diffcore_count_changes: pass diffcore_filespec

We may want to use richer information on the data we are dealing
with in this function, so instead of passing a buffer address
and length, just pass the diffcore_filespec structure.  Existing
callers always call this function with parameters taken from a
filespec anyway, so there is no functionality changes.

Signed-off-by: Junio C Hamano <gitster@pobox.com>

diffcore-break.c

@@ -66,8 +66,7 @@ static int should_break(struct diff_filespec *src,
 	if (base_size < MINIMUM_BREAK_SIZE)
 		return 0; /* we do not break too small filepair */
 
-	if (diffcore_count_changes(src->data, src->size,
-				   dst->data, dst->size,
+	if (diffcore_count_changes(src, dst,
 				   NULL, NULL,
 				   0,
 				   &src_copied, &literal_added))

diffcore-delta.c

@@ -156,8 +156,8 @@ static struct spanhash_top *hash_chars(unsigned char *buf, unsigned int sz)
 	return hash;
 }
 
-int diffcore_count_changes(void *src, unsigned long src_size,
-			   void *dst, unsigned long dst_size,
+int diffcore_count_changes(struct diff_filespec *src,
+			   struct diff_filespec *dst,
 			   void **src_count_p,
 			   void **dst_count_p,
 			   unsigned long delta_limit,
@@ -172,14 +172,14 @@ int diffcore_count_changes(void *src, unsigned long src_size,
 	if (src_count_p)
 		src_count = *src_count_p;
 	if (!src_count) {
-		src_count = hash_chars(src, src_size);
+		src_count = hash_chars(src->data, src->size);
 		if (src_count_p)
 			*src_count_p = src_count;
 	}
 	if (dst_count_p)
 		dst_count = *dst_count_p;
 	if (!dst_count) {
-		dst_count = hash_chars(dst, dst_size);
+		dst_count = hash_chars(dst->data, dst->size);
 		if (dst_count_p)
 			*dst_count_p = dst_count;
 	}

diffcore-rename.c

@@ -189,8 +189,7 @@ static int estimate_similarity(struct diff_filespec *src,
 
 	delta_limit = (unsigned long)
 		(base_size * (MAX_SCORE-minimum_score) / MAX_SCORE);
-	if (diffcore_count_changes(src->data, src->size,
-				   dst->data, dst->size,
+	if (diffcore_count_changes(src, dst,
 				   &src->cnt_data, &dst->cnt_data,
 				   delta_limit,
 				   &src_copied, &literal_added))

diffcore.h

@@ -103,8 +103,8 @@ void diff_debug_queue(const char *, struct diff_queue_struct *);
 #define diff_debug_queue(a,b) do {} while(0)
 #endif
 
-extern int diffcore_count_changes(void *src, unsigned long src_size,
-				  void *dst, unsigned long dst_size,
+extern int diffcore_count_changes(struct diff_filespec *src,
+				  struct diff_filespec *dst,
 				  void **src_count_p,
 				  void **dst_count_p,
 				  unsigned long delta_limit,