char *result;
-  char *ptr;
-  char *end;
+  Sbitset result;
+  Sbitset ptr;
+  Sbitset end;
   aver (nbits);
   result = obstack_alloc (obstackp, Sbitset__nbytes (nbits));
   for (ptr = result, end = result + Sbitset__nbytes (nbits); ptr < end; ++ptr)
@@ -52,7 +52,7 @@ Sbitset__delete (Sbitset self)
 bool
 Sbitset__isEmpty (Sbitset self, Sbitset__Index nbits)
 {
-  char *last = self + Sbitset__nbytes (nbits) - 1;
+  Sbitset last = self + Sbitset__nbytes (nbits) - 1;
   for (; self < last; ++self)
     if (*self != 0)
       return false;
diff --git a/src/Sbitset.h b/src/Sbitset.h
index 0d0aabf..e379398 100644
--- a/src/Sbitset.h
+++ b/src/Sbitset.h
@@ -20,7 +20,7 @@
 #ifndef SBITSET_H_
 # define SBITSET_H_
 
-typedef char *Sbitset;
+typedef unsigned char *Sbitset;
 typedef size_t Sbitset__Index;
 #define SBITSET__INDEX__CONVERSION_SPEC "zu"
 
@@ -73,10 +73,10 @@ do {                                                        
                  \
 /* NBITS is the size of every bitset.  More than NBITS bits might be set.  */
 #define Sbitset__or(SELF, OTHER1, OTHER2, NBITS)                              \
 do {                                                                          \
-  char *ptr_self = (SELF);                                                    \
-  char *ptr_other1 = (OTHER1);                                                \
-  char *ptr_other2 = (OTHER2);                                                \
-  char *end_self = ptr_self + Sbitset__nbytes (NBITS);                        \
+  Sbitset ptr_self = (SELF);                                                  \
+  Sbitset ptr_other1 = (OTHER1);                                              \
+  Sbitset ptr_other2 = (OTHER2);                                              \
+  Sbitset end_self = ptr_self + Sbitset__nbytes (NBITS);                      \
   for (; ptr_self < end_self; ++ptr_self, ++ptr_other1, ++ptr_other2)         \
     *ptr_self = *ptr_other1 | *ptr_other2;                                    \
 } while(0)
-- 
1.5.4.3