In choose-by-bw, scale to better use the range of uint64

The smart part of this is based on an approach and a suggestion by
rransom. The unsmart part is my own fault.

1 files changed, 11 insertions, 2 deletions

diff --git a/src/or/routerlist.h b/src/or/routerlist.h
index 0b9b297514..2072611897 100644
--- a/src/or/routerlist.h
+++ b/src/or/routerlist.h
@@ -217,8 +217,17 @@ int hex_digest_nickname_decode(const char *hexdigest,
                                char *nickname_out);
 
 #ifdef ROUTERLIST_PRIVATE
-int choose_array_element_by_weight(const uint64_t *entries, int n_entries,
-                                   uint64_t *total_out);
+/** Helper type for choosing routers by bandwidth: contains a union of
+ * double and uint64_t. Before we call scale_array_elements_to_u64, it holds
+ * a double; after, it holds a uint64_t. */
+typedef union u64_dbl_t {
+  uint64_t u64;
+  double dbl;
+} u64_dbl_t;
+
+int choose_array_element_by_weight(const u64_dbl_t *entries, int n_entries);
+void scale_array_elements_to_u64(u64_dbl_t *entries, int n_entries,
+                                 uint64_t *total_out);
 #endif
 
 #endif