static void hash_search(int f,struct sum_struct *s,
			struct map_struct *buf, OFF_T len)
{
	OFF_T offset, aligned_offset, end;
	int32 k, want_i, aligned_i, backup;
	char sum2[SUM_LENGTH];
	uint32 s1, s2, sum;
	int more;
	schar *map;

	/* want_i is used to encourage adjacent matches, allowing the RLL
	 * coding of the output to work more efficiently. */
	want_i = 0;

	if (verbose > 2) {
		rprintf(FINFO, "hash search b=%ld len=%.0f\n",
			(long)s->blength, (double)len);
	}

	k = (int32)MIN(len, (OFF_T)s->blength);

	map = (schar *)map_ptr(buf, 0, k);

	sum = get_checksum1((char *)map, k);
	s1 = sum & 0xFFFF;
	s2 = sum >> 16;
	if (verbose > 3)
		rprintf(FINFO, "sum=%.8x k=%ld\n", sum, (long)k);

	offset = aligned_offset = aligned_i = 0;

	end = len + 1 - s->sums[s->count-1].len;

	if (verbose > 3) {
		rprintf(FINFO, "hash search s->blength=%ld len=%.0f count=%.0f\n",
			(long)s->blength, (double)len, (double)s->count);
	}

	do {
		int done_csum2 = 0;
		int32 i;

		if (verbose > 4) {
			rprintf(FINFO, "offset=%.0f sum=%04x%04x\n",
				(double)offset, s2 & 0xFFFF, s1 & 0xFFFF);
		}

		if (tablesize == TRADITIONAL_TABLESIZE) {
			if ((i = hash_table[SUM2HASH2(s1,s2)]) < 0)
				goto null_hash;
			sum = (s1 & 0xffff) | (s2 << 16);
		} else {
			sum = (s1 & 0xffff) | (s2 << 16);
			if ((i = hash_table[BIG_SUM2HASH(sum)]) < 0)
				goto null_hash;
		}

		hash_hits++;
		do {
			int32 l;

			if (sum != s->sums[i].sum1)
				continue;

			/* also make sure the two blocks are the same length */
			l = (int32)MIN((OFF_T)s->blength, len-offset);
			if (l != s->sums[i].len)
				continue;

			/* in-place: ensure chunk's offset is either >= our
			 * offset or that the data didn't move. */
			if (updating_basis_file && s->sums[i].offset < offset
			    && !(s->sums[i].flags & SUMFLG_SAME_OFFSET))
				continue;

			if (verbose > 3) {
				rprintf(FINFO,
					"potential match at %.0f i=%ld sum=%08x\n",
					(double)offset, (long)i, sum);
			}

			if (!done_csum2) {
				map = (schar *)map_ptr(buf,offset,l);
				get_checksum2((char *)map,l,sum2);
				done_csum2 = 1;
			}

			if (memcmp(sum2,s->sums[i].sum2,s->s2length) != 0) {
				false_alarms++;
				continue;
			}

			/* When updating in-place, the best possible match is
			 * one with an identical offset, so we prefer that over
			 * the adjacent want_i optimization. */
			if (updating_basis_file) {
				/* All the generator's chunks start at blength boundaries. */
				while (aligned_offset < offset) {
					aligned_offset += s->blength;
					aligned_i++;
				}
				if (offset == aligned_offset) {
					if (i != aligned_i) {
						if (sum != s->sums[aligned_i].sum1
						 || l != s->sums[aligned_i].len
						 || memcmp(sum2, s->sums[aligned_i].sum2, s->s2length) != 0)
							goto check_want_i;
						i = aligned_i;
					}
					/* This identical chunk is in the same spot in the old and new file. */
					s->sums[i].flags |= SUMFLG_SAME_OFFSET;
					want_i = i;
				}
			}

		  check_want_i:
			/* we've found a match, but now check to see
			 * if want_i can hint at a better match. */
			if (i != want_i && want_i < s->count
			    && (!updating_basis_file || s->sums[want_i].offset >= offset
			     || s->sums[want_i].flags & SUMFLG_SAME_OFFSET)
			    && sum == s->sums[want_i].sum1
			    && memcmp(sum2, s->sums[want_i].sum2, s->s2length) == 0) {
				/* we've found an adjacent match - the RLL coder
				 * will be happy */
				i = want_i;
			}
			want_i = i + 1;

			matched(f,s,buf,offset,i);
			offset += s->sums[i].len - 1;
			k = (int32)MIN((OFF_T)s->blength, len-offset);
			map = (schar *)map_ptr(buf, offset, k);
			sum = get_checksum1((char *)map, k);
			s1 = sum & 0xFFFF;
			s2 = sum >> 16;
			matches++;
			break;
		} while ((i = s->sums[i].chain) >= 0);

	  null_hash:
		backup = (int32)(offset - last_match);
		/* We sometimes read 1 byte prior to last_match... */
		if (backup < 0)
			backup = 0;

		/* Trim off the first byte from the checksum */
		more = offset + k < len;
		map = (schar *)map_ptr(buf, offset - backup, k + more + backup)
		    + backup;
		s1 -= map[0] + CHAR_OFFSET;
		s2 -= k * (map[0]+CHAR_OFFSET);

		/* Add on the next byte (if there is one) to the checksum */
		if (more) {
			s1 += map[k] + CHAR_OFFSET;
			s2 += s1;
		} else
			--k;

