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bitset: A more-efficient bit(set)_run_count

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nick
2013-07-24 12:03:24 +01:00
parent f8fd4e0437
commit efe9eaef7c
1 changed files with 21 additions and 17 deletions
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32
src/bitset.h
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@@ -75,29 +75,33 @@ static inline void bit_clear_range(char* b, uint64_t from, uint64_t len)
* bits that are the same as the first one specified. * bits that are the same as the first one specified.
*/ */
static inline int bit_run_count(char* b, uint64_t from, uint64_t len) { static inline int bit_run_count(char* b, uint64_t from, uint64_t len) {
uint64_t count; uint64_t* current_block;
uint64_t count = 0;
int first_value = bit_is_set(b, from); int first_value = bit_is_set(b, from);
for (count=0; len > 0 && bit_has_value(b, from+count, first_value); count++, len--) for ( ; (from+count) % 64 != 0 && len > 0; len--) {
; if (bit_has_value(b, from+count, first_value)) {
/* FIXME: debug this later */
/*
for (; (from+count) % 64 != 0 && len > 0; len--)
if (bit_has_value(b, from+count, first_value))
count++; count++;
else } else {
return count; return count;
}
}
for ( ; len >= 64 ; len -= 64 ) { for ( ; len >= 64 ; len -= 64 ) {
if (*((uint64_t*)(b + ((from+count)/8))) == UINT64_MAX) current_block = (uint64_t*) (b + ((from+count)/8));
if (*current_block == ( first_value ? UINT64_MAX : 0 ) ) {
count += 64; count += 64;
else } else {
break; break;
} }
for (; len > 0; len--) }
if (bit_is_set(b, from+count))
for ( ; len > 0; len-- ) {
if ( bit_has_value(b, from+count, first_value) ) {
count++; count++;
*/ }
}
return count; return count;
} }