X-Git-Url: https://git.tokkee.org/?a=blobdiff_plain;f=diff-delta.c;h=a4e28df714b4834e5efe42fa3abb647711913d71;hb=bba0fd22ad654460a81c4b35462b600d9432a869;hp=7f8a60de18584fa18dba71a454a6f2300674f47f;hpb=d2100860fd67dec6474157697888caaa0a0f51d0;p=git.git

diff --git a/diff-delta.c b/diff-delta.c
index 7f8a60de1..a4e28df71 100644
--- a/diff-delta.c
+++ b/diff-delta.c
@@ -207,31 +207,52 @@ struct delta_index * create_delta_index(const void *buf, unsigned long bufsize)
 	 * the reference buffer.
 	 */
 	for (i = 0; i < hsize; i++) {
-		if (hash_count[i] < HASH_LIMIT)
+		int acc;
+
+		if (hash_count[i] <= HASH_LIMIT)
 			continue;
+
+		/* We leave exactly HASH_LIMIT entries in the bucket */
+		entries -= hash_count[i] - HASH_LIMIT;
+
 		entry = hash[i];
+		acc = 0;
+
+		/*
+		 * Assume that this loop is gone through exactly
+		 * HASH_LIMIT times and is entered and left with
+		 * acc==0.  So the first statement in the loop
+		 * contributes (hash_count[i]-HASH_LIMIT)*HASH_LIMIT
+		 * to the accumulator, and the inner loop consequently
+		 * is run (hash_count[i]-HASH_LIMIT) times, removing
+		 * one element from the list each time.  Since acc
+		 * balances out to 0 at the final run, the inner loop
+		 * body can't be left with entry==NULL.  So we indeed
+		 * encounter entry==NULL in the outer loop only.
+		 */
 		do {
-			struct unpacked_index_entry *keep = entry;
-			int skip = hash_count[i] / HASH_LIMIT;
-			do {
-				--entries;
-				entry = entry->next;
-			} while(--skip && entry);
-			++entries;
-			keep->next = entry;
-		} while(entry);
+			acc += hash_count[i] - HASH_LIMIT;
+			if (acc > 0) {
+				struct unpacked_index_entry *keep = entry;
+				do {
+					entry = entry->next;
+					acc -= HASH_LIMIT;
+				} while (acc > 0);
+				keep->next = entry->next;
+			}
+			entry = entry->next;
+		} while (entry);
 	}
 	free(hash_count);
 
-	/* Now create the packed index in array form rather than
-	 * linked lists */
-
+	/*
+	 * Now create the packed index in array form
+	 * rather than linked lists.
+	 */
 	memsize = sizeof(*index)
 		+ sizeof(*packed_hash) * (hsize+1)
 		+ sizeof(*packed_entry) * entries;
-
 	mem = malloc(memsize);
-
 	if (!mem) {
 		free(hash);
 		return NULL;
@@ -243,24 +264,24 @@ struct delta_index * create_delta_index(const void *buf, unsigned long bufsize)
 	index->src_size = bufsize;
 	index->hash_mask = hmask;
 
-	mem = index + 1;
+	mem = index->hash;
 	packed_hash = mem;
 	mem = packed_hash + (hsize+1);
 	packed_entry = mem;
 
-	/* Coalesce all entries belonging to one linked list into
-	 * consecutive array entries */
-
 	for (i = 0; i < hsize; i++) {
+		/*
+		 * Coalesce all entries belonging to one linked list
+		 * into consecutive array entries.
+		 */
 		packed_hash[i] = packed_entry;
 		for (entry = hash[i]; entry; entry = entry->next)
 			*packed_entry++ = entry->entry;
 	}
 
-	/* Sentinel value to indicate the length of the last hash
-	 * bucket */
-
+	/* Sentinel value to indicate the length of the last hash bucket */
 	packed_hash[hsize] = packed_entry;
+
 	assert(packed_entry - (struct index_entry *)mem == entries);
 	free(hash);