		/* By matching early we avoid re-reading the
		   data 3 times in the case where a token
		   match comes a long way after last
		   match. The 3 reads are caused by the
		   running match, the checksum update and the
		   literal send. */
		if (backup >= s->blength+CHUNK_SIZE && end-offset > CHUNK_SIZE)
			matched(f, s, buf, offset - s->blength, -2);
	} while (++offset < end);

	matched(f, s, buf, len, -1);
	map_ptr(buf, len-1, 1);
}
static void hash_search(int f,struct sum_struct *s,
			struct map_struct *buf, OFF_T len)
{
	OFF_T offset, aligned_offset, end;
	int32 k, want_i, aligned_i, backup;
	char sum2[SUM_LENGTH];
	uint32 s1, s2, sum;
	int more;
	schar *map;

	 
	want_i = 0;

	if (verbose > 2) {
		rprintf(FINFO, "hash search b=%ld len=%.0f\n",
			(long)s->blength, (double)len);
	}

	k = (int32)MIN(len, (OFF_T)s->blength);

	map = (schar *)map_ptr(buf, 0, k);

	sum = get_checksum1((char *)map, k);
	s1 = sum & 0xFFFF;
	s2 = sum >> 16;
	if (verbose > 3)
		rprintf(FINFO, "sum=%.8x k=%ld\n", sum, (long)k);

	offset = aligned_offset = aligned_i = 0;

	end = len + 1 - s->sums[s->count-1].len;

	if (verbose > 3) {
		rprintf(FINFO, "hash search s->blength=%ld len=%.0f count=%.0f\n",
			(long)s->blength, (double)len, (double)s->count);
	}

	do {
		int done_csum2 = 0;
		int32 i;

		if (verbose > 4) {
			rprintf(FINFO, "offset=%.0f sum=%04x%04x\n",
				(double)offset, s2 & 0xFFFF, s1 & 0xFFFF);
		}

		if (tablesize == TRADITIONAL_TABLESIZE) {
			if ((i = hash_table[SUM2HASH2(s1,s2)]) < 0)
				goto null_hash;
			sum = (s1 & 0xffff) | (s2 << 16);
		} else {
			sum = (s1 & 0xffff) | (s2 << 16);
			if ((i = hash_table[BIG_SUM2HASH(sum)]) < 0)
				goto null_hash;
		}

		hash_hits++;
		do {
			int32 l;

			if (sum != s->sums[i].sum1)
				continue;

			 
			l = (int32)MIN((OFF_T)s->blength, len-offset);
			if (l != s->sums[i].len)
				continue;

			 
			if (updating_basis_file && s->sums[i].offset < offset
			    && !(s->sums[i].flags & SUMFLG_SAME_OFFSET))
				continue;

			if (verbose > 3) {
				rprintf(FINFO,
					"potential match at %.0f i=%ld sum=%08x\n",
					(double)offset, (long)i, sum);
			}

			if (!done_csum2) {
				map = (schar *)map_ptr(buf,offset,l);
				get_checksum2((char *)map,l,sum2);
				done_csum2 = 1;
			}

			if (memcmp(sum2,s->sums[i].sum2,s->s2length) != 0) {
				false_alarms++;
				continue;
			}

			 
			if (updating_basis_file) {
				 
				while (aligned_offset < offset) {
					aligned_offset += s->blength;
					aligned_i++;
				}
				if (offset == aligned_offset) {
					if (i != aligned_i) {
						if (sum != s->sums[aligned_i].sum1
						 || l != s->sums[aligned_i].len
						 || memcmp(sum2, s->sums[aligned_i].sum2, s->s2length) != 0)
							goto check_want_i;
						i = aligned_i;
					}
					 
					s->sums[i].flags |= SUMFLG_SAME_OFFSET;
					want_i = i;
				}
			}

		  check_want_i:
			 
			if (i != want_i && want_i < s->count
			    && (!updating_basis_file || s->sums[want_i].offset >= offset
			     || s->sums[want_i].flags & SUMFLG_SAME_OFFSET)
			    && sum == s->sums[want_i].sum1
			    && memcmp(sum2, s->sums[want_i].sum2, s->s2length) == 0) {
				 
				i = want_i;
			}
			want_i = i + 1;

			matched(f,s,buf,offset,i);
			offset += s->sums[i].len - 1;
			k = (int32)MIN((OFF_T)s->blength, len-offset);
			map = (schar *)map_ptr(buf, offset, k);
			sum = get_checksum1((char *)map, k);
			s1 = sum & 0xFFFF;
			s2 = sum >> 16;
			matches++;
			break;
		} while ((i = s->sums[i].chain) >= 0);

	  null_hash:
		backup = (int32)(offset - last_match);
		 
		if (backup < 0)
			backup = 0;

		 
		more = offset + k < len;
		map = (schar *)map_ptr(buf, offset - backup, k + more + backup)
		    + backup;
		s1 -= map[0] + CHAR_OFFSET;
		s2 -= k * (map[0]+CHAR_OFFSET);

		 
		if (more) {
			s1 += map[k] + CHAR_OFFSET;
			s2 += s1;
		} else
			--k;

		 
		if (backup >= s->blength+CHUNK_SIZE && end-offset > CHUNK_SIZE)
			matched(f, s, buf, offset - s->blength, -2);
	} while (++offset < end);

	matched(f, s, buf, len, -1);
	map_ptr(buf, len-1, 1);
}