DragonFlyBSD

Hi Guys,

I found some problems in your implementation of bitstring.h. First,
the bit_nsearch was trying to find a cluster of zeros longer than
required. It also miss a break making the loop go through the entire
bitstring.
I also found that the implementation of fls was incorrect. The patch
also includes a fix where I replace the old fls with a modified
version of ffs which also makes the code more consistent.

Below, I am attaching the patch.

Thanks,
Luis.

--- /home/lmarmol/Projects/SoftPM/out-of-core/include/bitstring.h 2011-04-08
12:01:00.992644001 -0400
+++ bitstring.h 2011-04-13 17:08:56.196957002 -0400
@ -153,34 +153,23 @
*(value) = _value; \
} while (0)

#define _fls(mask, value) do { \
int _fmask = (mask); \
- int _value = (value); \
- int _bit = 0; \
- if (_fmask == 0) { \
- *(_value) = 0; \
- break; \
- } \
- for (_bit = 1; _fmask != 1; _bit++) \
- _fmask = (unsigned char) _fmask >> 1; \
- *(_value) = _bit; \
} while (0)

/ find last bit set in name */
#define bit_fls(name, nbits, value) do { \
#define bit_fls(name, nbits, value) do { \
bitstr_t *_name = (name); \
int _nbits = (nbits); \
- int _byte = _bit_byte(_nbits - 1); \
- int *_value = (value); \
- int _mask = 0;\
int _byte, _nbits = (nbits); \
+ int _startbyte = _bit_byte(_nbits - 1), _value = 1; \
if (_nbits > 0) \
for (; _byte >= 0; _byte--) { \
- if (!_name[_byte]) \
- continue; \
- _fls(_name[_byte], &_mask); \
- break; \
- } \
- *(_value) = (_mask * (_byte + 1)) - 1; \
+ for (_byte = _startbyte; _byte >= 0; --_byte) \
+ if (_name[_byte]) { \
+ bitstr_t _lb; \
+ _value = _byte << 3; \
+ for (_lb = _name[_byte]; _lb != 0x1; \
+ +_value, _lb >>= 1); \
break; \
+ } \
+ if (_value >= nbits) \
+ _value = -1; \
+ *(value) = _value; \
} while (0)

/* find clear range of length len */
@ -203,7 +192,7 @
                 continue; \
             } \
         } else { \
-            if (_tmplen >= 0) { \
+            if (_tmplen > 0) { \
                 if (bit_test((_name), _bit) == 0) { \
                     _tmplen--; \
                 } else { \
@ -213,6 +202,7 @
                 } \
             } else { \
                 *(_value) = _bit0; \
+                                break; \
             } \
         } \
     } \