hash-lookup: rename from sha1-lookup

Change all remnants of "sha1" in hash-lookup.c and .h and rename them to
reflect that we're not just able to handle SHA-1 these days.

Signed-off-by: Martin Ågren <martin.agren@gmail.com>
Reviewed-by: Derrick Stolee <dstolee@microsoft.com>
Signed-off-by: Junio C Hamano <gitster@pobox.com>

hash-lookup.h

@@ -0,0 +1,32 @@
+#ifndef HASH_LOOKUP_H
+#define HASH_LOOKUP_H
+
+typedef const unsigned char *hash_access_fn(size_t index, void *table);
+
+int hash_pos(const unsigned char *hash,
+	     void *table,
+	     size_t nr,
+	     hash_access_fn fn);
+
+/*
+ * Searches for hash in table, using the given fanout table to determine the
+ * interval to search, then using binary search. Returns 1 if found, 0 if not.
+ *
+ * Takes the following parameters:
+ *
+ *  - hash: the hash to search for
+ *  - fanout_nbo: a 256-element array of NETWORK-order 32-bit integers; the
+ *    integer at position i represents the number of elements in table whose
+ *    first byte is less than or equal to i
+ *  - table: a sorted list of hashes with optional extra information in between
+ *  - stride: distance between two consecutive elements in table (should be
+ *    GIT_MAX_RAWSZ or greater)
+ *  - result: if not NULL, this function stores the element index of the
+ *    position found (if the search is successful) or the index of the least
+ *    element that is greater than hash (if the search is not successful)
+ *
+ * This function does not verify the validity of the fanout table.
+ */
+int bsearch_hash(const unsigned char *hash, const uint32_t *fanout_nbo,
+		 const unsigned char *table, size_t stride, uint32_t *result);
+#endif