*
*/
+#include <limits.h>
+#include <assert.h>
#include "xinclude.h"
return ha;
}
+#ifdef XDL_FAST_HASH
+
+#define ONEBYTES 0x0101010101010101ul
+#define NEWLINEBYTES 0x0a0a0a0a0a0a0a0aul
+#define HIGHBITS 0x8080808080808080ul
+
+/* Return the high bit set in the first byte that is a zero */
+static inline unsigned long has_zero(unsigned long a)
+{
+ return ((a - ONEBYTES) & ~a) & HIGHBITS;
+}
+
+static inline long count_masked_bytes(unsigned long mask)
+{
+ if (sizeof(long) == 8) {
+ /*
+ * Jan Achrenius on G+: microoptimized version of
+ * the simpler "(mask & ONEBYTES) * ONEBYTES >> 56"
+ * that works for the bytemasks without having to
+ * mask them first.
+ */
+ return mask * 0x0001020304050608 >> 56;
+ } else {
+ /*
+ * Modified Carl Chatfield G+ version for 32-bit *
+ *
+ * (a) gives us
+ * -1 (0, ff), 0 (ffff) or 1 (ffffff)
+ * (b) gives us
+ * 0 for 0, 1 for (ff ffff ffffff)
+ * (a+b+1) gives us
+ * correct 0-3 bytemask count result
+ */
+ long a = (mask - 256) >> 23;
+ long b = mask & 1;
+ return a + b + 1;
+ }
+}
+
+unsigned long xdl_hash_record(char const **data, char const *top, long flags)
+{
+ unsigned long hash = 5381;
+ unsigned long a = 0, mask = 0;
+ char const *ptr = *data;
+ char const *end = top - sizeof(unsigned long) + 1;
+
+ if (flags & XDF_WHITESPACE_FLAGS)
+ return xdl_hash_record_with_whitespace(data, top, flags);
+
+ ptr -= sizeof(unsigned long);
+ do {
+ hash += hash << 5;
+ hash ^= a;
+ ptr += sizeof(unsigned long);
+ if (ptr >= end)
+ break;
+ a = *(unsigned long *)ptr;
+ /* Do we have any '\n' bytes in this word? */
+ mask = has_zero(a ^ NEWLINEBYTES);
+ } while (!mask);
+
+ if (ptr >= end) {
+ /*
+ * There is only a partial word left at the end of the
+ * buffer. Because we may work with a memory mapping,
+ * we have to grab the rest byte by byte instead of
+ * blindly reading it.
+ *
+ * To avoid problems with masking in a signed value,
+ * we use an unsigned char here.
+ */
+ const char *p;
+ for (p = top - 1; p >= ptr; p--)
+ a = (a << 8) + *((const unsigned char *)p);
+ mask = has_zero(a ^ NEWLINEBYTES);
+ if (!mask)
+ /*
+ * No '\n' found in the partial word. Make a
+ * mask that matches what we read.
+ */
+ mask = 1UL << (8 * (top - ptr) + 7);
+ }
+
+ /* The mask *below* the first high bit set */
+ mask = (mask - 1) & ~mask;
+ mask >>= 7;
+ hash += hash << 5;
+ hash ^= a & mask;
+
+ /* Advance past the last (possibly partial) word */
+ ptr += count_masked_bytes(mask);
+
+ if (ptr < top) {
+ assert(*ptr == '\n');
+ ptr++;
+ }
+
+ *data = ptr;
+
+ return hash;
+}
+
+#else /* XDL_FAST_HASH */
unsigned long xdl_hash_record(char const **data, char const *top, long flags) {
unsigned long ha = 5381;
return ha;
}
+#endif /* XDL_FAST_HASH */
unsigned int xdl_hashbits(unsigned int size) {
unsigned int val = 1, bits = 0;